#include "cpl_port.h"
#include <unistd.h>
#include <sys/stat.h>
Go to the source code of this file.
Functions | |
VSILFILE CPL_DLL * | VSIFOpenL (const char *, const char *) CPL_WARN_UNUSED_RESULT |
Open file. | |
int CPL_DLL | VSIFCloseL (VSILFILE *) |
Close file. | |
int CPL_DLL | VSIFSeekL (VSILFILE *, vsi_l_offset, int) |
Seek to requested offset. | |
vsi_l_offset CPL_DLL | VSIFTellL (VSILFILE *) |
Tell current file offset. | |
size_t CPL_DLL | VSIFReadL (void *, size_t, size_t, VSILFILE *) |
Read bytes from file. | |
int CPL_DLL | VSIFReadMultiRangeL (int nRanges, void **ppData, const vsi_l_offset *panOffsets, const size_t *panSizes, VSILFILE *) |
Read several ranges of bytes from file. | |
size_t CPL_DLL | VSIFWriteL (const void *, size_t, size_t, VSILFILE *) |
Write bytes to file. | |
int CPL_DLL | VSIFEofL (VSILFILE *) |
Test for end of file. | |
int CPL_DLL | VSIFTruncateL (VSILFILE *, vsi_l_offset) |
Truncate/expand the file to the specified size. | |
int CPL_DLL | VSIFFlushL (VSILFILE *) |
Flush pending writes to disk. | |
int CPL_DLL | VSIStatL (const char *, VSIStatBufL *) |
Get filesystem object info. | |
int CPL_DLL | VSIStatExL (const char *pszFilename, VSIStatBufL *psStatBuf, int nFlags) |
Get filesystem object info. | |
int CPL_DLL | VSIIsCaseSensitiveFS (const char *pszFilename) |
Returns if the filenames of the filesystem are case sensitive. | |
void CPL_DLL * | VSIMalloc2 (size_t nSize1, size_t nSize2) CPL_WARN_UNUSED_RESULT |
void CPL_DLL * | VSIMalloc3 (size_t nSize1, size_t nSize2, size_t nSize3) CPL_WARN_UNUSED_RESULT |
char CPL_DLL ** | VSIReadDir (const char *) |
Read names in a directory. | |
int CPL_DLL | VSIMkdir (const char *pathname, long mode) |
Create a directory. | |
int CPL_DLL | VSIRmdir (const char *pathname) |
Delete a directory. | |
int CPL_DLL | VSIUnlink (const char *pathname) |
Delete a file. | |
int CPL_DLL | VSIRename (const char *oldpath, const char *newpath) |
Rename a file. | |
void CPL_DLL | VSIInstallMemFileHandler (void) |
Install "memory" file system handler. | |
void CPL_DLL | VSIInstallSubFileHandler (void) |
void | VSIInstallGZipFileHandler (void) |
Install GZip file system handler. | |
void | VSIInstallZipFileHandler (void) |
Install ZIP file system handler. | |
void | VSIInstallStdinHandler (void) |
Install /vsistdin/ file system handler. | |
void | VSIInstallStdoutHandler (void) |
Install /vsistdout/ file system handler. | |
void CPL_DLL | VSIInstallSparseFileHandler (void) |
void | VSIInstallTarFileHandler (void) |
Install /vsitar/ file system handler. | |
VSILFILE CPL_DLL * | VSIFileFromMemBuffer (const char *pszFilename, GByte *pabyData, vsi_l_offset nDataLength, int bTakeOwnership) |
Create memory "file" from a buffer. | |
GByte CPL_DLL * | VSIGetMemFileBuffer (const char *pszFilename, vsi_l_offset *pnDataLength, int bUnlinkAndSeize) |
Fetch buffer underlying memory file. |
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.
Is 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.
int CPL_DLL 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.
fp | file handle opened with VSIFOpenL(). |
int CPL_DLL VSIFEofL | ( | VSILFILE * | fp | ) |
Test for end of file.
Returns TRUE (non-zero) if an end-of-file condition occured during the previous read operation. The end-of-file flag is cleared by a successfull 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.
fp | file handle opened with VSIFOpenL(). |
int CPL_DLL 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.
fp | file handle opened with VSIFOpenL(). |
VSILFILE CPL_DLL* 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.
