popen.c: some cleanup, use other wait_child() from now on

[s-mailx.git] / popen.c

/*@ S-nail - a mail user agent derived from Berkeley Mail.
 *@ Handling of pipes, child processes, temporary files, file enwrapping
 *
 * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
 * Copyright (c) 2012 - 2013 Steffen "Daode" Nurpmeso <sdaoden@users.sf.net>.
 */
/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 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 HAVE_AMALGAMATION
# include "nail.h"
#endif

#include <sys/wait.h>

#include <fcntl.h>

#define READ    0
#define WRITE   1

struct fp {
        FILE *fp;
        struct fp *link;
        char *realfile;
        long offset;
        int omode;
        int pipe;
        int pid;
        enum {
                FP_UNCOMPRESSED = 00,
                FP_GZIPPED      = 01,
                FP_BZIP2ED      = 02,
                FP_IMAP         = 03,
                FP_MAILDIR      = 04,
                FP_MASK         = 0177,
                FP_READONLY     = 0200
        } compressed;
};
static struct fp *fp_head;

struct child {
        int pid;
        char done;
        char free;
        int status;
        struct child *link;
};
static struct child     *_popen_child;

static int scan_mode(const char *mode, int *omode);
static void register_file(FILE *fp, int omode, int ispipe, int pid,
                int compressed, const char *realfile, long offset);
static enum okay compress(struct fp *fpp);
static int decompress(int compression, int infd, int outfd);
static enum okay unregister_file(FILE *fp);
static int file_pid(FILE *fp);
static int wait_command(int pid);
static struct child *findchild(int pid);
static void delchild(struct child *cp);

static int
scan_mode(const char *mode, int *omode)
{

        if (!strcmp(mode, "r")) {
                *omode = O_RDONLY;
        } else if (!strcmp(mode, "w")) {
                *omode = O_WRONLY | O_CREAT | O_TRUNC;
        } else if (!strcmp(mode, "wx")) {
                *omode = O_WRONLY | O_CREAT | O_EXCL;
        } else if (!strcmp(mode, "a")) {
                *omode = O_WRONLY | O_APPEND | O_CREAT;
        } else if (!strcmp(mode, "a+")) {
                *omode = O_RDWR | O_APPEND;
        } else if (!strcmp(mode, "r+")) {
                *omode = O_RDWR;
        } else if (!strcmp(mode, "w+")) {
                *omode = O_RDWR   | O_CREAT | O_EXCL;
        } else {
                fprintf(stderr, tr(152,
                        "Internal error: bad stdio open mode %s\n"), mode);
                errno = EINVAL;
                *omode = 0; /* (silence CC) */
                return -1;
        }
        return 0;
}

FL FILE *
safe_fopen(const char *file, const char *mode, int *omode)
{
        int  fd;

        if (scan_mode(mode, omode) < 0)
                return NULL;
        if ((fd = open(file, *omode, 0666)) < 0)
                return NULL;
        return fdopen(fd, mode);
}

FL FILE *
Fopen(const char *file, const char *mode)
{
        FILE *fp;
        int omode;

        if ((fp = safe_fopen(file, mode, &omode)) != NULL) {
                (void)fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
                register_file(fp, omode, 0, 0, FP_UNCOMPRESSED, NULL, 0L);
        }
        return fp;
}

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

        scan_mode(mode, &omode);
        if ((fp = fdopen(fd, mode)) != NULL) {
                (void)fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
                register_file(fp, omode, 0, 0, FP_UNCOMPRESSED, NULL, 0L);
        }
        return fp;
}

FL int
Fclose(FILE *fp)
{
        int     i = 0;
        if (unregister_file(fp) == OKAY)
                i |= 1;
        if (fclose(fp) == 0)
                i |= 2;
        return i == 3 ? 0 : EOF;
}

FL FILE *
Zopen(const char *file, const char *mode, int *compression) /* TODO MESS!
        * TODO maybe we shouldn't be simple and run commands but instead
        * TODO links against any of available zlib.h, bzlib.h, lzma.h!
        * TODO even libzip?  Much faster, not that much more work, and we're
        * TODO *so* fixed anyway!!
        * TODO *or*: make it all hookable via BOXEXTENSION/DECOMPRESS etc.
        * TODO by the user;  but not like this, Coverity went grazy about it */
{
        int     infd;
        FILE    *outf;
        const char      *rp;
        int     omode;
        char    *tempfn;
        int     bits;
        int     _compression;
        long    offset;
        char    *extension;
        enum protocol   p;

