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[dragonfly/vkernel-mp.git] / contrib / libarchive-2.1 / libarchive / archive_read_support_compression_none.c

/*-
 * Copyright (c) 2003-2007 Tim Kientzle
 * 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_none.c,v 1.16 2007/04/05 05:18:16 kientzle Exp $");

#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_LIMITS_H
#include <limits.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"

struct archive_decompress_none {
        char            *buffer;
        size_t           buffer_size;
        char            *next;          /* Current read location. */
        size_t           avail;         /* Bytes in my buffer. */
        const void      *client_buff;   /* Client buffer information. */
        size_t           client_total;
        const char      *client_next;
        size_t           client_avail;
        char             end_of_file;
        char             fatal;
};

/*
 * Size of internal buffer used for combining short reads.  This is
 * also an upper limit on the size of a read request.  Recall,
 * however, that we can (and will!) return blocks of data larger than
 * this.  The read semantics are: you ask for a minimum, I give you a
 * pointer to my best-effort match and tell you how much data is
 * there.  It could be less than you asked for, it could be much more.
 * For example, a client might use mmap() to "read" the entire file as
 * a single block.  In that case, I will return that entire block to
 * my clients.
 */
#define BUFFER_SIZE     65536

#define minimum(a, b) (a < b ? a : b)

static int      archive_decompressor_none_bid(const void *, size_t);
static int      archive_decompressor_none_finish(struct archive_read *);
static int      archive_decompressor_none_init(struct archive_read *,
                    const void *, size_t);
static ssize_t  archive_decompressor_none_read_ahead(struct archive_read *,
                    const void **, size_t);
static ssize_t  archive_decompressor_none_read_consume(struct archive_read *,
                    size_t);
static off_t    archive_decompressor_none_skip(struct archive_read *, off_t);

int
archive_read_support_compression_none(struct archive *_a)
{
        struct archive_read *a = (struct archive_read *)_a;
        if (__archive_read_register_compression(a,
                archive_decompressor_none_bid,
                archive_decompressor_none_init) != NULL)
                return (ARCHIVE_OK);
        return (ARCHIVE_FATAL);
}

/*
 * Try to detect an "uncompressed" archive.
 */
static int
archive_decompressor_none_bid(const void *buff, size_t len)
{
        (void)buff;
        (void)len;

        return (1); /* Default: We'll take it if noone else does. */
}

static int
archive_decompressor_none_init(struct archive_read *a, const void *buff, size_t n)
{
        struct archive_decompress_none  *state;

        a->archive.compression_code = ARCHIVE_COMPRESSION_NONE;
        a->archive.compression_name = "none";

        state = (struct archive_decompress_none *)malloc(sizeof(*state));
        if (!state) {
                archive_set_error(&a->archive, ENOMEM, "Can't allocate input data");
                return (ARCHIVE_FATAL);
        }
        memset(state, 0, sizeof(*state));

        state->buffer_size = BUFFER_SIZE;
        state->buffer = (char *)malloc(state->buffer_size);
        state->next = state->buffer;
        if (state->buffer == NULL) {
                free(state);
                archive_set_error(&a->archive, ENOMEM, "Can't allocate input buffer");
                return (ARCHIVE_FATAL);
        }

        /* Save reference to first block of data. */
        state->client_buff = buff;
        state->client_total = n;
        state->client_next = state->client_buff;
        state->client_avail = state->client_total;

        a->decompressor->data = state;
        a->decompressor->read_ahead = archive_decompressor_none_read_ahead;
        a->decompressor->consume = archive_decompressor_none_read_consume;
        a->decompressor->skip = archive_decompressor_none_skip;
        a->decompressor->finish = archive_decompressor_none_finish;

        return (ARCHIVE_OK);
}

/*
 * We just pass through pointers to the client buffer if we can.
 * If the client buffer is short, then we copy stuff to our internal
 * buffer to combine reads.
 */
static ssize_t
archive_decompressor_none_read_ahead(struct archive_read *a, const void **buff,
    size_t min)
{
        struct archive_decompress_none *state;
        ssize_t bytes_read;

        state = (struct archive_decompress_none *)a->decompressor->data;
        if (state->fatal)
                return (-1);

        /*
         * Don't make special efforts to handle requests larger than
         * the copy buffer.
         */
        if (min > state->buffer_size)
                min = state->buffer_size;

        /*
         * Try to satisfy the request directly from the client
         * buffer.  We can do this if all of the data in the copy
         * buffer was copied from the current client buffer.  This
         * also covers the case where the copy buffer is empty and
         * the client buffer has all the data we need.
         */
        if (state->client_total >= state->client_avail + state->avail
            && state->client_avail + state->avail >= min) {
                state->client_avail += state->avail;
                state->client_next -= state->avail;
                state->avail = 0;
                state->next = state->buffer;
                *buff = state->client_next;
                return (state->client_avail);
        }

        /*
         * If we can't use client buffer, we'll have to use copy buffer.
         */

        /* Move data forward in copy buffer if necessary. */
        if (state->next > state->buffer &&
            state->next + min > state->buffer + state->buffer_size) {
                if (state->avail > 0)
                        memmove(state->buffer, state->next, state->avail);
                state->next = state->buffer;
        }

