popen.c revision 45369 
1/*
2 * Copyright (c) 1988 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software written by Ken Arnold and
6 * published in UNIX Review, Vol. 6, No. 8.
7 *
8 * Redistribution and use in source and binary forms are permitted
9 * provided that the above copyright notice and this paragraph are
10 * duplicated in all such forms and that any documentation,
11 * advertising materials, and other materials related to such
12 * distribution and use acknowledge that the software was developed
13 * by the University of California, Berkeley.  The name of the
14 * University may not be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
19 *
20 */
21
22/* this came out of the ftpd sources; it's been modified to avoid the
23 * globbing stuff since we don't need it.  also execvp instead of execv.
24 */
25
26#ifndef lint
27#if 0
28static char sccsid[] = "@(#)popen.c	5.7 (Berkeley) 2/14/89";
29#endif
30static const char rcsid[] =
31	"$Id: popen.c,v 1.5 1997/09/15 06:39:07 charnier Exp $";
32#endif /* not lint */
33
34#include "cron.h"
35#include <sys/signal.h>
36#include <fcntl.h>
37
38
39#define MAX_ARGS 100
40#define WANT_GLOBBING 0
41
42/*
43 * Special version of popen which avoids call to shell.  This insures noone
44 * may create a pipe to a hidden program as a side effect of a list or dir
45 * command.
46 */
47static PID_T *pids;
48static int fds;
49
50FILE *
51cron_popen(program, type)
52	char *program, *type;
53{
54	register char *cp;
55	FILE *iop;
56	int argc, pdes[2];
57	PID_T pid;
58	char *argv[MAX_ARGS + 1];
59#if WANT_GLOBBING
60	char **pop, *vv[2];
61	int gargc;
62	char *gargv[1000];
63	extern char **glob(), **copyblk();
64#endif
65
66	if ((*type != 'r' && *type != 'w') || type[1])
67		return(NULL);
68
69	if (!pids) {
70		if ((fds = getdtablesize()) <= 0)
71			return(NULL);
72		if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
73			return(NULL);
74		bzero((char *)pids, fds * sizeof(PID_T));
75	}
76	if (pipe(pdes) < 0)
77		return(NULL);
78
79	/* break up string into pieces */
80	for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
81		if (!(argv[argc++] = strtok(cp, " \t\n")))
82			break;
83
84#if WANT_GLOBBING
85	/* glob each piece */
86	gargv[0] = argv[0];
87	for (gargc = argc = 1; argv[argc]; argc++) {
88		if (!(pop = glob(argv[argc]))) {	/* globbing failed */
89			vv[0] = argv[argc];
90			vv[1] = NULL;
91			pop = copyblk(vv);
92		}
93		argv[argc] = (char *)pop;		/* save to free later */
94		while (*pop && gargc < 1000)
95			gargv[gargc++] = *pop++;
96	}
97	gargv[gargc] = NULL;
98#endif
99
100	iop = NULL;
101	switch(pid = vfork()) {
102	case -1:			/* error */
103		(void)close(pdes[0]);
104		(void)close(pdes[1]);
105		goto pfree;
106		/* NOTREACHED */
107	case 0:				/* child */
108		if (*type == 'r') {
109			/* Do not share our parent's stdin */
110			(void)close(0);
111			(void)open("/dev/null", O_RDWR);
112			if (pdes[1] != 1) {
113				dup2(pdes[1], 1);
114				dup2(pdes[1], 2);	/* stderr, too! */
115				(void)close(pdes[1]);
116			}
117			(void)close(pdes[0]);
118		} else {
119			if (pdes[0] != 0) {
120				dup2(pdes[0], 0);
121				(void)close(pdes[0]);
122			}
123			/* Hack: stdout gets revoked */
124			(void)close(1);
125			(void)open("/dev/null", O_RDWR);
126			(void)close(2);
127			(void)open("/dev/null", O_RDWR);
128			(void)close(pdes[1]);
129		}
130#if WANT_GLOBBING
131		execvp(gargv[0], gargv);
132#else
133		execvp(argv[0], argv);
134#endif
135		_exit(1);
136	}
137	/* parent; assume fdopen can't fail...  */
138	if (*type == 'r') {
139		iop = fdopen(pdes[0], type);
140		(void)close(pdes[1]);
141	} else {
142		iop = fdopen(pdes[1], type);
143		(void)close(pdes[0]);
144	}
145	pids[fileno(iop)] = pid;
146
147pfree:
148#if WANT_GLOBBING
149	for (argc = 1; argv[argc] != NULL; argc++) {
150/*		blkfree((char **)argv[argc]);	*/
151		free((char *)argv[argc]);
152	}
153#endif
154	return(iop);
155}
156
157int
158cron_pclose(iop)
159	FILE *iop;
160{
161	register int fdes;
162	int omask;
163	WAIT_T stat_loc;
164	PID_T pid;
165
166	/*
167	 * pclose returns -1 if stream is not associated with a
168	 * `popened' command, or, if already `pclosed'.
169	 */
170	if (pids == 0 || pids[fdes = fileno(iop)] == 0)
171		return(-1);
172	(void)fclose(iop);
173	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
174	while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
175		;
176	(void)sigsetmask(omask);
177	pids[fdes] = 0;
178	return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
179}
180