        if (scan_mode(mode, &omode) < 0)
                return NULL;
        if (compression == NULL)
                compression = &_compression;
        bits = R_OK | (omode == O_RDONLY ? 0 : W_OK);
        if (omode & O_APPEND && ((p = which_protocol(file)) == PROTO_IMAP ||
                        p == PROTO_MAILDIR)) {
                *compression = p == PROTO_IMAP ? FP_IMAP : FP_MAILDIR;
                omode = O_RDWR | O_APPEND | O_CREAT;
                rp = file;
                infd = -1;
                goto open;
        }
        if ((extension = strrchr(file, '.')) != NULL) {
                rp = file;
                if (strcmp(extension, ".gz") == 0)
                        goto gzip;
                if (strcmp(extension, ".bz2") == 0)
                        goto bz2;
        }

        if (access(file, F_OK) == 0) {
                *compression = FP_UNCOMPRESSED;
                return Fopen(file, mode);
        } else if (access(rp=savecat(file, ".gz"), bits) == 0) {
        gzip:   *compression = FP_GZIPPED;
        } else if (access(rp=savecat(file, ".bz2"), bits) == 0) {
        bz2:    *compression = FP_BZIP2ED;
        } else {
                *compression = FP_UNCOMPRESSED;
                return Fopen(file, mode);
        }
        if (access(rp, W_OK) < 0)
                *compression |= FP_READONLY;

        if ((infd = open(rp, bits & W_OK ? O_RDWR : O_RDONLY)) < 0
                        && ((omode&O_CREAT) == 0 || errno != ENOENT))
                return NULL;
open:   if ((outf = Ftemp(&tempfn, "Rz", "w+", 0600, 0)) == NULL) {
                perror(tr(167, "tmpfile"));
                if (infd >= 0)
                        close(infd);
                return NULL;
        }
        unlink(tempfn);
        Ftfree(&tempfn);

        if (infd >= 0 || (*compression&FP_MASK) == FP_IMAP ||
                        (*compression&FP_MASK) == FP_MAILDIR) {
                if (decompress(*compression, infd, fileno(outf)) < 0) {
                        if (infd >= 0)
                                close(infd);
                        Fclose(outf);
                        return NULL;
                }
        } else {
                if ((infd = creat(rp, 0666)) < 0) {
                        Fclose(outf);
                        return NULL;
                }
        }
        if (infd >= 0)
                close(infd);
        fflush(outf);

        if (omode & O_APPEND) {
                int     flags;

                if ((flags = fcntl(fileno(outf), F_GETFL)) < 0 ||
                                fcntl(fileno(outf), F_SETFL, flags|O_APPEND)
                                < 0 || (offset = ftell(outf)) < 0) {
                        Fclose(outf);
                        return NULL;
                }
        } else {
                rewind(outf);
                offset = 0;
        }

        register_file(outf, omode, 0, 0, *compression, rp, offset);
        return outf;
}

FL FILE *
Ftemp(char **fn, char const *prefix, char const *mode, int bits,
        int doregfile)
{
        FILE *fp = NULL;
        char *cp;
        int fd;

        *fn =
        cp = smalloc(strlen(tempdir) + 1 + sizeof("mail") + strlen(prefix) +
                + 7 + 1);
        cp = sstpcpy(cp, tempdir);
        *cp++ = '/';
        cp = sstpcpy(cp, "mail");
        if (*prefix) {
                *cp++ = '-';
                cp = sstpcpy(cp, prefix);
        }
        sstpcpy(cp, ".XXXXXX");

#ifdef HAVE_MKSTEMP
        if ((fd = mkstemp(*fn)) < 0)
                goto jtemperr;
        if (bits != (S_IRUSR|S_IWUSR) && fchmod(fd, bits) < 0)
                goto jtemperr;
#else
        if (mktemp(*fn) == NULL)
                goto Ftemperr;
        if ((fd = open(*fn, O_CREAT|O_EXCL|O_RDWR, bits)) < 0)
                goto jtemperr;
#endif

        if (doregfile)
                fp = Fdopen(fd, mode);
        else {
                (void)fcntl(fd, F_SETFD, FD_CLOEXEC);
                fp = fdopen(fd, mode);
        }
jleave:
        return fp;
jtemperr:
        Ftfree(fn);
        goto jleave;
}

FL void
Ftfree(char **fn)
{
        char *cp = *fn;

        *fn = NULL;
        free(cp);
}

FL bool_t
pipe_cloexec(int fd[2])
{
        bool_t rv = FAL0;

        if (pipe(fd) < 0)
                goto jleave;
        fcntl(fd[0], F_SETFD, FD_CLOEXEC);
        fcntl(fd[1], F_SETFD, FD_CLOEXEC);
        rv = TRU1;
jleave:
        return rv;
}

