GDAL
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Standard C Covers. More...
Go to the source code of this file.
Macros | |
#define | EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
#define | VSI_ISLNK(x) S_ISLNK(x) |
#define | VSI_ISREG(x) S_ISREG(x) |
#define | VSI_ISDIR(x) S_ISDIR(x) |
#define | VSI_ISCHR(x) S_ISCHR(x) |
#define | VSI_ISBLK(x) S_ISBLK(x) |
#define | VSI_L_OFFSET_MAX GUINTBIG_MAX |
#define | VSI_STAT_EXISTS_FLAG 0x1 |
#define | VSI_STAT_NATURE_FLAG 0x2 |
#define | VSI_STAT_SIZE_FLAG 0x4 |
#define | VSI_STAT_SET_ERROR_FLAG 0x8 |
#define | VSI_MALLOC_VERBOSE(size) VSIMallocVerbose(size,__FILE__,__LINE__) |
#define | VSI_MALLOC2_VERBOSE(nSize1, nSize2) VSIMalloc2Verbose(nSize1,nSize2,__FILE__,__LINE__) |
#define | VSI_MALLOC3_VERBOSE(nSize1, nSize2, nSize3) VSIMalloc3Verbose(nSize1,nSize2,nSize3,__FILE__,__LINE__) |
#define | VSI_CALLOC_VERBOSE(nCount, nSize) VSICallocVerbose(nCount,nSize,__FILE__,__LINE__) |
#define | VSI_REALLOC_VERBOSE(pOldPtr, nNewSize) VSIReallocVerbose(pOldPtr,nNewSize,__FILE__,__LINE__) |
#define | VSI_STRDUP_VERBOSE(pszStr) VSIStrdupVerbose(pszStr,__FILE__,__LINE__) |
#define | CPLReadDir VSIReadDir |
#define | VSIDebug4(f, a1, a2, a3, a4) {} |
#define | VSIDebug3(f, a1, a2, a3) {} |
#define | VSIDebug2(f, a1, a2) {} |
#define | VSIDebug1(f, a1) {} |
Functions | |
FILE * | VSIFOpen (const char *, const char *) CPL_WARN_UNUSED_RESULT |
int | VSIFClose (FILE *) |
int | VSIFSeek (FILE *, long, int) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
long | VSIFTell (FILE *) CPL_WARN_UNUSED_RESULT |
void | VSIRewind (FILE *) |
void | VSIFFlush (FILE *) |
size_t | VSIFRead (void *, size_t, size_t, FILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
size_t | VSIFWrite (const void *, size_t, size_t, FILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
char * | VSIFGets (char *, int, FILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
int | VSIFPuts (const char *, FILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
int | VSIFPrintf (FILE *, const char *,...) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
int | VSIFGetc (FILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
int | VSIFPutc (int, FILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
int | VSIUngetc (int, FILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
int | VSIFEof (FILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
int | VSIStat (const char *, VSIStatBuf *) CPL_WARN_UNUSED_RESULT |
VSILFILE * | VSIFOpenL (const char *, const char *) CPL_WARN_UNUSED_RESULT |
Open file. More... | |
VSILFILE * | VSIFOpenExL (const char *, const char *, int) CPL_WARN_UNUSED_RESULT |
Open file. More... | |
int | VSIFCloseL (VSILFILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Close file. More... | |
int | VSIFSeekL (VSILFILE *, vsi_l_offset, int) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Seek to requested offset. More... | |
vsi_l_offset | VSIFTellL (VSILFILE *) CPL_WARN_UNUSED_RESULT |
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 *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Read bytes from file. More... | |
int | VSIFReadMultiRangeL (int nRanges, void **ppData, const vsi_l_offset *panOffsets, const size_t *panSizes, VSILFILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Read several ranges of bytes from file. More... | |
size_t | VSIFWriteL (const void *, size_t, size_t, VSILFILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Write bytes to file. More... | |
int | VSIFEofL (VSILFILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Test for end of file. More... | |
int | VSIFTruncateL (VSILFILE *, vsi_l_offset) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Truncate/expand the file to the specified size. More... | |
int | VSIFFlushL (VSILFILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Flush pending writes to disk. More... | |
int | VSIFPrintfL (VSILFILE *, const char *,...) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Formatted write to file. More... | |
int | VSIFPutcL (int, VSILFILE *) EXPERIMENTAL_CPL_WARN_UNUSED_RESULT |
Write a single byte to the file. More... | |
