popen.c revision 2312 
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
27static char rcsid[] = "$Id: popen.c,v 1.5 1994/01/15 20:43:43 vixie Exp $";
28static char sccsid[] = "@(#)popen.c	5.7 (Berkeley) 2/14/89";
29#endif /* not lint */
30
31#include "cron.h"
32#include <sys/signal.h>
33
34
35#define WANT_GLOBBING 0
36
37/*
38 * Special version of popen which avoids call to shell.  This insures noone
39 * may create a pipe to a hidden program as a side effect of a list or dir
40 * command.
41 */
42static PID_T *pids;
43static int fds;
44
45FILE *
46cron_popen(program, type)
47	char *program, *type;
48{
49	register char *cp;
50	FILE *iop;
51	int argc, pdes[2];
52	PID_T pid;
53	char *argv[100];
54#if WANT_GLOBBING
55	char **pop, *vv[2];
56	int gargc;
57	char *gargv[1000];
58	extern char **glob(), **copyblk();
59#endif
60
61	if (*type != 'r' && *type != 'w' || type[1])
62		return(NULL);
63
64	if (!pids) {
65		if ((fds = getdtablesize()) <= 0)
66			return(NULL);
67		if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
68			return(NULL);
69		bzero((char *)pids, fds * sizeof(PID_T));
70	}
71	if (pipe(pdes) < 0)
72		return(NULL);
73
74	/* break up string into pieces */
75	for (argc = 0, cp = program;; cp = NULL)
76		if (!(argv[argc++] = strtok(cp, " \t\n")))
77			break;
78
79#if WANT_GLOBBING
80	/* glob each piece */
81	gargv[0] = argv[0];
82	for (gargc = argc = 1; argv[argc]; argc++) {
83		if (!(pop = glob(argv[argc]))) {	/* globbing failed */
84			vv[0] = argv[argc];
85			vv[1] = NULL;
86			pop = copyblk(vv);
87		}
88		argv[argc] = (char *)pop;		/* save to free later */
89		while (*pop && gargc < 1000)
90			gargv[gargc++] = *pop++;
91	}
92	gargv[gargc] = NULL;
93#endif
94
95	iop = NULL;
96	switch(pid = vfork()) {
97	case -1:			/* error */
98		(void)close(pdes[0]);
99		(void)close(pdes[1]);
100		goto pfree;
101		/* NOTREACHED */
102	case 0:				/* child */
103		if (*type == 'r') {
104			if (pdes[1] != 1) {
105				dup2(pdes[1], 1);
106				dup2(pdes[1], 2);	/* stderr, too! */
107				(void)close(pdes[1]);
108			}
109			(void)close(pdes[0]);
110		} else {
111			if (pdes[0] != 0) {
112				dup2(pdes[0], 0);
113				(void)close(pdes[0]);
114			}
115			(void)close(pdes[1]);
116		}
117#if WANT_GLOBBING
118		execvp(gargv[0], gargv);
119#else
120		execvp(argv[0], argv);
121#endif
122		_exit(1);
123	}
124	/* parent; assume fdopen can't fail...  */
125	if (*type == 'r') {
126		iop = fdopen(pdes[0], type);
127		(void)close(pdes[1]);
128	} else {
129		iop = fdopen(pdes[1], type);
130		(void)close(pdes[0]);
131	}
132	pids[fileno(iop)] = pid;
133
134pfree:
135#if WANT_GLOBBING
136	for (argc = 1; argv[argc] != NULL; argc++) {
137/*		blkfree((char **)argv[argc]);	*/
138		free((char *)argv[argc]);
139	}
140#endif
141	return(iop);
142}
143
144int
145cron_pclose(iop)
146	FILE *iop;
147{
148	register int fdes;
149	int omask;
150	WAIT_T stat_loc;
151	PID_T pid;
152
153	/*
154	 * pclose returns -1 if stream is not associated with a
155	 * `popened' command, or, if already `pclosed'.
156	 */
157	if (pids == 0 || pids[fdes = fileno(iop)] == 0)
158		return(-1);
159	(void)fclose(iop);
160	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
161	while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
162		;
163	(void)sigsetmask(omask);
164	pids[fdes] = 0;
165	return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
166}
167