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- /* gzio.c - decompression support for gzip */
- /*
- * GRUB -- GRand Unified Bootloader
- * Copyright (C) 1999,2005,2006,2007,2009 Free Software Foundation, Inc.
- *
- * GRUB is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * GRUB is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
- */
- /*
- * Most of this file was originally the source file "inflate.c", written
- * by Mark Adler. It has been very heavily modified. In particular, the
- * original would run through the whole file at once, and this version can
- * be stopped and restarted on any boundary during the decompression process.
- *
- * The license and header comments that file are included here.
- */
- /* inflate.c -- Not copyrighted 1992 by Mark Adler
- version c10p1, 10 January 1993 */
- /* You can do whatever you like with this source file, though I would
- prefer that if you modify it and redistribute it that you include
- comments to that effect with your name and the date. Thank you.
- */
- #include <grub/err.h>
- #include <grub/types.h>
- #include <grub/mm.h>
- #include <grub/misc.h>
- #include <grub/fs.h>
- #include <grub/file.h>
- #include <grub/gzio.h>
- GRUB_EXPORT(grub_gzfile_open);
- GRUB_EXPORT(grub_gzio_open);
- /*
- * Window Size
- *
- * This must be a power of two, and at least 32K for zip's deflate method
- */
- #define WSIZE 0x8000
- #define INBUFSIZ 0x2000
- /* The state stored in filesystem-specific data. */
- struct grub_gzio
- {
- /* The underlying file object. */
- grub_file_t file;
- /* The offset at which the data starts in the underlying file. */
- grub_off_t data_offset;
- /* The type of current block. */
- int block_type;
- /* The length of current block. */
- int block_len;
- /* The flag of the last block. */
- int last_block;
- /* The flag of codes. */
- int code_state;
- /* The length of a copy. */
- unsigned inflate_n;
- /* The index of a copy. */
- unsigned inflate_d;
- /* The input buffer. */
- grub_uint8_t inbuf[INBUFSIZ];
- int inbuf_d;
- /* The bit buffer. */
- unsigned long bb;
- /* The bits in the bit buffer. */
- unsigned bk;
- /* The sliding window in uncompressed data. */
- grub_uint8_t slide[WSIZE];
- /* Current position in the slide. */
- unsigned wp;
- /* The literal/length code table. */
- struct huft *tl;
- /* The distance code table. */
- struct huft *td;
- /* The lookup bits for the literal/length code table. */
- int bl;
- /* The lookup bits for the distance code table. */
- int bd;
- /* The original offset value. */
- grub_off_t saved_offset;
- };
- typedef struct grub_gzio *grub_gzio_t;
- /* Declare the filesystem structure for grub_gzio_open. */
- static struct grub_fs grub_gzio_fs;
- /* Function prototypes */
- static void initialize_tables (grub_file_t file);
- /* Eat variable-length header fields. */
- static int
- eat_field (grub_file_t file, int len)
- {
- char ch = 1;
- int not_retval = 1;
- do
- {
- if (len >= 0)
- {
- if (! (len--))
- break;
- }
- else
- {
- if (! ch)
- break;
- }
- }
- while ((not_retval = grub_file_read (file, &ch, 1)) == 1);
- return ! not_retval;
- }
- /* Little-Endian defines for the 2-byte magic numbers for gzip files. */
- #define GZIP_MAGIC grub_le_to_cpu16 (0x8B1F)
- #define OLD_GZIP_MAGIC grub_le_to_cpu16 (0x9E1F)
- /* Compression methods (see algorithm.doc) */
- #define STORED 0
- #define COMPRESSED 1
- #define PACKED 2
- #define LZHED 3
- /* methods 4 to 7 reserved */
- #define DEFLATED 8
- #define MAX_METHODS 9
- /* gzip flag byte */
- #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
- #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
- #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
- #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
- #define COMMENT 0x10 /* bit 4 set: file comment present */
- #define ENCRYPTED 0x20 /* bit 5 set: file is encrypted */
- #define RESERVED 0xC0 /* bit 6,7: reserved */
- #define UNSUPPORTED_FLAGS (CONTINUATION | ENCRYPTED | RESERVED)
- /* inflate block codes */
- #define INFLATE_STORED 0
- #define INFLATE_FIXED 1
- #define INFLATE_DYNAMIC 2
- typedef unsigned char uch;
- typedef unsigned short ush;
- typedef unsigned long ulg;
- static int
- test_header (grub_file_t file)
- {
- struct {
- grub_uint16_t magic;
- grub_uint8_t method;
- grub_uint8_t flags;
- grub_uint32_t timestamp;
- grub_uint8_t extra_flags;
- grub_uint8_t os_type;
- } hdr;
- grub_uint16_t extra_len;
- grub_uint32_t orig_len;
- grub_gzio_t gzio = file->data;
- if (grub_file_tell (gzio->file) != 0)
- grub_file_seek (gzio->file, 0);
- /*
- * This checks if the file is gzipped. If a problem occurs here
- * (other than a real error with the disk) then we don't think it
- * is a compressed file, and simply mark it as such.