int | VSIIngestFile (VSILFILE *fp, const char *pszFilename, GByte **ppabyRet, vsi_l_offset *pnSize, GIntBig nMaxSize) CPL_WARN_UNUSED_RESULT |
Ingest a file into memory. More... | |
int | VSIStatL (const char *, VSIStatBufL *) CPL_WARN_UNUSED_RESULT |
Get filesystem object info. More... | |
int | VSIStatExL (const char *pszFilename, VSIStatBufL *psStatBuf, int nFlags) CPL_WARN_UNUSED_RESULT |
Get filesystem object info. More... | |
int | VSIIsCaseSensitiveFS (const char *pszFilename) |
Returns if the filenames of the filesystem are case sensitive. More... | |
void * | VSIFGetNativeFileDescriptorL (VSILFILE *) |
Returns the "native" file descriptor for the virtual handle. More... | |
void * | VSICalloc (size_t, size_t) CPL_WARN_UNUSED_RESULT |
void * | VSIMalloc (size_t) CPL_WARN_UNUSED_RESULT |
void | VSIFree (void *) |
void * | VSIRealloc (void *, size_t) CPL_WARN_UNUSED_RESULT |
char * | VSIStrdup (const char *) CPL_WARN_UNUSED_RESULT |
void * | VSIMalloc2 (size_t nSize1, size_t nSize2) CPL_WARN_UNUSED_RESULT |
VSIMalloc2 allocates (nSize1 * nSize2) bytes. More... | |
void * | VSIMalloc3 (size_t nSize1, size_t nSize2, size_t nSize3) CPL_WARN_UNUSED_RESULT |
VSIMalloc3 allocates (nSize1 * nSize2 * nSize3) bytes. More... | |
void * | VSIMallocVerbose (size_t nSize, const char *pszFile, int nLine) CPL_WARN_UNUSED_RESULT |
void * | VSIMalloc2Verbose (size_t nSize1, size_t nSize2, const char *pszFile, int nLine) CPL_WARN_UNUSED_RESULT |
void * | VSIMalloc3Verbose (size_t nSize1, size_t nSize2, size_t nSize3, const char *pszFile, int nLine) CPL_WARN_UNUSED_RESULT |
void * | VSICallocVerbose (size_t nCount, size_t nSize, const char *pszFile, int nLine) CPL_WARN_UNUSED_RESULT |
void * | VSIReallocVerbose (void *pOldPtr, size_t nNewSize, const char *pszFile, int nLine) CPL_WARN_UNUSED_RESULT |
char * | VSIStrdupVerbose (const char *pszStr, const char *pszFile, int nLine) CPL_WARN_UNUSED_RESULT |
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... | |
int | VSIMkdir (const char *pathname, long mode) |
Create a directory. More... | |
int | VSIRmdir (const char *pathname) |
Delete a directory. More... | |
int | VSIUnlink (const char *pathname) |
Delete a file. More... | |
int | VSIRename (const char *oldpath, const char *newpath) |
Rename a file. More... | |
char * | VSIStrerror (int) |
GIntBig | VSIGetDiskFreeSpace (const char *pszDirname) |
Return free disk space available on the filesystem. More... | |
void | VSIInstallMemFileHandler (void) |
Install "memory" file system handler. More... | |
void | VSIInstallLargeFileHandler (void) |
void | VSIInstallSubFileHandler (void) |
Install /vsisubfile/ virtual file handler. More... | |
void | VSIInstallCurlFileHandler (void) |
Install /vsicurl/ HTTP/FTP file system handler (requires libcurl) 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 | 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 | 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... | |
void | VSICleanupFileManager (void) |
VSILFILE * | VSIFileFromMemBuffer (const char *pszFilename, GByte *pabyData, vsi_l_offset nDataLength, int bTakeOwnership) CPL_WARN_UNUSED_RESULT |
Create memory "file" from a buffer. More... | |
GByte * | VSIGetMemFileBuffer (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... | |
unsigned long | VSITime (unsigned long *) |
const char * | VSICTime (unsigned long) |
struct tm * | VSIGMTime (const time_t *pnTime, struct tm *poBrokenTime) |
struct tm * | VSILocalTime (const time_t *pnTime, struct tm *poBrokenTime) |
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.
GIntBig CPLGetPhysicalRAM | ( | void | ) |
Return the total physical RAM in bytes.
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.
Note: This memory may already be partly used by other processes.
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.
fp | file handle opened with VSIFOpenL(). Passing a nullptr produces undefined behavior. |
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.
fp | file handle opened with VSIFOpenL(). |
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.
fp | file handle opened with VSIFOpenL(). |
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.
fp | file handle opened with VSIFOpenL(). |
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.
