lib/findprog.c

   1 /* Locating a program in PATH.
   2    Copyright (C) 2001-2004, 2006-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <haible@clisp.cons.org>, 2001.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file 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 Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include "findprog.h"
  23
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #if !(defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__)
  28 # include <sys/stat.h>
  29 #endif
  30
  31 /* Avoid collision between findprog.c and findprog-lgpl.c.  */
  32 #if IN_FINDPROG_LGPL || ! GNULIB_FINDPROG_LGPL
  33
  34 #if !IN_FINDPROG_LGPL
  35 # include "xalloc.h"
  36 #endif
  37 #include "concat-filename.h"
  38
  39
  40 const char *
  41 find_in_path (const char *progname)
  42 {
  43 #if defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
  44   /* Native Windows, Cygwin, OS/2, DOS */
  45   /* The searching rules with .COM, .EXE, .BAT, .CMD etc. suffixes are
  46      too complicated.  Leave it to the OS.  */
  47   return progname;
  48 #else
  49   /* Unix */
  50   char *path;
  51   char *path_rest;
  52   char *cp;
  53
  54   if (strchr (progname, '/') != NULL)
  55     /* If progname contains a slash, it is either absolute or relative to
  56        the current directory.  PATH is not used.  */
  57     return progname;
  58
  59   path = getenv ("PATH");
  60   if (path == NULL || *path == '\0')
  61     /* If PATH is not set, the default search path is implementation
  62        dependent.  */
  63     return progname;
  64
  65   /* Make a copy, to prepare for destructive modifications.  */
  66 # if !IN_FINDPROG_LGPL
  67   path = xstrdup (path);
  68 # else
  69   path = strdup (path);
  70   if (path == NULL)
  71     /* Out of memory.  */
  72     return progname;
  73 # endif
  74   for (path_rest = path; ; path_rest = cp + 1)
  75     {
  76       const char *dir;
  77       bool last;
  78       char *progpathname;
  79
  80       /* Extract next directory in PATH.  */
  81       dir = path_rest;
  82       for (cp = path_rest; *cp != '\0' && *cp != ':'; cp++)
  83         ;
  84       last = (*cp == '\0');
  85       *cp = '\0';
  86
  87       /* Empty PATH components designate the current directory.  */
  88       if (dir == cp)
  89         dir = ".";
  90
  91       /* Concatenate dir and progname.  */
  92 # if !IN_FINDPROG_LGPL
  93       progpathname = xconcatenated_filename (dir, progname, NULL);
  94 # else
  95       progpathname = concatenated_filename (dir, progname, NULL);
  96       if (progpathname == NULL)
  97         {
  98           /* Out of memory.  */
  99           free (path);
 100           return progname;
 101         }
 102 # endif
 103
 104       /* On systems which have the eaccess() system call, let's use it.
 105          On other systems, let's hope that this program is not installed
 106          setuid or setgid, so that it is ok to call access() despite its
 107          design flaw.  */
 108       if (eaccess (progpathname, X_OK) == 0)
 109         {
 110           /* Check that the progpathname does not point to a directory.  */
 111           struct stat statbuf;
 112
 113           if (stat (progpathname, &statbuf) >= 0
 114               && ! S_ISDIR (statbuf.st_mode))
 115             {
 116               /* Found!  */
 117               if (strcmp (progpathname, progname) == 0)
 118                 {
 119                   free (progpathname);
 120
 121                   /* Add the "./" prefix for real, that xconcatenated_filename()
 122                      optimized away.  This avoids a second PATH search when the
 123                      caller uses execlp/execvp.  */
 124 # if !IN_FINDPROG_LGPL
 125                   progpathname = XNMALLOC (2 + strlen (progname) + 1, char);
 126 # else
 127                   progpathname = (char *) malloc (2 + strlen (progname) + 1);
 128                   if (progpathname == NULL)
 129                     {
 130                       /* Out of memory.  */
 131                       free (path);
 132                       return progname;
 133                     }
 134 # endif
 135                   progpathname[0] = '.';
 136                   progpathname[1] = '/';
 137                   memcpy (progpathname + 2, progname, strlen (progname) + 1);
 138                 }
 139
 140               free (path);
 141               return progpathname;
 142             }
 143         }
 144
 145       free (progpathname);
 146
 147       if (last)
 148         break;
 149     }
 150
 151   /* Not found in PATH.  An error will be signalled at the first call.  */
 152   free (path);
 153   return progname;
 154 #endif
 155 }
 156
 157 #endif