- */
- if (grub_file_read (gzio->file, &hdr, 10) != 10
- || ((hdr.magic != GZIP_MAGIC)
- && (hdr.magic != OLD_GZIP_MAGIC)))
- {
- grub_error (GRUB_ERR_BAD_FILE_TYPE, "no gzip magic found");
- return 0;
- }
- /*
- * This does consistency checking on the header data. If a
- * problem occurs from here on, then we have corrupt or otherwise
- * bad data, and the error should be reported to the user.
- */
- if (hdr.method != DEFLATED
- || (hdr.flags & UNSUPPORTED_FLAGS)
- || ((hdr.flags & EXTRA_FIELD)
- && (grub_file_read (gzio->file, &extra_len, 2) != 2
- || eat_field (gzio->file,
- grub_le_to_cpu16 (extra_len))))
- || ((hdr.flags & ORIG_NAME) && eat_field (gzio->file, -1))
- || ((hdr.flags & COMMENT) && eat_field (gzio->file, -1)))
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA, "unsupported gzip format");
- return 0;
- }
- gzio->data_offset = grub_file_tell (gzio->file);
- grub_file_seek (gzio->file, grub_file_size (gzio->file) - 4);
- if (grub_file_read (gzio->file, &orig_len, 4) != 4)
- {
- grub_error (GRUB_ERR_BAD_FILE_TYPE, "unsupported gzip format");
- return 0;
- }
- /* FIXME: this does not handle files whose original size is over 4GB.
- But how can we know the real original size? */
- file->size = grub_le_to_cpu32 (orig_len);
- initialize_tables (file);
- return 1;
- }
- /* Huffman code lookup table entry--this entry is four bytes for machines
- that have 16-bit pointers (e.g. PC's in the small or medium model).
- Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16
- means that v is a literal, 16 < e < 32 means that v is a pointer to
- the next table, which codes e - 16 bits, and lastly e == 99 indicates
- an unused code. If a code with e == 99 is looked up, this implies an
- error in the data. */
- struct huft
- {
- uch e; /* number of extra bits or operation */
- uch b; /* number of bits in this code or subcode */
- union
- {
- ush n; /* literal, length base, or distance base */
- struct huft *t; /* pointer to next level of table */
- }
- v;
- };
- /* The inflate algorithm uses a sliding 32K byte window on the uncompressed
- stream to find repeated byte strings. This is implemented here as a
- circular buffer. The index is updated simply by incrementing and then
- and'ing with 0x7fff (32K-1). */
- /* It is left to other modules to supply the 32K area. It is assumed
- to be usable as if it were declared "uch slide[32768];" or as just
- "uch *slide;" and then malloc'ed in the latter case. The definition
- must be in unzip.h, included above. */
- /* Tables for deflate from PKZIP's appnote.txt. */
- static unsigned bitorder[] =
- { /* Order of the bit length code lengths */
- 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
- static ush cplens[] =
- { /* Copy lengths for literal codes 257..285 */
- 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
- 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
- /* note: see note #13 above about the 258 in this list. */
- static ush cplext[] =
- { /* Extra bits for literal codes 257..285 */
- 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
- 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */
- static ush cpdist[] =
- { /* Copy offsets for distance codes 0..29 */
- 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
- 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
- 8193, 12289, 16385, 24577};
- static ush cpdext[] =
- { /* Extra bits for distance codes */
- 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
- 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
- 12, 12, 13, 13};
- /*
- Huffman code decoding is performed using a multi-level table lookup.
- The fastest way to decode is to simply build a lookup table whose
- size is determined by the longest code. However, the time it takes
- to build this table can also be a factor if the data being decoded
- is not very long. The most common codes are necessarily the
- shortest codes, so those codes dominate the decoding time, and hence
- the speed. The idea is you can have a shorter table that decodes the
- shorter, more probable codes, and then point to subsidiary tables for
- the longer codes. The time it costs to decode the longer codes is
- then traded against the time it takes to make longer tables.
- This results of this trade are in the variables lbits and dbits
- below. lbits is the number of bits the first level table for literal/
- length codes can decode in one step, and dbits is the same thing for
- the distance codes. Subsequent tables are also less than or equal to
- those sizes. These values may be adjusted either when all of the
- codes are shorter than that, in which case the longest code length in
- bits is used, or when the shortest code is *longer* than the requested
- table size, in which case the length of the shortest code in bits is
- used.
