gnu/dist/gettext/gettext-tools/lib/findprog.c

   1 /* Locating a program in PATH.
   2    Copyright (C) 2001-2004 Free Software Foundation, Inc.
   3    Written by Bruno Haible <haible@clisp.cons.org>, 2001.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software Foundation,
  17    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  18
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include "config.h"
  22 #endif
  23
  24 /* Specification.  */
  25 #include "findprog.h"
  26
  27 #include <stdbool.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30
  31 #ifdef HAVE_UNISTD_H
  32 # include <unistd.h>
  33 #endif
  34
  35 #include "xalloc.h"
  36 #include "pathname.h"
  37
  38
  39 const char *
  40 find_in_path (const char *progname)
  41 {
  42 #if defined _WIN32 || defined __WIN32__ || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
  43   /* Win32, Cygwin, OS/2, DOS */
  44   /* The searching rules with .COM, .EXE, .BAT, .CMD etc. suffixes are
  45      too complicated.  Leave it to the OS.  */
  46   return progname;
  47 #else
  48   /* Unix */
  49   char *path;
  50   char *dir;
  51   char *cp;
  52
  53   if (strchr (progname, '/') != NULL)
  54     /* If progname contains a slash, it is either absolute or relative to
  55        the current directory.  PATH is not used.  */
  56     return progname;
  57
  58   path = getenv ("PATH");
  59   if (path == NULL || *path == '\0')
  60     /* If PATH is not set, the default search path is implementation
  61        dependent.  */
  62     return progname;
  63
  64   /* Make a copy, to prepare for destructive modifications.  */
  65   path = xstrdup (path);
  66   for (dir = path; ; dir = cp + 1)
  67     {
  68       bool last;
  69       char *progpathname;
  70
  71       /* Extract next directory in PATH.  */
  72       for (cp = dir; *cp != '\0' && *cp != ':'; cp++)
  73         ;
  74       last = (*cp == '\0');
  75       *cp = '\0';
  76
  77       /* Empty PATH components designate the current directory.  */
  78       if (dir == cp)
  79         dir = ".";
  80
  81       /* Concatenate dir and progname.  */
  82       progpathname = concatenated_pathname (dir, progname, NULL);
  83
  84       /* On systems which have the eaccess() system call, let's use it.
  85          On other systems, let's hope that this program is not installed
  86          setuid or setgid, so that it is ok to call access() despite its
  87          design flaw.  */
  88       if (eaccess (progpathname, X_OK) == 0)
  89         {
  90           /* Found!  */
  91           if (strcmp (progpathname, progname) == 0)
  92             {
  93               free (progpathname);
  94
  95               /* Add the "./" prefix for real, that concatenated_pathname()
  96                  optimized away.  This avoids a second PATH search when the
  97                  caller uses execlp/execvp.  */
  98               progpathname = xmalloc (2 + strlen (progname) + 1);
  99               progpathname[0] = '.';
 100               progpathname[1] = '/';
 101               memcpy (progpathname + 2, progname, strlen (progname) + 1);
 102             }
 103
 104           free (path);
 105           return progpathname;
 106         }
 107
 108       free (progpathname);
 109
 110       if (last)
 111         break;
 112     }
 113
 114   /* Not found in PATH.  An error will be signalled at the first call.  */
 115   free (path);
 116   return progname;
 117 #endif
 118 }