int VSIUnixStdioHandle::Seek( vsi_l_offset nOffset, int nWhence )
{
// seeks that do nothing are still surprisingly expensive with MSVCRT.
// try and short circuit if possible.
if( nWhence == SEEK_SET && nOffset == this->nOffset )
return 0;
int nResult = VSI_FSEEK64( fp, nOffset, nWhence );
int nError = errno;
#ifdef VSI_DEBUG
if( nWhence == SEEK_SET )
{
VSIDebug3( "VSIUnixStdioHandle::Seek(%p," CPL_FRMT_GUIB ",SEEK_SET) = %d",
fp, nOffset, nResult );
}
else if( nWhence == SEEK_END )
{
VSIDebug3( "VSIUnixStdioHandle::Seek(%p," CPL_FRMT_GUIB ",SEEK_END) = %d",
fp, nOffset, nResult );
}
else if( nWhence == SEEK_CUR )
{
VSIDebug3( "VSIUnixStdioHandle::Seek(%p," CPL_FRMT_GUIB ",SEEK_CUR) = %d",
fp, nOffset, nResult );
}
else
{
VSIDebug4( "VSIUnixStdioHandle::Seek(%p," CPL_FRMT_GUIB ",%d-Unknown) = %d",
fp, nOffset, nWhence, nResult );
}
#endif
if( nResult != -1 )
{
if( nWhence == SEEK_SET )
{
this->nOffset = nOffset;
}
else if( nWhence == SEEK_END )
{
this->nOffset = VSI_FTELL64( fp );
}
else if( nWhence == SEEK_CUR )
{
this->nOffset += nOffset;
}
}
bLastOpWrite = FALSE;
bLastOpRead = FALSE;
bAtEOF = FALSE;
errno = nError;
return nResult;
}
vsi_l_offset VSIUnixStdioHandle::Tell()
{
#ifdef notdef
vsi_l_offset nOffset = VSI_FTELL64( fp );
int nError = errno;
VSIDebug2( "VSIUnixStdioHandle::Tell(%p) = %ld", fp, (long)nOffset );
errno = nError;
return nOffset;
#endif
return nOffset;
}
size_t VSIUnixStdioHandle::Read( void * pBuffer, size_t nSize, size_t nCount )
{
/* -------------------------------------------------------------------- */
/* If a fwrite() is followed by an fread(), the POSIX rules are */
/* that some of the write may still be buffered and lost. We */
/* are required to do a seek between to force flushing. So we */
/* keep careful track of what happened last to know if we */
/* skipped a flushing seek that we may need to do now. */
/* -------------------------------------------------------------------- */
if( bLastOpWrite )
VSI_FSEEK64( fp, nOffset, SEEK_SET );
/* -------------------------------------------------------------------- */
/* Perform the read. */
/* -------------------------------------------------------------------- */
size_t nResult = fread( pBuffer, nSize, nCount, fp );
int nError = errno;
VSIDebug4( "VSIUnixStdioHandle::Read(%p,%ld,%ld) = %ld",
fp, (long)nSize, (long)nCount, (long)nResult );
errno = nError;
/* -------------------------------------------------------------------- */
/* Update current offset. */
/* -------------------------------------------------------------------- */
#ifdef VSI_COUNT_BYTES_READ
nTotalBytesRead += nSize * nResult;
#endif
nOffset += nSize * nResult;
bLastOpWrite = FALSE;
bLastOpRead = TRUE;
if (nResult != nCount)
{
errno = 0;
vsi_l_offset nNewOffset = VSI_FTELL64( fp );
if( errno == 0 ) /* ftell() can fail if we are end of file with a pipe */
nOffset = nNewOffset;
else
CPLDebug("VSI", "%s", VSIStrerror(errno));
bAtEOF = feof(fp);
}
return nResult;
}
vsi_l_offset VSIUnixStdioHandle::Tell()
{
return( VSI_FTELL64( fp ) );
}
int VSIUnixStdioHandle::Seek( vsi_l_offset nOffset, int nWhence )
{
bAtEOF = FALSE;
// seeks that do nothing are still surprisingly expensive with MSVCRT.
// try and short circuit if possible.
if( nWhence == SEEK_SET && nOffset == this->nOffset )
return 0;
// on a read-only file, we can avoid a lseek() system call to be issued
// if the next position to seek to is within the buffered page
if( bReadOnly && nWhence == SEEK_SET )
{
GIntBig nDiff = (GIntBig)nOffset - (GIntBig)this->nOffset;
if( nDiff > 0 && nDiff < 4096 )
{
GByte abyTemp[4096];
int nRead = (int)fread(abyTemp, 1, (int)nDiff, fp);
if( nRead == (int)nDiff )
{
this->nOffset = nOffset;
bLastOpWrite = FALSE;
bLastOpRead = FALSE;
return 0;
}
}
}
const int nResult = VSI_FSEEK64( fp, nOffset, nWhence );
int nError = errno;
#ifdef VSI_DEBUG
if( nWhence == SEEK_SET )
{
VSIDebug3( "VSIUnixStdioHandle::Seek(%p," CPL_FRMT_GUIB ",SEEK_SET) = %d",
fp, nOffset, nResult );
}
else if( nWhence == SEEK_END )
{
VSIDebug3( "VSIUnixStdioHandle::Seek(%p," CPL_FRMT_GUIB ",SEEK_END) = %d",
fp, nOffset, nResult );
}
else if( nWhence == SEEK_CUR )
{
VSIDebug3( "VSIUnixStdioHandle::Seek(%p," CPL_FRMT_GUIB ",SEEK_CUR) = %d",
fp, nOffset, nResult );
}
else
{
VSIDebug4( "VSIUnixStdioHandle::Seek(%p," CPL_FRMT_GUIB ",%d-Unknown) = %d",
fp, nOffset, nWhence, nResult );
}
#endif
if( nResult != -1 )
{
if( nWhence == SEEK_SET )
{
this->nOffset = nOffset;
}
else if( nWhence == SEEK_END )
{
this->nOffset = VSI_FTELL64( fp );
}
else if( nWhence == SEEK_CUR )
{
this->nOffset += nOffset;
}
}
bLastOpWrite = FALSE;
bLastOpRead = FALSE;
errno = nError;
return nResult;
}