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* 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.
pszFilename | the file to open. UTF-8 encoded. |
pszAccess | access requested (i.e. "r", "r+", "w") |
bSetError | flag determining whether or not this open call should set VSIErrors on failure. |
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.
pszFilename | the file to open. UTF-8 encoded. |
pszAccess | access requested (i.e. "r", "r+", "w") |
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.
fp | file handle opened with VSIFOpenL(). |
pszFormat | the printf style format string. |
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.
nChar | character to write. |
fp | file handle opened with VSIFOpenL(). |
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.
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 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 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 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 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 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(). |
GIntBig VSIGetDiskFreeSpace | ( | const char * | pszDirname | ) |
Return free disk space available on the filesystem.
This function returns the free disk space available on the filesystem.
pszDirname | a directory of the filesystem to query. |
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.
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. |
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.
fp | file handle opened with VSIFOpenL(). |
pszFilename | filename. |
ppabyRet | pointer to the target buffer. *ppabyRet must be freed with VSIFree() |
pnSize | pointer to variable to store the file size. May be NULL. |
nMaxSize | maximum size of file allowed. If no limit, set to a negative value. |
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 :
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 :
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 :
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.
void VSIInstallCurlFileHandler | ( | void | ) |
Install /vsicurl/ HTTP/FTP file system handler (requires libcurl)
A special file handler is installed that allows on-the-fly random reading of files available through HTTP/FTP web protocols, without prior download of the entire file.
Recognized filenames are of the form /vsicurl/http://path/to/remote/resource or /vsicurl/ftp://path/to/remote/resource where path/to/remote/resource is the URL of a remote resource.
Partial downloads (requires the HTTP server to support random reading) are done with a 16 KB granularity by default. If the driver detects sequential reading it will progressively increase the chunk size up to 2 MB to improve download performance.
The GDAL_HTTP_PROXY, GDAL_HTTP_PROXYUSERPWD and GDAL_PROXY_AUTH configuration options can be used to define a proxy server. The syntax to use is the one of Curl CURLOPT_PROXY, CURLOPT_PROXYUSERPWD and CURLOPT_PROXYAUTH options.
Starting with GDAL 1.10, the file can be cached in RAM by setting the configuration option VSI_CACHE to TRUE. The cache size defaults to 25 MB, but can be modified by setting the configuration option VSI_CACHE_SIZE (in bytes).
Starting with GDAL 2.1, /vsicurl/ will try to query directly redirected URLs to Amazon S3 signed URLs during their validity period, so as to minimize round-trips. This behaviour can be disabled by setting the configuration option CPL_VSIL_CURL_USE_S3_REDIRECT to NO.
VSIStatL() will return the size in st_size member and file nature- file or directory - in st_mode member (the later only reliable with FTP resources for now).
VSIReadDir() should be able to parse the HTML directory listing returned by the most popular web servers, such as Apache or Microsoft IIS.
This special file handler can be combined with other virtual filesystems handlers, such as /vsizip. For example, /vsizip//vsicurl/path/to/remote/file.zip/path/inside/zip
void VSIInstallCurlStreamingFileHandler | ( | void | ) |
Install /vsicurl_streaming/ HTTP/FTP file system handler (requires libcurl)
A special file handler is installed that allows on-the-fly sequential reading of files streamed through HTTP/FTP web protocols (typically dynamically generated files), without prior download of the entire file.
Although this file handler is able seek to random offsets in the file, this will not be efficient. If you need efficient random access and that the server supports range dowloading, you should use the /vsicurl/ file system handler instead.
Recognized filenames are of the form /vsicurl_streaming/http://path/to/remote/resource or /vsicurl_streaming/ftp://path/to/remote/resource where path/to/remote/resource is the URL of a remote resource.
The GDAL_HTTP_PROXY, GDAL_HTTP_PROXYUSERPWD and GDAL_PROXY_AUTH configuration options can be used to define a proxy server. The syntax to use is the one of Curl CURLOPT_PROXY, CURLOPT_PROXYUSERPWD and CURLOPT_PROXYAUTH options.
The file can be cached in RAM by setting the configuration option VSI_CACHE to TRUE. The cache size defaults to 25 MB, but can be modified by setting the configuration option VSI_CACHE_SIZE (in bytes).
VSIStatL() will return the size in st_size member and file nature- file or directory - in st_mode member (the later only reliable with FTP resources for now).
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 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 (i.e. VSIFOpenL(), VSIMkDir(), etc) is called.
This code example demonstrates using GDAL to translate from one memory buffer to another.
void VSIInstallS3FileHandler | ( | void | ) |
Install /vsis3/ Amazon S3 file system handler (requires libcurl)
A special file handler is installed that allows on-the-fly random reading of files available in AWS S3 buckets, without prior download of the entire file. It also allows sequential writing of files (no seeks or read operations are then allowed).
