Common Portability Library C++ API

cpl_odbc.h

ODBC Abstraction Layer (C++).

class CPLODBCDriverInstaller
#include <cpl_odbc.h>

A class providing functions to install or remove ODBC driver.

Public Functions

CPLODBCDriverInstaller()
int InstallDriver(const char *pszDriver, const char *pszPathIn, WORD fRequest = ODBC_INSTALL_COMPLETE)

Installs ODBC driver or updates definition of already installed driver.

Interanally, it calls ODBC’s SQLInstallDriverEx function.

Return

TRUE indicates success, FALSE if it fails.

Parameters
  • pszDriver: - The driver definition as a list of keyword-value pairs describing the driver (See ODBC API Reference).

  • pszPathIn: - Full path of the target directory of the installation, or a null pointer (for unixODBC, NULL is passed).

  • fRequest: - The fRequest argument must contain one of the following values: ODBC_INSTALL_COMPLETE - (default) complete the installation request ODBC_INSTALL_INQUIRY - inquire about where a driver can be installed

int RemoveDriver(const char *pszDriverName, int fRemoveDSN = FALSE)

Removes or changes information about the driver from the Odbcinst.ini entry in the system information.

Return

The function returns TRUE if it is successful, FALSE if it fails. If no entry exists in the system information when this function is called, the function returns FALSE. In order to obtain usage count value, call GetUsageCount().

Parameters
  • pszDriverName: - The name of the driver as registered in the Odbcinst.ini key of the system information.

  • fRemoveDSN: - TRUE: Remove DSNs associated with the driver specified in lpszDriver. FALSE: Do not remove DSNs associated with the driver specified in lpszDriver.

int GetUsageCount() const

The usage count of the driver after this function has been called.

const char *GetPathOut() const

Path of the target directory where the driver should be installed.

For details, see ODBC API Reference and lpszPathOut parameter of SQLInstallDriverEx

const char *GetLastError() const

If InstallDriver returns FALSE, then GetLastError then error message can be obtained by calling this function.

Internally, it calls ODBC’s SQLInstallerError function.

DWORD GetLastErrorCode() const

If InstallDriver returns FALSE, then GetLastErrorCode then error code can be obtained by calling this function.

Internally, it calls ODBC’s SQLInstallerError function. See ODBC API Reference for possible error flags.

Private Members

char m_szPathOut[ODBC_FILENAME_MAX]
char m_szError[SQL_MAX_MESSAGE_LENGTH]
DWORD m_nErrorCode
DWORD m_nUsageCount
class CPLODBCSession
#include <cpl_odbc.h>

A class representing an ODBC database session.

Includes error collection services.

Public Functions

CPLODBCSession()

Constructor.

~CPLODBCSession()

Destructor.

int EstablishSession(const char *pszDSN, const char *pszUserid, const char *pszPassword)

Connect to database and logon.

Return

TRUE on success or FALSE on failure. Call GetLastError() to get details on failure.

Parameters
  • pszDSN: The name of the DSN being used to connect. This is not optional.

  • pszUserid: the userid to logon as, may be NULL if not not required, or provided by the DSN.

  • pszPassword: the password to logon with. May be NULL if not required or provided by the DSN.

const char *GetLastError()

Returns the last ODBC error message.

Return

pointer to an internal buffer with the error message in it. Do not free or alter. Will be an empty (but not NULL) string if there is no pending error info.

int ClearTransaction()

Clear transaction.

int BeginTransaction()

Begin transaction.

int CommitTransaction()

Commit transaction.

int RollbackTransaction()

Rollback transaction.

int IsInTransaction()

Returns whether a transaction is active.

int CloseSession()

Close session.

int Failed(int nRetCode, HSTMT hStmt = nullptr)

Test if a return code indicates failure, return TRUE if that is the case.

Also update error text.

ODBC error messages are reported in the following format: [SQLState]ErrorMessage(NativeErrorCode)

Multiple error messages are delimeted by “,”.

HDBC GetConnection()

Return connection handle.

HENV GetEnvironment()

Return GetEnvironment handle.

Private Members

CPLString m_osLastError = {}
HENV m_hEnv = nullptr
HDBC m_hDBC = nullptr
int m_bInTransaction = false
int m_bAutoCommit = true
class CPLODBCStatement
#include <cpl_odbc.h>

Abstraction for statement, and resultset.

Includes methods for executing an SQL statement, and for accessing the resultset from that statement. Also provides for executing other ODBC requests that produce results sets such as SQLColumns() and SQLTables() requests.

