Re: lib/59711: "#define HAVE_UNISTD_H 1" breaks 32-bit libz

["Tom Lane via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR lib/59711; it has been noted by GNATS.

From: Tom Lane <tgl%sss.pgh.pa.us@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: lib/59711: "#define HAVE_UNISTD_H 1" breaks 32-bit libz
Date: Sat, 18 Oct 2025 23:23:57 -0400

 Here's the promised test case.  You can exercise it along the lines of
 
 $ gcc libztest.c -lz
 $ cp libztest.c datafile
 $ gzip datafile
 $ ./a.out datafile.gz | diff - libztest.c
 
 If things are working, "diff" will not complain, and you'll just
 see a report about "sizeof pos" on stderr.  However, on macppc
 I see
 
 sizeof pos = 8
 could not read from input file: (null)
 
 on stderr, and then diff reports that most of the file is missing.
 Removing "#define HAVE_UNISTD_H 1" results in a working program
 that reports sizeof pos = 4.
 
 			regards, tom lane
 
 ------------ cut here: libztest.c -------------
 #define HAVE_UNISTD_H 1
 
 #include <zlib.h>
 
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
 
 int
 main(int argc, char **argv)
 {
 	gzFile		gzfp;
 
 	fprintf(stderr, "sizeof pos = %zu\n", sizeof(gzfp->pos));
 
 	gzfp = gzopen(argv[1], "r");
 
 	if (gzfp == NULL)
 	{
 		fprintf(stderr, "gzopen(%s) failed\n", argv[1]);
 		return 1;
 	}
 
 	for (;;)
 	{
 		char		buf[8];
 		int			gzret;
 
 		gzret = gzread(gzfp, buf, sizeof(buf));
 		if (gzret <= 0)
 		{
 			int			errnum;
 			const char *errmsg;
 
 			if (gzret == 0 && gzeof(gzfp))
 				break;
 			errmsg = gzerror(gzfp, &errnum);
 			fprintf(stderr, "could not read from input file: %s\n",
 					errnum == Z_ERRNO ? strerror(errno) : errmsg);
 			return 1;
 		}
 		fwrite(buf, 1, gzret, stdout);
 
 		gzret = gzgetc(gzfp);
 		if (gzret == -1)
 			break;
 		putchar(gzret);
 	}
 
 	gzclose(gzfp);
 	return 0;
 }
 ------------ cut here: libztest.c -------------