preprocessor/7988: POSIX broken in gcc

[cs720@unh.edu]

>Number:         7988
>Category:       preprocessor
>Synopsis:       Programs defining _POSIX_C_SOURCE compile but won't run
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Fri Sep 20 08:06:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     cs720 Administrator
>Release:        3.2
>Organization:
University of New Hampshire
>Environment:
System: OSF1 hypatia.unh.edu V5.1 1885 alpha
Machine: alpha
	
host: alphaev56-dec-osf5.1
build: alphaev56-dec-osf5.1
target: alphaev56-dec-osf5.1
configured with: ../gcc-3.2/configure 
>Description:
	Many of my programs contain the line
	#define _POSIX_C_SOURCE 199506L
	before all #include lines.
	These used to work (over 1 year ago).
	Now they compile but give Segmentation faults or wrong answers when run.

>How-To-Repeat:
	Attached below is a sample program called ftype.c
	If I compile it with "gcc ftype.c"
	and then run it with "a.out /dev/tty"
	it gives me a segmentation fault.
	If I compile it with "gcc -O ftype.c"
	and then run it with "a.out /dev/tty"
	it produces the output "/dev/tty: UNKNOWN FILE TYPE"
	which is the wrong answer.
	If I delete the line defining _POSIX_C_SOURCE
	and compile it with "gcc ftype.c" or "gcc -O ftype.c"
	and then run it with "a.out /dev/tty"
	it procudes the output "/dev/ttyp: character special file"
	which is the correct answer.
/***********************************************************************/
/*	ftype.c	- program to demonstrate POSIX stat() and file-type macros */

#define _POSIX_C_SOURCE	199506L

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>

int main( int argc, char *argv[] )
	{
	int				i;
	char			*ptr;
	struct stat		statbuf;

	if( argc < 2 )
		{
		fprintf(stderr, "Usage: ftype file1 [file2 ...]\n");
		exit(EXIT_FAILURE);
		}

	for( i = 1;  i < argc;  i++ )
		{
		if( stat(argv[i], &statbuf) < 0 )
			perror(argv[i]);
		else
			{
				if( S_ISREG(statbuf.st_mode) )	ptr ="regular file";
			else if( S_ISDIR(statbuf.st_mode) )	ptr ="directory";
			else if( S_ISCHR(statbuf.st_mode) )	ptr ="character special file";
			else if( S_ISBLK(statbuf.st_mode) )	ptr ="block special file";
			else if( S_ISFIFO(statbuf.st_mode))	ptr ="FIFO file";
			else								ptr ="UNKNOWN FILE TYPE";
			printf("%s: %s\n", argv[i], ptr);
			}
		}

	return EXIT_SUCCESS;
	}
/***********************************************************************/

>Fix:
	Just delete the line defining _POSIX_C_SOURCE.
	However, this worked in previous versions of gcc on OSF systems,
	and continues to work in current versions of gcc on Linux and
	Solaris systems.

>Release-Note:
>Audit-Trail:
>Unformatted: