/*-
 * Copyright (c) 2007 Joerg Sonnenberger
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``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 AUTHOR(S) 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 "archive_platform.h"
__FBSDID("$FreeBSD: src/lib/libarchive/archive_read_support_compression_program.c,v 1.6 2008/12/06 06:45:15 kientzle Exp $");

#ifdef HAVE_SYS_WAIT_H
#  include <sys/wait.h>
#endif
#ifdef HAVE_ERRNO_H
#  include <errno.h>
#endif
#ifdef HAVE_FCNTL_H
#  include <fcntl.h>
#endif
#ifdef HAVE_LIMITS_H
#  include <limits.h>
#endif
#ifdef HAVE_SIGNAL_H
#  include <signal.h>
#endif
#ifdef HAVE_STDLIB_H
#  include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#  include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#  include <unistd.h>
#endif

#include "archive.h"
#include "archive_private.h"
#include "archive_read_private.h"

int
archive_read_support_compression_program(struct archive *a, const char *cmd)
{
    return (archive_read_support_compression_program_signature(a, cmd, NULL, 0));
}


/* This capability is only available on POSIX systems. */
#if (!defined(HAVE_PIPE) || !defined(HAVE_FCNTL) || \
    !(defined(HAVE_FORK) || defined(HAVE_VFORK))) && (!defined(_WIN32) || defined(__CYGWIN__))

/*
 * On non-Posix systems, allow the program to build, but choke if
 * this function is actually invoked.
 */
int
archive_read_support_compression_program_signature(struct archive *_a,
    const char *cmd, void *signature, size_t signature_len)
{
    (void)_a; /* UNUSED */
    (void)cmd; /* UNUSED */
    (void)signature; /* UNUSED */
    (void)signature_len; /* UNUSED */

    archive_set_error(_a, -1,
        "External compression programs not supported on this platform");
    return (ARCHIVE_FATAL);
}

int
__archive_read_program(struct archive_read_filter *self, const char *cmd)
{
    (void)self; /* UNUSED */
    (void)cmd; /* UNUSED */

    archive_set_error(&self->archive->archive, -1,
        "External compression programs not supported on this platform");
    return (ARCHIVE_FATAL);
}

#else

#include "filter_fork.h"

/*
 * The bidder object stores the command and the signature to watch for.
 * The 'inhibit' entry here is used to ensure that unchecked filters never
 * bid twice in the same pipeline.
 */
struct program_bidder {
    char *cmd;
    void *signature;
    size_t signature_len;
    int inhibit;
};

static int  program_bidder_bid(struct archive_read_filter_bidder *,
            struct archive_read_filter *upstream);
static int  program_bidder_init(struct archive_read_filter *);
static int  program_bidder_free(struct archive_read_filter_bidder *);

/*
 * The actual filter needs to track input and output data.
 */
struct program_filter {
    char        *description;
    pid_t        child;
    int      exit_status;
    int      waitpid_return;
    int      child_stdin, child_stdout;

    char        *out_buf;
    size_t       out_buf_len;
};

static ssize_t  program_filter_read(struct archive_read_filter *,
            const void **);
static int  program_filter_close(struct archive_read_filter *);

int
archive_read_support_compression_program_signature(struct archive *_a,
    const char *cmd, const void *signature, size_t signature_len)
{
    struct archive_read *a = (struct archive_read *)_a;
    struct archive_read_filter_bidder *bidder;
    struct program_bidder *state;

    /*
     * Get a bidder object from the read core.
     */
    bidder = __archive_read_get_bidder(a);
    if (bidder == NULL)
        return (ARCHIVE_FATAL);

    /*
     * Allocate our private state.
     */
    state = (struct program_bidder *)calloc(sizeof (*state), 1);
    if (state == NULL)
        return (ARCHIVE_FATAL);
    state->cmd = strdup(cmd);
    if (signature != NULL && signature_len > 0) {
        state->signature_len = signature_len;
        state->signature = malloc(signature_len);
        memcpy(state->signature, signature, signature_len);
    }

