74 lines
1.9 KiB
C
74 lines
1.9 KiB
C
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/* execvp() - execute with PATH search and prepared arguments
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* Author: Kees J. Bot
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* 21 Jan 1994
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*/
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#define _MINIX_SOURCE
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#define nil 0
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#define execve _execve
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#define execvp _execvp
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#define sbrk _sbrk
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#define stat _stat
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/stat.h>
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extern char * const **_penviron; /* The default environment. */
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int execvp(const char *file, char * const *argv)
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/* Execute the file with a path search on $PATH, just like the shell. The
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* search continues on the errors ENOENT (not there), and EACCES (file not
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* executable or leading directories protected.)
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* Unlike other execvp implementations there is no default path, and no shell
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* is started for scripts. One is supposed to define $PATH, and use #!/bin/sh.
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*/
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{
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struct stat sb;
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const char *path; /* $PATH */
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char *full; /* Full name to try. */
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char *f;
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size_t full_size;
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int err= ENOENT; /* Error return on failure. */
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if (strchr(file, '/') != nil || (path= getenv("PATH")) == nil)
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path= "";
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/* Compute the maximum length the full name may have, and align. */
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full_size= strlen(path) + 1 + strlen(file) + 1 + sizeof(char *) - 1;
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full_size&= ~(sizeof(char *) - 1);
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/* Claim space. */
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if ((full= (char *) sbrk(full_size)) == (char *) -1) {
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errno= E2BIG;
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return -1;
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}
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/* For each directory in the path... */
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do {
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f= full;
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while (*path != 0 && *path != ':') *f++= *path++;
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if (f > full) *f++= '/';
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strcpy(f, file);
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/* Stat first, small speed-up, better for ptrace. */
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if (stat(full, &sb) == -1) continue;
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(void) execve(full, argv, *_penviron);
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/* Prefer more interesting errno values then "not there". */
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if (errno != ENOENT) err= errno;
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/* Continue only on some errors. */
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if (err != ENOENT && err != EACCES) break;
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} while (*path++ != 0);
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(void) sbrk(-full_size);
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errno= err;
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return -1;
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}
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