GDAL
Classes | Macros | Typedefs | Enumerations | Functions
cpl_vsi.h File Reference

Standard C Covers. More...

#include "cpl_port.h"
#include "cpl_progress.h"
#include <stdbool.h>
#include <unistd.h>
#include <sys/stat.h>

Go to the source code of this file.

Classes

struct  VSIDIREntry
 Directory entry. More...
 
struct  VSIFilesystemPluginCallbacksStruct
 struct containing callbacks to used by the handler. More...
 

Macros

#define VSI_ISLNK(x)   S_ISLNK(x)
 Test if the file is a symbolic link.
 
#define VSI_ISREG(x)   S_ISREG(x)
 Test if the file is a regular file.
 
#define VSI_ISDIR(x)   S_ISDIR(x)
 Test if the file is a directory.
 
#define VSI_L_OFFSET_MAX   GUINTBIG_MAX
 Maximum value for a file offset.
 
#define VSIStatBufL   VSIStatBuf
 Type for VSIStatL()
 
#define VSI_STAT_EXISTS_FLAG   0x1
 Flag provided to VSIStatExL() to test if the file exists.
 
#define VSI_STAT_NATURE_FLAG   0x2
 Flag provided to VSIStatExL() to query the nature (file/dir) of the file.
 
#define VSI_STAT_SIZE_FLAG   0x4
 Flag provided to VSIStatExL() to query the file size.
 
#define VSI_STAT_SET_ERROR_FLAG   0x8
 Flag provided to VSIStatExL() to issue a VSIError in case of failure.
 
#define VSI_STAT_CACHE_ONLY   0x10
 Flag provided to VSIStatExL() to only use already cached results. More...
 
#define VSI_MALLOC_ALIGNED_AUTO_VERBOSE(size)   VSIMallocAlignedAutoVerbose(size,__FILE__,__LINE__)
 VSIMallocAlignedAutoVerbose() with FILE and LINE reporting.
 
#define VSI_MALLOC_VERBOSE(size)   VSIMallocVerbose(size,__FILE__,__LINE__)
 VSI_MALLOC_VERBOSE.
 
#define VSI_MALLOC2_VERBOSE(nSize1, nSize2)   VSIMalloc2Verbose(nSize1,nSize2,__FILE__,__LINE__)
 VSI_MALLOC2_VERBOSE.
 
#define VSI_MALLOC3_VERBOSE(nSize1, nSize2, nSize3)   VSIMalloc3Verbose(nSize1,nSize2,nSize3,__FILE__,__LINE__)
 VSI_MALLOC3_VERBOSE.
 
#define VSI_CALLOC_VERBOSE(nCount, nSize)   VSICallocVerbose(nCount,nSize,__FILE__,__LINE__)
 VSI_CALLOC_VERBOSE.
 
#define VSI_REALLOC_VERBOSE(pOldPtr, nNewSize)   VSIReallocVerbose(pOldPtr,nNewSize,__FILE__,__LINE__)
 VSI_REALLOC_VERBOSE.
 
#define VSI_STRDUP_VERBOSE(pszStr)   VSIStrdupVerbose(pszStr,__FILE__,__LINE__)
 VSI_STRDUP_VERBOSE.
 
#define CPLReadDir   VSIReadDir
 Alias of VSIReadDir()
 

Typedefs

typedef GUIntBig vsi_l_offset
 Type for a file offset.
 
typedef FILE VSILFILE
 Opaque type for a FILE that implements the VSIVirtualHandle API.
 
typedef struct VSIDIR VSIDIR
 Opaque type for a directory iterator.
 
typedef size_t(* VSIWriteFunction) (const void *ptr, size_t size, size_t nmemb, FILE *stream)
 Callback used by VSIStdoutSetRedirection()
 
typedef int(* VSIFilesystemPluginStatCallback) (void *pUserData, const char *pszFilename, VSIStatBufL *pStatBuf, int nFlags)
 Return information about a handle. More...
 
typedef int(* VSIFilesystemPluginUnlinkCallback) (void *pUserData, const char *pszFilename)
 Remove handle by name. More...
 
typedef int(* VSIFilesystemPluginRenameCallback) (void *pUserData, const char *oldpath, const char *newpath)
 Rename handle. More...
 
typedef int(* VSIFilesystemPluginMkdirCallback) (void *pUserData, const char *pszDirname, long nMode)
 Create Directory. More...
 
typedef int(* VSIFilesystemPluginRmdirCallback) (void *pUserData, const char *pszDirname)
 Delete Directory. More...
 
typedef char **(* VSIFilesystemPluginReadDirCallback) (void *pUserData, const char *pszDirname, int nMaxFiles)
 List directory content. More...
 
typedef char **(* VSIFilesystemPluginSiblingFilesCallback) (void *pUserData, const char *pszDirname)
 List related files. More...
 
typedef void *(* VSIFilesystemPluginOpenCallback) (void *pUserData, const char *pszFilename, const char *pszAccess)
 Open a handle. More...
 
typedef vsi_l_offset(* VSIFilesystemPluginTellCallback) (void *pFile)
 Return current position in handle. More...
 
typedef int(* VSIFilesystemPluginSeekCallback) (void *pFile, vsi_l_offset nOffset, int nWhence)
 Seek to position in handle. More...
 
typedef size_t(* VSIFilesystemPluginReadCallback) (void *pFile, void *pBuffer, size_t nSize, size_t nCount)
 Read data from current position, returns the number of blocks correctly read. More...
 
typedef int(* VSIFilesystemPluginReadMultiRangeCallback) (void *pFile, int nRanges, void **ppData, const vsi_l_offset *panOffsets, const size_t *panSizes)
 Read from multiple offsets. More...
 
typedef VSIRangeStatus(* VSIFilesystemPluginGetRangeStatusCallback) (void *pFile, vsi_l_offset nOffset, vsi_l_offset nLength)
 Get empty ranges. More...
 
typedef int(* VSIFilesystemPluginEofCallback) (void *pFile)
 Has end of file been reached. More...
 
typedef size_t(* VSIFilesystemPluginWriteCallback) (void *pFile, const void *pBuffer, size_t nSize, size_t nCount)
 Write bytes at current offset. More...
 
typedef int(* VSIFilesystemPluginFlushCallback) (void *pFile)
 Sync written bytes. More...
 
typedef int(* VSIFilesystemPluginTruncateCallback) (void *pFile, vsi_l_offset nNewSize)
 Truncate handle. More...
 
typedef int(* VSIFilesystemPluginCloseCallback) (void *pFile)
 Close file handle. More...
 

Enumerations

enum  VSIRangeStatus { VSI_RANGE_STATUS_UNKNOWN , VSI_RANGE_STATUS_DATA , VSI_RANGE_STATUS_HOLE }
 Range status. More...
 

Functions

VSILFILEVSIFOpenL (const char *, const char *)
 Open file. More...
 
VSILFILEVSIFOpenExL (const char *, const char *, int)
 Open file. More...
 
VSILFILEVSIFOpenEx2L (const char *, const char *, int, CSLConstList)
 Open file. More...
 
int VSIFCloseL (VSILFILE *)
 Close file. More...
 
int VSIFSeekL (VSILFILE *, vsi_l_offset, int)
 Seek to requested offset. More...
 
vsi_l_offset VSIFTellL (VSILFILE *)
 Tell current file offset. More...
 
void VSIRewindL (VSILFILE *)
 Rewind the file pointer to the beginning of the file. More...
 
size_t VSIFReadL (void *, size_t, size_t, VSILFILE *)
 Read bytes from file. More...
 
int VSIFReadMultiRangeL (int nRanges, void **ppData, const vsi_l_offset *panOffsets, const size_t *panSizes, VSILFILE *)
 Read several ranges of bytes from file. More...
 
size_t VSIFWriteL (const void *, size_t, size_t, VSILFILE *)
 Write bytes to file. More...
 
int VSIFEofL (VSILFILE *)
 Test for end of file. More...
 
int VSIFTruncateL (VSILFILE *, vsi_l_offset)
 Truncate/expand the file to the specified size. More...
 
int VSIFFlushL (VSILFILE *)
 Flush pending writes to disk. More...
 
int VSIFPrintfL (VSILFILE *, const char *,...)
 Formatted write to file. More...
 
int VSIFPutcL (int, VSILFILE *)
 Write a single byte to the file. More...
 
VSIRangeStatus VSIFGetRangeStatusL (VSILFILE *fp, vsi_l_offset nStart, vsi_l_offset nLength)
 Return if a given file range contains data or holes filled with zeroes. More...
 
int VSIIngestFile (VSILFILE *fp, const char *pszFilename, GByte **ppabyRet, vsi_l_offset *pnSize, GIntBig nMaxSize)
 Ingest a file into memory. More...
 
int VSIOverwriteFile (VSILFILE *fpTarget, const char *pszSourceFilename)
 Overwrite an existing file with content from another one. More...
 
int VSIStatL (const char *, VSIStatBufL *)
 Get filesystem object info. More...
 
int VSIStatExL (const char *pszFilename, VSIStatBufL *psStatBuf, int nFlags)
 Get filesystem object info. More...
 
int VSIIsCaseSensitiveFS (const char *pszFilename)
 Returns if the filenames of the filesystem are case sensitive. More...
 
int VSISupportsSparseFiles (const char *pszPath)
 Returns if the filesystem supports sparse files. More...
 
bool VSIIsLocal (const char *pszPath)
 Returns if the file/filesystem is "local". More...
 
bool VSISupportsSequentialWrite (const char *pszPath, bool bAllowLocalTempFile)
 Returns if the filesystem supports sequential write. More...
 
bool VSISupportsRandomWrite (const char *pszPath, bool bAllowLocalTempFile)
 Returns if the filesystem supports random write. More...
 
int VSIHasOptimizedReadMultiRange (const char *pszPath)
 Returns if the filesystem supports efficient multi-range reading. More...
 
const char * VSIGetActualURL (const char *pszFilename)
 Returns the actual URL of a supplied filename. More...
 
char * VSIGetSignedURL (const char *pszFilename, CSLConstList papszOptions)
 Returns a signed URL of a supplied filename. More...
 
const char * VSIGetFileSystemOptions (const char *pszFilename)
 Return the list of options associated with a virtual file system handler as a serialized XML string. More...
 
char ** VSIGetFileSystemsPrefixes (void)
 Return the list of prefixes for virtual file system handlers currently registered. More...
 
void * VSIFGetNativeFileDescriptorL (VSILFILE *)
 Returns the "native" file descriptor for the virtual handle. More...
 
char ** VSIGetFileMetadata (const char *pszFilename, const char *pszDomain, CSLConstList papszOptions)
 Get metadata on files. More...
 
int VSISetFileMetadata (const char *pszFilename, CSLConstList papszMetadata, const char *pszDomain, CSLConstList papszOptions)
 Set metadata on files. More...
 
void VSISetCredential (const char *pszPathPrefix, const char *pszKey, const char *pszValue)
 Set a credential (or more generally an option related to a virtual file system) for a given path prefix. More...
 
void VSIClearCredentials (const char *pszPathPrefix)
 Clear credentials set with VSISetCredential() More...
 
const char * VSIGetCredential (const char *pszPath, const char *pszKey, const char *pszDefault)
 Get a credential option for a given path. More...
 