FL FILE *
Popen(const char *cmd, const char *mode, const char *sh, int newfd1)
{
        int p[2];
        int myside, hisside, fd0, fd1;
        int pid;
        char mod[2] = { '0', '\0' };
        sigset_t nset;
        FILE *fp;

        if (! pipe_cloexec(p))
                return NULL;

        if (*mode == 'r') {
                myside = p[READ];
                fd0 = -1;
                hisside = fd1 = p[WRITE];
                mod[0] = *mode;
        } else if (*mode == 'W') {
                myside = p[WRITE];
                hisside = fd0 = p[READ];
                fd1 = newfd1;
                mod[0] = 'w';
        } else {
                myside = p[WRITE];
                hisside = fd0 = p[READ];
                fd1 = -1;
                mod[0] = 'w';
        }
        sigemptyset(&nset);
        if (sh == NULL) {
                pid = start_command(cmd, &nset, fd0, fd1, NULL, NULL, NULL);
        } else {
                pid = start_command(sh, &nset, fd0, fd1, "-c", cmd, NULL);
        }
        if (pid < 0) {
                close(p[READ]);
                close(p[WRITE]);
                return NULL;
        }
        close(hisside);
        if ((fp = fdopen(myside, mod)) != NULL)
                register_file(fp, 0, 1, pid, FP_UNCOMPRESSED, NULL, 0L);
        return fp;
}

FL int
Pclose(FILE *ptr, bool_t dowait)
{
        int pid;
        sigset_t nset, oset;

        pid = file_pid(ptr);
        if (pid < 0)
                return 0;
        unregister_file(ptr);
        fclose(ptr);
        if (dowait) {
                sigemptyset(&nset);
                sigaddset(&nset, SIGINT);
                sigaddset(&nset, SIGHUP);
                sigprocmask(SIG_BLOCK, &nset, &oset);
                pid = wait_child(pid);
                sigprocmask(SIG_SETMASK, &oset, (sigset_t*)NULL);
        } else
                free_child(pid);
        return pid;
}

FL void
close_all_files(void)
{
        while (fp_head)
                if (fp_head->pipe)
                        Pclose(fp_head->fp, TRU1);
                else
                        Fclose(fp_head->fp);
}

static void
register_file(FILE *fp, int omode, int ispipe, int pid, int compressed,
                const char *realfile, long offset)
{
        struct fp *fpp;

        fpp = (struct fp*)smalloc(sizeof *fpp);
        fpp->fp = fp;
        fpp->omode = omode;
        fpp->pipe = ispipe;
        fpp->pid = pid;
        fpp->link = fp_head;
        fpp->compressed = compressed;
        fpp->realfile = realfile ? sstrdup(realfile) : NULL;
        fpp->offset = offset;
        fp_head = fpp;
}

static enum okay
compress(struct fp *fpp)
{
        int     outfd;
        char const *command[2];
        enum okay       ok;

        if (fpp->omode == O_RDONLY)
                return OKAY;
        fflush(fpp->fp);
        clearerr(fpp->fp);
        if (fseek(fpp->fp, fpp->offset, SEEK_SET) < 0)
                return STOP;
#ifdef HAVE_IMAP
        if ((fpp->compressed&FP_MASK) == FP_IMAP) {
                return imap_append(fpp->realfile, fpp->fp);
        }
#endif
        if ((fpp->compressed&FP_MASK) == FP_MAILDIR) {
                return maildir_append(fpp->realfile, fpp->fp);
        }
        if ((outfd = open(fpp->realfile,
                        (fpp->omode|O_CREAT)&~O_EXCL,
                        0666)) < 0) {
                fprintf(stderr, "Fatal: cannot create ");
                perror(fpp->realfile);
                return STOP;
        }
        if ((fpp->omode & O_APPEND) == 0)
                ftruncate(outfd, 0);
        switch (fpp->compressed & FP_MASK) {
        case FP_GZIPPED:
                command[0] = "gzip"; command[1] = "-c"; break;
        case FP_BZIP2ED:
                command[0] = "bzip2"; command[1] = "-c"; break;
        default:
                command[0] = "cat"; command[1] = NULL; break;
        }
        if (run_command(command[0], 0, fileno(fpp->fp), outfd,
                                command[1], NULL, NULL) < 0)
                ok = STOP;
        else
                ok = OKAY;
        close(outfd);
        return ok;
}

static int
decompress(int compression, int infd, int outfd)
{
        char const *command[2];