Public Functions

CPLODBCStatement(CPLODBCSession *poSession)

Constructor.

~CPLODBCStatement()

Destructor.

HSTMT GetStatement()

Return statement handle.

void Clear()

Clear internal command text and result set definitions.

void AppendEscaped(const char *pszText)

Append text to internal command.

The passed text is appended to the internal SQL command text after escaping any special characters so it can be used as a character string in an SQL statement.

Parameters
  • pszText: text to append.

void Append(const char *pszText)

Append text to internal command.

The passed text is appended to the internal SQL command text.

Parameters
  • pszText: text to append.

void Append(int nValue)

Append to internal command.

The passed value is formatted and appended to the internal SQL command text.

Parameters
  • nValue: value to append to the command.

void Append(double dfValue)

Append to internal command.

The passed value is formatted and appended to the internal SQL command text.

Parameters
  • dfValue: value to append to the command.

int Appendf(const char *pszFormat, ...)

Append to internal command.

The passed format is used to format other arguments and the result is appended to the internal command text. Long results may not be formatted properly, and should be appended with the direct Append() methods.

Return

FALSE if formatting fails due to result being too large.

Parameters
  • pszFormat: printf() style format string.

const char *GetCommand()

Return statement string.

int ExecuteSQL(const char *pszStatement = nullptr)

Execute an SQL statement.

This method will execute the passed (or stored) SQL statement, and initialize information about the resultset if there is one. If a NULL statement is passed, the internal stored statement that has been previously set via Append() or Appendf() calls will be used.

Return

TRUE on success or FALSE if there is an error. Error details can be fetched with OGRODBCSession::GetLastError().

Parameters
  • pszStatement: the SQL statement to execute, or NULL if the internally saved one should be used.

int Fetch(int nOrientation = SQL_FETCH_NEXT, int nOffset = 0)

Fetch a new record.

Requests the next row in the current resultset using the SQLFetchScroll() call. Note that many ODBC drivers only support the default forward fetching one record at a time. Only SQL_FETCH_NEXT (the default) should be considered reliable on all drivers.

Currently it isn’t clear how to determine whether an error or a normal out of data condition has occurred if Fetch() fails.

Return

TRUE if a new row is successfully fetched, or FALSE if not.

Parameters
  • nOrientation: One of SQL_FETCH_NEXT, SQL_FETCH_LAST, SQL_FETCH_PRIOR, SQL_FETCH_ABSOLUTE, or SQL_FETCH_RELATIVE (default is SQL_FETCH_NEXT).

  • nOffset: the offset (number of records), ignored for some orientations.

void ClearColumnData()

ClearColumnData.

int GetColCount()

Fetch the resultset column count.

Return

the column count, or zero if there is no resultset.

const char *GetColName(int iCol)

Fetch a column name.

Return

NULL on failure (out of bounds column), or a pointer to an internal copy of the column name.

Parameters
  • iCol: the zero based column index.

short GetColType(int iCol)

Fetch a column data type.

The return type code is a an ODBC SQL_ code, one of SQL_UNKNOWN_TYPE, SQL_CHAR, SQL_NUMERIC, SQL_DECIMAL, SQL_INTEGER, SQL_SMALLINT, SQL_FLOAT, SQL_REAL, SQL_DOUBLE, SQL_DATETIME, SQL_VARCHAR, SQL_TYPE_DATE, SQL_TYPE_TIME, SQL_TYPE_TIMESTAMPT.

Return

type code or -1 if the column is illegal.

Parameters
  • iCol: the zero based column index.

const char *GetColTypeName(int iCol)

Fetch a column data type name.

Returns data source-dependent data type name; for example, “CHAR”, “VARCHAR”, “MONEY”, “LONG VARBINAR”, or “CHAR ( ) FOR BIT DATA”.

Return

NULL on failure (out of bounds column), or a pointer to an internal copy of the column dat type name.

Parameters
  • iCol: the zero based column index.

short GetColSize(int iCol)

Fetch the column width.

Return

column width, zero for unknown width columns.

Parameters
  • iCol: the zero based column index.

short GetColPrecision(int iCol)

Fetch the column precision.

Return

column precision, may be zero or the same as column size for columns to which it does not apply.

Parameters
  • iCol: the zero based column index.

short GetColNullable(int iCol)

Fetch the column nullability.

Return

TRUE if the column may contains or FALSE otherwise.

