/*      $NetBSD: popen.c,v 1.27 2012/04/29 23:50:22 christos Exp $      */

/*
 * 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.
 * 3. 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.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)popen.c     8.1 (Berkeley) 6/6/93";
#else
__RCSID("$NetBSD: popen.c,v 1.27 2012/04/29 23:50:22 christos Exp $");
#endif
#endif /* not lint */

#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <util.h>
#include <sys/wait.h>

#include "rcv.h"
#include "extern.h"
#include "sig.h"

#define READ 0
#define WRITE 1

struct fp {
        FILE *fp;
        int pipe;
        pid_t pid;
        struct fp *link;
};
static struct fp *fp_head;

struct child {
        pid_t pid;
        char done;
        char free;
        int status;
        struct child *link;
};
static struct child *child, *child_freelist = NULL;
static struct child *findchild(pid_t, int);


#if 0   /* XXX - debugging stuff.  This should go away eventually! */
static void
show_one_file(FILE *fo, struct fp *fpp)
{
        (void)fprintf(fo, ">>> fp: %p,  pipe: %d,  pid: %d,  link: %p\n",
            fpp->fp, fpp->pipe, fpp->pid, fpp->link);
}

void show_all_files(FILE *fo);
__unused
PUBLIC void
show_all_files(FILE *fo)
{
        struct fp *fpp;

        (void)fprintf(fo, ">> FILES\n");
        for (fpp = fp_head; fpp; fpp = fpp->link)
                show_one_file(fo, fpp);
        (void)fprintf(fo, ">> -------\n");
        (void)fflush(fo);
}
#endif /* end debugging stuff */


static 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(EXIT_FAILURE, "Invalid file pointer");
}

PUBLIC void
register_file(FILE *fp, int pipefd, pid_t pid)
{
        struct fp *fpp;

        fpp = emalloc(sizeof(*fpp));
        fpp->fp = fp;
        fpp->pipe = pipefd;
        fpp->pid = pid;
        fpp->link = fp_head;
        fp_head = fpp;
}

PUBLIC FILE *
Fopen(const char *fn, const char *mode)
{
        FILE *fp;

        if ((fp = fopen(fn, mode)) != NULL)
                register_file(fp, 0, 0);
        return fp;
}

PUBLIC FILE *
Fdopen(int fd, const char *mode)
{
        FILE *fp;

        if ((fp = fdopen(fd, mode)) != NULL)
                register_file(fp, 0, 0);
        return fp;
}

PUBLIC int
Fclose(FILE *fp)
{

        if (fp == NULL)
                return 0;

        unregister_file(fp);
        return fclose(fp);
}

PUBLIC 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) {
                (void)dup2(infd, 0);
        } else if (infd != 0) {
                /* we don't want the child stealing my stdin input */
                (void)close(0);
                (void)open(_PATH_DEVNULL, O_RDONLY, 0);
        }
        if (outfd >= 0 && outfd != 1)
                (void)dup2(outfd, 1);

        if (nset != NULL) {
                for (i = 1; i < NSIG; i++) {
                        if (sigismember(nset, i))
                                (void)signal(i, SIG_IGN);
                }
                if (!sigismember(nset, SIGINT))
                        (void)signal(SIGINT, SIG_DFL);
                (void)sigemptyset(&eset);
                (void)sigprocmask(SIG_SETMASK, &eset, NULL);
        }
}

/*
 * Run a command without a shell, with optional arguments and splicing
 * of stdin (-1 means none) and stdout.  The command name can be a sequence
 * of words.
 * Signals must be handled by the caller.
 * "nset" contains the signals to ignore in the new process.
 * SIGINT is enabled unless it's in "nset".
 */
static pid_t
start_commandv(const char *cmd, sigset_t *nset, int infd, int outfd,
    va_list args)
{
        pid_t pid;

        sig_check();
        if ((pid = fork()) < 0) {
                warn("fork");
                return -1;
        }
        if (pid == 0) {
                char *argv[100];
                size_t i;

                i = getrawlist(cmd, argv, (int)__arraycount(argv));
                while (i < __arraycount(argv) - 1 &&
                    (argv[i++] = va_arg(args, char *)) != NULL)
                        continue;
                argv[i] = NULL;
                prepare_child(nset, infd, outfd);
                (void)execvp(argv[0], argv);
                warn("%s", argv[0]);
                _exit(1);
        }
        (void)findchild(pid, 0);
        return pid;
}