void * VSICalloc (size_t, size_t)
 Analog of calloc(). More...
 
void * VSIMalloc (size_t)
 Analog of malloc(). More...
 
void VSIFree (void *)
 Analog of free() for data allocated with VSIMalloc(), VSICalloc(), VSIRealloc()
 
void * VSIRealloc (void *, size_t)
 Analog of realloc(). More...
 
char * VSIStrdup (const char *)
 Analog of strdup(). More...
 
void * VSIMallocAligned (size_t nAlignment, size_t nSize)
 Allocates a buffer with an alignment constraint. More...
 
void * VSIMallocAlignedAuto (size_t nSize)
 Allocates a buffer with an alignment constraint such that it can be used by the most demanding vector instruction set on that platform. More...
 
void VSIFreeAligned (void *ptr)
 Free a buffer allocated with VSIMallocAligned(). More...
 
void * VSIMallocAlignedAutoVerbose (size_t nSize, const char *pszFile, int nLine)
 See VSIMallocAlignedAuto()
 
void * VSIMalloc2 (size_t nSize1, size_t nSize2)
 VSIMalloc2 allocates (nSize1 * nSize2) bytes. More...
 
void * VSIMalloc3 (size_t nSize1, size_t nSize2, size_t nSize3)
 VSIMalloc3 allocates (nSize1 * nSize2 * nSize3) bytes. More...
 
void * VSIMallocVerbose (size_t nSize, const char *pszFile, int nLine)
 VSIMallocVerbose.
 
void * VSIMalloc2Verbose (size_t nSize1, size_t nSize2, const char *pszFile, int nLine)
 VSIMalloc2Verbose.
 
void * VSIMalloc3Verbose (size_t nSize1, size_t nSize2, size_t nSize3, const char *pszFile, int nLine)
 VSIMalloc3Verbose.
 
void * VSICallocVerbose (size_t nCount, size_t nSize, const char *pszFile, int nLine)
 VSICallocVerbose.
 
void * VSIReallocVerbose (void *pOldPtr, size_t nNewSize, const char *pszFile, int nLine)
 VSIReallocVerbose.
 
char * VSIStrdupVerbose (const char *pszStr, const char *pszFile, int nLine)
 VSIStrdupVerbose.
 
GIntBig CPLGetPhysicalRAM (void)
 Return the total physical RAM in bytes. More...
 
GIntBig CPLGetUsablePhysicalRAM (void)
 Return the total physical RAM, usable by a process, in bytes. More...
 
char ** VSIReadDir (const char *)
 Read names in a directory. More...
 
char ** VSIReadDirRecursive (const char *pszPath)
 Read names in a directory recursively. More...
 
char ** VSIReadDirEx (const char *pszPath, int nMaxFiles)
 Read names in a directory. More...
 
char ** VSISiblingFiles (const char *pszPath)
 Return related filenames. More...
 
VSIDIRVSIOpenDir (const char *pszPath, int nRecurseDepth, const char *const *papszOptions)
 Open a directory to read its entries. More...
 
const VSIDIREntryVSIGetNextDirEntry (VSIDIR *dir)
 Return the next entry of the directory. More...
 
void VSICloseDir (VSIDIR *dir)
 Close a directory. More...
 
int VSIMkdir (const char *pszPathname, long mode)
 Create a directory. More...
 
int VSIMkdirRecursive (const char *pszPathname, long mode)
 Create a directory and all its ancestors. More...
 
int VSIRmdir (const char *pszDirname)
 Delete a directory. More...
 
int VSIRmdirRecursive (const char *pszDirname)
 Delete a directory recursively. More...
 
int VSIUnlink (const char *pszFilename)
 Delete a file. More...
 
int * VSIUnlinkBatch (CSLConstList papszFiles)
 Delete several files, possibly in a batch. More...
 
int VSIRename (const char *oldpath, const char *newpath)
 Rename a file. More...
 
int VSISync (const char *pszSource, const char *pszTarget, const char *const *papszOptions, GDALProgressFunc pProgressFunc, void *pProgressData, char ***ppapszOutputs)
 Synchronize a source file/directory with a target file/directory. More...
 
int VSIAbortPendingUploads (const char *pszFilename)
 Abort ongoing multi-part uploads. More...
 
char * VSIStrerror (int)
 Return the error string corresponding to the error number. More...
 
GIntBig VSIGetDiskFreeSpace (const char *pszDirname)
 Return free disk space available on the filesystem. More...
 
void VSINetworkStatsReset (void)
 Clear network related statistics. More...
 
char * VSINetworkStatsGetAsSerializedJSON (char **papszOptions)
 Return network related statistics, as a JSON serialized object. More...
 
void VSIInstallMemFileHandler (void)
 Install "memory" file system handler. More...
 
void VSIInstallSubFileHandler (void)
 Install /vsisubfile/ virtual file handler. More...
 
void VSIInstallCurlFileHandler (void)
 Install /vsicurl/ HTTP/FTP file system handler (requires libcurl) More...
 
void VSICurlClearCache (void)
 Clean local cache associated with /vsicurl/ (and related file systems) More...
 
void VSICurlPartialClearCache (const char *pszFilenamePrefix)
 Clean local cache associated with /vsicurl/ (and related file systems) for a given filename (and its subfiles and subdirectories if it is a directory) More...
 
void VSIInstallCurlStreamingFileHandler (void)
 Install /vsicurl_streaming/ HTTP/FTP file system handler (requires libcurl). More...
 
void VSIInstallS3FileHandler (void)
 Install /vsis3/ Amazon S3 file system handler (requires libcurl) More...
 
void VSIInstallS3StreamingFileHandler (void)
 Install /vsis3_streaming/ Amazon S3 file system handler (requires libcurl). More...
 
void VSIInstallGSFileHandler (void)
 Install /vsigs/ Google Cloud Storage file system handler (requires libcurl) More...
 
void VSIInstallGSStreamingFileHandler (void)
 Install /vsigs_streaming/ Google Cloud Storage file system handler (requires libcurl) More...
 
void VSIInstallAzureFileHandler (void)
 Install /vsiaz/ Microsoft Azure Blob file system handler (requires libcurl) More...
 
void VSIInstallAzureStreamingFileHandler (void)
 Install /vsiaz_streaming/ Microsoft Azure Blob file system handler (requires libcurl) More...
 
void VSIInstallADLSFileHandler (void)
 Install /vsiaz/ Microsoft Azure Data Lake Storage Gen2 file system handler (requires libcurl) More...
 
void VSIInstallOSSFileHandler (void)
 Install /vsioss/ Alibaba Cloud Object Storage Service (OSS) file system handler (requires libcurl) More...
 
void VSIInstallOSSStreamingFileHandler (void)
 Install /vsiaz_streaming/ Alibaba Cloud Object Storage Service (OSS) (requires libcurl) More...
 
void VSIInstallSwiftFileHandler (void)
 Install /vsiswift/ OpenStack Swif Object Storage (Swift) file system handler (requires libcurl) More...
 
void VSIInstallSwiftStreamingFileHandler (void)
 Install /vsiswift_streaming/ OpenStack Swif Object Storage (Swift) file system handler (requires libcurl) More...
 
void VSIInstallGZipFileHandler (void)
 Install GZip file system handler. More...
 
void VSIInstallZipFileHandler (void)
 Install ZIP file system handler. More...
 
void VSIInstallStdinHandler (void)
 Install /vsistdin/ file system handler. More...
 
void VSIInstallHdfsHandler (void)
 Install /vsihdfs/ file system handler (requires JVM and HDFS support) More...
 
void VSIInstallWebHdfsHandler (void)
 Install /vsiwebhdfs/ WebHDFS (Hadoop File System) REST API file system handler (requires libcurl) More...
 
void VSIInstallStdoutHandler (void)
 Install /vsistdout/ file system handler. More...
 
void VSIInstallSparseFileHandler (void)
 Install /vsisparse/ virtual file handler. More...
 
void VSIInstallTarFileHandler (void)
 Install /vsitar/ file system handler. More...
 
void VSIInstallCryptFileHandler (void)
 Install /vsicrypt/ encrypted file system handler (requires libcrypto++) More...
 
void VSISetCryptKey (const GByte *pabyKey, int nKeySize)
 Installs the encryption/decryption key. More...
 
VSILFILEVSIFileFromMemBuffer (const char *pszFilename, GByte *pabyData, vsi_l_offset nDataLength, int bTakeOwnership)
 Create memory "file" from a buffer. More...
 
GByteVSIGetMemFileBuffer (const char *pszFilename, vsi_l_offset *pnDataLength, int bUnlinkAndSeize)
 Fetch buffer underlying memory file. More...
 
void VSIStdoutSetRedirection (VSIWriteFunction pFct, FILE *stream)
 Set an alternative write function and output file handle instead of fwrite() / stdout. More...
 
VSIFilesystemPluginCallbacksStructVSIAllocFilesystemPluginCallbacksStruct (void)
 return a VSIFilesystemPluginCallbacksStruct to be populated at runtime with handler callbacks More...
 
void VSIFreeFilesystemPluginCallbacksStruct (VSIFilesystemPluginCallbacksStruct *poCb)
 free resources allocated by VSIAllocFilesystemPluginCallbacksStruct More...
 
int VSIInstallPluginHandler (const char *pszPrefix, const VSIFilesystemPluginCallbacksStruct *poCb)
 register a handler on the given prefix. More...
 

Detailed Description

Standard C Covers.

The VSI functions are intended to be hookable aliases for Standard C I/O, memory allocation and other system functions. They are intended to allow virtualization of disk I/O so that non file data sources can be made to appear as files, and so that additional error trapping and reporting can be interested. The memory access API is aliased so that special application memory management services can be used.

It is intended that each of these functions retains exactly the same calling pattern as the original Standard C functions they relate to. This means we don't have to provide custom documentation, and also means that the default implementation is very simple.

Macro Definition Documentation

◆ VSI_STAT_CACHE_ONLY

#define VSI_STAT_CACHE_ONLY   0x10

Flag provided to VSIStatExL() to only use already cached results.

Since
GDAL 3.4

Typedef Documentation

◆ VSIFilesystemPluginCloseCallback

typedef int(* VSIFilesystemPluginCloseCallback) (void *pFile)

Close file handle.

Optional

Since
GDAL 3.0

◆ VSIFilesystemPluginEofCallback

typedef int(* VSIFilesystemPluginEofCallback) (void *pFile)

Has end of file been reached.

Mandatory? for read handles.

Since
GDAL 3.0

◆ VSIFilesystemPluginFlushCallback

typedef int(* VSIFilesystemPluginFlushCallback) (void *pFile)

Sync written bytes.

Optional

Since
GDAL 3.0

◆ VSIFilesystemPluginGetRangeStatusCallback

typedef VSIRangeStatus(* VSIFilesystemPluginGetRangeStatusCallback) (void *pFile, vsi_l_offset nOffset, vsi_l_offset nLength)

Get empty ranges.

Optional

Since
GDAL 3.0

◆ VSIFilesystemPluginMkdirCallback

typedef int(* VSIFilesystemPluginMkdirCallback) (void *pUserData, const char *pszDirname, long nMode)

Create Directory.

