Octave + ZLIB + Win32

[John W. Eaton]

On  7-Dec-2006, address@hidden wrote:

| This is a little bit off-topic, but maybe I can get some good advices. I'm 
trying
| to integrate ZLIB within my octave under MSVC, however I found that the
| generated compressed MAT files (save -z -text ...) were corrupted. I tracked
| down the problem until I found I could reproduce corruption outside octave
| with a program as simple as:
| 
| #include <zlib.h>
| int main(int argc, char **argv)
| {
|  gzFile *f = gzopen(\"test1.txt.gz\", \"w\");

I suspect you need to use "wb" here.  The zlib.h header says

  ZEXTERN gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
  /*
       Opens a gzip (.gz) file for reading or writing. The mode parameter
     is as in fopen ("rb" or "wb") but can also include a compression level
     ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
     Huffman only compression as in "wb1h", or 'R' for run-length encoding
     as in "wb1R". (See the description of deflateInit2 for more information
     about the strategy parameter.)

       gzopen can be used to read a file which is not in gzip format; in this
     case gzread will directly read from the file without decompression.

       gzopen returns NULL if the file could not be opened or if there was
     insufficient memory to allocate the (de)compression state; errno
     can be checked to distinguish the two cases (if errno is zero, the
     zlib error is Z_MEM_ERROR).  */

Strange that they would allow these other extensions to the mode
string and not automatically open the stream in binary mode (since it
would seem to be required) whether or not "b" is specified.

Is Octave failing to open a stream in binary mode when it should?

jwe