src/common/unix_process.c

#ifndef lint
static const char       RCSid[] = "$Id: unix_process.c,v 3.14 2019/05/14 18:37:36 greg Exp $";
#endif
/*
 * Routines to communicate with separate process via dual pipes
 * Unix version
 *
 * External symbols declared in standard.h
 */

#include "copyright.h"

#include <sys/wait.h>
#include <stdlib.h>

#include "rtprocess.h"
#include "rtio.h"


int
open_process(           /* open communication to separate process */
SUBPROC *pd,
char    *av[]
)
{
        char    *compath;
        int     p0[2], p1[2];

        pd->pid = -1;
        pd->running = 0;                /* not going yet */
        
        if (av == NULL)                 /* cloning operation? */
                compath = NULL;
        else if ((compath = getpath(av[0], getenv("PATH"), X_OK)) == NULL)
                return(0);
        if (pipe(p0) < 0 || pipe(p1) < 0)
                return(-1);
#ifdef BSD
        if (compath != NULL)
                pd->pid = vfork();      /* more efficient with exec() */
        else
#endif
        pd->pid = fork();
        if (pd->pid == 0) {             /* if child... */
                close(p0[1]);
                close(p1[0]);
                if (p0[0] != 0) {       /* connect p0 to stdin */
                        dup2(p0[0], 0);
                        close(p0[0]);
                }
                if (p1[1] != 1) {       /* connect p1 to stdout */
                        dup2(p1[1], 1);
                        close(p1[1]);
                }
                if (compath == NULL)    /* just cloning? */
                        return(0);
                execv(compath, av);     /* else exec command */
                perror(compath);
                _exit(127);
        }
        if (pd->pid == -1)
                return(-1);
        close(p0[0]);
        close(p1[1]);
        pd->r = p1[0];
        pd->w = p0[1];
        /*
         * Close write stream on exec to avoid multiprocessing deadlock.
         * No use in read stream without it, so set flag there as well.
         * GW: This bug took me two days to figure out!!
         */
        fcntl(pd->r, F_SETFD, FD_CLOEXEC);
        fcntl(pd->w, F_SETFD, FD_CLOEXEC);
        pd->running = 1;
        return(PIPE_BUF);
}


int
close_processes(        /* close pipes and wait for processes to finish */
SUBPROC pd[],
int nproc
)
{
        int     togo = nproc;
        int     status, rtn_status = 0;
        RT_PID  pid;
        int     i;