Optional

Since
GDAL 3.0

◆ VSIFilesystemPluginOpenCallback

typedef void *(* VSIFilesystemPluginOpenCallback) (void *pUserData, const char *pszFilename, const char *pszAccess)

Open a handle.

Mandatory. Returns an opaque pointer that will be used in subsequent file I/O calls. Should return null and/or set errno if the handle does not exist or the access mode is incorrect.

Since
GDAL 3.0

◆ VSIFilesystemPluginReadCallback

typedef size_t(* VSIFilesystemPluginReadCallback) (void *pFile, void *pBuffer, size_t nSize, size_t nCount)

Read data from current position, returns the number of blocks correctly read.

Mandatory except for write only handles

Since
GDAL 3.0

◆ VSIFilesystemPluginReadDirCallback

typedef char **(* VSIFilesystemPluginReadDirCallback) (void *pUserData, const char *pszDirname, int nMaxFiles)

List directory content.

Optional

Since
GDAL 3.0

◆ VSIFilesystemPluginReadMultiRangeCallback

typedef int(* VSIFilesystemPluginReadMultiRangeCallback) (void *pFile, int nRanges, void **ppData, const vsi_l_offset *panOffsets, const size_t *panSizes)

Read from multiple offsets.

Optional, will be replaced by multiple calls to Read() if not provided

Since
GDAL 3.0

◆ VSIFilesystemPluginRenameCallback

typedef int(* VSIFilesystemPluginRenameCallback) (void *pUserData, const char *oldpath, const char *newpath)

Rename handle.

Optional

Since
GDAL 3.0

◆ VSIFilesystemPluginRmdirCallback

typedef int(* VSIFilesystemPluginRmdirCallback) (void *pUserData, const char *pszDirname)

Delete Directory.

Optional

Since
GDAL 3.0

◆ VSIFilesystemPluginSeekCallback

typedef int(* VSIFilesystemPluginSeekCallback) (void *pFile, vsi_l_offset nOffset, int nWhence)

Seek to position in handle.

Mandatory except for write only handles

Since
GDAL 3.0

◆ VSIFilesystemPluginSiblingFilesCallback

typedef char **(* VSIFilesystemPluginSiblingFilesCallback) (void *pUserData, const char *pszDirname)

List related files.

Must return NULL if unknown, or a list of relative filenames that can be opened along the main file. If no other file than pszFilename needs to be opened, return static_cast<char**> (CPLCalloc(1,sizeof(char*)));

Optional

Since
GDAL 3.2

◆ VSIFilesystemPluginStatCallback

typedef int(* VSIFilesystemPluginStatCallback) (void *pUserData, const char *pszFilename, VSIStatBufL *pStatBuf, int nFlags)

Return information about a handle.

Optional (driver dependent)

Since
GDAL 3.0

◆ VSIFilesystemPluginTellCallback

typedef vsi_l_offset(* VSIFilesystemPluginTellCallback) (void *pFile)

Return current position in handle.

Mandatory

Since
GDAL 3.0

◆ VSIFilesystemPluginTruncateCallback

typedef int(* VSIFilesystemPluginTruncateCallback) (void *pFile, vsi_l_offset nNewSize)

Truncate handle.

Mandatory (driver dependent?) for write handles

◆ VSIFilesystemPluginUnlinkCallback

typedef int(* VSIFilesystemPluginUnlinkCallback) (void *pUserData, const char *pszFilename)

Remove handle by name.

Optional

Since
GDAL 3.0

◆ VSIFilesystemPluginWriteCallback

typedef size_t(* VSIFilesystemPluginWriteCallback) (void *pFile, const void *pBuffer, size_t nSize, size_t nCount)

Write bytes at current offset.

Mandatory for writable handles

Since
GDAL 3.0

Enumeration Type Documentation

◆ VSIRangeStatus

Range status.

Enumerator
VSI_RANGE_STATUS_UNKNOWN 

Unknown.

VSI_RANGE_STATUS_DATA 

Data present.

VSI_RANGE_STATUS_HOLE 

Hole.

Function Documentation

◆ CPLGetPhysicalRAM()

GIntBig CPLGetPhysicalRAM ( void  )

Return the total physical RAM in bytes.

In the context of a container using cgroups (typically Docker), this will take into account that limitation (starting with GDAL 2.4.0)

You should generally use CPLGetUsablePhysicalRAM() instead.

Returns
the total physical RAM in bytes (or 0 in case of failure).
Since
GDAL 2.0

◆ CPLGetUsablePhysicalRAM()

GIntBig CPLGetUsablePhysicalRAM ( void  )

Return the total physical RAM, usable by a process, in bytes.

This is the same as CPLGetPhysicalRAM() except it will limit to 2 GB for 32 bit processes.

Starting with GDAL 2.4.0, it will also take account resource limits on Posix systems.

Note: This memory may already be partly used by other processes.

Returns
the total physical RAM, usable by a process, in bytes (or 0 in case of failure).
Since
GDAL 2.0

◆ VSIAbortPendingUploads()

int VSIAbortPendingUploads ( const char *  pszFilename)

Abort ongoing multi-part uploads.

Abort ongoing multi-part uploads on AWS S3 and Google Cloud Storage. This can be used in case a process doing such uploads was killed in a unclean way.

Without effect on other virtual file systems.

Parameters
pszFilenamefilename or prefix of a directory into which multipart uploads must be aborted. This can be the root directory of a bucket. UTF-8 encoded.
Returns
TRUE on success or FALSE on an error.
Since
GDAL 3.4

◆ VSIAllocFilesystemPluginCallbacksStruct()

VSIFilesystemPluginCallbacksStruct * VSIAllocFilesystemPluginCallbacksStruct ( void  )

return a VSIFilesystemPluginCallbacksStruct to be populated at runtime with handler callbacks

Since
GDAL 3.0

◆ VSICalloc()

void * VSICalloc ( size_t  nCount,
size_t  nSize 
)

Analog of calloc().

Use VSIFree() to free

◆ VSIClearCredentials()

void VSIClearCredentials ( const char *  pszPathPrefix)

Clear credentials set with VSISetCredential()

Note that no particular care is taken to remove them from RAM in a secure way.

Parameters
pszPathPrefixIf set to NULL, all credentials are cleared. If set to not-NULL, only those set with VSISetCredential(pszPathPrefix, ...) will be cleared.
Since
GDAL 3.5

◆ VSICloseDir()

void VSICloseDir ( VSIDIR dir)

Close a directory.

This function is close to the POSIX closedir() function.

Parameters
dirDirectory handled returned by VSIOpenDir().
Since
GDAL 2.4

◆ VSICurlClearCache()

void VSICurlClearCache ( void  )

Clean local cache associated with /vsicurl/ (and related file systems)

/vsicurl (and related file systems like /vsis3/, /vsigs/, /vsiaz/, /vsioss/, /vsiswift/) cache a number of metadata and data for faster execution in read-only scenarios. But when the content on the server-side may change during the same process, those mechanisms can prevent opening new files, or give an outdated version of them.

Since
GDAL 2.2.1

◆ VSICurlPartialClearCache()

void VSICurlPartialClearCache ( const char *  pszFilenamePrefix)

Clean local cache associated with /vsicurl/ (and related file systems) for a given filename (and its subfiles and subdirectories if it is a directory)

/vsicurl (and related file systems like /vsis3/, /vsigs/, /vsiaz/, /vsioss/, /vsiswift/) cache a number of metadata and data for faster execution in read-only scenarios. But when the content on the server-side may change during the same process, those mechanisms can prevent opening new files, or give an outdated version of them.

Parameters
pszFilenamePrefixFilename prefix
Since
GDAL 2.4.0

◆ VSIFCloseL()

int VSIFCloseL ( VSILFILE fp)

Close file.

This function closes the indicated file.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX fclose() function.

Parameters
fpfile handle opened with VSIFOpenL(). Passing a nullptr produces undefined behavior.
Returns
0 on success or -1 on failure.

◆ VSIFEofL()

int VSIFEofL ( VSILFILE fp)

Test for end of file.

Returns TRUE (non-zero) if an end-of-file condition occurred during the previous read operation. The end-of-file flag is cleared by a successful VSIFSeekL() call.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX feof() call.

Parameters
fpfile handle opened with VSIFOpenL().
Returns
TRUE if at EOF else FALSE.

◆ VSIFFlushL()

int VSIFFlushL ( VSILFILE fp)

Flush pending writes to disk.

For files in write or update mode and on filesystem types where it is applicable, all pending output on the file is flushed to the physical disk.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX fflush() call.

Parameters
fpfile handle opened with VSIFOpenL().
Returns
0 on success or -1 on error.

◆ VSIFGetNativeFileDescriptorL()

void * VSIFGetNativeFileDescriptorL ( VSILFILE fp)

Returns the "native" file descriptor for the virtual handle.

This will only return a non-NULL value for "real" files handled by the operating system (to be opposed to GDAL virtual file systems).

On POSIX systems, this will be a integer value ("fd") cast as a void*. On Windows systems, this will be the HANDLE.

Parameters
fpfile handle opened with VSIFOpenL().
Returns
the native file descriptor, or NULL.

◆ VSIFGetRangeStatusL()

VSIRangeStatus VSIFGetRangeStatusL ( VSILFILE fp,
vsi_l_offset  nOffset,
vsi_l_offset  nLength 
)

Return if a given file range contains data or holes filled with zeroes.

This uses the filesystem capabilities of querying which regions of a sparse file are allocated or not. This is currently only implemented for Linux (and no other Unix derivatives) and Windows.

Note: A return of VSI_RANGE_STATUS_DATA doesn't exclude that the extent is filled with zeroes! It must be interpreted as "may contain non-zero data".

Parameters
fpfile handle opened with VSIFOpenL().
nOffsetoffset of the start of the extent.
nLengthextent length.
Returns
extent status: VSI_RANGE_STATUS_UNKNOWN, VSI_RANGE_STATUS_DATA or VSI_RANGE_STATUS_HOLE
Since
GDAL 2.2

◆ VSIFileFromMemBuffer()

VSILFILE * VSIFileFromMemBuffer ( const char *  pszFilename,
GByte pabyData,
vsi_l_offset  nDataLength,
int  bTakeOwnership 
)

Create memory "file" from a buffer.

A virtual memory file is created from the passed buffer with the indicated filename. Under normal conditions the filename would need to be absolute and within the /vsimem/ portion of the filesystem. Starting with GDAL 3.6, nullptr can also be passed as pszFilename to mean an anonymous file, that is destroyed when the handle is closed.

If bTakeOwnership is TRUE, then the memory file system handler will take ownership of the buffer, freeing it when the file is deleted. Otherwise it remains the responsibility of the caller, but should not be freed as long as it might be accessed as a file. In no circumstances does this function take a copy of the pabyData contents.

Parameters
pszFilenamethe filename to be created, or nullptr
pabyDatathe data buffer for the file.
nDataLengththe length of buffer in bytes.
bTakeOwnershipTRUE to transfer "ownership" of buffer or FALSE.
Returns
open file handle on created file (see VSIFOpenL()).

◆ VSIFOpenEx2L()

VSILFILE * VSIFOpenEx2L ( const char *  pszFilename,
const char *  pszAccess,
int  bSetError,
CSLConstList  papszOptions 
)

Open file.