PUBLIC int
start_command(const char *cmd, sigset_t *nset, int infd, int outfd, ...)
{
        va_list args;
        int r;

        va_start(args, outfd);
        r = start_commandv(cmd, nset, infd, outfd, args);
        va_end(args);
        return r;
}

PUBLIC FILE *
Popen(const char *cmd, const char *mode)
{
        int p[2];
        int myside, hisside, fd0, fd1;
        pid_t pid;
        sigset_t nset;
        FILE *fp;
        char *shellcmd;

        if (pipe2(p, O_CLOEXEC) < 0)
                return NULL;
        if (*mode == 'r') {
                myside = p[READ];
                hisside = fd0 = fd1 = p[WRITE];
        } else {
                myside = p[WRITE];
                hisside = fd0 = p[READ];
                fd1 = -1;
        }
        (void)sigemptyset(&nset);
        if ((shellcmd = value(ENAME_SHELL)) == NULL)
                shellcmd = __UNCONST(_PATH_CSHELL);
        pid = start_command(shellcmd, &nset, fd0, fd1, "-c", cmd, NULL);
        if (pid < 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;
}

static struct child *
findchild(pid_t pid, int dont_alloc)
{
        struct child **cpp;

        for (cpp = &child; *cpp != NULL && (*cpp)->pid != pid;
             cpp = &(*cpp)->link)
                        continue;
        if (*cpp == NULL) {
                if (dont_alloc)
                        return NULL;
                if (child_freelist) {
                        *cpp = child_freelist;
                        child_freelist = (*cpp)->link;
                } else
                        *cpp = emalloc(sizeof(**cpp));

                (*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)
                continue;
        *cpp = cp->link;
        cp->link = child_freelist;
        child_freelist = cp;
}

/*
 * Wait for a specific child to die.
 */
PUBLIC int
wait_child(pid_t pid)
{
        struct child *cp;
        sigset_t nset, oset;
        pid_t rv = 0;

        (void)sigemptyset(&nset);
        (void)sigaddset(&nset, SIGCHLD);
        (void)sigprocmask(SIG_BLOCK, &nset, &oset);
        /*
         * If we have not already waited on the pid (via sigchild)
         * wait on it now.  Otherwise, use the wait status stashed
         * by sigchild.
         */
        cp = findchild(pid, 1);
        if (cp == NULL || !cp->done)
                rv = waitpid(pid, &wait_status, 0);
        else
                wait_status = cp->status;
        if (cp != NULL)
                delchild(cp);
        (void)sigprocmask(SIG_SETMASK, &oset, NULL);
        if (rv == -1 || (WIFEXITED(wait_status) && WEXITSTATUS(wait_status)))
                return -1;
        else
                return 0;
}

static pid_t
file_pid(FILE *fp)
{
        struct fp *p;

        for (p = fp_head; p; p = p->link)
                if (p->fp == fp)
                        return p->pid;
        errx(EXIT_FAILURE, "Invalid file pointer");
        /*NOTREACHED*/
}

PUBLIC int
Pclose(FILE *ptr)
{
        int i;
        sigset_t nset, oset;

        if (ptr == NULL)
                return 0;

        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;
}

PUBLIC void
close_all_files(void)
{
        while (fp_head)
                if (fp_head->pipe)
                        (void)Pclose(fp_head->fp);
                else
                        (void)Fclose(fp_head->fp);
}