Recognized filenames are of the form /vsis3/bucket/key where bucket is the name of the S3 bucket and key the S3 object "key", i.e. a filename potentially containing subdirectories.
Partial downloads are done with a 16 KB granularity by default. If the driver detects sequential reading it will progressively increase the chunk size up to 2 MB to improve download performance.
The AWS_SECRET_ACCESS_KEY and AWS_ACCESS_KEY_ID configuration options must be set. The AWS_SESSION_TOKEN configuration option must be set when temporary credentials are used. The AWS_REGION configuration option may be set to one of the supported S3 regions and defaults to 'us-east-1' The AWS_S3_ENDPOINT configuration option defaults to s3.amazonaws.com.
The GDAL_HTTP_PROXY, GDAL_HTTP_PROXYUSERPWD and GDAL_PROXY_AUTH configuration options can be used to define a proxy server. The syntax to use is the one of Curl CURLOPT_PROXY, CURLOPT_PROXYUSERPWD and CURLOPT_PROXYAUTH options.
On reading, the file can be cached in RAM by setting the configuration option VSI_CACHE to TRUE. The cache size defaults to 25 MB, but can be modified by setting the configuration option VSI_CACHE_SIZE (in bytes).
On writing, the file is uploaded using the S3 multipart upload API. The size of chunks is set to 50 MB by default, allowing creating files up to 500 GB (10000 parts of 50 MB each). If larger files are needed, then increase the value of the VSIS3_CHUNK_SIZE config option to a larger value (expressed in MB). In case the process is killed and the file not properly closed, the multipart upload will remain open, causing Amazon to charge you for the parts storage. You'll have to abort yourself with other means such "ghost" uploads (e.g. with the s3cmd utility) For files smaller than the chunk size, a simple PUT request is used instead of the multipart upload API.
VSIStatL() will return the size in st_size member.
void VSIInstallS3StreamingFileHandler | ( | void | ) |
Install /vsis3_streaming/ Amazon S3 file system handler (requires libcurl)
A special file handler is installed that allows on-the-fly sequential reading of files streamed from AWS S3 buckets without prior download of the entire file.
Recognized filenames are of the form /vsis3_streaming/bucket/key where bucket is the name of the S3 bucket and resource the S3 object "key", i.e. a filename potentially containing subdirectories.
The AWS_SECRET_ACCESS_KEY and AWS_ACCESS_KEY_ID configuration options must be set. The AWS_SESSION_TOKEN configuration option must be set when temporary credentials are used. The AWS_REGION configuration option may be set to one of the supported S3 regions and defaults to 'us-east-1' The AWS_S3_ENDPOINT configuration option defaults to s3.amazonaws.com.
The GDAL_HTTP_PROXY, GDAL_HTTP_PROXYUSERPWD and GDAL_PROXY_AUTH configuration options can be used to define a proxy server. The syntax to use is the one of Curl CURLOPT_PROXY, CURLOPT_PROXYUSERPWD and CURLOPT_PROXYAUTH options.
The file can be cached in RAM by setting the configuration option VSI_CACHE to TRUE. The cache size defaults to 25 MB, but can be modified by setting the configuration option VSI_CACHE_SIZE (in bytes).
VSIStatL() will return the size in st_size member.
void 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 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
Syntactic 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
Syntactic sugar : if the .zip file contains only one file located at its root, just mentioning "/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 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* 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* 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 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** 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. |
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.
pszPath | the relative, or absolute path of a directory to read. UTF-8 encoded. |
nMaxFiles | maximum number of files after which to stop, or 0 for no limit. |
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.
pszPathIn | the relative, or absolute path of a directory to read. UTF-8 encoded. |
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.
oldpath | the name of the file to be renamed. UTF-8 encoded. |
newpath | the name the file should be given. UTF-8 encoded. |
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.
fp | file handle opened with VSIFOpenL(). |
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.
pszDirname | the path of the directory to be deleted. UTF-8 encoded. |
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.
pabyKey | key. Might be NULL to clear previously set key. |
nKeySize | length of the key in bytes. Might be 0 to clear previously set key. |
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/)
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 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.
pszFilename | the path of the filesystem object to be queried. UTF-8 encoded. |
psStatBuf | the structure to load with information. |
void VSIStdoutSetRedirection | ( | VSIWriteFunction | pFct, |
FILE * | stream | ||
) |
Set an alternative write function and output file handle instead of fwrite() / stdout.
pFct | Function with same signature as fwrite() |
stream | File handle on which to output. Passed to pFct. |
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.
pszFilename | the path of the file to be deleted. UTF-8 encoded. |