This function opens a file with the desired access. Large files (larger than 2GB) should be supported. Binary access is always implied and the "b" does not need to be included in the pszAccess string.

Note that the "VSILFILE *" returned by this function is NOT a standard C library FILE *, and cannot be used with any functions other than the "VSI*L" family of functions. They aren't "real" FILE objects.

On windows it is possible to define the configuration option GDAL_FILE_IS_UTF8 to have pszFilename treated as being in the local encoding instead of UTF-8, restoring the pre-1.8.0 behavior of VSIFOpenL().

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX fopen() function.

Parameters
pszFilenamethe file to open. UTF-8 encoded.
pszAccessaccess requested (i.e. "r", "r+", "w")
bSetErrorflag determining whether or not this open call should set VSIErrors on failure.
papszOptionsNULL or NULL-terminated list of strings. The content is highly file system dependent. Currently only MIME headers such as Content-Type and Content-Encoding are supported for the /vsis3/, /vsigs/, /vsiaz/, /vsiadls/ file systems.
Returns
NULL on failure, or the file handle.
Since
GDAL 3.3

◆ VSIFOpenExL()

VSILFILE * VSIFOpenExL ( const char *  pszFilename,
const char *  pszAccess,
int  bSetError 
)

Open file.

This function opens a file with the desired access. Large files (larger than 2GB) should be supported. Binary access is always implied and the "b" does not need to be included in the pszAccess string.

Note that the "VSILFILE *" returned by this function is NOT a standard C library FILE *, and cannot be used with any functions other than the "VSI*L" family of functions. They aren't "real" FILE objects.

On windows it is possible to define the configuration option GDAL_FILE_IS_UTF8 to have pszFilename treated as being in the local encoding instead of UTF-8, restoring the pre-1.8.0 behavior of VSIFOpenL().

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX fopen() function.

Parameters
pszFilenamethe file to open. UTF-8 encoded.
pszAccessaccess requested (i.e. "r", "r+", "w")
bSetErrorflag determining whether or not this open call should set VSIErrors on failure.
Returns
NULL on failure, or the file handle.
Since
GDAL 2.1

◆ VSIFOpenL()

VSILFILE * VSIFOpenL ( const char *  pszFilename,
const char *  pszAccess 
)

Open file.

This function opens a file with the desired access. Large files (larger than 2GB) should be supported. Binary access is always implied and the "b" does not need to be included in the pszAccess string.

Note that the "VSILFILE *" returned since GDAL 1.8.0 by this function is NOT a standard C library FILE *, and cannot be used with any functions other than the "VSI*L" family of functions. They aren't "real" FILE objects.

On windows it is possible to define the configuration option GDAL_FILE_IS_UTF8 to have pszFilename treated as being in the local encoding instead of UTF-8, restoring the pre-1.8.0 behavior of VSIFOpenL().

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX fopen() function.

Parameters
pszFilenamethe file to open. UTF-8 encoded.
pszAccessaccess requested (i.e. "r", "r+", "w")
Returns
NULL on failure, or the file handle.

◆ VSIFPrintfL()

int VSIFPrintfL ( VSILFILE fp,
const char *  pszFormat,
  ... 
)

Formatted write to file.

Provides fprintf() style formatted output to a VSI*L file. This formats an internal buffer which is written using VSIFWriteL().

Analog of the POSIX fprintf() call.

Parameters
fpfile handle opened with VSIFOpenL().
pszFormatthe printf() style format string.
Returns
the number of bytes written or -1 on an error.

◆ VSIFPutcL()

int VSIFPutcL ( int  nChar,
VSILFILE fp 
)

Write a single byte to the file.

Writes the character nChar, cast to an unsigned char, to file.

Almost an analog of the POSIX fputc() call, except that it returns the number of character written (1 or 0), and not the (cast) character itself or EOF.

Parameters
nCharcharacter to write.
fpfile handle opened with VSIFOpenL().
Returns
1 in case of success, 0 on error.

◆ VSIFReadL()

size_t VSIFReadL ( void *  pBuffer,
size_t  nSize,
size_t  nCount,
VSILFILE fp 
)

Read bytes from file.

Reads nCount objects of nSize bytes from the indicated file at the current offset into the indicated buffer.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX fread() call.

Parameters
pBufferthe buffer into which the data should be read (at least nCount * nSize bytes in size.
nSizesize of objects to read in bytes.
nCountnumber of objects to read.
fpfile handle opened with VSIFOpenL().
Returns
number of objects successfully read.

◆ VSIFReadMultiRangeL()

int VSIFReadMultiRangeL ( int  nRanges,
void **  ppData,
const vsi_l_offset panOffsets,
const size_t *  panSizes,
VSILFILE fp 
)

Read several ranges of bytes from file.

Reads nRanges objects of panSizes[i] bytes from the indicated file at the offset panOffsets[i] into the buffer ppData[i].

Ranges must be sorted in ascending start offset, and must not overlap each other.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory or /vsicurl/.

Parameters
nRangesnumber of ranges to read.
ppDataarray of nRanges buffer into which the data should be read (ppData[i] must be at list panSizes[i] bytes).
panOffsetsarray of nRanges offsets at which the data should be read.
panSizesarray of nRanges sizes of objects to read (in bytes).
fpfile handle opened with VSIFOpenL().
Returns
0 in case of success, -1 otherwise.
Since
GDAL 1.9.0

◆ VSIFreeAligned()

void VSIFreeAligned ( void *  ptr)

Free a buffer allocated with VSIMallocAligned().

Parameters
ptrBuffer to free.
Since
GDAL 2.2

◆ VSIFreeFilesystemPluginCallbacksStruct()

void VSIFreeFilesystemPluginCallbacksStruct ( VSIFilesystemPluginCallbacksStruct poCb)

free resources allocated by VSIAllocFilesystemPluginCallbacksStruct

Since
GDAL 3.0

◆ VSIFSeekL()

int VSIFSeekL ( VSILFILE fp,
vsi_l_offset  nOffset,
int  nWhence 
)

Seek to requested offset.

Seek to the desired offset (nOffset) in the indicated file.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX fseek() call.

Caution: vsi_l_offset is a unsigned type, so SEEK_CUR can only be used for positive seek. If negative seek is needed, use VSIFSeekL( fp, VSIFTellL(fp) + negative_offset, SEEK_SET ).

Parameters
fpfile handle opened with VSIFOpenL().
nOffsetoffset in bytes.
nWhenceone of SEEK_SET, SEEK_CUR or SEEK_END.
Returns
0 on success or -1 one failure.

◆ VSIFTellL()

vsi_l_offset VSIFTellL ( VSILFILE fp)

Tell current file offset.

Returns the current file read/write offset in bytes from the beginning of the file.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX ftell() call.

Parameters
fpfile handle opened with VSIFOpenL().
Returns
file offset in bytes.

◆ VSIFTruncateL()

int VSIFTruncateL ( VSILFILE fp,
vsi_l_offset  nNewSize 
)

Truncate/expand the file to the specified size.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX ftruncate() call.

Parameters
fpfile handle opened with VSIFOpenL().
nNewSizenew size in bytes.
Returns
0 on success
Since
GDAL 1.9.0

◆ VSIFWriteL()

size_t VSIFWriteL ( const void *  pBuffer,
size_t  nSize,
size_t  nCount,
VSILFILE fp 
)

Write bytes to file.

Writess nCount objects of nSize bytes to the indicated file at the current offset into the indicated buffer.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX fwrite() call.

Parameters
pBufferthe buffer from which the data should be written (at least nCount * nSize bytes in size.
nSizesize of objects to read in bytes.
nCountnumber of objects to read.
fpfile handle opened with VSIFOpenL().
Returns
number of objects successfully written.

◆ VSIGetActualURL()

const char * VSIGetActualURL ( const char *  pszFilename)

Returns the actual URL of a supplied filename.

Currently only returns a non-NULL value for network-based virtual file systems. For example "/vsis3/bucket/filename" will be expanded as "https://bucket.s3.amazon.com/filename"

Note that the lifetime of the returned string, is short, and may be invalidated by any following GDAL functions.

Parameters
pszFilenamethe path of the filesystem object. UTF-8 encoded.
Returns
the actual URL corresponding to the supplied filename, or NULL. Should not be freed.
Since
GDAL 2.3

◆ VSIGetCredential()

const char * VSIGetCredential ( const char *  pszPath,
const char *  pszKey,
const char *  pszDefault 
)

Get a credential option for a given path.

If no match occurs, CPLGetConfigOption(pszKey, pszDefault) is returned.

Mostly to be use by virtual file system implementations.

Since
GDAL 3.5
See also
VSISetCredential()

◆ VSIGetDiskFreeSpace()

GIntBig VSIGetDiskFreeSpace ( const char *  pszDirname)

Return free disk space available on the filesystem.

This function returns the free disk space available on the filesystem.

Parameters
pszDirnamea directory of the filesystem to query.
Returns
The free space in bytes. Or -1 in case of error.
Since
GDAL 2.1

◆ VSIGetFileMetadata()

char ** VSIGetFileMetadata ( const char *  pszFilename,
const char *  pszDomain,
CSLConstList  papszOptions 
)

Get metadata on files.

Implemented currently only for network-like filesystems.

Parameters
pszFilenamethe path of the filesystem object to be queried. UTF-8 encoded.
pszDomainMetadata domain to query. Depends on the file system. The following are supported:
papszOptionsUnused. Should be set to NULL.
Returns
a NULL-terminated list of key=value strings, to be freed with CSLDestroy() or NULL in case of error / empty list.
Since
GDAL 3.1.0

◆ VSIGetFileSystemOptions()

const char * VSIGetFileSystemOptions ( const char *  pszFilename)

Return the list of options associated with a virtual file system handler as a serialized XML string.

Those options may be set as configuration options with CPLSetConfigOption().

Parameters
pszFilenamea filename, or prefix of a virtual file system handler.
Returns
a string, which must not be freed, or NULL if no options is declared.
Since
GDAL 2.3

◆ VSIGetFileSystemsPrefixes()

char ** VSIGetFileSystemsPrefixes ( void  )

Return the list of prefixes for virtual file system handlers currently registered.

Typically: "", "/vsimem/", "/vsicurl/", etc

Returns
a NULL terminated list of prefixes. Must be freed with CSLDestroy()
Since
GDAL 2.3

◆ VSIGetMemFileBuffer()

GByte * VSIGetMemFileBuffer ( const char *  pszFilename,
vsi_l_offset pnDataLength,
int  bUnlinkAndSeize 
)

Fetch buffer underlying memory file.

This function returns a pointer to the memory buffer underlying a virtual "in memory" file. If bUnlinkAndSeize is TRUE the filesystem object will be deleted, and ownership of the buffer will pass to the caller otherwise the underlying file will remain in existence.

Parameters
pszFilenamethe name of the file to grab the buffer of.
pnDataLength(file) length returned in this variable.
bUnlinkAndSeizeTRUE to remove the file, or FALSE to leave unaltered.
Returns
pointer to memory buffer or NULL on failure.

◆ VSIGetNextDirEntry()

const VSIDIREntry * VSIGetNextDirEntry ( VSIDIR dir)

Return the next entry of the directory.

This function is close to the POSIX readdir() function. It actually returns more information (file size, last modification time), which on 'real' file systems involve one 'stat' call per file.

