text: /* -*- mode: C; c-file-style: "k&r"; tab-width 4; indent-tabs-mode: t; -*- */
  
  /*
   * Copyright (C) 2014 Rob Clark <robclark@freedesktop.org>
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   *
   * Authors:
   *    Rob Clark <robclark@freedesktop.org>
   */
  
  #include <archive.h>
  #include <fcntl.h>
  #include <stdlib.h>
  #include <string.h>
  #include <sys/stat.h>
  #include <sys/types.h>
  #include <archive_entry.h>
  
  #include "io.h"
  
  struct io {
     struct archive *a;
     struct archive_entry *entry;
     unsigned offset;
  };
  
  static void
  io_error(struct io *io)
  {
     fprintf(stderr, "%s\n", archive_error_string(io->a));
     io_close(io);
  }
  
  static struct io *
  io_new(void)
  {
     struct io *io = calloc(1, sizeof(*io));
     int ret;
  
     if (!io)
        return NULL;
  
     io->a = archive_read_new();
     ret = archive_read_support_filter_gzip(io->a);
     if (ret != ARCHIVE_OK) {
        io_error(io);
        return NULL;
     }
  
     ret = archive_read_support_filter_none(io->a);
     if (ret != ARCHIVE_OK) {
        io_error(io);
        return NULL;
     }
  
     ret = archive_read_support_format_all(io->a);
     if (ret != ARCHIVE_OK) {
        io_error(io);
        return NULL;
     }
  
     ret = archive_read_support_format_raw(io->a);
     if (ret != ARCHIVE_OK) {
        io_error(io);
        return NULL;
     }
  
     return io;
  }
  
  struct io *
  io_open(const char *filename)
  {
     struct io *io = io_new();
     int ret;
  
     if (!io)
        return NULL;
  
     ret = archive_read_open_filename(io->a, filename, 10240);
     if (ret != ARCHIVE_OK) {
        io_error(io);
        return NULL;
     }
  
     ret = archive_read_next_header(io->a, &io->entry);
     if (ret != ARCHIVE_OK) {
        io_error(io);
        return NULL;
     }
  
     return io;
  }
  
  struct io *
  io_openfd(int fd)
  {
     struct io *io = io_new();
     int ret;
  
     if (!io)
        return NULL;
  
     ret = archive_read_open_fd(io->a, fd, 10240);
     if (ret != ARCHIVE_OK) {
        io_error(io);
        return NULL;
     }
  
     ret = archive_read_next_header(io->a, &io->entry);
     if (ret != ARCHIVE_OK) {
        io_error(io);
        return NULL;
     }
  
     return io;
  }
  
  void
  io_close(struct io *io)
  {
     archive_read_free(io->a);
     free(io);
  }
  
  unsigned
  io_offset(struct io *io)
  {
     return io->offset;
  }
  
  #include <assert.h>
  int
  io_readn(struct io *io, void *buf, int nbytes)
  {
     char *ptr = buf;
     int ret = 0;
     while (nbytes > 0) {
        int n = archive_read_data(io->a, ptr, nbytes);
        if (n < 0) {
           fprintf(stderr, "%s\n", archive_error_string(io->a));
           return n;
        }
        if (n == 0)
           break;
        ptr += n;
        nbytes -= n;
        ret += n;
        io->offset += n;
     }
     return ret;
  }
  