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popen.c revision 1.20 
      1 /*	$NetBSD: popen.c,v 1.20 2006/10/21 21:37:21 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1980, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #ifndef lint
     34 #if 0
     35 static char sccsid[] = "@(#)popen.c	8.1 (Berkeley) 6/6/93";
     36 #else
     37 __RCSID("$NetBSD: popen.c,v 1.20 2006/10/21 21:37:21 christos Exp $");
     38 #endif
     39 #endif /* not lint */
     40 
     41 #include <errno.h>
     42 #include <fcntl.h>
     43 #include <stdarg.h>
     44 #include <util.h>
     45 #include <sys/wait.h>
     46 
     47 #include "rcv.h"
     48 #include "extern.h"
     49 
     50 #define READ 0
     51 #define WRITE 1
     52 
     53 struct fp {
     54 	FILE *fp;
     55 	int pipe;
     56 	pid_t pid;
     57 	struct fp *link;
     58 };
     59 static struct fp *fp_head;
     60 
     61 struct child {
     62 	pid_t pid;
     63 	char done;
     64 	char free;
     65 	int status;
     66 	struct child *link;
     67 };
     68 static struct child *child, *child_freelist = NULL;
     69 
     70 static struct child *findchild(pid_t, int);
     71 static void delchild(struct child *);
     72 static pid_t file_pid(FILE *);
     73 static pid_t start_commandv(const char *, sigset_t *, int, int, va_list);
     74 
     75 FILE *
     76 Fopen(const char *fn, const char *mode)
     77 {
     78 	FILE *fp;
     79 
     80 	if ((fp = fopen(fn, mode)) != NULL) {
     81 		register_file(fp, 0, 0);
     82 		(void)fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
     83 	}
     84 	return fp;
     85 }
     86 
     87 FILE *
     88 Fdopen(int fd, const char *mode)
     89 {
     90 	FILE *fp;
     91 
     92 	if ((fp = fdopen(fd, mode)) != NULL) {
     93 		register_file(fp, 0, 0);
     94 		(void)fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
     95 	}
     96 	return fp;
     97 }
     98 
     99 int
    100 Fclose(FILE *fp)
    101 {
    102 
    103 	unregister_file(fp);
    104 	return fclose(fp);
    105 }
    106 
    107 FILE *
    108 Popen(const char *cmd, const char *mode)
    109 {
    110 	int p[2];
    111 	int myside, hisside, fd0, fd1;
    112 	pid_t pid;
    113 	sigset_t nset;
    114 	FILE *fp;
    115 	char *shellcmd;
    116 
    117 	if (pipe(p) < 0)
    118 		return NULL;
    119 	(void)fcntl(p[READ], F_SETFD, FD_CLOEXEC);
    120 	(void)fcntl(p[WRITE], F_SETFD, FD_CLOEXEC);
    121 	if (*mode == 'r') {
    122 		myside = p[READ];
    123 		hisside = fd0 = fd1 = p[WRITE];
    124 	} else {
    125 		myside = p[WRITE];
    126 		hisside = fd0 = p[READ];
    127 		fd1 = -1;
    128 	}
    129 	(void)sigemptyset(&nset);
    130 	if ((shellcmd = value("SHELL")) == NULL)
    131 		shellcmd = __UNCONST(_PATH_CSHELL);
    132 	pid = start_command(shellcmd, &nset, fd0, fd1, "-c", cmd, NULL);
    133 	if (pid < 0) {
    134 		(void)close(p[READ]);
    135 		(void)close(p[WRITE]);
    136 		return NULL;
    137 	}
    138 	(void)close(hisside);
    139 	if ((fp = fdopen(myside, mode)) != NULL)
    140 		register_file(fp, 1, pid);
    141 	return fp;
    142 }
    143 
    144 int
    145 Pclose(FILE *ptr)
    146 {
    147 	int i;
    148 	sigset_t nset, oset;
    149 
    150 	i = file_pid(ptr);
    151 	unregister_file(ptr);
    152 	(void)fclose(ptr);
    153 	(void)sigemptyset(&nset);
    154 	(void)sigaddset(&nset, SIGINT);
    155 	(void)sigaddset(&nset, SIGHUP);
    156 	(void)sigprocmask(SIG_BLOCK, &nset, &oset);
    157 	i = wait_child(i);
    158 	(void)sigprocmask(SIG_SETMASK, &oset, NULL);
    159 	return i;
    160 }
    161 
    162 void
    163 close_all_files(void)
    164 {
    165 	while (fp_head)
    166 		if (fp_head->pipe)
    167 			(void)Pclose(fp_head->fp);
    168 		else
    169 			(void)Fclose(fp_head->fp);
    170 }
    171 
    172 #ifdef MIME_SUPPORT
    173 #if 0	/* XXX - debugging stuff.  This should go away eventually! */
    174 static void
    175 show_one_file(FILE *fo, struct fp *fpp)
    176 {
    177 	(void)fprintf(fo, ">>> fp: %p,  pipe: %d,  pid: %d,  link: %p\n",
    178 	    fpp->fp, fpp->pipe, fpp->pid, fpp->link);
    179 }
    180 