For filesystems that can have both a regular file and a directory name of the same name (typically /vsis3/), when this situation of duplicate happens, the directory name will be suffixed by a slash character. Otherwise directory names are not suffixed by slash.

The returned entry remains valid until the next call to VSINextDirEntry() or VSICloseDir() with the same handle.

Parameters
dirDirectory handled returned by VSIOpenDir(). Must not be NULL.
Returns
a entry, or NULL if there is no more entry in the directory. This return value must not be freed.
Since
GDAL 2.4

◆ VSIGetSignedURL()

char * VSIGetSignedURL ( const char *  pszFilename,
CSLConstList  papszOptions 
)

Returns a signed URL of a supplied filename.

Currently only returns a non-NULL value for /vsis3/, /vsigs/, /vsiaz/ and /vsioss/ For example "/vsis3/bucket/filename" will be expanded as "https://bucket.s3.amazon.com/filename?X-Amz-Algorithm=AWS4-HMAC-SHA256..." Configuration options that apply for file opening (typically to provide credentials), and are returned by VSIGetFileSystemOptions(), are also valid in that context.

Parameters
pszFilenamethe path of the filesystem object. UTF-8 encoded.
papszOptionslist of options, or NULL. Depend on file system handler. For /vsis3/, /vsigs/, /vsiaz/ and /vsioss/, the following options are supported:
  • START_DATE=YYMMDDTHHMMSSZ: date and time in UTC following ISO 8601 standard, corresponding to the start of validity of the URL. If not specified, current date time.
  • EXPIRATION_DELAY=number_of_seconds: number between 1 and 604800 (seven days) for the validity of the signed URL. Defaults to 3600 (one hour)
  • VERB=GET/HEAD/DELETE/PUT/POST: HTTP VERB for which the request will be used. Default to GET.

/vsiaz/ supports additional options:

  • SIGNEDIDENTIFIER=value: to relate the given shared access signature to a corresponding stored access policy.
  • SIGNEDPERMISSIONS=r|w: permissions associated with the shared access signature. Normally deduced from VERB.
Returns
a signed URL, or NULL. Should be freed with CPLFree().
Since
GDAL 2.3

◆ VSIHasOptimizedReadMultiRange()

int VSIHasOptimizedReadMultiRange ( const char *  pszPath)

Returns if the filesystem supports efficient multi-range reading.

Currently only returns TRUE for /vsicurl/ and derived file systems.

Parameters
pszPaththe path of the filesystem object to be tested. UTF-8 encoded.
Returns
TRUE if the file system is known to have an efficient multi-range reading.
Since
GDAL 2.3

◆ VSIIngestFile()

int VSIIngestFile ( VSILFILE fp,
const char *  pszFilename,
GByte **  ppabyRet,
vsi_l_offset pnSize,
GIntBig  nMaxSize 
)

Ingest a file into memory.

Read the whole content of a file into a memory buffer.

Either fp or pszFilename can be NULL, but not both at the same time.

If fp is passed non-NULL, it is the responsibility of the caller to close it.

If non-NULL, the returned buffer is guaranteed to be NUL-terminated.

Parameters
fpfile handle opened with VSIFOpenL().
pszFilenamefilename.
ppabyRetpointer to the target buffer. *ppabyRet must be freed with VSIFree()
pnSizepointer to variable to store the file size. May be NULL.
nMaxSizemaximum size of file allowed. If no limit, set to a negative value.
Returns
TRUE in case of success.
Since
GDAL 1.11

◆ VSIInstallADLSFileHandler()

void VSIInstallADLSFileHandler ( void  )

Install /vsiaz/ Microsoft Azure Data Lake Storage Gen2 file system handler (requires libcurl)

embed:rst
See :ref:`/vsiadls/ documentation <vsiadls>`
Since
GDAL 3.3

◆ VSIInstallAzureFileHandler()

void VSIInstallAzureFileHandler ( void  )

Install /vsiaz/ Microsoft Azure Blob file system handler (requires libcurl)

embed:rst
See :ref:`/vsiaz/ documentation <vsiaz>`
Since
GDAL 2.3

◆ VSIInstallAzureStreamingFileHandler()

void VSIInstallAzureStreamingFileHandler ( void  )

Install /vsiaz_streaming/ Microsoft Azure Blob file system handler (requires libcurl)

embed:rst
See :ref:`/vsiaz_streaming/ documentation <vsiaz_streaming>`
Since
GDAL 2.3

◆ VSIInstallCryptFileHandler()

void VSIInstallCryptFileHandler ( void  )

Install /vsicrypt/ encrypted file system handler (requires libcrypto++)

A special file handler is installed that allows reading/creating/update encrypted files on the fly, with random access capabilities.

The cryptographic algorithms used are block ciphers, with symmetric key.

In their simplest form, recognized filenames are of the form /vsicrypt//absolute_path/to/file, /vsicrypt/c:/absolute_path/to/file or /vsicrypt/relative/path/to/file.

Options can also be used with the following format : /vsicrypt/option1=val1,option2=val2,...,file=/path/to/file

They can also be passed as configuration option/environment variable, because in some use cases, the syntax with option in the filename might not properly work with some drivers.

In all modes, the encryption key must be provided. There are several ways of doing so :

  • By adding a key= parameter to the filename, like /vsicrypt/key=my_secret_key,file=/path/to/file. Note that this restricts the key to be in text format, whereas at its full power, it can be binary content.
  • By adding a key_b64= parameter to the filename, to specify a binary key expressed in Base64 encoding, like /vsicrypt/key_b64=th1sl00kslikebase64=,file=/path/to/file.
  • By setting the VSICRYPT_KEY configuration option. The key should be in text format.
  • By setting the VSICRYPT_KEY_B64 configuration option. The key should be encoded in Base64.
  • By using the VSISetCryptKey() C function.

When creating a file, if key=GENERATE_IT or VSICRYPT_KEY=GENERATE_IT is passed, the encryption key will be generated from the pseudo-random number generator of the operating system. The key will be displayed on the standard error stream in a Base64 form (unless the VSICRYPT_DISPLAY_GENERATED_KEY configuration option is set to OFF), and the VSICRYPT_KEY_B64 configuration option will also be set with the Base64 form of the key (so that CPLGetConfigOption("VSICRYPT_KEY_B64", NULL) can be used to get it back).

The available options are :

  • alg=AES/Blowfish/Camellia/CAST256/DES_EDE2/DES_EDE3/MARS/IDEA/RC5/RC6/Serpent/SHACAL2/SKIPJACK/Twofish/XTEA: to specify the block cipher algorithm. The default is AES. Only used on creation. Ignored otherwise. Note: depending on how GDAL is build, if linked against the DLL version of libcrypto++, only a subset of those algorithms will be available, namely AES, DES_EDE2, DES_EDE3 and SKIPJACK. Also available as VSICRYPT_ALG configuration option.
  • mode=CBC/CFB/OFB/CTR/CBC_CTS: to specify the block cipher mode of operation. The default is CBC. Only used on creation. Ignored otherwise. Also available as VSICRYPT_MODE configuration option.
  • key=text_key: see above.
  • key_b64=base64_encoded_key: see above.
  • freetext=some_text: to specify a text content that will be written unencrypted in the file header, for informational purposes. Default to empty. Only used on creation. Ignored otherwise. Also available as VSICRYPT_FREETEXT configuration option.
  • sector_size=int_value: to specify the size of the "sector", which is the unit chunk of information that is encrypted/decrypted. Default to 512 bytes. The valid values depend on the algorithm and block cipher mode of operation. Only used on creation. Ignored otherwise. Also available as VSICRYPT_SECTOR_SIZE configuration option.
  • iv=initial_vector_as_text: to specify the Initial Vector. This is an advanced option that should generally NOT be used. It is only useful to get completely deterministic output given the plaintext, key and other parameters, which in general NOT what you want to do. By default, a random initial vector of the appropriate size will be generated for each new file created. Only used on creation. Ignored otherwise. Also available as VSICRYPT_IV configuration option.

  • add_key_check=YES/NO: whether a special value should be encrypted in the header, so as to be quickly able to determine if the decryption key is correct. Defaults to NO. Only used on creation. Ignored otherwise. Also available as VSICRYPT_ADD_KEY_CHECK configuration option.
  • file=filename. To specify the filename. This must be the last option put in the option list (so as to make it possible to use filenames with comma in them. )

This special file handler can be combined with other virtual filesystems handlers, such as /vsizip. For example, /vsicrypt//vsicurl/path/to/remote/encrypted/file.tif

Implementation details:

The structure of encrypted files is the following: a header, immediately followed by the encrypted payload (by sectors, i.e. chunks of sector_size bytes).

The header structure is the following :

  1. 8 bytes. Signature. Fixed value: VSICRYPT.
  2. UINT16_LE. Header size (including previous signature bytes).
  3. UINT8. Format major version. Current value: 1.
  4. UINT8. Format minor version. Current value: 0.
  5. UINT16. Sector size.
  6. UINT8. Cipher algorithm. Valid values are: 0 = AES (Rijndael), 1 = Blowfish, 2 = Camellia, 3 = CAST256, 4 = DES_EDE2, 5 = DES_EDE3, 6 = MARS, 7 = IDEA, 8 = RC5, 9 = RC6, 10 = Serpent, 11 = SHACAL2, 12 = SKIPJACK, 13 = Twofish, 14 = XTEA.
  7. UINT8. Block cipher mode of operation. Valid values are: 0 = CBC, 1 = CFB, 2 = OFB, 3 = CTR, 4 = CBC_CTS.
  8. UINT8. Size in bytes of the Initial Vector.
  9. N bytes with the content of the Initial Vector, where N is the value of the previous field.
  10. UINT16_LE. Size in bytes of the free text.
  11. N bytes with the content of the free text, where N is the value of the previous field.
  12. UINT8. Size in bytes of encrypted content (key check), or 0 if key check is absent.
  13. N bytes with encrypted content (key check), where N is the value of the previous field.
  14. UINT64_LE. Size of the unencrypted file, in bytes.
  15. UINT16_LE. Size in bytes of extra content (of unspecified semantics). For v1.0, fixed value of 0
  16. N bytes with extra content (of unspecified semantics), where N is the value of the previous field.

This design does not provide any means of authentication or integrity check.

Each sector is encrypted/decrypted independently of other sectors. For that, the Initial Vector contained in the header is XOR'ed with the file offset (relative to plain text file) of the start of the sector being processed, as a 8-byte integer. More precisely, the first byte of the main IV is XOR'ed with the 8 least-significant bits of the sector offset, the second byte of the main IV is XOR'ed with the following 8 bits of the sector offset, etc... until the 8th byte.

This design could potentially be prone to chosen-plaintext attack, for example if the attacker managed to get (part of) an existing encrypted file to be encrypted from plaintext he might have selected.

Note: if "hostile" code can explore process content, or attach to it with a debugger, it might be relatively easy to retrieve the encryption key. A GDAL plugin could for example get the content of configuration options, or list opened datasets and see the key/key_b64 values, so disabling plugin loading might be a first step, as well as linking statically GDAL to application code. If plugin loading is enabled or GDAL dynamically linked, using VSISetCryptKey() to set the key might make it a bit more complicated to spy the key. But, as said initially, this is in no way a perfect protection.

