48 lines
1 KiB
C
48 lines
1 KiB
C
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/*
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* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
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* See the copyright notice in the ACK home directory, in the file "Copyright".
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*/
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/* $Header$ */
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#include <stdlib.h>
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#include <signal.h>
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extern int fork(void);
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extern int wait(int *);
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extern void _exit(int);
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extern void execl(char *, ...);
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extern void close(int);
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#define FAIL 127
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int
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system(const char *str)
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{
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int pid, exitstatus, waitval;
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int i;
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if ((pid = fork()) < 0) return str ? -1 : 0;
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if (pid == 0) {
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for (i = 3; i <= 20; i++)
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close(i);
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if (!str) str = "cd ."; /* just testing for a shell */
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execl("/bin/sh", "sh", "-c", str, (char *) NULL);
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/* get here if execl fails ... */
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_exit(FAIL); /* see manual page */
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}
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while ((waitval = wait(&exitstatus)) != pid) {
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if (waitval == -1) break;
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}
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if (waitval == -1) {
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/* no child ??? or maybe interrupted ??? */
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exitstatus = -1;
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}
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if (!str) {
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if (exitstatus == FAIL << 8) /* execl() failed */
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exitstatus = 0;
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else exitstatus = 1; /* /bin/sh exists */
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}
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return exitstatus;
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}
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