1 /* Locating a program in PATH.
2 Copyright (C) 2001-2004, 2006-2021 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 3 of the License, or
8 (at your option) 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, see <https://www.gnu.org/licenses/>. */
17
18
19 #include <config.h>
20
21 /* Specification. */
22 #include "findprog.h"
23
24 #include <stdbool.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28 #if !(defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__)
29 # include <sys/stat.h>
30 #endif
31
32 /* Avoid collision between findprog.c and findprog-lgpl.c. */
33 #if IN_FINDPROG_LGPL || ! GNULIB_FINDPROG_LGPL
34
35 #if !IN_FINDPROG_LGPL
36 # include "xalloc.h"
37 #endif
38 #include "concat-filename.h"
39
40
41 const char *
42 find_in_path (const char *progname)
43 {
44 #if defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
45 /* Native Windows, Cygwin, OS/2, DOS */
46 /* The searching rules with .COM, .EXE, .BAT, .CMD etc. suffixes are
47 too complicated. Leave it to the OS. */
48 return progname;
49 #else
50 /* Unix */
51 char *path;
52 char *path_rest;
53 char *cp;
54
55 if (strchr (progname, '/') != NULL)
56 /* If progname contains a slash, it is either absolute or relative to
57 the current directory. PATH is not used. */
58 return progname;
59
60 path = getenv ("PATH");
61 if (path == NULL || *path == '\0')
62 /* If PATH is not set, the default search path is implementation
63 dependent. */
64 return progname;
65
66 /* Make a copy, to prepare for destructive modifications. */
67 # if !IN_FINDPROG_LGPL
68 path = xstrdup (path);
69 # else
70 path = strdup (path);
71 if (path == NULL)
72 /* Out of memory. */
73 return progname;
74 # endif
75 for (path_rest = path; ; path_rest = cp + 1)
76 {
77 const char *dir;
78 bool last;
79 char *progpathname;
80
81 /* Extract next directory in PATH. */
82 dir = path_rest;
83 for (cp = path_rest; *cp != '\0' && *cp != ':'; cp++)
84 ;
85 last = (*cp == '\0');
86 *cp = '\0';
87
88 /* Empty PATH components designate the current directory. */
89 if (dir == cp)
90 dir = ".";
91
92 /* Concatenate dir and progname. */
93 # if !IN_FINDPROG_LGPL
94 progpathname = xconcatenated_filename (dir, progname, NULL);
95 # else
96 progpathname = concatenated_filename (dir, progname, NULL);
97 if (progpathname == NULL)
98 {
99 /* Out of memory. */
100 free (path);
101 return progname;
102 }
103 # endif
104
105 /* On systems which have the eaccess() system call, let's use it.
106 On other systems, let's hope that this program is not installed
107 setuid or setgid, so that it is ok to call access() despite its
108 design flaw. */
109 if (eaccess (progpathname, X_OK) == 0)
110 {
111 /* Check that the progpathname does not point to a directory. */
112 struct stat statbuf;
113
114 if (stat (progpathname, &statbuf) >= 0
115 && ! S_ISDIR (statbuf.st_mode))
116 {
117 /* Found! */
118 if (strcmp (progpathname, progname) == 0)
119 {
120 free (progpathname);
121
122 /* Add the "./" prefix for real, that xconcatenated_filename()
123 optimized away. This avoids a second PATH search when the
124 caller uses execlp/execvp. */
125 # if !IN_FINDPROG_LGPL
126 progpathname = XNMALLOC (2 + strlen (progname) + 1, char);
127 # else
128 progpathname = (char *) malloc (2 + strlen (progname) + 1);
129 if (progpathname == NULL)
130 {
131 /* Out of memory. */
132 free (path);
133 return progname;
134 }
135 # endif
136 progpathname[0] = '.';
137 progpathname[1] = '/';
138 memcpy (progpathname + 2, progname, strlen (progname) + 1);
139 }
140
141 free (path);
142 return progpathname;
143 }
144 }
145
146 free (progpathname);
147
148 if (last)
149 break;
150 }
151
152 /* Not found in PATH. An error will be signalled at the first call. */
153 free (path);
154 return progname;
155 #endif
156 }
157
158 #endif