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#ifndef lint |
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static const char RCSid[] = "$Id: unix_process.c,v 3.9 2009/12/12 23:08:13 greg Exp $"; |
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#endif |
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/* |
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* Routines to communicate with separate process via dual pipes |
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* Unix version |
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* |
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* External symbols declared in standard.h |
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*/ |
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|
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#include "copyright.h" |
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|
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#include <sys/types.h> |
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#include <sys/wait.h> |
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#include <fcntl.h> |
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#include <stdlib.h> |
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|
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#include "rtprocess.h" |
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#include "rtio.h" |
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|
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|
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int |
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open_process( /* open communication to separate process */ |
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SUBPROC *pd, |
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char *av[] |
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) |
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{ |
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char *compath; |
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int p0[2], p1[2]; |
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|
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pd->running = 0; /* not going yet */ |
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|
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if (av == NULL) /* cloning operation? */ |
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compath = NULL; |
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else if ((compath = getpath(av[0], getenv("PATH"), X_OK)) == NULL) |
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return(0); |
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if (pipe(p0) < 0 || pipe(p1) < 0) |
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return(-1); |
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if ((pd->pid = fork()) == 0) { /* if child... */ |
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close(p0[1]); |
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close(p1[0]); |
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if (p0[0] != 0) { /* connect p0 to stdin */ |
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dup2(p0[0], 0); |
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close(p0[0]); |
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} |
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if (p1[1] != 1) { /* connect p1 to stdout */ |
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dup2(p1[1], 1); |
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close(p1[1]); |
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} |
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if (compath == NULL) /* just cloning? */ |
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return(0); |
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execv(compath, av); /* else exec command */ |
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perror(compath); |
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_exit(127); |
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} |
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if (pd->pid == -1) |
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return(-1); |
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close(p0[0]); |
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close(p1[1]); |
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pd->r = p1[0]; |
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pd->w = p0[1]; |
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/* |
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* Close write stream on exec to avoid multiprocessing deadlock. |
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* No use in read stream without it, so set flag there as well. |
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* GW: This bug took me two days to figure out!! |
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*/ |
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fcntl(pd->r, F_SETFD, FD_CLOEXEC); |
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fcntl(pd->w, F_SETFD, FD_CLOEXEC); |
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pd->running = 1; |
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return(PIPE_BUF); |
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} |
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|
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|
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|
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int |
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close_process( /* close pipes and wait for process */ |
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SUBPROC *pd |
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) |
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{ |
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int status; |
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|
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if (!pd->running) |
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return(0); |
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close(pd->w); |
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close(pd->r); |
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pd->running = 0; |
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if (waitpid(pd->pid, &status, 0) == pd->pid) |
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return(status>>8 & 0xff); |
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|
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return(-1); /* ? unknown status */ |
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} |
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|
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