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fix map of custom seekable streams

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We failed for seekable custom streams.

See https://github.com/libvips/libvips/issues/1494#issuecomment-567190830
This commit is contained in:
John Cupitt 2019-12-20 12:44:56 +00:00
parent 53dac98b55
commit 8030d7b926
1 changed files with 87 additions and 18 deletions
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105
libvips/iofuncs/streami.c
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@ -672,7 +672,7 @@ vips_streami_read( VipsStreami *streami, void *buffer, size_t length )
bytes_read += available;
}
else {
/* Some kind of filesystem source.
/* Some kind of filesystem or custom source.
*
* Get what we can from header_bytes. We may need to read
* some more after this.
@ -769,12 +769,12 @@ vips_streami_pipe_read_to_position( VipsStreami *streami, gint64 target )
while( target == -1 ||
streami->read_position < target ) {
ssize_t read;
ssize_t bytes_read;
read = vips_streami_read( streami, buffer, 4096 );
if( read == -1 )
bytes_read = vips_streami_read( streami, buffer, 4096 );
if( bytes_read == -1 )
return( -1 );
if( read == 0 )
if( bytes_read == 0 )
break;
if( target == -1 &&
@ -790,6 +790,66 @@ vips_streami_pipe_read_to_position( VipsStreami *streami, gint64 target )
return( 0 );
}
/* Convert a seekable source that can't be mapped (eg. a custom input with a
* seek method) into a memory source.
*/
static int
vips_streami_read_to_memory( VipsStreami *streami )
{
GByteArray *byte_array;
gint64 read_position;
unsigned char *q;
VIPS_DEBUG_MSG( "vips_streami_read_to_memory:\n" );
g_assert( !streami->is_pipe );
g_assert( !streami->blob );
g_assert( !streami->header_bytes );
g_assert( streami->length >= 0 );
if( vips_streami_rewind( streami ) )
return( -1 );
/* We know the length, so we can size the buffer correctly and read
* directly to it.
*/
byte_array = g_byte_array_new();
g_byte_array_set_size( byte_array, streami->length );
/* Read in a series of chunks to reduce stress upstream.
*/
read_position = 0;
q = byte_array->data;
while( read_position < streami->length ) {
ssize_t bytes_read;
bytes_read = vips_streami_read( streami, q,
VIPS_MAX( 4096, streami->length - read_position ) );
if( bytes_read == -1 ) {
VIPS_FREEF( g_byte_array_unref, byte_array );
return( -1 );
}
if( bytes_read == 0 )
break;
read_position += bytes_read;
q += bytes_read;
}
/* Steal the byte_array pointer and turn into a memory source.
*
* We save byte_array in the header_bytes field to get it freed when
* we are freed.
*/
streami->data = byte_array->data;
streami->is_pipe = FALSE;
streami->header_bytes = byte_array;
vips_streami_minimise( streami );
return( 0 );
}
/* Read the entire pipe into memory and turn this into a memory source stream.
*/
static int
@ -844,6 +904,10 @@ vips_streami_descriptor_to_memory( VipsStreami *streami )
* vips_streami_is_mappable:
* @streami: input stream to operate on
*
* Some streams can be efficiently mapped into memory.
* You can still use vips_streami_map() if this function returns %FALSE,
* but it will be slow.
*
* Returns: %TRUE if the stream can be efficiently mapped into memory.
*/
gboolean
@ -859,7 +923,7 @@ vips_streami_is_mappable( VipsStreami *streami )
return( streami->data ||
VIPS_STREAM( streami )->filename ||
(!streami->is_pipe &&
VIPS_STREAM( streami )->descriptor) );
VIPS_STREAM( streami )->descriptor != -1) );
}
/**
@ -889,13 +953,17 @@ vips_streami_map( VipsStreami *streami, size_t *length_out )
return( NULL );
if( !streami->data ) {
/* Seekable descriptors can simply be mapped. All other sources
* must be read into memory.
/* Seekable descriptors can simply be mapped. Seekable sources
* can be read. All other sources must be streamed into memory.
*/
if( vips_streami_is_mappable( streami ) ) {
if( vips_streami_descriptor_to_memory( streami ) )
return( NULL );
}
else if( !streami->is_pipe ) {
if( vips_streami_read_to_memory( streami ) )
return( NULL );
}
else {
if( vips_streami_pipe_to_memory( streami ) )
return( NULL );
@ -1131,7 +1199,7 @@ vips_streami_sniff_at_most( VipsStreami *streami,
unsigned char **data, size_t length )
{
unsigned char *q;
size_t bytes_read;
gint64 read_position;
VIPS_DEBUG_MSG( "vips_streami_sniff_at_most: %zd bytes\n", length );
@ -1143,26 +1211,27 @@ vips_streami_sniff_at_most( VipsStreami *streami,
g_byte_array_set_size( streami->sniff, length );
read_position = 0;
q = streami->sniff->data;
bytes_read = 0;
while( bytes_read < length ) {
ssize_t n;
while( read_position < length ) {
ssize_t bytes_read;
n = vips_streami_read( streami, q, length - bytes_read );
if( n == -1 )
bytes_read = vips_streami_read( streami, q,
length - read_position );
if( bytes_read == -1 )
return( -1 );
if( n == 0 )
if( bytes_read == 0 )
break;
bytes_read += n;
q += n;
read_position += bytes_read;
q += bytes_read;
}
SANITY( streami );
*data = streami->sniff->data;
return( bytes_read );
return( read_position );
}
/**