        /*
         * Note that it is not possible to handle 'pack' or 'compress'
         * formats because appending data does not work with them.
         */
        switch (compression & FP_MASK) {
        case FP_GZIPPED:        command[0] = "gzip"; command[1] = "-cd"; break;
        case FP_BZIP2ED:        command[0] = "bzip2"; command[1] = "-cd"; break;
        case FP_IMAP:           return 0;
        case FP_MAILDIR:        return 0;
        default:                command[0] = "cat"; command[1] = NULL;
        }
        return run_command(command[0], 0, infd, outfd, command[1], NULL, NULL);
}

static enum okay
unregister_file(FILE *fp)
{
        struct fp **pp, *p;
        enum okay       ok = OKAY;

        for (pp = &fp_head; (p = *pp) != (struct fp *)NULL; pp = &p->link)
                if (p->fp == fp) {
                        if ((p->compressed&FP_MASK) != FP_UNCOMPRESSED)
                                ok = compress(p);
                        *pp = p->link;
                        free(p);
                        return ok;
                }
        panic(tr(153, "Invalid file pointer"));
        /*NOTREACHED*/
        return STOP;
}

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

        for (p = fp_head; p; p = p->link)
                if (p->fp == fp)
                        return (p->pid);
        return -1;
}

/*
 * 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*/
FL int
run_command(char const *cmd, sigset_t *mask, int infd, int outfd,
                char const *a0, char const *a1, char const *a2)
{
        int pid;

        if ((pid = start_command(cmd, mask, infd, outfd, a0, a1, a2)) < 0)
                return -1;
        return wait_command(pid);
}

/*VARARGS4*/
FL int
start_command(const char *cmd, sigset_t *mask, int infd, int outfd,
                const char *a0, const char *a1, const char *a2)
{
        int pid;

        if ((pid = fork()) < 0) {
                perror("fork");
                return -1;
        }
        if (pid == 0) {
                char *argv[100];
                int i = getrawlist(cmd, strlen(cmd),
                                argv, sizeof argv / sizeof *argv, 0);

                if ((argv[i++] = UNCONST(a0)) != NULL &&
                    (argv[i++] = UNCONST(a1)) != NULL &&
                    (argv[i++] = UNCONST(a2)) != NULL)
                        argv[i] = NULL;
                prepare_child(mask, infd, outfd);
                execvp(argv[0], argv);
                perror(argv[0]);
                _exit(1);
        }
        return pid;
}

FL void
prepare_child(sigset_t *nset, int infd, int outfd)
{
        int i;
        sigset_t fset;

        /* 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);

        if (nset) {
                for (i = 1; i < NSIG; i++)
                        if (sigismember(nset, i))
                                safe_signal(i, SIG_IGN);
                if (!sigismember(nset, SIGINT))
                        safe_signal(SIGINT, SIG_DFL);
        }

        sigemptyset(&fset);
        sigprocmask(SIG_SETMASK, &fset, NULL);
}

static int
wait_command(int pid)
{
        int rv = 0;

        if (wait_child(pid) < 0) {
                if (boption("bsdcompat") || boption("bsdmsgs"))
                        fprintf(stderr, tr(154, "Fatal error in process.\n"));
                rv = -1;
        }
        return rv;
}

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

        for (cpp = &_popen_child; *cpp != NULL && (*cpp)->pid != pid;
             cpp = &(*cpp)->link)
                        ;
        if (*cpp == NULL) {
                *cpp = smalloc(sizeof (struct child));
                (*cpp)->pid = pid;
                (*cpp)->done = (*cpp)->free = 0;
                (*cpp)->link = NULL;
        }
        return *cpp;
}

static void
delchild(struct child *cp)
{
        struct child **cpp;

        for (cpp = &_popen_child; *cpp != cp; cpp = &(*cpp)->link)
                ;
        *cpp = cp->link;
        free(cp);
}

/*ARGSUSED*/
FL void
sigchild(int signo)
{
        int pid, status;
        struct child *cp;
        UNUSED(signo);

jagain:
        while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
                cp = findchild(pid);
                if (cp->free)
                        delchild(cp);
                else {
                        cp->done = 1;
                        cp->status = status;
                }
        }
        if (pid == -1 && errno == EINTR)
                goto jagain;
}

int wait_status;

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

        sigemptyset(&nset);
        sigaddset(&nset, SIGCHLD);
        sigprocmask(SIG_BLOCK, &nset, &oset);

        cp = findchild(pid);
        if (cp->done)
                delchild(cp);
        else
                cp->free = 1;

        sigprocmask(SIG_SETMASK, &oset, NULL);
}

/* Wait for a specific child to die */
FL int
wait_child(int pid)
{
        sigset_t nset, oset;
        struct child *cp;

        sigemptyset(&nset);
        sigaddset(&nset, SIGCHLD);
        sigprocmask(SIG_BLOCK, &nset, &oset);

        cp = findchild(pid);
        while (!cp->done)
                sigsuspend(&oset);
        wait_status = cp->status;
        delchild(cp);

        sigprocmask(SIG_SETMASK, &oset, NULL);

        return ((!WIFEXITED(wait_status) || WEXITSTATUS(wait_status)) ? -1 : 0);
}