Since
GDAL 2.1.0

◆ VSIInstallCurlFileHandler()

void VSIInstallCurlFileHandler ( void  )

Install /vsicurl/ HTTP/FTP file system handler (requires libcurl)

embed:rst
See :ref:`/vsicurl/ documentation <vsicurl>`
Since
GDAL 1.8.0

◆ VSIInstallCurlStreamingFileHandler()

void VSIInstallCurlStreamingFileHandler ( void  )

Install /vsicurl_streaming/ HTTP/FTP file system handler (requires libcurl).

embed:rst
See :ref:`/vsicurl_streaming/ documentation <vsicurl_streaming>`
Since
GDAL 1.10

◆ VSIInstallGSFileHandler()

void VSIInstallGSFileHandler ( void  )

Install /vsigs/ Google Cloud Storage file system handler (requires libcurl)

embed:rst
See :ref:`/vsigs/ documentation <vsigs>`
Since
GDAL 2.2

◆ VSIInstallGSStreamingFileHandler()

void VSIInstallGSStreamingFileHandler ( void  )

Install /vsigs_streaming/ Google Cloud Storage file system handler (requires libcurl)

embed:rst
See :ref:`/vsigs_streaming/ documentation <vsigs_streaming>`
Since
GDAL 2.2

◆ VSIInstallGZipFileHandler()

void VSIInstallGZipFileHandler ( void  )

Install GZip file system handler.

A special file handler is installed that allows reading on-the-fly and writing in GZip (.gz) files.

All portions of the file system underneath the base path "/vsigzip/" will be handled by this driver.

embed:rst
See :ref:`/vsigzip/ documentation <vsigzip>`
Since
GDAL 1.6.0

◆ VSIInstallHdfsHandler()

void VSIInstallHdfsHandler ( void  )

Install /vsihdfs/ file system handler (requires JVM and HDFS support)

Since
GDAL 2.4.0

◆ VSIInstallMemFileHandler()

void VSIInstallMemFileHandler ( void  )

Install "memory" file system handler.

A special file handler is installed that allows block of memory to be treated as files. All portions of the file system underneath the base path "/vsimem/" will be handled by this driver.

Normal VSI*L functions can be used freely to create and destroy memory arrays treating them as if they were real file system objects. Some additional methods exist to efficient create memory file system objects without duplicating original copies of the data or to "steal" the block of memory associated with a memory file.

Directory related functions are supported.

This code example demonstrates using GDAL to translate from one memory buffer to another.

GByte *ConvertBufferFormat( GByte *pabyInData, vsi_l_offset nInDataLength,
vsi_l_offset *pnOutDataLength )
{
// create memory file system object from buffer.
VSIFCloseL( VSIFileFromMemBuffer( "/vsimem/work.dat", pabyInData,
nInDataLength, FALSE ) );
// Open memory buffer for read.
GDALDatasetH hDS = GDALOpen( "/vsimem/work.dat", GA_ReadOnly );
// Get output format driver.
GDALDriverH hDriver = GDALGetDriverByName( "GTiff" );
GDALDatasetH hOutDS;
hOutDS = GDALCreateCopy( hDriver, "/vsimem/out.tif", hDS, TRUE, NULL,
NULL, NULL );
// close source file, and "unlink" it.
GDALClose( hDS );
VSIUnlink( "/vsimem/work.dat" );
// seize the buffer associated with the output file.
return VSIGetMemFileBuffer( "/vsimem/out.tif", pnOutDataLength, TRUE );
}
unsigned char GByte
Unsigned byte type.
Definition: cpl_port.h:203
int VSIUnlink(const char *pszFilename)
Delete a file.
Definition: cpl_vsil.cpp:423
int VSIFCloseL(VSILFILE *)
Close file.
Definition: cpl_vsil.cpp:1824
GByte * VSIGetMemFileBuffer(const char *pszFilename, vsi_l_offset *pnDataLength, int bUnlinkAndSeize)
Fetch buffer underlying memory file.
Definition: cpl_vsi_mem.cpp:1011
VSILFILE * VSIFileFromMemBuffer(const char *pszFilename, GByte *pabyData, vsi_l_offset nDataLength, int bTakeOwnership)
Create memory "file" from a buffer.
Definition: cpl_vsi_mem.cpp:943
GUIntBig vsi_l_offset
Type for a file offset.
Definition: cpl_vsi.h:142
@ GA_ReadOnly
Definition: gdal.h:117
void GDALClose(GDALDatasetH)
Close GDAL dataset.
Definition: gdaldataset.cpp:3760
void * GDALDatasetH
Opaque type used for the C bindings of the C++ GDALDataset class.
Definition: gdal.h:269
void * GDALDriverH
Opaque type used for the C bindings of the C++ GDALDriver class.
Definition: gdal.h:275
GDALDriverH GDALGetDriverByName(const char *)
Fetch a driver based on the short name.
Definition: gdaldrivermanager.cpp:621
GDALDatasetH GDALOpen(const char *pszFilename, GDALAccess eAccess)
Open a raster file as a GDALDataset.
Definition: gdaldataset.cpp:3235
GDALDatasetH GDALCreateCopy(GDALDriverH, const char *, GDALDatasetH, int, CSLConstList, GDALProgressFunc, void *)
Create a copy of a dataset.
Definition: gdaldriver.cpp:1242

◆ VSIInstallOSSFileHandler()

void VSIInstallOSSFileHandler ( void  )

Install /vsioss/ Alibaba Cloud Object Storage Service (OSS) file system handler (requires libcurl)

embed:rst
See :ref:`/vsioss/ documentation <vsioss>`
Since
GDAL 2.3

◆ VSIInstallOSSStreamingFileHandler()

void VSIInstallOSSStreamingFileHandler ( void  )

Install /vsiaz_streaming/ Alibaba Cloud Object Storage Service (OSS) (requires libcurl)

embed:rst
See :ref:`/vsioss_streaming/ documentation <vsioss_streaming>`
Since
GDAL 2.3

◆ VSIInstallPluginHandler()

int VSIInstallPluginHandler ( const char *  pszPrefix,
const VSIFilesystemPluginCallbacksStruct poCb 
)

register a handler on the given prefix.

All IO on datasets opened with the filename /prefix/xxxxxx will go through these callbacks. pszPrefix must begin and end with a '/'

Since
GDAL 3.0

◆ VSIInstallS3FileHandler()

void VSIInstallS3FileHandler ( void  )

Install /vsis3/ Amazon S3 file system handler (requires libcurl)

embed:rst
See :ref:`/vsis3/ documentation <vsis3>`
Since
GDAL 2.1

◆ VSIInstallS3StreamingFileHandler()

void VSIInstallS3StreamingFileHandler ( void  )

Install /vsis3_streaming/ Amazon S3 file system handler (requires libcurl).

embed:rst
See :ref:`/vsis3_streaming/ documentation <vsis3_streaming>`
Since
GDAL 2.1

◆ VSIInstallSparseFileHandler()

void VSIInstallSparseFileHandler ( void  )

Install /vsisparse/ virtual file handler.

embed:rst
See :ref:`/vsisparse/ documentation <vsisparse>`

◆ VSIInstallStdinHandler()

void VSIInstallStdinHandler ( void  )

Install /vsistdin/ file system handler.

A special file handler is installed that allows reading from the standard input stream.

The file operations available are of course limited to Read() and forward Seek() (full seek in the first MB of a file by default).

Starting with GDAL 3.6, this limit can be configured either by setting the CPL_VSISTDIN_BUFFER_LIMIT configuration option to a number of bytes (can be -1 for unlimited), or using the "/vsistdin?buffer_limit=value" filename.

embed:rst
See :ref:`/vsistdin/ documentation <vsistdin>`
Since
GDAL 1.8.0

◆ VSIInstallStdoutHandler()

void VSIInstallStdoutHandler ( void  )

Install /vsistdout/ file system handler.

A special file handler is installed that allows writing to the standard output stream.

The file operations available are of course limited to Write().

A variation of this file system exists as the /vsistdout_redirect/ file system handler, where the output function can be defined with VSIStdoutSetRedirection().

embed:rst
See :ref:`/vsistdout/ documentation <vsistdout>`
Since
GDAL 1.8.0

◆ VSIInstallSubFileHandler()

void VSIInstallSubFileHandler ( void  )

Install /vsisubfile/ virtual file handler.

embed:rst
See :ref:`/vsisubfile/ documentation <vsisubfile>`

◆ VSIInstallSwiftFileHandler()

void VSIInstallSwiftFileHandler ( void  )

Install /vsiswift/ OpenStack Swif Object Storage (Swift) file system handler (requires libcurl)

embed:rst
See :ref:`/vsiswift/ documentation <vsiswift>`
Since
GDAL 2.3

◆ VSIInstallSwiftStreamingFileHandler()

void VSIInstallSwiftStreamingFileHandler ( void  )

Install /vsiswift_streaming/ OpenStack Swif Object Storage (Swift) file system handler (requires libcurl)

embed:rst
See :ref:`/vsiswift_streaming/ documentation <vsiswift_streaming>`
Since
GDAL 2.3

◆ VSIInstallTarFileHandler()

void VSIInstallTarFileHandler ( void  )

Install /vsitar/ file system handler.

A special file handler is installed that allows reading on-the-fly in TAR (regular .tar, or compressed .tar.gz/.tgz) archives.

All portions of the file system underneath the base path "/vsitar/" will be handled by this driver.

embed:rst
See :ref:`/vsitar/ documentation <vsitar>`
Since
GDAL 1.8.0

◆ VSIInstallWebHdfsHandler()

void VSIInstallWebHdfsHandler ( void  )

Install /vsiwebhdfs/ WebHDFS (Hadoop File System) REST API file system handler (requires libcurl)

embed:rst
See :ref:`/vsiwebhdfs/ documentation <vsiwebhdfs>`
Since
GDAL 2.4

◆ VSIInstallZipFileHandler()

void VSIInstallZipFileHandler ( void  )

Install ZIP file system handler.

A special file handler is installed that allows reading on-the-fly in ZIP (.zip) archives.

All portions of the file system underneath the base path "/vsizip/" will be handled by this driver.

embed:rst
See :ref:`/vsizip/ documentation <vsizip>`
Since
GDAL 1.6.0

◆ VSIIsCaseSensitiveFS()

int VSIIsCaseSensitiveFS ( const char *  pszFilename)

Returns if the filenames of the filesystem are case sensitive.

This method retrieves to which filesystem belongs the passed filename and return TRUE if the filenames of that filesystem are case sensitive.

Currently, this will return FALSE only for Windows real filenames. Other VSI virtual filesystems are case sensitive.

This methods avoid ugly #ifndef WIN32 / #endif code, that is wrong when dealing with virtual filenames.

Parameters
pszFilenamethe path of the filesystem object to be tested. UTF-8 encoded.
Returns
TRUE if the filenames of the filesystem are case sensitive.
Since
GDAL 1.8.0

◆ VSIIsLocal()

bool VSIIsLocal ( const char *  pszPath)

Returns if the file/filesystem is "local".

The concept of local is mostly by opposition with a network / remote file system whose access time can be long.

/vsimem/ is considered to be a local file system, although a non-persistent one.