Parameters
  • iCol: the zero based column index.

const char *GetColColumnDef(int iCol)

Fetch a column default value.

Returns the default value of a column.

Return

NULL if the default value is not dpecified or the internal copy of the default value.

Parameters
  • iCol: the zero based column index.

int GetColId(const char *pszColName)

Fetch column index.

Gets the column index corresponding with the passed name. The name comparisons are case insensitive.

Return

the column index, or -1 if not found.

Parameters
  • pszColName: the name to search for.

const char *GetColData(int iCol, const char *pszDefault = nullptr)

Fetch column data.

Fetches the data contents of the requested column for the currently loaded row. The result is returned as a string regardless of the column type. NULL is returned if an illegal column is given, or if the actual column is “NULL”.

Return

pointer to internal column data or NULL on failure.

Parameters
  • iCol: the zero based column to fetch.

  • pszDefault: the value to return if the column does not exist, or is NULL. Defaults to NULL.

const char *GetColData(const char *pszColName, const char *pszDefault = nullptr)

Fetch column data.

Fetches the data contents of the requested column for the currently loaded row. The result is returned as a string regardless of the column type. NULL is returned if an illegal column is given, or if the actual column is “NULL”.

Return

pointer to internal column data or NULL on failure.

Parameters
  • pszColName: the name of the column requested.

  • pszDefault: the value to return if the column does not exist, or is NULL. Defaults to NULL.

int GetColDataLength(int iCol)

GetColDataLength.

int GetRowCountAffected()

GetRowCountAffected.

int GetColumns(const char *pszTable, const char *pszCatalog = nullptr, const char *pszSchema = nullptr)

Fetch column definitions for a table.

The SQLColumn() method is used to fetch the definitions for the columns of a table (or other queryable object such as a view). The column definitions are digested and used to populate the CPLODBCStatement column definitions essentially as if a “SELECT * FROM tablename” had been done; however, no resultset will be available.

Return

TRUE on success or FALSE on failure.

Parameters
  • pszTable: the name of the table to query information on. This should not be empty.

  • pszCatalog: the catalog to find the table in, use NULL (the default) if no catalog is available.

  • pszSchema: the schema to find the table in, use NULL (the default) if no schema is available.

int GetPrimaryKeys(const char *pszTable, const char *pszCatalog = nullptr, const char *pszSchema = nullptr)

Fetch primary keys for a table.

The SQLPrimaryKeys() function is used to fetch a list of fields forming the primary key. The result is returned as a result set matching the SQLPrimaryKeys() function result set. The 4th column in the result set is the column name of the key, and if the result set contains only one record then that single field will be the complete primary key.

Return

TRUE on success or FALSE on failure.

Parameters
  • pszTable: the name of the table to query information on. This should not be empty.

  • pszCatalog: the catalog to find the table in, use NULL (the default) if no catalog is available.

  • pszSchema: the schema to find the table in, use NULL (the default) if no schema is available.

int GetTables(const char *pszCatalog = nullptr, const char *pszSchema = nullptr)

Fetch tables in database.

The SQLTables() function is used to fetch a list tables in the database. The result is returned as a result set matching the SQLTables() function result set. The 3rd column in the result set is the table name. Only tables of type “TABLE” are returned.

Return

TRUE on success or FALSE on failure.

Parameters
  • pszCatalog: the catalog to find the table in, use NULL (the default) if no catalog is available.

  • pszSchema: the schema to find the table in, use NULL (the default) if no schema is available.

void DumpResult(FILE *fp, int bShowSchema = FALSE)

Dump resultset to file.

The contents of the current resultset are dumped in a simply formatted form to the provided file. If requested, the schema definition will be written first.

Parameters
  • fp: the file to write to. stdout or stderr are acceptable.

  • bShowSchema: TRUE to force writing schema information for the rowset before the rowset data itself. Default is FALSE.

int CollectResultsInfo()

CollectResultsInfo.

Public Static Functions

CPLString GetTypeName(int nTypeCode)

Get name for SQL column type.

Returns a string name for the indicated type code (as returned from CPLODBCStatement::GetColType()).

Return

internal string, “UNKNOWN” if code not recognised.

Parameters
  • nTypeCode: the SQL_ code, such as SQL_CHAR.

SQLSMALLINT GetTypeMapping(SQLSMALLINT nTypeCode)

Get appropriate C data type for SQL column type.

Returns a C data type code, corresponding to the indicated SQL data type code (as returned from CPLODBCStatement::GetColType()).

