122 lines
2.2 KiB
C
122 lines
2.2 KiB
C
/*
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* popen - open a pipe
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*/
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/* $Header$ */
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#include <sys/types.h>
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#include <limits.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#if defined(__BSD4_2)
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union wait {
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int w_status;
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};
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typedef union wait wait_arg;
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#else
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typedef int wait_arg;
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#endif /* __BSD4_2 */
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#include "../stdio/loc_incl.h"
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#ifdef _ANSI
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int _close(int d);
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int _dup2(int oldd, int newd); /* not present in System 5 */
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int _execl(const char *name, const char *_arg, ... );
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pid_t _fork(void);
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int _pipe(int fildes[2]);
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pid_t _wait(wait_arg *status);
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void _exit(int status);
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#endif
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static int pids[OPEN_MAX];
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FILE *
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popen(command, type)
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_CONST char *command;
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_CONST char *type;
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{
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int piped[2];
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int Xtype = *type == 'r' ? 0 : *type == 'w' ? 1 : 2;
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int pid;
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if (Xtype == 2 ||
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_pipe(piped) < 0 ||
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(pid = _fork()) < 0) return 0;
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if (pid == 0) {
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/* child */
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register int *p;
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for (p = pids; p < &pids[OPEN_MAX]; p++) {
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if (*p) _close((int)(p - pids));
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}
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_close(piped[Xtype]);
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_dup2(piped[!Xtype], !Xtype);
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_close(piped[!Xtype]);
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_execl("/bin/sh", "sh", "-c", command, (char *) 0);
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_exit(127); /* like system() ??? */
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}
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pids[piped[Xtype]] = pid;
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_close(piped[!Xtype]);
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return fdopen(piped[Xtype], type);
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}
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#if defined(__BSD4_2)
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#define ret_val status.w_status
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#else
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#define ret_val status
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#endif
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int
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pclose(stream)
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FILE *stream;
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{
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int fd = fileno(stream);
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wait_arg status;
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int wret;
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#ifdef _ANSI
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void (*intsave)(int) = signal(SIGINT, SIG_IGN);
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void (*quitsave)(int) = signal(SIGQUIT, SIG_IGN);
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#else
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void (*intsave)() = signal(SIGINT, SIG_IGN);
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void (*quitsave)() = signal(SIGQUIT, SIG_IGN);
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#endif
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fclose(stream);
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while ((wret = _wait(&status)) != -1) {
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if (wret == pids[fd]) break;
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}
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if (wret == -1) ret_val = -1;
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signal(SIGINT, intsave);
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signal(SIGQUIT, quitsave);
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pids[fd] = 0;
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return ret_val;
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}
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#if defined(__USG)
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int _dup(int fildes);
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static int
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_dup2(oldd, newd)
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int oldd, newd;
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{
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int i = 0, fd, tmp;
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int fdbuf[_NFILES];
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/* ignore the error on the close() */
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tmp = errno; (void) _close(newd); errno = tmp;
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while ((fd = _dup(oldd)) != newd) {
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if (fd == -1) break;
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fdbuf[i++] = fd;
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}
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tmp = errno;
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while (--i >= 0) {
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_close(fdbuf[i]);
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}
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errno = tmp;
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return -(fd == -1);
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}
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#endif /* __USG */
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