Parameters
pszPaththe path of the filesystem object to be tested. UTF-8 encoded.
Returns
TRUE or FALSE
Since
GDAL 3.6

◆ VSIMalloc()

void * VSIMalloc ( size_t  nSize)

Analog of malloc().

Use VSIFree() to free

◆ VSIMalloc2()

void * VSIMalloc2 ( size_t  nSize1,
size_t  nSize2 
)

VSIMalloc2 allocates (nSize1 * nSize2) bytes.

In case of overflow of the multiplication, or if memory allocation fails, a NULL pointer is returned and a CE_Failure error is raised with CPLError(). If nSize1 == 0 || nSize2 == 0, a NULL pointer will also be returned. CPLFree() or VSIFree() can be used to free memory allocated by this function.

◆ VSIMalloc3()

void * VSIMalloc3 ( size_t  nSize1,
size_t  nSize2,
size_t  nSize3 
)

VSIMalloc3 allocates (nSize1 * nSize2 * nSize3) bytes.

In case of overflow of the multiplication, or if memory allocation fails, a NULL pointer is returned and a CE_Failure error is raised with CPLError(). If nSize1 == 0 || nSize2 == 0 || nSize3 == 0, a NULL pointer will also be returned. CPLFree() or VSIFree() can be used to free memory allocated by this function.

◆ VSIMallocAligned()

void * VSIMallocAligned ( size_t  nAlignment,
size_t  nSize 
)

Allocates a buffer with an alignment constraint.

The return value must be freed with VSIFreeAligned().

Parameters
nAlignmentMust be a power of 2, multiple of sizeof(void*), and lesser than 256.
nSizeSize of the buffer to allocate.
Returns
a buffer aligned on nAlignment and of size nSize, or NULL
Since
GDAL 2.2

◆ VSIMallocAlignedAuto()

void * VSIMallocAlignedAuto ( size_t  nSize)

Allocates a buffer with an alignment constraint such that it can be used by the most demanding vector instruction set on that platform.

The return value must be freed with VSIFreeAligned().

Parameters
nSizeSize of the buffer to allocate.
Returns
an aligned buffer of size nSize, or NULL
Since
GDAL 2.2

◆ VSIMkdir()

int VSIMkdir ( const char *  pszPathname,
long  mode 
)

Create a directory.

Create a new directory with the indicated mode. For POSIX-style systems, the mode is modified by the file creation mask (umask). However, some file systems and platforms may not use umask, or they may ignore the mode completely. So a reasonable cross-platform default mode value is 0755.

Analog of the POSIX mkdir() function.

Parameters
pszPathnamethe path to the directory to create. UTF-8 encoded.
modethe permissions mode.
Returns
0 on success or -1 on an error.

◆ VSIMkdirRecursive()

int VSIMkdirRecursive ( const char *  pszPathname,
long  mode 
)

Create a directory and all its ancestors.

Parameters
pszPathnamethe path to the directory to create. UTF-8 encoded.
modethe permissions mode.
Returns
0 on success or -1 on an error.
Since
GDAL 2.3

◆ VSINetworkStatsGetAsSerializedJSON()

char * VSINetworkStatsGetAsSerializedJSON ( char **  papszOptions)

Return network related statistics, as a JSON serialized object.

Statistics collecting should be enabled with the CPL_VSIL_NETWORK_STATS_ENABLED configuration option set to YES before any network activity starts (for efficiency, reading it is cached on first access, until VSINetworkStatsReset() is called)

Statistics can also be emitted on standard output at process termination if the CPL_VSIL_SHOW_NETWORK_STATS configuration option is set to YES.

Example of output:

{
  "methods":{
    "GET":{
      "count":6,
      "downloaded_bytes":40825
    },
    "PUT":{
      "count":1,
      "uploaded_bytes":35472
    }
  },
  "handlers":{
    "vsigs":{
      "methods":{
        "GET":{
          "count":2,
          "downloaded_bytes":446
        },
        "PUT":{
          "count":1,
          "uploaded_bytes":35472
        }
      },
      "files":{
        "\/vsigs\/spatialys\/byte.tif":{
          "methods":{
            "PUT":{
              "count":1,
              "uploaded_bytes":35472
            }
          },
          "actions":{
            "Write":{
              "methods":{
                "PUT":{
                  "count":1,
                  "uploaded_bytes":35472
                }
              }
            }
          }
        }
      },
      "actions":{
        "Stat":{
          "methods":{
            "GET":{
              "count":2,
              "downloaded_bytes":446
            }
          },
          "files":{
            "\/vsigs\/spatialys\/byte.tif\/":{
              "methods":{
                "GET":{
                  "count":1,
                  "downloaded_bytes":181
                }
              }
            }
          }
        }
      }
    },
    "vsis3":{
         [...]
    }
  }
}

Parameters
papszOptionsUnused.
Returns
a JSON serialized string to free with VSIFree(), or nullptr
Since
GDAL 3.2.0

◆ VSINetworkStatsReset()

void VSINetworkStatsReset ( void  )

Clear network related statistics.

The effect of the CPL_VSIL_NETWORK_STATS_ENABLED configuration option will also be reset. That is, that the next network access will check its value again.

Since
GDAL 3.2.0

◆ VSIOpenDir()

VSIDIR * VSIOpenDir ( const char *  pszPath,
int  nRecurseDepth,
const char *const *  papszOptions 
)

Open a directory to read its entries.

This function is close to the POSIX opendir() function.

For /vsis3/, /vsigs/, /vsioss/, /vsiaz/ and /vsiadls/, this function has an efficient implementation, minimizing the number of network requests, when invoked with nRecurseDepth <= 0.

Entries are read by calling VSIGetNextDirEntry() on the handled returned by that function, until it returns NULL. VSICloseDir() must be called once done with the returned directory handle.

Parameters
pszPaththe relative, or absolute path of a directory to read. UTF-8 encoded.
nRecurseDepth0 means do not recurse in subdirectories, 1 means recurse only in the first level of subdirectories, etc. -1 means unlimited recursion level
papszOptionsNULL terminated list of options, or NULL. The following options are implemented:
  • PREFIX=string: (GDAL >= 3.4) Filter to select filenames only starting with the specified prefix. Implemented efficiently for /vsis3/, /vsigs/, and /vsiaz/ (but not /vsiadls/)
  • NAME_AND_TYPE_ONLY=YES/NO: (GDAL >= 3.4) Defaults to NO. If set to YES, only the pszName and nMode members of VSIDIR are guaranteed to be set. This is implemented efficiently for the Unix virtual file system.
Returns
a handle, or NULL in case of error
Since
GDAL 2.4

◆ VSIOverwriteFile()

int VSIOverwriteFile ( VSILFILE fpTarget,
const char *  pszSourceFilename 
)

Overwrite an existing file with content from another one.

Parameters
fpTargetfile handle opened with VSIFOpenL() with "rb+" flag.
pszSourceFilenamesource filename
Returns
TRUE in case of success.
Since
GDAL 3.1

◆ VSIReadDir()

char ** VSIReadDir ( const char *  pszPath)

Read names in a directory.

This function abstracts access to directory contains. It returns a list of strings containing the names of files, and directories in this directory. The resulting string list becomes the responsibility of the application and should be freed with CSLDestroy() when no longer needed.

Note that no error is issued via CPLError() if the directory path is invalid, though NULL is returned.

This function used to be known as CPLReadDir(), but the old name is now deprecated.

Parameters
pszPaththe relative, or absolute path of a directory to read. UTF-8 encoded.
Returns
The list of entries in the directory, or NULL if the directory doesn't exist. Filenames are returned in UTF-8 encoding.

◆ VSIReadDirEx()

char ** VSIReadDirEx ( const char *  pszPath,
int  nMaxFiles 
)

Read names in a directory.

This function abstracts access to directory contains. It returns a list of strings containing the names of files, and directories in this directory. The resulting string list becomes the responsibility of the application and should be freed with CSLDestroy() when no longer needed.

Note that no error is issued via CPLError() if the directory path is invalid, though NULL is returned.

If nMaxFiles is set to a positive number, directory listing will stop after that limit has been reached. Note that to indicate truncate, at least one element more than the nMaxFiles limit will be returned. If CSLCount() on the result is lesser or equal to nMaxFiles, then no truncation occurred.

Parameters
pszPaththe relative, or absolute path of a directory to read. UTF-8 encoded.
nMaxFilesmaximum number of files after which to stop, or 0 for no limit.
Returns
The list of entries in the directory, or NULL if the directory doesn't exist. Filenames are returned in UTF-8 encoding.
Since
GDAL 2.1

◆ VSIReadDirRecursive()

char ** VSIReadDirRecursive ( const char *  pszPathIn)

Read names in a directory recursively.

This function abstracts access to directory contents and subdirectories. It returns a list of strings containing the names of files and directories in this directory and all subdirectories. The resulting string list becomes the responsibility of the application and should be freed with CSLDestroy() when no longer needed.

Note that no error is issued via CPLError() if the directory path is invalid, though NULL is returned.

Parameters
pszPathInthe relative, or absolute path of a directory to read. UTF-8 encoded.
Returns
The list of entries in the directory and subdirectories or NULL if the directory doesn't exist. Filenames are returned in UTF-8 encoding.
Since
GDAL 1.10.0

◆ VSIRealloc()

void * VSIRealloc ( void *  pData,
size_t  nNewSize 
)

Analog of realloc().

Use VSIFree() to free

◆ VSIRename()

int VSIRename ( const char *  oldpath,
const char *  newpath 
)

Rename a file.

Renames a file object in the file system. It should be possible to rename a file onto a new filesystem, but it is safest if this function is only used to rename files that remain in the same directory.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX rename() function.

Parameters
oldpaththe name of the file to be renamed. UTF-8 encoded.
newpaththe name the file should be given. UTF-8 encoded.
Returns
0 on success or -1 on an error.

◆ VSIRewindL()

void VSIRewindL ( VSILFILE fp)

Rewind the file pointer to the beginning of the file.

This is equivalent to VSIFSeekL( fp, 0, SEEK_SET )

Analog of the POSIX rewind() call.

Parameters
fpfile handle opened with VSIFOpenL().

◆ VSIRmdir()

int VSIRmdir ( const char *  pszDirname)

Delete a directory.

Deletes a directory object from the file system. On some systems the directory must be empty before it can be deleted.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX rmdir() function.

Parameters
pszDirnamethe path of the directory to be deleted. UTF-8 encoded.
Returns
0 on success or -1 on an error.

◆ VSIRmdirRecursive()

int VSIRmdirRecursive ( const char *  pszDirname)

Delete a directory recursively.

Deletes a directory object and its content from the file system.

Starting with GDAL 3.1, /vsis3/ has an efficient implementation of this function. Starting with GDAL 3.4, /vsigs/ has an efficient implementation of this function, provided that OAuth2 authentication is used.

Returns
0 on success or -1 on an error.
Since
GDAL 2.3

◆ VSISetCredential()

void VSISetCredential ( const char *  pszPathPrefix,
const char *  pszKey,
const char *  pszValue 
)

Set a credential (or more generally an option related to a virtual file system) for a given path prefix.

