120 lines
2 KiB
C
120 lines
2 KiB
C
/*
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* popen - open a pipe
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*/
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/* $Id$ */
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#include <errno.h>
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#include <stdio.h>
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#include <signal.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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int _close(int d);
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#if defined(__USG)
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static
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#endif
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int
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_dup2(int oldd, int newd); /* not present in System 5 */
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int _execl(const char* name, ...);
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int _fork(void);
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int _pipe(int fildes[2]);
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int _wait(wait_arg* status);
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void _exit(int status);
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static int pids[FOPEN_MAX];
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FILE* popen(const char* command, 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 || _pipe(piped) < 0 || (pid = _fork()) < 0)
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return 0;
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if (pid == 0)
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{
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/* child */
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register int* p;
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for (p = pids; p < &pids[FOPEN_MAX]; p++)
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{
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if (*p)
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_close(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 pclose(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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void (*intsave)(int) = signal(SIGINT, SIG_IGN);
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void (*quitsave)(int) = signal(SIGQUIT, SIG_IGN);
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fclose(stream);
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while ((wret = _wait(&status)) != -1)
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{
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if (wret == pids[fd])
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break;
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}
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if (wret == -1)
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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(int oldd, int newd)
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{
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int i = 0, fd, tmp;
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int fdbuf[FOPEN_MAX];
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/* ignore the error on the close() */
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tmp = errno;
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(void)_close(newd);
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errno = tmp;
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while ((fd = _dup(oldd)) != newd)
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{
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if (fd == -1)
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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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{
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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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