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.
pszFilename | the filename to be created. | |
pabyData | the data buffer for the file. | |
nDataLength | the length of buffer in bytes. | |
bTakeOwnership | TRUE to transfer "ownership" of buffer or FALSE. |
VSILFILE CPL_DLL* 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, retoring 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.
pszFilename | the file to open. UTF-8 encoded. | |
pszAccess | access requested (ie. "r", "r+", "w". |
size_t CPL_DLL 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.
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. | |
fp | file handle opened with VSIFOpenL(). |
int CPL_DLL 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/.
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). | |
fp | file handle opened with VSIFOpenL(). |
int CPL_DLL 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.
fp | file handle opened with VSIFOpenL(). | |
nOffset | offset in bytes. | |
nWhence | one of SEEK_SET, SEEK_CUR or SEEK_END. |
vsi_l_offset CPL_DLL 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.
fp | file handle opened with VSIFOpenL(). |
int CPL_DLL 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.
fp | file handle opened with VSIFOpenL(). | |
nNewSize | new size in bytes. |
size_t CPL_DLL 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.
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. | |
fp | file handle opened with VSIFOpenL(). |
GByte CPL_DLL* 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 existance.
pszFilename | the name of the file to grab the buffer of. | |
pnDataLength | (file) length returned in this variable. | |
bUnlinkAndSeize | TRUE to remove the file, or FALSE to leave unaltered. |
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.
Additional documentation is to be found at http://trac.osgeo.org/gdal/wiki/UserDocs/ReadInZip
void CPL_DLL 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.
At this time the memory handler does not properly handle directory semantics for the memory portion of the filesystem. The VSIReadDir() function is not supported though this will be corrected in the future.
Calling this function repeatedly should do no harm, though it is not necessary. It is already called the first time a virtualizable file access function (ie. VSIFOpenL(), VSIMkDir(), etc) is called.
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 ); }
void CPL_DLL VSIInstallSparseFileHandler | ( | void | ) |
Install /vsisparse/ virtual file handler.
The sparse virtual file handler allows a virtual file to be composed from chunks of data in other files, potentially with large spaces in the virtual file set to a constant value. This can make it possible to test some sorts of operations on what seems to be a large file with image data set to a constant value. It is also helpful when wanting to add test files to the test suite that are too large, but for which most of the data can be ignored. It could, in theory, also be used to treat several files on different file systems as one large virtual file.
The file referenced by /vsisparse/ should be an XML control file formatted something like:
<VSISparseFile> <Length>87629264</Length> <SubfileRegion> Stuff at start of file. <Filename relative="1">251_head.dat</Filename> <DestinationOffset>0</DestinationOffset> <SourceOffset>0</SourceOffset> <RegionLength>2768</RegionLength> </SubfileRegion> <SubfileRegion> RasterDMS node. <Filename relative="1">251_rasterdms.dat</Filename> <DestinationOffset>87313104</DestinationOffset> <SourceOffset>0</SourceOffset> <RegionLength>160</RegionLength> </SubfileRegion> <SubfileRegion> Stuff at end of file. <Filename relative="1">251_tail.dat</Filename> <DestinationOffset>87611924</DestinationOffset> <SourceOffset>0</SourceOffset> <RegionLength>17340</RegionLength> </SubfileRegion> <ConstantRegion> Default for the rest of the file. <DestinationOffset>0</DestinationOffset> <RegionLength>87629264</RegionLength> <Value>0</Value> </ConstantRegion> </VSISparseFile>
Hopefully the values and semantics are fairly obvious.
This driver is installed by default.
void VSIInstallStdinHandler | ( | void | ) |
Install /vsistdin/ file system handler.
A special file handler is installed that allows reading from the standard input steam.
The file operations available are of course limited to Read() and forward Seek() (full seek in the first MB of a file).
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().
void CPL_DLL VSIInstallSubFileHandler | ( | void | ) |
Install /vsisubfile/ virtual file handler.
This virtual file system handler allows access to subregions of files, treating them as a file on their own to the virtual file system functions (VSIFOpenL(), etc).
