popen.c revision 62365 
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  "$FreeBSD: head/usr.sbin/cron/cron/popen.c 62365 2000-07-01 22:37:02Z ache $";
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	argv[MAX_ARGS] = NULL;
84
85#if WANT_GLOBBING
86	/* glob each piece */
87	gargv[0] = argv[0];
88	for (gargc = argc = 1; argv[argc]; argc++) {
89		if (!(pop = glob(argv[argc]))) {	/* globbing failed */
90			vv[0] = argv[argc];
91			vv[1] = NULL;
92			pop = copyblk(vv);
93		}
94		argv[argc] = (char *)pop;		/* save to free later */
95		while (*pop && gargc < 1000)
96			gargv[gargc++] = *pop++;
97	}
98	gargv[gargc] = NULL;
99#endif
100
101	iop = NULL;
102	switch(pid = vfork()) {
103	case -1:			/* error */
104		(void)close(pdes[0]);
105		(void)close(pdes[1]);
106		goto pfree;
107		/* NOTREACHED */
108	case 0:				/* child */
109		if (*type == 'r') {
110			/* Do not share our parent's stdin */
111			(void)close(0);
112			(void)open("/dev/null", O_RDWR);
113			if (pdes[1] != 1) {
114				dup2(pdes[1], 1);
115				dup2(pdes[1], 2);	/* stderr, too! */
116				(void)close(pdes[1]);
117			}
118			(void)close(pdes[0]);
119		} else {
120			if (pdes[0] != 0) {
121				dup2(pdes[0], 0);
122				(void)close(pdes[0]);
123			}
124			/* Hack: stdout gets revoked */
125			(void)close(1);
126			(void)open("/dev/null", O_RDWR);
127			(void)close(2);
128			(void)open("/dev/null", O_RDWR);
129			(void)close(pdes[1]);
130		}
131#if WANT_GLOBBING
132		execvp(gargv[0], gargv);
133#else
134		execvp(argv[0], argv);
135#endif
136		_exit(1);
137	}
138	/* parent; assume fdopen can't fail...  */
139	if (*type == 'r') {
140		iop = fdopen(pdes[0], type);
141		(void)close(pdes[1]);
142	} else {
143		iop = fdopen(pdes[1], type);
144		(void)close(pdes[0]);
145	}
146	pids[fileno(iop)] = pid;
147
148pfree:
149#if WANT_GLOBBING
150	for (argc = 1; argv[argc] != NULL; argc++) {
151/*		blkfree((char **)argv[argc]);	*/
152		free((char *)argv[argc]);
153	}
154#endif
155	return(iop);
156}
157
158int
159cron_pclose(iop)
160	FILE *iop;
161{
162	register int fdes;
163	int omask;
164	WAIT_T stat_loc;
165	PID_T pid;
166
167	/*
168	 * pclose returns -1 if stream is not associated with a
169	 * `popened' command, or, if already `pclosed'.
170	 */
171	if (pids == 0 || pids[fdes = fileno(iop)] == 0)
172		return(-1);
173	(void)fclose(iop);
174	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
175	while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
176		;
177	(void)sigsetmask(omask);
178	pids[fdes] = 0;
179	return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
180}
181