Bug#556652: octave can't load files created by libmatio

[Bas Zoetekouw]

Package: libmatio0
Version: 1.3.3-5
Severity: normal

octave can't read compressed files written by libmatio.  I'm not sure
if this is a problem in libmatio or in octave, so feel free to
reassign as necessary.

The following program uses libmatio to write a simple data structure
to a compressed mat file:

#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <matio.h>

#define NRSIGNALS 2
#define NRSAMPLES 100

int write_matfile( const char *fname )
{
	mat_t *mat = NULL;
	matvar_t **matchannels = NULL;

	mat = Mat_Open( fname, 0 );
	if ( mat==NULL )
	{
		fprintf( stderr, "Can't open file `%s' for output\n", fname );
		return 0;
	}

	/* allocate memory for the channels */
	matchannels = malloc( NRSIGNALS * sizeof(*matchannels) );

	/* create a structure for each channel */
	for ( int i = 0; i < NRSIGNALS; i++ )
	{
		int dims[2] = {1,1};
		matvar_t ** matdata = malloc( 2 * sizeof(*matdata) );

		matdata[0] = Mat_VarCreate( "channel",    MAT_C_INT16,  MAT_T_INT16,  2, dims, &i, 0 );
		matdata[1] = NULL;

		matchannels[i] = Mat_VarCreate( "", MAT_C_STRUCT, MAT_T_STRUCT, 2, dims, matdata, 0 );

	}

	/* the structures for the channels are combined into a single cell array */
	int dims[2] = {1,NRSIGNALS};
	matvar_t * matvar_cell = Mat_VarCreate("data",MAT_C_CELL,MAT_T_CELL,2,dims,matchannels,0);

	/* write the file to disk */
	Mat_VarWrite( mat, matvar_cell, COMPRESSION_ZLIB );
	//Mat_VarWrite( mat, matvar_cell, 0 );

	Mat_Close( mat );

	return 1;

}

int main()
{
	write_matfile( "/tmp/foo.mat" );
	return(0);
} 



Observe:

[bas at basbak2]/tmp> gcc edf2mat.c -std=c99 -lmatio && ./a.out
[bas at basbak2]/tmp> ls -la foo.mat
-rw-r--r-- 1 bas bas 215 nov 17 13:47 foo.mat
[bas at basbak2]/tmp> file foo.mat
foo.mat: Matlab v5 mat-file (little endian) version 0x0100
[bas at basbak2]/tmp> octave3.2 -q
octave3.2:1> load('foo.mat')
error: load: error uncompressing data element


The file loads fine in matlab.  If the file is written without
compression, it also loads fine in octave.



-- System Information:
Debian Release: 5.0.3
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.26-2-amd64 (SMP w/1 CPU core)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash