source: trunk/minix/lib/posix/_execvp.c@ 10

Last change on this file since 10 was 9, checked in by Mattia Monga, 13 years ago

Minix 3.1.2a

File size: 1.9 KB
Line 
1/* execvp() - execute with PATH search and prepared arguments
2 * Author: Kees J. Bot
3 * 21 Jan 1994
4 */
5
6#define _MINIX_SOURCE
7
8#define nil 0
9#define execve _execve
10#define execvp _execvp
11#define sbrk _sbrk
12#define stat _stat
13#include <stdlib.h>
14#include <string.h>
15#include <unistd.h>
16#include <errno.h>
17#include <sys/stat.h>
18
19extern char * const **_penviron; /* The default environment. */
20
21int execvp(const char *file, char * const *argv)
22/* Execute the file with a path search on $PATH, just like the shell. The
23 * search continues on the errors ENOENT (not there), and EACCES (file not
24 * executable or leading directories protected.)
25 * Unlike other execvp implementations there is no default path, and no shell
26 * is started for scripts. One is supposed to define $PATH, and use #!/bin/sh.
27 */
28{
29 struct stat sb;
30 const char *path; /* $PATH */
31 char *full; /* Full name to try. */
32 char *f;
33 size_t full_size;
34 int err= ENOENT; /* Error return on failure. */
35
36 if (strchr(file, '/') != nil || (path= getenv("PATH")) == nil)
37 path= "";
38
39 /* Compute the maximum length the full name may have, and align. */
40 full_size= strlen(path) + 1 + strlen(file) + 1 + sizeof(char *) - 1;
41 full_size&= ~(sizeof(char *) - 1);
42
43 /* Claim space. */
44 if ((full= (char *) sbrk(full_size)) == (char *) -1) {
45 errno= E2BIG;
46 return -1;
47 }
48
49 /* For each directory in the path... */
50 do {
51 f= full;
52 while (*path != 0 && *path != ':') *f++= *path++;
53
54 if (f > full) *f++= '/';
55
56 strcpy(f, file);
57
58 /* Stat first, small speed-up, better for ptrace. */
59 if (stat(full, &sb) == -1) continue;
60
61 (void) execve(full, argv, *_penviron);
62
63 /* Prefer more interesting errno values then "not there". */
64 if (errno != ENOENT) err= errno;
65
66 /* Continue only on some errors. */
67 if (err != ENOENT && err != EACCES) break;
68 } while (*path++ != 0);
69
70 (void) sbrk(-full_size);
71 errno= err;
72 return -1;
73}
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