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Issue of the Implementation # S0684

Brief

Error in psignal(int sig, const char * s) if s is an empty string

Detailed Description

If string s is empty, psignal shall display only a message describing the signal number sig.

SYNOPSIS
  void psignal(int sig, const char * s);

DESCRIPTION
  If s is not the null pointer, and does not point to an empty string
  (e.g. "\0"), the message shall consist of the string s, a colon, 
  a space, and a string describing the signal number sig; otherwise
  psignal() shall display only a message describing the signal number sig.

But actually psignal prints a colon, a space, and a string describing the signal number sig.

Problem location(s) in the standard

Linux Standard Base Core Specification 3.1, Chapter 13. Base Libraries, 13.5. Interface Definitions for libc, psignal() function.

Example

#include <stdio.h>
#include <signal.h>

int main( int argc, char ** argv ) {
    printf( "If string s is empty, psignal( sig, s ) shall display only a message describing the signal number sig.\n" );
    printf( "Call psignal( 1, \"\" ) now...\n" );
    psignal( 1, "" );
    return 0;
}

Possible solutions

diff -r1.15 psignal.c
/* Print out on stderr a line consisting of the test in S, a colon, a space,
   a message describing the meaning of the signal number SIG and a newline.
   If S is NULL or "", the colon and space are omitted.  */
void
psignal (int sig, const char *s)
{
  const char *colon, *desc;

- if (s == NULL || s == '\0')
+ if (s == NULL || *s == '\0')
    s = colon = "";
  else
    colon = ": ";

  if (sig >= 0 && sig < NSIG && (desc = INTUSE(_sys_siglist)[sig]) != NULL)
    (void) __fxprintf (NULL, "%s%s%s\n", s, colon, _(desc));
  else

Component

glibc

Accepted

Red Hat Bugzilla, 9823

Status

Fixed in glibc-2.10

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