        /* Collect data in copy buffer to fulfill request. */
        while (state->avail < min) {
                /* Copy data from client buffer to our copy buffer. */
                if (state->client_avail > 0) {
                        /* First estimate: copy to fill rest of buffer. */
                        size_t tocopy = (state->buffer + state->buffer_size)
                            - (state->next + state->avail);
                        /* Don't copy more than is available. */
                        if (tocopy > state->client_avail)
                                tocopy = state->client_avail;
                        memcpy(state->next + state->avail, state->client_next,
                            tocopy);
                        state->client_next += tocopy;
                        state->client_avail -= tocopy;
                        state->avail += tocopy;
                } else {
                        /* There is no more client data: fetch more. */
                        /*
                         * It seems to me that const void ** and const
                         * char ** should be compatible, but they
                         * aren't, hence the cast.
                         */
                        bytes_read = (a->client_reader)(&a->archive,
                            a->client_data, &state->client_buff);
                        if (bytes_read < 0) {           /* Read error. */
                                state->client_total = state->client_avail = 0;
                                state->client_next = state->client_buff = NULL;
                                state->fatal = 1;
                                return (-1);
                        }
                        if (bytes_read == 0) {          /* End-of-file. */
                                state->client_total = state->client_avail = 0;
                                state->client_next = state->client_buff = NULL;
                                state->end_of_file = 1;
                                break;
                        }
                        a->archive.raw_position += bytes_read;
                        state->client_total = bytes_read;
                        state->client_avail = state->client_total;
                        state->client_next = state->client_buff;
                }
        }

        *buff = state->next;
        return (state->avail);
}

/*
 * Mark the appropriate data as used.  Note that the request here will
 * often be much smaller than the size of the previous read_ahead
 * request.
 */
static ssize_t
archive_decompressor_none_read_consume(struct archive_read *a, size_t request)
{
        struct archive_decompress_none *state;

        state = (struct archive_decompress_none *)a->decompressor->data;
        if (state->avail > 0) {
                /* Read came from copy buffer. */
                state->next += request;
                state->avail -= request;
        } else {
                /* Read came from client buffer. */
                state->client_next += request;
                state->client_avail -= request;
        }
        a->archive.file_position += request;
        return (request);
}

/*
 * Skip forward by exactly the requested bytes or else return
 * ARCHIVE_FATAL.  Note that this differs from the contract for
 * read_ahead, which does not guarantee a minimum count.
 */
static off_t
archive_decompressor_none_skip(struct archive_read *a, off_t request)
{
        struct archive_decompress_none *state;
        off_t bytes_skipped, total_bytes_skipped = 0;
        size_t min;

        state = (struct archive_decompress_none *)a->decompressor->data;
        if (state->fatal)
                return (-1);
        /*
         * If there is data in the buffers already, use that first.
         */
        if (state->avail > 0) {
                min = minimum(request, (off_t)state->avail);
                bytes_skipped = archive_decompressor_none_read_consume(a, min);
                request -= bytes_skipped;
                total_bytes_skipped += bytes_skipped;
        }
        if (state->client_avail > 0) {
                min = minimum(request, (off_t)state->client_avail);
                bytes_skipped = archive_decompressor_none_read_consume(a, min);
                request -= bytes_skipped;
                total_bytes_skipped += bytes_skipped;
        }
        if (request == 0)
                return (total_bytes_skipped);
        /*
         * If a client_skipper was provided, try that first.
         */
#if ARCHIVE_API_VERSION < 2
        if ((a->client_skipper != NULL) && (request < SSIZE_MAX)) {
#else
        if (a->client_skipper != NULL) {
#endif
                bytes_skipped = (a->client_skipper)(&a->archive,
                    a->client_data, request);
                if (bytes_skipped < 0) {        /* error */
                        state->client_total = state->client_avail = 0;
                        state->client_next = state->client_buff = NULL;
                        state->fatal = 1;
                        return (bytes_skipped);
                }
                total_bytes_skipped += bytes_skipped;
                a->archive.file_position += bytes_skipped;
                request -= bytes_skipped;
                state->client_next = state->client_buff;
                a->archive.raw_position += bytes_skipped;
                state->client_avail = state->client_total = 0;
        }
        /*
         * Note that client_skipper will usually not satisfy the
         * full request (due to low-level blocking concerns),
         * so even if client_skipper is provided, we may still
         * have to use ordinary reads to finish out the request.
         */
        while (request > 0) {
                const void* dummy_buffer;
                ssize_t bytes_read;
                bytes_read = archive_decompressor_none_read_ahead(a,
                    &dummy_buffer, request);
                if (bytes_read < 0)
                        return (bytes_read);
                if (bytes_read == 0) {
                        /* We hit EOF before we satisfied the skip request. */
                        archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
                            "Truncated input file (need to skip %jd bytes)",
                            (intmax_t)request);
                        return (ARCHIVE_FATAL);
                }
                min = (size_t)(minimum(bytes_read, request));
                bytes_read = archive_decompressor_none_read_consume(a, min);
                total_bytes_skipped += bytes_read;
                request -= bytes_read;
        }
        return (total_bytes_skipped);
}

static int
archive_decompressor_none_finish(struct archive_read *a)
{
        struct archive_decompress_none  *state;

        state = (struct archive_decompress_none *)a->decompressor->data;
        free(state->buffer);
        free(state);
        a->decompressor->data = NULL;
        return (ARCHIVE_OK);
}