    181 void show_all_files(FILE *fo);
    182 __unused
    183 void
    184 show_all_files(FILE *fo)
    185 {
    186 	struct fp *fpp;
    187 
    188 	(void)fprintf(fo, ">> FILES\n");
    189 	for (fpp = fp_head; fpp; fpp = fpp->link)
    190 		show_one_file(fo, fpp);
    191 	(void)fprintf(fo, ">> -------\n");
    192 	(void)fflush(fo);
    193 }
    194 #endif
    195 
    196 FILE *
    197 last_registered_file(int last_pipe)
    198 {
    199 	struct fp *fpp;
    200 
    201 	if (last_pipe == 0)
    202 		return fp_head ? fp_head->fp : NULL;
    203 
    204 	for (fpp = fp_head; fpp; fpp = fpp->link)
    205 		if (fpp->pipe)
    206 			return fpp->fp;
    207 	return NULL;
    208 }
    209 
    210 void
    211 close_top_files(FILE *fp_stop)
    212 {
    213 	while (fp_head && fp_head->fp != fp_stop)
    214 		if (fp_head->pipe)
    215 			(void)Pclose(fp_head->fp);
    216 		else
    217 			(void)Fclose(fp_head->fp);
    218 }
    219 
    220 void
    221 flush_files(FILE *fo, int only_pipes)
    222 {
    223 	struct fp *fpp;
    224 
    225 	if (fo)
    226 		(void)fflush(fo);
    227 
    228 	for (fpp = fp_head; fpp; fpp = fpp->link)
    229 		if (!only_pipes || fpp->pipe)
    230 			(void)fflush(fpp->fp);
    231 
    232 	(void)fflush(stdout);
    233 }
    234 #endif /* ENABLE_MIME */
    235 
    236 void
    237 register_file(FILE *fp, int pipefd, pid_t pid)
    238 {
    239 	struct fp *fpp;
    240 
    241 	fpp = (struct fp *)emalloc(sizeof(*fpp));
    242 	fpp->fp = fp;
    243 	fpp->pipe = pipefd;
    244 	fpp->pid = pid;
    245 	fpp->link = fp_head;
    246 	fp_head = fpp;
    247 }
    248 
    249 void
    250 unregister_file(FILE *fp)
    251 {
    252 	struct fp **pp, *p;
    253 
    254 	for (pp = &fp_head; (p = *pp) != NULL; pp = &p->link)
    255 		if (p->fp == fp) {
    256 			*pp = p->link;
    257 			(void)free(p);
    258 			return;
    259 		}
    260 	errx(1, "Invalid file pointer");
    261 }
    262 
    263 static pid_t
    264 file_pid(FILE *fp)
    265 {
    266 	struct fp *p;
    267 
    268 	for (p = fp_head; p; p = p->link)
    269 		if (p->fp == fp)
    270 			return p->pid;
    271 	errx(1, "Invalid file pointer");
    272 	/*NOTREACHED*/
    273 }
    274 
    275 /*
    276  * Run a command without a shell, with optional arguments and splicing
    277  * of stdin (-1 means none) and stdout.  The command name can be a sequence
    278  * of words.
    279  * Signals must be handled by the caller.
    280  * "nset" contains the signals to ignore in the new process.
    281  * SIGINT is enabled unless it's in "nset".
    282  */
    283 static pid_t
    284 start_commandv(const char *cmd, sigset_t *nset, int infd, int outfd,
    285     va_list args)
    286 {
    287 	pid_t pid;
    288 
    289 	if ((pid = fork()) < 0) {
    290 		warn("fork");
    291 		return -1;
    292 	}
    293 	if (pid == 0) {
    294 		char *argv[100];
    295 		int i = getrawlist(cmd, argv, sizeof(argv)/ sizeof(*argv));
    296 
    297 		while ((argv[i++] = va_arg(args, char *)) != NULL)
    298 			continue;
    299 		argv[i] = NULL;
    300 		prepare_child(nset, infd, outfd);
    301 		(void)execvp(argv[0], argv);
    302 		warn("%s", argv[0]);
    303 		_exit(1);
    304 	}
    305 	return pid;
    306 }
    307 
    308 int
    309 run_command(const char *cmd, sigset_t *nset, int infd, int outfd, ...)
    310 {
    311 	pid_t pid;
    312 	va_list args;
    313 
    314 	va_start(args, outfd);
    315 	pid = start_commandv(cmd, nset, infd, outfd, args);
    316 	va_end(args);
    317 	if (pid < 0)
    318 		return -1;
    319 	return wait_command(pid);
    320 }
    321 
    322 int
    323 start_command(const char *cmd, sigset_t *nset, int infd, int outfd, ...)
    324 {
    325 	va_list args;
    326 	int r;
    327 
    328 	va_start(args, outfd);
    329 	r = start_commandv(cmd, nset, infd, outfd, args);
    330 	va_end(args);
    331 	return r;
    332 }
    333 
    334 void
    335 prepare_child(sigset_t *nset, int infd, int outfd)
    336 {
    337 	int i;
    338 	sigset_t eset;
    339 
    340 	/*
    341 	 * All file descriptors other than 0, 1, and 2 are supposed to be
    342 	 * close-on-exec.
