1 | /* Copyright (C) 2006 by Paolo Giarrusso - modified from glibc' execvp.c. |
2 | Original copyright notice follows: |
3 | |
4 | Copyright (C) 1991,92,1995-99,2002,2004 Free Software Foundation, Inc. |
5 | This file is part of the GNU C Library. |
6 | |
7 | The GNU C Library is free software; you can redistribute it and/or |
8 | modify it under the terms of the GNU Lesser General Public |
9 | License as published by the Free Software Foundation; either |
10 | version 2.1 of the License, or (at your option) any later version. |
11 | |
12 | The GNU C Library is distributed in the hope that it will be useful, |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
15 | Lesser General Public License for more details. |
16 | |
17 | You should have received a copy of the GNU Lesser General Public |
18 | License along with the GNU C Library; if not, write to the Free |
19 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
20 | 02111-1307 USA. */ |
21 | #include <unistd.h> |
22 | |
23 | #include <stdbool.h> |
24 | #include <stdlib.h> |
25 | #include <string.h> |
26 | #include <errno.h> |
27 | #include <limits.h> |
28 | |
29 | #ifndef TEST |
30 | #include <um_malloc.h> |
31 | #else |
32 | #include <stdio.h> |
33 | #define um_kmalloc malloc |
34 | #endif |
35 | #include <os.h> |
36 | |
37 | /* Execute FILE, searching in the `PATH' environment variable if it contains |
38 | no slashes, with arguments ARGV and environment from `environ'. */ |
39 | int execvp_noalloc(char *buf, const char *file, char *const argv[]) |
40 | { |
41 | if (*file == '\0') { |
42 | return -ENOENT; |
43 | } |
44 | |
45 | if (strchr (file, '/') != NULL) { |
46 | /* Don't search when it contains a slash. */ |
47 | execv(file, argv); |
48 | } else { |
49 | int got_eacces; |
50 | size_t len, pathlen; |
51 | char *name, *p; |
52 | char *path = getenv("PATH" ); |
53 | if (path == NULL) |
54 | path = ":/bin:/usr/bin" ; |
55 | |
56 | len = strlen(file) + 1; |
57 | pathlen = strlen(path); |
58 | /* Copy the file name at the top. */ |
59 | name = memcpy(buf + pathlen + 1, file, len); |
60 | /* And add the slash. */ |
61 | *--name = '/'; |
62 | |
63 | got_eacces = 0; |
64 | p = path; |
65 | do { |
66 | char *startp; |
67 | |
68 | path = p; |
69 | //Let's avoid this GNU extension. |
70 | //p = strchrnul (path, ':'); |
71 | p = strchr(path, ':'); |
72 | if (!p) |
73 | p = strchr(path, '\0'); |
74 | |
75 | if (p == path) |
76 | /* Two adjacent colons, or a colon at the beginning or the end |
77 | of `PATH' means to search the current directory. */ |
78 | startp = name + 1; |
79 | else |
80 | startp = memcpy(name - (p - path), path, p - path); |
81 | |
82 | /* Try to execute this name. If it works, execv will not return. */ |
83 | execv(startp, argv); |
84 | |
85 | /* |
86 | if (errno == ENOEXEC) { |
87 | } |
88 | */ |
89 | |
90 | switch (errno) { |
91 | case EACCES: |
92 | /* Record the we got a `Permission denied' error. If we end |
93 | up finding no executable we can use, we want to diagnose |
94 | that we did find one but were denied access. */ |
95 | got_eacces = 1; |
96 | break; |
97 | case ENOENT: |
98 | case ESTALE: |
99 | case ENOTDIR: |
100 | /* Those errors indicate the file is missing or not executable |
101 | by us, in which case we want to just try the next path |
102 | directory. */ |
103 | case ENODEV: |
104 | case ETIMEDOUT: |
105 | /* Some strange filesystems like AFS return even |
106 | stranger error numbers. They cannot reasonably mean |
107 | anything else so ignore those, too. */ |
108 | case ENOEXEC: |
109 | /* We won't go searching for the shell |
110 | * if it is not executable - the Linux |
111 | * kernel already handles this enough, |
112 | * for us. */ |
113 | break; |
114 | |
115 | default: |
116 | /* Some other error means we found an executable file, but |
117 | something went wrong executing it; return the error to our |
118 | caller. */ |
119 | return -errno; |
120 | } |
121 | } while (*p++ != '\0'); |
122 | |
123 | /* We tried every element and none of them worked. */ |
124 | if (got_eacces) |
125 | /* At least one failure was due to permissions, so report that |
126 | error. */ |
127 | return -EACCES; |
128 | } |
129 | |
130 | /* Return the error from the last attempt (probably ENOENT). */ |
131 | return -errno; |
132 | } |
133 | #ifdef TEST |
134 | int main(int argc, char**argv) |
135 | { |
136 | char buf[PATH_MAX]; |
137 | int ret; |
138 | argc--; |
139 | if (!argc) { |
140 | os_warn("Not enough arguments\n" ); |
141 | return 1; |
142 | } |
143 | argv++; |
144 | if (ret = execvp_noalloc(buf, argv[0], argv)) { |
145 | errno = -ret; |
146 | perror("execvp_noalloc" ); |
147 | } |
148 | return 0; |
149 | } |
150 | #endif |
151 | |