A special form of the filename is used to indicate a subportion of another file:
/vsisubfile/<offset>[_<size>],<filename>
The size parameter is optional. Without it the remainder of the file from the start offset as treated as part of the subfile. Otherwise only <size> bytes from <offset> are treated as part of the subfile. The <filename> portion may be a relative or absolute path using normal rules. The <offset> and <size> values are in bytes.
eg. /vsisubfile/1000_3000,/data/abc.ntf /vsisubfile/5000,../xyz/raw.dat
Unlike the /vsimem/ or conventional file system handlers, there is no meaningful support for filesystem operations for creating new files, traversing directories, and deleting files within the /vsisubfile/ area. Only the VSIStatL(), VSIFOpenL() and operations based on the file handle returned by VSIFOpenL() operate properly.
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.
The syntax to open a file inside a zip file is /vsitar/path/to/the/file.tar/path/inside/the/tar/file were path/to/the/file.tar is relative or absolute and path/inside/the/tar/file is the relative path to the file inside the archive.
If the path is absolute, it should begin with a / on a Unix-like OS (or C:\ on Windows), so the line looks like /vsitar//home/gdal/... For example gdalinfo /vsitar/myarchive.tar/subdir1/file1.tif
Syntaxic sugar : if the tar archive contains only one file located at its root, just mentionning "/vsitar/path/to/the/file.tar" will work
VSIStatL() will return the uncompressed size in st_size member and file nature- file or directory - in st_mode member.
Directory listing is available through VSIReadDir().
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.
The syntax to open a file inside a zip file is /vsizip/path/to/the/file.zip/path/inside/the/zip/file were path/to/the/file.zip is relative or absolute and path/inside/the/zip/file is the relative path to the file inside the archive.
If the path is absolute, it should begin with a / on a Unix-like OS (or C:\ on Windows), so the line looks like /vsizip//home/gdal/... For example gdalinfo /vsizip/myarchive.zip/subdir1/file1.tif
Syntaxic sugar : if the .zip file contains only one file located at its root, just mentionning "/vsizip/path/to/the/file.zip" will work
VSIStatL() will return the uncompressed size in st_size member and file nature- file or directory - in st_mode member.
Directory listing is available through VSIReadDir().
Since GDAL 1.8.0, write capabilities are available. They allow creating a new zip file and adding new files to an already existing (or just created) zip file. Read and write operations cannot be interleaved : the new zip must be closed before being re-opened for read.
Additional documentation is to be found at http://trac.osgeo.org/gdal/wiki/UserDocs/ReadInZip
int CPL_DLL 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.
pszFilename | the path of the filesystem object to be tested. UTF-8 encoded. |
void CPL_DLL* 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.
void CPL_DLL* 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.
int CPL_DLL VSIMkdir | ( | const char * | pszPathname, | |
long | mode | |||
) |
Create a directory.
Create a new directory with the indicated mode. The mode is ignored on some platforms. A reasonable default mode value would be 0666. This method goes through the VSIFileHandler virtualization and may work on unusual filesystems such as in memory.
Analog of the POSIX mkdir() function.
pszPathname | the path to the directory to create. UTF-8 encoded. | |
mode | the permissions mode. |
char CPL_DLL** 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.
pszPath | the relative, or absolute path of a directory to read. UTF-8 encoded. |
int CPL_DLL 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.
oldpath | the name of the file to be renamed. UTF-8 encoded. | |
newpath | the name the file should be given. UTF-8 encoded. |
int CPL_DLL 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.
pszDirname | the path of the directory to be deleted. UTF-8 encoded. |
int CPL_DLL 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 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/)
pszFilename | the path of the filesystem object to be queried. UTF-8 encoded. | |
psStatBuf | the structure to load with information. | |
nFlags | 0 to get all information, or VSI_STAT_EXISTS_FLAG, VSI_STAT_NATURE_FLAG or VSI_STAT_SIZE_FLAG, or a combination of those to get partial info. |
int CPL_DLL 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 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.
pszFilename | the path of the filesystem object to be queried. UTF-8 encoded. | |
psStatBuf | the structure to load with information. |
int CPL_DLL 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.
pszFilename | the path of the file to be deleted. UTF-8 encoded. |