freebsd-dev/usr.bin/mail/popen.c
Eitan Adler 35f8ab70be Fix likely race condition if wait_child() is interrupted by sigchild()
PR:		bin/102834
Submitted by:	Andreas Longwitz <longwitz@incore.de>
Approved by:	cperciva
MFC after:	2 weeks
2012-05-30 03:55:44 +00:00

374 lines
7.5 KiB
C

/*
* Copyright (c) 1980, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/6/93";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "rcv.h"
#include <sys/wait.h>
#include <fcntl.h>
#include "extern.h"
#define READ 0
#define WRITE 1
struct fp {
FILE *fp;
int pipe;
int pid;
struct fp *link;
};
static struct fp *fp_head;
struct child {
int pid;
char done;
char free;
int status;
struct child *link;
};
static struct child *child;
static struct child *findchild(int);
static void delchild(struct child *);
static int file_pid(FILE *);
FILE *
Fopen(const char *path, const char *mode)
{
FILE *fp;
if ((fp = fopen(path, mode)) != NULL) {
register_file(fp, 0, 0);
(void)fcntl(fileno(fp), F_SETFD, 1);
}
return (fp);
}
FILE *
Fdopen(int fd, const char *mode)
{
FILE *fp;
if ((fp = fdopen(fd, mode)) != NULL) {
register_file(fp, 0, 0);
(void)fcntl(fileno(fp), F_SETFD, 1);
}
return (fp);
}
int
Fclose(FILE *fp)
{
unregister_file(fp);
return (fclose(fp));
}
FILE *
Popen(char *cmd, const char *mode)
{
int p[2];
int myside, hisside, fd0, fd1;
int pid;
sigset_t nset;
FILE *fp;
if (pipe(p) < 0)
return (NULL);
(void)fcntl(p[READ], F_SETFD, 1);
(void)fcntl(p[WRITE], F_SETFD, 1);
if (*mode == 'r') {
myside = p[READ];
fd0 = -1;
hisside = fd1 = p[WRITE];
} else {
myside = p[WRITE];
hisside = fd0 = p[READ];
fd1 = -1;
}
(void)sigemptyset(&nset);
if ((pid = start_command(cmd, &nset, fd0, fd1, NULL, NULL, NULL)) < 0) {
(void)close(p[READ]);
(void)close(p[WRITE]);
return (NULL);
}
(void)close(hisside);
if ((fp = fdopen(myside, mode)) != NULL)
register_file(fp, 1, pid);
return (fp);
}
int
Pclose(FILE *ptr)
{
int i;
sigset_t nset, oset;
i = file_pid(ptr);
unregister_file(ptr);
(void)fclose(ptr);
(void)sigemptyset(&nset);
(void)sigaddset(&nset, SIGINT);
(void)sigaddset(&nset, SIGHUP);
(void)sigprocmask(SIG_BLOCK, &nset, &oset);
i = wait_child(i);
(void)sigprocmask(SIG_SETMASK, &oset, NULL);
return (i);
}
void
close_all_files(void)
{
while (fp_head != NULL)
if (fp_head->pipe)
(void)Pclose(fp_head->fp);
else
(void)Fclose(fp_head->fp);
}
void
register_file(FILE *fp, int pipe, int pid)
{
struct fp *fpp;
if ((fpp = malloc(sizeof(*fpp))) == NULL)
err(1, "Out of memory");
fpp->fp = fp;
fpp->pipe = pipe;
fpp->pid = pid;
fpp->link = fp_head;
fp_head = fpp;
}
void
unregister_file(FILE *fp)
{
struct fp **pp, *p;
for (pp = &fp_head; (p = *pp) != NULL; pp = &p->link)
if (p->fp == fp) {
*pp = p->link;
(void)free(p);
return;
}
errx(1, "Invalid file pointer");
/*NOTREACHED*/
}
int
file_pid(FILE *fp)
{
struct fp *p;
for (p = fp_head; p != NULL; p = p->link)
if (p->fp == fp)
return (p->pid);
errx(1, "Invalid file pointer");
/*NOTREACHED*/
}
/*
* Run a command without a shell, with optional arguments and splicing
* of stdin and stdout. The command name can be a sequence of words.