PUBLIC FILE *
last_registered_file(int last_pipe)
{
        struct fp *fpp;

        if (last_pipe == 0)
                return fp_head ? fp_head->fp : NULL;

        for (fpp = fp_head; fpp; fpp = fpp->link)
                if (fpp->pipe)
                        return fpp->fp;
        return NULL;
}

PUBLIC void
close_top_files(FILE *fp_stop)
{
        while (fp_head && fp_head->fp != fp_stop)
                if (fp_head->pipe)
                        (void)Pclose(fp_head->fp);
                else
                        (void)Fclose(fp_head->fp);
}

#ifdef MIME_SUPPORT
PUBLIC void
flush_files(FILE *fo, int only_pipes)
{
        struct fp *fpp;

        if (fo)
                (void)fflush(fo);

        for (fpp = fp_head; fpp; fpp = fpp->link)
                if (!only_pipes || fpp->pipe)
                        (void)fflush(fpp->fp);

        (void)fflush(stdout);
}
#endif /* MIME_SUPPORT */

static int
wait_command(pid_t pid)
{

        if (wait_child(pid) < 0) {
                (void)puts("Fatal error in process.");
                return -1;
        }
        return 0;
}

PUBLIC int
run_command(const char *cmd, sigset_t *nset, int infd, int outfd, ...)
{
        pid_t pid;
        va_list args;
        int rval;

#ifdef BROKEN_EXEC_TTY_RESTORE
        struct termios ttybuf;
        int tcrval;
        /*
         * XXX - grab the tty settings as currently they can get
         * trashed by emacs-21 when suspending with bash-3.2.25 as the
         * shell.
         *
         * 1) from the mail editor, start "emacs -nw" (21.4)
         * 2) suspend emacs to the shell (bash 3.2.25)
         * 3) resume emacs
         * 4) exit emacs back to the mail editor
         * 5) discover the tty is screwed: the mail editor is no
         *    longer receiving characters
         *
         * - This occurs on both i386 and amd64.
         * - This did _NOT_ occur before 4.99.10.
         * - This does _NOT_ occur if the editor is vi(1) or if the shell
         *   is /bin/sh.
         * - This _DOES_ happen with the old mail(1) from 2006-01-01 (long
         *   before my changes).
         *
         * This is the commit that introduced this "feature":
         * http://mail-index.netbsd.org/source-changes/2007/02/09/0020.html
         */
        if ((tcrval = tcgetattr(fileno(stdin), &ttybuf)) == -1)
                warn("tcgetattr");
#endif
        va_start(args, outfd);
        pid = start_commandv(cmd, nset, infd, outfd, args);
        va_end(args);
        if (pid < 0)
                return -1;
        rval = wait_command(pid);
#ifdef BROKEN_EXEC_TTY_RESTORE
        if (tcrval != -1 && tcsetattr(fileno(stdin), TCSADRAIN, &ttybuf) == -1)
                warn("tcsetattr");
#endif
        return rval;

}

/*ARGSUSED*/
PUBLIC void
sigchild(int signo __unused)
{
        pid_t pid;
        int status;
        struct child *cp;
        int save_errno;

        save_errno = errno;
        while ((pid = waitpid((pid_t)-1, &status, WNOHANG)) > 0) {
                cp = findchild(pid, 1); /* async-signal-safe: we don't alloc */
                if (!cp)
                        continue;
                if (cp->free)
                        delchild(cp);   /* async-signal-safe: list changes */
                else {
                        cp->done = 1;
                        cp->status = status;
                }
        }
        errno = save_errno;
}

/*
 * Mark a child as don't care.
 */
PUBLIC void
free_child(pid_t pid)
{
        struct child *cp;
        sigset_t nset, oset;

        (void)sigemptyset(&nset);
        (void)sigaddset(&nset, SIGCHLD);
        (void)sigprocmask(SIG_BLOCK, &nset, &oset);
        if ((cp = findchild(pid, 0)) != NULL) {
                if (cp->done)
                        delchild(cp);
                else
                        cp->free = 1;
        }
        (void)sigprocmask(SIG_SETMASK, &oset, NULL);
}