minix/lib/ansi/system.c

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2005-04-21 16:53:53 +02:00
/*
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Header$ */
#if defined(_POSIX_SOURCE)
#include <sys/types.h>
#endif
#include <stdlib.h>
#include <signal.h>
extern pid_t _fork(void);
extern pid_t _wait(int *);
extern void _exit(int);
extern void _execve(const char *path, const char ** argv, const char ** envp);
extern int _close(int);
#define FAIL 127
extern const char ***_penviron;
static const char *exec_tab[] = {
"sh", /* argv[0] */
"-c", /* argument to the shell */
NULL, /* to be filled with user command */
NULL /* terminating NULL */
};
int
system(const char *str)
{
int pid, exitstatus, waitval;
int i;
if ((pid = _fork()) < 0) return str ? -1 : 0;
if (pid == 0) {
for (i = 3; i <= 20; i++)
_close(i);
if (!str) str = "cd ."; /* just testing for a shell */
exec_tab[2] = str; /* fill in command */
_execve("/bin/sh", exec_tab, *_penviron);
/* get here if execve fails ... */
_exit(FAIL); /* see manual page */
}
while ((waitval = _wait(&exitstatus)) != pid) {
if (waitval == -1) break;
}
if (waitval == -1) {
/* no child ??? or maybe interrupted ??? */
exitstatus = -1;
}
if (!str) {
if (exitstatus == FAIL << 8) /* execve() failed */
exitstatus = 0;
else exitstatus = 1; /* /bin/sh exists */
}
return exitstatus;
}