    343 	 */
    344 	if (infd > 0) {
    345 		(void)dup2(infd, 0);
    346 	} else if (infd != 0) {
    347 		/* we don't want the child stealing my stdin input */
    348 		(void)close(0);
    349 		(void)open(_PATH_DEVNULL, O_RDONLY, 0);
    350 	}
    351 	if (outfd >= 0 && outfd != 1)
    352 		(void)dup2(outfd, 1);
    353 	if (nset == NULL)
    354 		return;
    355 	if (nset != NULL) {
    356 		for (i = 1; i < NSIG; i++)
    357 			if (sigismember(nset, i))
    358 				(void)signal(i, SIG_IGN);
    359 	}
    360 	if (nset == NULL || !sigismember(nset, SIGINT))
    361 		(void)signal(SIGINT, SIG_DFL);
    362 	(void)sigemptyset(&eset);
    363 	(void)sigprocmask(SIG_SETMASK, &eset, NULL);
    364 }
    365 
    366 int
    367 wait_command(pid_t pid)
    368 {
    369 
    370 	if (wait_child(pid) < 0) {
    371 		(void)puts("Fatal error in process.");
    372 		return -1;
    373 	}
    374 	return 0;
    375 }
    376 
    377 static struct child *
    378 findchild(pid_t pid, int dont_alloc)
    379 {
    380 	struct child **cpp;
    381 
    382 	for (cpp = &child; *cpp != NULL && (*cpp)->pid != pid;
    383 	     cpp = &(*cpp)->link)
    384 			continue;
    385 	if (*cpp == NULL) {
    386 		if (dont_alloc)
    387 			return NULL;
    388 		if (child_freelist) {
    389 			*cpp = child_freelist;
    390 			child_freelist = (*cpp)->link;
    391 		} else
    392 			*cpp = (struct child *)emalloc(sizeof(struct child));
    393 
    394 		(*cpp)->pid = pid;
    395 		(*cpp)->done = (*cpp)->free = 0;
    396 		(*cpp)->link = NULL;
    397 	}
    398 	return *cpp;
    399 }
    400 
    401 static void
    402 delchild(struct child *cp)
    403 {
    404 	struct child **cpp;
    405 
    406 	for (cpp = &child; *cpp != cp; cpp = &(*cpp)->link)
    407 		continue;
    408 	*cpp = cp->link;
    409 	cp->link = child_freelist;
    410 	child_freelist = cp;
    411 }
    412 
    413 void
    414 /*ARGSUSED*/
    415 sigchild(int signo __unused)
    416 {
    417 	pid_t pid;
    418 	int status;
    419 	struct child *cp;
    420 	int save_errno = errno;
    421 
    422 	while ((pid =
    423 	    waitpid((pid_t)-1, &status, WNOHANG)) > 0) {
    424 		cp = findchild(pid, 1);
    425 		if (!cp)
    426 			continue;
    427 		if (cp->free)
    428 			delchild(cp);
    429 		else {
    430 			cp->done = 1;
    431 			cp->status = status;
    432 		}
    433 	}
    434 	errno = save_errno;
    435 }
    436 
    437 int wait_status;
    438 
    439 /*
    440  * Wait for a specific child to die.
    441  */
    442 int
    443 wait_child(pid_t pid)
    444 {
    445 	struct child *cp;
    446 	sigset_t nset, oset;
    447 	pid_t rv = 0;
    448 
    449 	(void)sigemptyset(&nset);
    450 	(void)sigaddset(&nset, SIGCHLD);
    451 	(void)sigprocmask(SIG_BLOCK, &nset, &oset);
    452 	/*
    453 	 * If we have not already waited on the pid (via sigchild)
    454 	 * wait on it now.  Otherwise, use the wait status stashed
    455 	 * by sigchild.
    456 	 */
    457 	cp = findchild(pid, 1);
    458 	if (cp == NULL || !cp->done)
    459 		rv = waitpid(pid, &wait_status, 0);
    460 	else
    461 		wait_status = cp->status;
    462 	if (cp != NULL)
    463 		delchild(cp);
    464 	(void)sigprocmask(SIG_SETMASK, &oset, NULL);
    465 	if (rv == -1 || (WIFEXITED(wait_status) && WEXITSTATUS(wait_status)))
    466 		return -1;
    467 	else
    468 		return 0;
    469 }
    470 
    471 /*
    472  * Mark a child as don't care.
    473  */
    474 void
    475 free_child(pid_t pid)
    476 {
    477 	struct child *cp;
    478 	sigset_t nset, oset;
    479 
    480 	(void)sigemptyset(&nset);
    481 	(void)sigaddset(&nset, SIGCHLD);
    482 	(void)sigprocmask(SIG_BLOCK, &nset, &oset);
    483 	if ((cp = findchild(pid, 0)) != NULL) {
    484 		if (cp->done)
    485 			delchild(cp);
    486 		else
    487 			cp->free = 1;
    488 	}
    489 	(void)sigprocmask(SIG_SETMASK, &oset, NULL);
    490 }
    491