    /*
     * Fill in the bidder object.
     */
    bidder->data = state;
    bidder->bid = program_bidder_bid;
    bidder->init = program_bidder_init;
    bidder->options = NULL;
    bidder->free = program_bidder_free;
    return (ARCHIVE_OK);
}

static int
program_bidder_free(struct archive_read_filter_bidder *self)
{
    struct program_bidder *state = (struct program_bidder *)self->data;
    free(state->cmd);
    free(state->signature);
    free(self->data);
    return (ARCHIVE_OK);
}

/*
 * If we do have a signature, bid only if that matches.
 *
 * If there's no signature, we bid INT_MAX the first time
 * we're called, then never bid again.
 */
static int
program_bidder_bid(struct archive_read_filter_bidder *self,
    struct archive_read_filter *upstream)
{
    struct program_bidder *state = self->data;
    const char *p;

    /* If we have a signature, use that to match. */
    if (state->signature_len > 0) {
        p = __archive_read_filter_ahead(upstream,
            state->signature_len, NULL);
        if (p == NULL)
            return (0);
        /* No match, so don't bid. */
        if (memcmp(p, state->signature, state->signature_len) != 0)
            return (0);
        return (state->signature_len * 8);
    }

    /* Otherwise, bid once and then never bid again. */
    if (state->inhibit)
        return (0);
    state->inhibit = 1;
    return (INT_MAX);
}

/*
 * Shut down the child, return ARCHIVE_OK if it exited normally.
 *
 * Note that the return value is sticky; if we're called again,
 * we won't reap the child again, but we will return the same status
 * (including error message if the child came to a bad end).
 */
static int
child_stop(struct archive_read_filter *self, struct program_filter *state)
{
    /* Close our side of the I/O with the child. */
    if (state->child_stdin != -1) {
        close(state->child_stdin);
        state->child_stdin = -1;
    }
    if (state->child_stdout != -1) {
        close(state->child_stdout);
        state->child_stdout = -1;
    }

    if (state->child != 0) {
        /* Reap the child. */
        do {
            state->waitpid_return
                = waitpid(state->child, &state->exit_status, 0);
        } while (state->waitpid_return == -1 && errno == EINTR);
        state->child = 0;
    }

    if (state->waitpid_return < 0) {
        /* waitpid() failed?  This is ugly. */
        archive_set_error(&self->archive->archive, ARCHIVE_ERRNO_MISC,
            "Child process exited badly");
        return (ARCHIVE_WARN);
    }

    if (WIFSIGNALED(state->exit_status)) {
#ifdef SIGPIPE
        /* If the child died because we stopped reading before
         * it was done, that's okay.  Some archive formats
         * have padding at the end that we routinely ignore. */
        /* The alternative to this would be to add a step
         * before close(child_stdout) above to read from the
         * child until the child has no more to write. */
        if (WTERMSIG(state->exit_status) == SIGPIPE)
            return (ARCHIVE_OK);
#endif
        archive_set_error(&self->archive->archive, ARCHIVE_ERRNO_MISC,
            "Child process exited with signal %d",
            WTERMSIG(state->exit_status));
        return (ARCHIVE_WARN);
    }

    if (WIFEXITED(state->exit_status)) {
        if (WEXITSTATUS(state->exit_status) == 0)
            return (ARCHIVE_OK);

        archive_set_error(&self->archive->archive,
            ARCHIVE_ERRNO_MISC,
            "Child process exited with status %d",
            WEXITSTATUS(state->exit_status));
        return (ARCHIVE_WARN);
    }

    return (ARCHIVE_WARN);
}

/*
 * Use select() to decide whether the child is ready for read or write.
 */
static ssize_t
child_read(struct archive_read_filter *self, char *buf, size_t buf_len)
{
    struct program_filter *state = self->data;
    ssize_t ret, requested, avail;
    const char *p;

    requested = buf_len > SSIZE_MAX ? SSIZE_MAX : buf_len;

    for (;;) {
        do {
            ret = read(state->child_stdout, buf, requested);
        } while (ret == -1 && errno == EINTR);

        if (ret > 0)
            return (ret);
        if (ret == 0 || (ret == -1 && errno == EPIPE))
            /* Child has closed its output; reap the child
             * and return the status. */
            return (child_stop(self, state));
        if (ret == -1 && errno != EAGAIN)
            return (-1);

        if (state->child_stdin == -1) {
            /* Block until child has some I/O ready. */
            __archive_check_child(state->child_stdin,
                state->child_stdout);
            continue;
        }