        for (i = 0; i < nproc; i++)             /* close pipes, first */
                if (pd[i].running) {
                        close(pd[i].w);
                        close(pd[i].r);
                        pd[i].running = 0;
                } else 
                        togo -= (pd[i].pid < 0);
        if (nproc == 1) {                       /* await specific process? */
                if (waitpid(pd->pid, &status, 0) != pd->pid)
                        return(-1);
                pd->pid = -1;
                return(status>>8 & 0xff);
        }
                                                /* else unordered wait */
        while (togo > 0 && (pid = wait(&status)) >= 0) {
                for (i = nproc; i-- > 0; )
                        if (pd[i].pid == pid) {
                                pd[i].pid = -1;
                                --togo;
                                break;
                        }
                if (i < 0)
                        continue;               /* child we don't know? */
                status = status>>8 & 0xff;
                if (status)                     /* record non-zero status */
                        rtn_status = status;
        }
        if (togo)                               /* child went missing? */
                return(-1);
        return(rtn_status);
}
Revision:	3.15
Committed:	Sat Dec 28 18:05:14 2019 UTC (4 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 3.14:	+1 -3 lines
Log Message:	Removed redundant include files
#	User	Rev	Content
1	schorsch	3.1	#ifndef lint
2	greg	3.15	static const char RCSid[] = "$Id: unix_process.c,v 3.14 2019/05/14 18:37:36 greg Exp $";
3	schorsch	3.1	#endif
4			/*
5			* Routines to communicate with separate process via dual pipes
6			* Unix version
7			*
8			* External symbols declared in standard.h
9			*/
10
11			#include "copyright.h"
12	schorsch	3.2
13			#include <sys/wait.h>
14	greg	3.7	#include <stdlib.h>
15	schorsch	3.1
16			#include "rtprocess.h"
17	greg	3.7	#include "rtio.h"
18	schorsch	3.1
19
20			int
21			open_process( /* open communication to separate process */
22			SUBPROC *pd,
23			char *av[]
24			)
25			{
26			char *compath;
27			int p0[2], p1[2];
28
29	greg	3.12	pd->pid = -1;
30	greg	3.10	pd->running = 0; /* not going yet */
31
32			if (av == NULL) /* cloning operation? */
33			compath = NULL;
34			else if ((compath = getpath(av[0], getenv("PATH"), X_OK)) == NULL)
35	schorsch	3.1	return(0);
36			if (pipe(p0) < 0 \|\| pipe(p1) < 0)
37			return(-1);
38	greg	3.14	#ifdef BSD
39			if (compath != NULL)
40			pd->pid = vfork(); /* more efficient with exec() */
41			else
42			#endif
43			pd->pid = fork();
44			if (pd->pid == 0) { /* if child... */
45	schorsch	3.1	close(p0[1]);
46			close(p1[0]);
47			if (p0[0] != 0) { /* connect p0 to stdin */
48			dup2(p0[0], 0);
49			close(p0[0]);
50			}
51			if (p1[1] != 1) { /* connect p1 to stdout */
52			dup2(p1[1], 1);
53			close(p1[1]);
54			}
55	greg	3.10	if (compath == NULL) /* just cloning? */
56			return(0);
57			execv(compath, av); /* else exec command */
58	schorsch	3.1	perror(compath);
59			_exit(127);
60			}
61			if (pd->pid == -1)
62			return(-1);
63			close(p0[0]);
64			close(p1[1]);
65			pd->r = p1[0];
66			pd->w = p0[1];
67	greg	3.6	/*
68			* Close write stream on exec to avoid multiprocessing deadlock.
69			* No use in read stream without it, so set flag there as well.
70			* GW: This bug took me two days to figure out!!
71			*/
72			fcntl(pd->r, F_SETFD, FD_CLOEXEC);
73			fcntl(pd->w, F_SETFD, FD_CLOEXEC);
74	schorsch	3.1	pd->running = 1;
75			return(PIPE_BUF);
76			}
77
78
79			int
80	greg	3.11	close_processes( /* close pipes and wait for processes to finish */
81			SUBPROC pd[],
82			int nproc
83	schorsch	3.1	)
84			{
85	greg	3.11	int togo = nproc;
86			int status, rtn_status = 0;
87			RT_PID pid;
88			int i;
89
90			for (i = 0; i < nproc; i++) /* close pipes, first */
91			if (pd[i].running) {
92			close(pd[i].w);
93			close(pd[i].r);
94			pd[i].running = 0;
95	greg	3.13	} else
96			togo -= (pd[i].pid < 0);
97	greg	3.11	if (nproc == 1) { /* await specific process? */
98			if (waitpid(pd->pid, &status, 0) != pd->pid)
99			return(-1);
100	greg	3.12	pd->pid = -1;
101	greg	3.5	return(status>>8 & 0xff);
102	greg	3.11	}
103			/* else unordered wait */
104			while (togo > 0 && (pid = wait(&status)) >= 0) {
105			for (i = nproc; i-- > 0; )
106			if (pd[i].pid == pid) {
107	greg	3.12	pd[i].pid = -1;
108	greg	3.11	--togo;
109			break;
110			}
111			if (i < 0)
112			continue; /* child we don't know? */
113			status = status>>8 & 0xff;
114			if (status) /* record non-zero status */
115			rtn_status = status;
116			}
117			if (togo) /* child went missing? */
118			return(-1);
119			return(rtn_status);
120	schorsch	3.1	}