com32/lib/sys/zfile.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2003-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 #include <errno.h>
  29 #include <string.h>
  30 #include <unistd.h>
  31 #include <fcntl.h>
  32 #include <stdlib.h>
  33 #include <syslinux/zio.h>
  34
  35 #include "file.h"
  36 #include "zlib.h"
  37
  38 /*
  39  * zopen.c
  40  *
  41  * Open an ordinary file, possibly compressed; if so, insert
  42  * an appropriate decompressor.
  43  */
  44
  45 int __file_get_block(struct file_info *fp);
  46 int __file_close(struct file_info *fp);
  47
  48 static ssize_t gzip_file_read(struct file_info *, void *, size_t);
  49 static int gzip_file_close(struct file_info *);
  50
  51 static const struct input_dev gzip_file_dev = {
  52     .dev_magic = __DEV_MAGIC,
  53     .flags = __DEV_FILE | __DEV_INPUT,
  54     .fileflags = O_RDONLY,
  55     .read = gzip_file_read,
  56     .close = gzip_file_close,
  57     .open = NULL,
  58 };
  59
  60 static int gzip_file_init(struct file_info *fp)
  61 {
  62     z_streamp zs = calloc(1, sizeof(z_stream));
  63
  64     if (!zs)
  65         return -1;
  66
  67     fp->i.pvt = zs;
  68
  69     zs->next_in = (void *)fp->i.datap;
  70     zs->avail_in = fp->i.nbytes;
  71
  72     if (inflateInit2(zs, 15 + 32) != Z_OK) {
  73         errno = EIO;
  74         return -1;
  75     }
  76
  77     fp->iop = &gzip_file_dev;
  78     fp->i.fd.size = -1;         /* Unknown */
  79
  80     return 0;
  81 }
  82
  83 static ssize_t gzip_file_read(struct file_info *fp, void *ptr, size_t n)
  84 {
  85     z_streamp zs = fp->i.pvt;
  86     int rv;
  87     ssize_t bytes;
  88     ssize_t nout = 0;
  89     unsigned char *p = ptr;
  90
  91     while (n) {
  92         zs->next_out = p;
  93         zs->avail_out = n;
  94
  95         if (!zs->avail_in && fp->i.fd.handle) {
  96             if (__file_get_block(fp))
  97                 return nout ? nout : -1;
  98
  99             zs->next_in = (void *)fp->i.datap;
 100             zs->avail_in = fp->i.nbytes;
 101         }
 102
 103         rv = inflate(zs, Z_SYNC_FLUSH);
 104
 105         bytes = n - zs->avail_out;
 106         nout += bytes;
 107         p += bytes;
 108         n -= bytes;
 109
 110         switch (rv) {
 111         case Z_DATA_ERROR:
 112         case Z_NEED_DICT:
 113         case Z_BUF_ERROR:
 114         case Z_STREAM_ERROR:
 115         default:
 116             errno = EIO;
 117             return nout ? nout : -1;
 118         case Z_MEM_ERROR:
 119             errno = ENOMEM;
 120             return nout ? nout : -1;
 121         case Z_STREAM_END:
 122             return nout;
 123         case Z_OK:
 124             break;
 125         }
 126     }
 127
 128     return nout;
 129 }
 130
 131 static int gzip_file_close(struct file_info *fp)
 132 {
 133     z_streamp zs = fp->i.pvt;
 134
 135     inflateEnd(zs);
 136     free(zs);
 137     return __file_close(fp);
 138 }
 139
 140 int zopen(const char *pathname, int flags, ...)
 141 {
 142     int fd, rv;
 143     struct file_info *fp;
 144
 145     /* We don't actually give a hoot about the creation bits... */
 146     fd = open(pathname, flags, 0);
 147
 148     if (fd < 0)
 149         return -1;
 150
 151     fp = &__file_info[fd];
 152
 153     /* Need to get the first block into the buffer, but not consumed */
 154     if (__file_get_block(fp))
 155         goto err;
 156
 157     if (fp->i.nbytes >= 14 &&
 158         (uint8_t) fp->i.buf[0] == 037 &&
 159         (uint8_t) fp->i.buf[1] == 0213 &&       /* gzip */
 160         fp->i.buf[2] == 8)      /* deflate */
 161         rv = gzip_file_init(fp);
 162     else
 163         rv = 0;                 /* Plain file */
 164
 165     if (!rv)
 166         return fd;
 167
 168 err:
 169     close(fd);
 170     return -1;
 171 }