/*-
 * Copyright (c) 2007 Joerg Sonnenberger
 * Copyright (c) 2012 Michihiro NAKAJIMA
 * 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"

#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_string.h"
#include "archive_read_private.h"
#include "filter_fork.h"


#if ARCHIVE_VERSION_NUMBER < 4000000
/* Deprecated; remove in libarchive 4.0 */
int
archive_read_support_compression_program(struct archive *a, const char *cmd)
{
	return archive_read_support_filter_program(a, cmd);
}

int
archive_read_support_compression_program_signature(struct archive *a,
    const char *cmd, const void *signature, size_t signature_len)
{
	return archive_read_support_filter_program_signature(a,
	    cmd, signature, signature_len);
}
#endif

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

/*
 * 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 *description;
	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 void	program_bidder_free(struct archive_read_filter_bidder *);

/*
 * The actual filter needs to track input and output data.
 */
struct program_filter {
	struct archive_string description;
#if defined(_WIN32) && !defined(__CYGWIN__)
	HANDLE		 child;
#else
	pid_t		 child;
#endif
	int		 exit_status;
	pid_t		 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 *);
static void	free_state(struct program_bidder *);

static const struct archive_read_filter_bidder_vtable
program_bidder_vtable = {
	.bid = program_bidder_bid,
	.init = program_bidder_init,
	.free = program_bidder_free,
};

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

	/*
	 * Allocate our private state.
	 */
	state = calloc(1, sizeof (*state));
	if (state == NULL)
		goto memerr;
	state->cmd = strdup(cmd);
	if (state->cmd == NULL)
		goto memerr;

	if (signature != NULL && signature_len > 0) {
		state->signature_len = signature_len;
		state->signature = malloc(signature_len);
		if (state->signature == NULL)
			goto memerr;
		memcpy(state->signature, signature, signature_len);
	}

	if (__archive_read_register_bidder(a, state, NULL,
				&program_bidder_vtable) != ARCHIVE_OK) {
		free_state(state);
		return (ARCHIVE_FATAL);
	}
	return (ARCHIVE_OK);

memerr:
	free_state(state);
	archive_set_error(_a, ENOMEM, "Can't allocate memory");
	return (ARCHIVE_FATAL);
}

static void
program_bidder_free(struct archive_read_filter_bidder *self)
{
	struct program_bidder *state = (struct program_bidder *)self->data;

	free_state(state);
}

static void
free_state(struct program_bidder *state)
{

	if (state) {
		free(state->cmd);
		free(state->signature);
		free(state);
	}
}

/*
 * 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 ((int)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,
		    "Error closing child process");
		return (ARCHIVE_WARN);
	}

#if !defined(_WIN32) || defined(__CYGWIN__)
	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);
	}
#endif /* !_WIN32 || __CYGWIN__ */

	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;
#if defined(_WIN32) && !defined(__CYGWIN__)
	HANDLE handle = (HANDLE)_get_osfhandle(state->child_stdout);
#endif

	requested = buf_len > SSIZE_MAX ? SSIZE_MAX : buf_len;

	for (;;) {
		do {
#if defined(_WIN32) && !defined(__CYGWIN__)
			/* Avoid infinity wait.
			 * Note: If there is no data in the pipe, ReadFile()
			 * called in read() never returns and so we won't
			 * write remaining encoded data to the pipe.
			 * Note: This way may cause performance problem.
			 * we are looking forward to great code to resolve
			 * this.  */
			DWORD pipe_avail = -1;
			int cnt = 2;

			while (PeekNamedPipe(handle, NULL, 0, NULL,
			    &pipe_avail, NULL) != 0 && pipe_avail == 0 &&
			    cnt--)
				Sleep(5);
			if (pipe_avail == 0) {
				ret = -1;
				errno = EAGAIN;
				break;
			}
#endif
			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);
		}
	}
}

static const struct archive_read_filter_vtable
program_reader_vtable = {
	.read = program_filter_read,
	.close = program_filter_close,
};

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;
	const char *prefix = "Program: ";
	int ret;
	size_t l;

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

	self->code = ARCHIVE_FILTER_PROGRAM;
	self->name = state->description.s;

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

	ret = __archive_create_child(cmd, &state->child_stdin,
	    &state->child_stdout, &state->child);
	if (ret != ARCHIVE_OK) {
		free(state->out_buf);
		archive_string_free(&state->description);
		free(state);
		archive_set_error(&self->archive->archive, EINVAL,
		    "Can't initialize filter; unable to run program \"%s\"",
		    cmd);
		return (ARCHIVE_FATAL);
	}

	self->data = state;
	self->vtable = &program_reader_vtable;

	/* 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);
	archive_string_free(&state->description);
	free(state);

	return (e);
}