Return

data type code. The valid code is always returned. If SQL code is not recognised, SQL_C_BINARY will be returned.

Parameters
  • nTypeCode: the SQL_ code, such as SQL_CHAR.

Private Functions

int Failed(int nResultCode)

Failed.

Private Members

CPLODBCSession *m_poSession = nullptr
HSTMT m_hStmt = nullptr
SQLSMALLINT m_nColCount = 0
char **m_papszColNames = nullptr
SQLSMALLINT *m_panColType = nullptr
char **m_papszColTypeNames = nullptr
CPL_SQLULEN *m_panColSize = nullptr
SQLSMALLINT *m_panColPrecision = nullptr
SQLSMALLINT *m_panColNullable = nullptr
char **m_papszColColumnDef = nullptr
char **m_papszColValues = nullptr
CPL_SQLLEN *m_panColValueLengths = nullptr
char *m_pszStatement = nullptr
size_t m_nStatementMax = 0
size_t m_nStatementLen = 0

cpl_vsi_virtual.h

Functions

VSIVirtualHandle *VSICreateBufferedReaderHandle(VSIVirtualHandle *poBaseHandle)
VSIVirtualHandle *VSICreateBufferedReaderHandle(VSIVirtualHandle *poBaseHandle, const GByte *pabyBeginningContent, vsi_l_offset nCheatFileSize)
VSIVirtualHandle *VSICreateCachedFile(VSIVirtualHandle *poBaseHandle, size_t nChunkSize = 32768, size_t nCacheSize = 0)
VSIVirtualHandle *VSICreateGZipWritable(VSIVirtualHandle *poBaseHandle, int nDeflateType, int bAutoCloseBaseHandle)
VSIVirtualHandle *VSICreateUploadOnCloseFile(VSIVirtualHandle *poBaseHandle)

Variables

const int CPL_DEFLATE_TYPE_GZIP = 0
const int CPL_DEFLATE_TYPE_ZLIB = 1
const int CPL_DEFLATE_TYPE_RAW_DEFLATE = 2
class VSIVirtualHandle
#include <cpl_vsi_virtual.h>

Virtual file handle.

Subclassed by VSISparseFileHandle, VSISubFileHandle, VSIUploadOnCloseHandle

Public Functions

int Seek(vsi_l_offset nOffset, int nWhence) = 0

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 handle->Seek( handle->Tell() + negative_offset, SEEK_SET ).

Return

0 on success or -1 one failure.

Parameters
  • nOffset: offset in bytes.

  • nWhence: one of SEEK_SET, SEEK_CUR or SEEK_END.

Tell() = 0

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.

Return

file offset in bytes.

Read(void *pBuffer, size_t nSize, size_t nCount) = 0

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.

Return

number of objects successfully read.

Parameters
  • pBuffer: the buffer into which the data should be read (at least nCount * nSize bytes in size.

  • nSize: size of objects to read in bytes.

  • nCount: number of objects to read.

ReadMultiRange(int nRanges, void **ppData, const vsi_l_offset *panOffsets, const size_t *panSizes)

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/.

Return

0 in case of success, -1 otherwise.

Since

GDAL 1.9.0

Parameters
  • nRanges: number of ranges to read.

  • ppData: array of nRanges buffer into which the data should be read (ppData[i] must be at list panSizes[i] bytes).

  • panOffsets: array of nRanges offsets at which the data should be read.

  • panSizes: array of nRanges sizes of objects to read (in bytes).

Write(const void *pBuffer, size_t nSize, size_t nCount) = 0

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.

Return

number of objects successfully written.

Parameters
  • pBuffer: the buffer from which the data should be written (at least nCount * nSize bytes in size.

  • nSize: size of objects to read in bytes.

  • nCount: number of objects to read.

Eof() = 0

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.

Return

TRUE if at EOF else FALSE.

Flush()

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.

Return

0 on success or -1 on error.

Close() = 0

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.

Return

0 on success or -1 on failure.

Truncate(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.

Return

0 on success

Since

GDAL 1.9.0

Parameters
  • nNewSize: new size in bytes.

GetNativeFileDescriptor()

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.

Return

the native file descriptor, or NULL.

GetRangeStatus(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”.

Return

extent status: VSI_RANGE_STATUS_UNKNOWN, VSI_RANGE_STATUS_DATA or VSI_RANGE_STATUS_HOLE

Since

GDAL 2.2

Parameters
  • nOffset: offset of the start of the extent.

  • nLength: extent length.

virtual ~VSIVirtualHandle()