That option may also be set as a configuration option with CPLSetConfigOption(), but this function allows to specify them with a granularity at the level of a file path, which makes it easier if using the same virtual file system but with different credentials (e.g. different credentials for bucket "/vsis3/foo" and "/vsis3/bar")

This is supported for the following virtual file systems: /vsis3/, /vsigs/, /vsiaz/, /vsioss/, /vsiwebhdfs, /vsiswift. Note: setting them for a path starting with /vsiXXX/ will also apply for /vsiXXX_streaming/ requests.

Note that no particular care is taken to store them in RAM in a secure way. So they might accidentally hit persistent storage if swapping occurs, or someone with access to the memory allocated by the process may be able to read them.

Parameters
pszPathPrefixa path prefix of a virtual file system handler. Typically of the form "/vsiXXX/bucket". Must NOT be NULL.
pszKeyOption name. Must NOT be NULL.
pszValueOption value. May be NULL to erase it.
Since
GDAL 3.5

◆ VSISetCryptKey()

void VSISetCryptKey ( const GByte pabyKey,
int  nKeySize 
)

Installs the encryption/decryption key.

By passing a NULL key, the previously installed key will be cleared. Note, however, that it is not guaranteed that there won't be trace of it in other places in memory or in on-disk temporary file.

Parameters
pabyKeykey. Might be NULL to clear previously set key.
nKeySizelength of the key in bytes. Might be 0 to clear previously set key.
See also
VSIInstallCryptFileHandler() for documentation on /vsicrypt/

◆ VSISetFileMetadata()

int VSISetFileMetadata ( const char *  pszFilename,
CSLConstList  papszMetadata,
const char *  pszDomain,
CSLConstList  papszOptions 
)

Set metadata on files.

Implemented currently only for /vsis3/, /vsigs/, /vsiaz/ and /vsiadls/

Parameters
pszFilenamethe path of the filesystem object to be set. UTF-8 encoded.
papszMetadataNULL-terminated list of key=value strings.
pszDomainMetadata domain to set. Depends on the file system. The following are supported:
papszOptionsNULL or NULL terminated list of options. For /vsiadls/ and pszDomain=ACL, "RECURSIVE=TRUE" can be set to set the access control list recursively. When RECURSIVE=TRUE is set, MODE should also be set to one of "set", "modify" or "remove".
Returns
TRUE in case of success.
Since
GDAL 3.1.0

◆ VSISiblingFiles()

char ** VSISiblingFiles ( const char *  pszFilename)

Return related filenames.

This function is essentially meant at being used by GDAL internals.

Parameters
pszFilenamethe path of a filename to inspect UTF-8 encoded.
Returns
The list of entries, relative to the directory, of all sidecar files available or NULL if the list is not known. Filenames are returned in UTF-8 encoding. Most implementations will return NULL, and a subsequent ReadDir will list all files available in the file's directory. This function will be overridden by VSI FilesystemHandlers that wish to force e.g. an empty list to avoid opening non-existent files on slow filesystems. The return value shall be destroyed with CSLDestroy()
Since
GDAL 3.2

◆ VSIStatExL()

int VSIStatExL ( const char *  pszFilename,
VSIStatBufL psStatBuf,
int  nFlags 
)

Get filesystem object info.

Fetches status information about a filesystem object (file, directory, etc). The returned information is placed in the VSIStatBufL structure. For portability, only use the st_size (size in bytes) and st_mode (file type). This method is similar to VSIStat(), but will work on large files on systems where this requires special calls.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX stat() function, with an extra parameter to specify which information is needed, which offers a potential for speed optimizations on specialized and potentially slow virtual filesystem objects (/vsigzip/, /vsicurl/)

Parameters
pszFilenamethe path of the filesystem object to be queried. UTF-8 encoded.
psStatBufthe structure to load with information.
nFlags0 to get all information, or VSI_STAT_EXISTS_FLAG, VSI_STAT_NATURE_FLAG, VSI_STAT_SIZE_FLAG, VSI_STAT_SET_ERROR_FLAG, VSI_STAT_CACHE_ONLY or a combination of those to get partial info.
Returns
0 on success or -1 on an error.
Since
GDAL 1.8.0

◆ VSIStatL()

int VSIStatL ( const char *  pszFilename,
VSIStatBufL psStatBuf 
)

Get filesystem object info.

Fetches status information about a filesystem object (file, directory, etc). The returned information is placed in the VSIStatBufL structure. For portability, only use the st_size (size in bytes) and st_mode (file type). This method is similar to VSIStat(), but will work on large files on systems where this requires special calls.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX stat() function.

Parameters
pszFilenamethe path of the filesystem object to be queried. UTF-8 encoded.
psStatBufthe structure to load with information.
Returns
0 on success or -1 on an error.

◆ VSIStdoutSetRedirection()

void VSIStdoutSetRedirection ( VSIWriteFunction  pFct,
FILE *  stream 
)

Set an alternative write function and output file handle instead of fwrite() / stdout.

Parameters
pFctFunction with same signature as fwrite()
streamFile handle on which to output. Passed to pFct.
Since
GDAL 2.0

◆ VSIStrdup()

char * VSIStrdup ( const char *  pszString)

Analog of strdup().

Use VSIFree() to free

◆ VSIStrerror()

char * VSIStrerror ( int  nErrno)

Return the error string corresponding to the error number.

Do not free it

◆ VSISupportsRandomWrite()

bool VSISupportsRandomWrite ( const char *  pszPath,
bool  bAllowLocalTempFile 
)

Returns if the filesystem supports random write.

Parameters
pszPaththe path of the filesystem object to be tested. UTF-8 encoded.
bAllowLocalTempFilewhether the file system is allowed to use a local temporary file before uploading to the target location.
Returns
TRUE or FALSE
Since
GDAL 3.6

◆ VSISupportsSequentialWrite()

bool VSISupportsSequentialWrite ( const char *  pszPath,
bool  bAllowLocalTempFile 
)

Returns if the filesystem supports sequential write.

Parameters
pszPaththe path of the filesystem object to be tested. UTF-8 encoded.
bAllowLocalTempFilewhether the file system is allowed to use a local temporary file before uploading to the target location.
Returns
TRUE or FALSE
Since
GDAL 3.6

◆ VSISupportsSparseFiles()

int VSISupportsSparseFiles ( const char *  pszPath)

Returns if the filesystem supports sparse files.

Only supported on Linux (and no other Unix derivatives) and Windows. On Linux, the answer depends on a few hardcoded signatures for common filesystems. Other filesystems will be considered as not supporting sparse files.

Parameters
pszPaththe path of the filesystem object to be tested. UTF-8 encoded.
Returns
TRUE if the file system is known to support sparse files. FALSE may be returned both in cases where it is known to not support them, or when it is unknown.
Since
GDAL 2.2

◆ VSISync()

int VSISync ( const char *  pszSource,
const char *  pszTarget,
const char *const *  papszOptions,
GDALProgressFunc  pProgressFunc,
void *  pProgressData,
char ***  ppapszOutputs 
)

Synchronize a source file/directory with a target file/directory.

This is a analog of the 'rsync' utility. In the current implementation, rsync would be more efficient for local file copying, but VSISync() main interest is when the source or target is a remote file system like /vsis3/ or /vsigs/, in which case it can take into account the timestamps of the files (or optionally the ETag/MD5Sum) to avoid unneeded copy operations.

This is only implemented efficiently for:

  • local filesystem <--> remote filesystem.
  • remote filesystem <--> remote filesystem (starting with GDAL 3.1). Where the source and target remote filesystems are the same and one of /vsis3/, /vsigs/ or /vsiaz/

Similarly to rsync behavior, if the source filename ends with a slash, it means that the content of the directory must be copied, but not the directory name. For example, assuming "/home/even/foo" contains a file "bar", VSISync("/home/even/foo/", "/mnt/media", ...) will create a "/mnt/media/bar" file. Whereas VSISync("/home/even/foo", "/mnt/media", ...) will create a "/mnt/media/foo" directory which contains a bar file.

Parameters
pszSourceSource file or directory. UTF-8 encoded.
pszTargetTarget file or directory. UTF-8 encoded.
papszOptionsNull terminated list of options, or NULL. Currently accepted options are:
  • RECURSIVE=NO (the default is YES)
  • SYNC_STRATEGY=TIMESTAMP/ETAG/OVERWRITE. Determines which criterion is used to determine if a target file must be replaced when it already exists and has the same file size as the source. Only applies for a source or target being a network filesystem.

    The default is TIMESTAMP (similarly to how 'aws s3 sync' works), that is to say that for an upload operation, a remote file is replaced if it has a different size or if it is older than the source. For a download operation, a local file is replaced if it has a different size or if it is newer than the remote file.

    The ETAG strategy assumes that the ETag metadata of the remote file is the MD5Sum of the file content, which is only true in the case of /vsis3/ for files not using KMS server side encryption and uploaded in a single PUT operation (so smaller than 50 MB given the default used by GDAL). Only to be used for /vsis3/, /vsigs/ or other filesystems using a MD5Sum as ETAG.

    The OVERWRITE strategy (GDAL >= 3.2) will always overwrite the target file with the source one.

  • NUM_THREADS=integer. (GDAL >= 3.1) Number of threads to use for parallel file copying. Only use for when /vsis3/, /vsigs/, /vsiaz/ or /vsiadls/ is in source or target. The default is 10 since GDAL 3.3
  • CHUNK_SIZE=integer. (GDAL >= 3.1) Maximum size of chunk (in bytes) to use to split large objects when downloading them from /vsis3/, /vsigs/, /vsiaz/ or /vsiadls/ to local file system, or for upload to /vsis3/, /vsiaz/ or /vsiadls/ from local file system. Only used if NUM_THREADS > 1. For upload to /vsis3/, this chunk size must be set at least to 5 MB. The default is 8 MB since GDAL 3.3
  • x-amz-KEY=value. (GDAL >= 3.5) MIME header to pass during creation of a /vsis3/ object.
  • x-goog-KEY=value. (GDAL >= 3.5) MIME header to pass during creation of a /vsigs/ object.
  • x-ms-KEY=value. (GDAL >= 3.5) MIME header to pass during creation of a /vsiaz/ or /vsiadls/ object.
pProgressFuncProgress callback, or NULL.
pProgressDataUser data of progress callback, or NULL.
ppapszOutputsUnused. Should be set to NULL for now.
Returns
TRUE on success or FALSE on an error.
Since
GDAL 2.4

◆ VSIUnlink()

int VSIUnlink ( const char *  pszFilename)

Delete a file.

Deletes a file object from the file system.

This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.

Analog of the POSIX unlink() function.

Parameters
pszFilenamethe path of the file to be deleted. UTF-8 encoded.
Returns
0 on success or -1 on an error.

◆ VSIUnlinkBatch()

int * VSIUnlinkBatch ( CSLConstList  papszFiles)

Delete several files, possibly in a batch.

All files should belong to the same file system handler.

This is implemented efficiently for /vsis3/ and /vsigs/ (provided for /vsigs/ that OAuth2 authentication is used).

Parameters
papszFilesNULL terminated list of files. UTF-8 encoded.
Returns
an array of size CSLCount(papszFiles), whose values are TRUE or FALSE depending on the success of deletion of the corresponding file. The array should be freed with VSIFree(). NULL might be return in case of a more general error (for example, files belonging to different file system handlers)
Since
GDAL 3.1