        /* Get some more data from upstream. */
        p = __archive_read_filter_ahead(self->upstream, 1, &avail);
        if (p == NULL) {
            close(state->child_stdin);
            state->child_stdin = -1;
            fcntl(state->child_stdout, F_SETFL, 0);
            if (avail < 0)
                return (avail);
            continue;
        }

        do {
            ret = write(state->child_stdin, p, avail);
        } while (ret == -1 && errno == EINTR);

        if (ret > 0) {
            /* Consume whatever we managed to write. */
            __archive_read_filter_consume(self->upstream, ret);
        } else if (ret == -1 && errno == EAGAIN) {
            /* Block until child has some I/O ready. */
            __archive_check_child(state->child_stdin,
                state->child_stdout);
        } else {
            /* Write failed. */
            close(state->child_stdin);
            state->child_stdin = -1;
            fcntl(state->child_stdout, F_SETFL, 0);
            /* If it was a bad error, we're done; otherwise
             * it was EPIPE or EOF, and we can still read
             * from the child. */
            if (ret == -1 && errno != EPIPE)
                return (-1);
        }
    }
}

int
__archive_read_program(struct archive_read_filter *self, const char *cmd)
{
    struct program_filter   *state;
    static const size_t out_buf_len = 65536;
    char *out_buf;
    char *description;
    const char *prefix = "Program: ";

    state = (struct program_filter *)calloc(1, sizeof(*state));
    out_buf = (char *)malloc(out_buf_len);
    description = (char *)malloc(strlen(prefix) + strlen(cmd) + 1);
    if (state == NULL || out_buf == NULL || description == NULL) {
        archive_set_error(&self->archive->archive, ENOMEM,
            "Can't allocate input data");
        free(state);
        free(out_buf);
        free(description);
        return (ARCHIVE_FATAL);
    }

    self->code = ARCHIVE_COMPRESSION_PROGRAM;
    state->description = description;
    strcpy(state->description, prefix);
    strcat(state->description, cmd);
    self->name = state->description;

    state->out_buf = out_buf;
    state->out_buf_len = out_buf_len;

    if ((state->child = __archive_create_child(cmd,
         &state->child_stdin, &state->child_stdout)) == -1) {
        free(state->out_buf);
        free(state);
        archive_set_error(&self->archive->archive, EINVAL,
            "Can't initialise filter");
        return (ARCHIVE_FATAL);
    }

    self->data = state;
    self->read = program_filter_read;
    self->skip = NULL;
    self->close = program_filter_close;

    /* XXX Check that we can read at least one byte? */
    return (ARCHIVE_OK);
}

static int
program_bidder_init(struct archive_read_filter *self)
{
    struct program_bidder   *bidder_state;

    bidder_state = (struct program_bidder *)self->bidder->data;
    return (__archive_read_program(self, bidder_state->cmd));
}

static ssize_t
program_filter_read(struct archive_read_filter *self, const void **buff)
{
    struct program_filter *state;
    ssize_t bytes;
    size_t total;
    char *p;

    state = (struct program_filter *)self->data;

    total = 0;
    p = state->out_buf;
    while (state->child_stdout != -1 && total < state->out_buf_len) {
        bytes = child_read(self, p, state->out_buf_len - total);
        if (bytes < 0)
            /* No recovery is possible if we can no longer
             * read from the child. */
            return (ARCHIVE_FATAL);
        if (bytes == 0)
            /* We got EOF from the child. */
            break;
        total += bytes;
        p += bytes;
    }

    *buff = state->out_buf;
    return (total);
}

static int
program_filter_close(struct archive_read_filter *self)
{
    struct program_filter   *state;
    int e;

    state = (struct program_filter *)self->data;
    e = child_stop(self, state);

    /* Release our private data. */
    free(state->out_buf);
    free(state->description);
    free(state);

    return (e);
}

#endif /* !defined(HAVE_PIPE) || !defined(HAVE_VFORK) || !defined(HAVE_FCNTL) */
