lib/progname.c

/* Program name management.
   Copyright (C) 2001-2003, 2005-2012 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2001.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */


#include <config.h>

/* Specification.  */
#undef ENABLE_RELOCATABLE /* avoid defining set_program_name as a macro */
#include "progname.h"

#include <errno.h> /* get program_invocation_name declaration */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


/* String containing name the program is called with.
   To be initialized by main().  */
const char *program_name = NULL;

/* Set program_name, based on argv[0].
   argv0 must be a string allocated with indefinite extent, and must not be
   modified after this call.  */
void
set_program_name (const char *argv0)
{
  /* libtool creates a temporary executable whose name is sometimes prefixed
     with "lt-" (depends on the platform).  It also makes argv[0] absolute.
     But the name of the temporary executable is a detail that should not be
     visible to the end user and to the test suite.
     Remove this "<dirname>/.libs/" or "<dirname>/.libs/lt-" prefix here.  */
  const char *slash;
  const char *base;

  /* Sanity check.  POSIX requires the invoking process to pass a non-NULL
     argv[0].  */
  if (argv0 == NULL)
    {
      /* It's a bug in the invoking program.  Help diagnosing it.  */
      fputs ("A NULL argv[0] was passed through an exec system call.\n",
             stderr);
      abort ();
    }

  slash = strrchr (argv0, '/');
  base = (slash != NULL ? slash + 1 : argv0);
  if (base - argv0 >= 7 && strncmp (base - 7, "/.libs/", 7) == 0)
    {
      argv0 = base;
      if (strncmp (base, "lt-", 3) == 0)
        {
          argv0 = base + 3;
          /* On glibc systems, remove the "lt-" prefix from the variable
             program_invocation_short_name.  */
#if HAVE_DECL_PROGRAM_INVOCATION_SHORT_NAME
          program_invocation_short_name = (char *) argv0;
#endif
        }
    }

  /* But don't strip off a leading <dirname>/ in general, because when the user
     runs
         /some/hidden/place/bin/cp foo foo
     he should get the error message
         /some/hidden/place/bin/cp: `foo' and `foo' are the same file
     not
         cp: `foo' and `foo' are the same file
   */

  program_name = argv0;

  /* On glibc systems, the error() function comes from libc and uses the
     variable program_invocation_name, not program_name.  So set this variable
     as well.  */
#if HAVE_DECL_PROGRAM_INVOCATION_NAME
  program_invocation_name = (char *) argv0;
#endif
}