* Signals must be handled by the caller.
* "Mask" contains the signals to ignore in the new process.
* SIGINT is enabled unless it's in the mask.
*/
/*VARARGS4*/
int
run_command(char *cmd, sigset_t *mask, int infd, int outfd, char *a0,
char *a1, char *a2)
{
int pid;
if ((pid = start_command(cmd, mask, infd, outfd, a0, a1, a2)) < 0)
return (-1);
return (wait_command(pid));
}
/*VARARGS4*/
int
start_command(char *cmd, sigset_t *mask, int infd, int outfd, char *a0,
char *a1, char *a2)
{
int pid;
if ((pid = fork()) < 0) {
warn("fork");
return (-1);
}
if (pid == 0) {
char *argv[100];
int i = getrawlist(cmd, argv, sizeof(argv) / sizeof(*argv));
if ((argv[i++] = a0) != NULL &&
(argv[i++] = a1) != NULL &&
(argv[i++] = a2) != NULL)
argv[i] = NULL;
prepare_child(mask, infd, outfd);
execvp(argv[0], argv);
warn("%s", argv[0]);
_exit(1);
}
return (pid);
}
void
prepare_child(sigset_t *nset, int infd, int outfd)
{
int i;
sigset_t eset;
/*
* All file descriptors other than 0, 1, and 2 are supposed to be
* close-on-exec.
*/
if (infd >= 0)
dup2(infd, 0);
if (outfd >= 0)
dup2(outfd, 1);
for (i = 1; i < NSIG; i++)
if (nset != NULL && sigismember(nset, i))
(void)signal(i, SIG_IGN);
if (nset == NULL || !sigismember(nset, SIGINT))
(void)signal(SIGINT, SIG_DFL);
(void)sigemptyset(&eset);
(void)sigprocmask(SIG_SETMASK, &eset, NULL);
}
int
wait_command(int pid)
{
if (wait_child(pid) < 0) {
printf("Fatal error in process.\n");
return (-1);
}
return (0);
}
static struct child *
findchild(int pid)
{
struct child **cpp;
for (cpp = &child; *cpp != NULL && (*cpp)->pid != pid;
cpp = &(*cpp)->link)
;
if (*cpp == NULL) {
*cpp = malloc(sizeof(struct child));
if (*cpp == NULL)
err(1, "Out of memory");
(*cpp)->pid = pid;
(*cpp)->done = (*cpp)->free = 0;
(*cpp)->link = NULL;
}
return (*cpp);
}
static void
delchild(struct child *cp)
{
struct child **cpp;
for (cpp = &child; *cpp != cp; cpp = &(*cpp)->link)
;
*cpp = cp->link;
(void)free(cp);
}
/*ARGSUSED*/
void
sigchild(int signo __unused)
{
int pid;
int status;
struct child *cp;
while ((pid = waitpid((pid_t)-1, &status, WNOHANG)) > 0) {
cp = findchild(pid);
if (cp->free)
delchild(cp);
else {
cp->done = 1;
cp->status = status;
}
}
}
int wait_status;
/*
* Wait for a specific child to die.
*/
int
wait_child(int pid)
{
sigset_t nset, oset;
struct child *cp;
(void)sigemptyset(&nset);
(void)sigaddset(&nset, SIGCHLD);
(void)sigprocmask(SIG_BLOCK, &nset, &oset);
cp = findchild(pid);
while (!cp->done)
(void)sigsuspend(&oset);
wait_status = cp->status;
delchild(cp);
(void)sigprocmask(SIG_SETMASK, &oset, NULL);
return ((WIFEXITED(wait_status) && WEXITSTATUS(wait_status)) ? -1 : 0);
}
/*
* Mark a child as don't care.
*/
void
free_child(int pid)
{
sigset_t nset, oset;
struct child *cp = findchild(pid);
(void)sigemptyset(&nset);
(void)sigaddset(&nset, SIGCHLD);
(void)sigprocmask(SIG_BLOCK, &nset, &oset);
if (cp->done)
delchild(cp);
else
cp->free = 1;
(void)sigprocmask(SIG_SETMASK, &oset, NULL);
}