- 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). */
+ gzopen returns NULL if the file could not be opened, if there was
+ insufficient memory to allocate the gzFile state, or if an invalid mode was
+ specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
+ errno can be checked to determine if the reason gzopen failed was that the
+ file could not be opened.
+*/
+
+ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
+/*
+ gzdopen associates a gzFile with the file descriptor fd. File descriptors
+ are obtained from calls like open, dup, creat, pipe or fileno (if the file
+ has been previously opened with fopen). The mode parameter is as in gzopen.
+
+ The next call of gzclose on the returned gzFile will also close the file
+ descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
+ fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
+ mode);. The duplicated descriptor should be saved to avoid a leak, since
+ gzdopen does not close fd if it fails.
+
+ gzdopen returns NULL if there was insufficient memory to allocate the
+ gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
+ provided, or '+' was provided), or if fd is -1. The file descriptor is not
+ used until the next gz* read, write, seek, or close operation, so gzdopen
+ will not detect if fd is invalid (unless fd is -1).
+*/