- There are two different values for the two tables, since they code a
- different number of possibilities each. The literal/length table
- codes 286 possible values, or in a flat code, a little over eight
- bits. The distance table codes 30 possible values, or a little less
- than five bits, flat. The optimum values for speed end up being
- about one bit more than those, so lbits is 8+1 and dbits is 5+1.
- The optimum values may differ though from machine to machine, and
- possibly even between compilers. Your mileage may vary.
- */
- static int lbits = 9; /* bits in base literal/length lookup table */
- static int dbits = 6; /* bits in base distance lookup table */
- /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
- #define BMAX 16 /* maximum bit length of any code (16 for explode) */
- #define N_MAX 288 /* maximum number of codes in any set */
- /* Macros for inflate() bit peeking and grabbing.
- The usage is:
- NEEDBITS(j)
- x = b & mask_bits[j];
- DUMPBITS(j)
- where NEEDBITS makes sure that b has at least j bits in it, and
- DUMPBITS removes the bits from b. The macros use the variable k
- for the number of bits in b. Normally, b and k are register
- variables for speed, and are initialized at the beginning of a
- routine that uses these macros from a global bit buffer and count.
- If we assume that EOB will be the longest code, then we will never
- ask for bits with NEEDBITS that are beyond the end of the stream.
- So, NEEDBITS should not read any more bytes than are needed to
- meet the request. Then no bytes need to be "returned" to the buffer
- at the end of the last block.
- However, this assumption is not true for fixed blocks--the EOB code
- is 7 bits, but the other literal/length codes can be 8 or 9 bits.
- (The EOB code is shorter than other codes because fixed blocks are
- generally short. So, while a block always has an EOB, many other
- literal/length codes have a significantly lower probability of
- showing up at all.) However, by making the first table have a
- lookup of seven bits, the EOB code will be found in that first
- lookup, and so will not require that too many bits be pulled from
- the stream.
- */
- static ush mask_bits[] =
- {
- 0x0000,
- 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
- 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
- };
- #define NEEDBITS(n) do {while(k<(n)){b|=((ulg)get_byte(file))<<k;k+=8;}} while (0)
- #define DUMPBITS(n) do {b>>=(n);k-=(n);} while (0)
- static int
- get_byte (grub_file_t file)
- {
- grub_gzio_t gzio = file->data;
- if (grub_file_tell (gzio->file) == (grub_off_t) gzio->data_offset
- || gzio->inbuf_d == INBUFSIZ)
- {
- gzio->inbuf_d = 0;
- grub_file_read (gzio->file, gzio->inbuf, INBUFSIZ);
- }
- return gzio->inbuf[gzio->inbuf_d++];
- }
- /* more function prototypes */
- static int huft_build (unsigned *, unsigned, unsigned, ush *, ush *,
- struct huft **, int *);
- static int huft_free (struct huft *);
- static int inflate_codes_in_window (grub_file_t);
- /* Given a list of code lengths and a maximum table size, make a set of
- tables to decode that set of codes. Return zero on success, one if
- the given code set is incomplete (the tables are still built in this
- case), two if the input is invalid (all zero length codes or an
- oversubscribed set of lengths), and three if not enough memory. */
- static int
- huft_build (unsigned *b, /* code lengths in bits (all assumed <= BMAX) */
- unsigned n, /* number of codes (assumed <= N_MAX) */
- unsigned s, /* number of simple-valued codes (0..s-1) */
- ush * d, /* list of base values for non-simple codes */
- ush * e, /* list of extra bits for non-simple codes */
- struct huft **t, /* result: starting table */
- int *m) /* maximum lookup bits, returns actual */
- {
- unsigned a; /* counter for codes of length k */
- unsigned c[BMAX + 1]; /* bit length count table */
- unsigned f; /* i repeats in table every f entries */
- int g; /* maximum code length */
- int h; /* table level */
- register unsigned i; /* counter, current code */
- register unsigned j; /* counter */
- register int k; /* number of bits in current code */
- int l; /* bits per table (returned in m) */
- register unsigned *p; /* pointer into c[], b[], or v[] */
- register struct huft *q; /* points to current table */
- struct huft r; /* table entry for structure assignment */
- struct huft *u[BMAX]; /* table stack */
- unsigned v[N_MAX]; /* values in order of bit length */
- register int w; /* bits before this table == (l * h) */
- unsigned x[BMAX + 1]; /* bit offsets, then code stack */
- unsigned *xp; /* pointer into x */
- int y; /* number of dummy codes added */
- unsigned z; /* number of entries in current table */
- /* Generate counts for each bit length */
- grub_memset ((char *) c, 0, sizeof (c));
- p = b;
- i = n;
- do
- {
- c[*p]++; /* assume all entries <= BMAX */
- p++; /* Can't combine with above line (Solaris bug) */
- }
- while (--i);
- if (c[0] == n) /* null input--all zero length codes */
- {
- *t = (struct huft *) NULL;
- *m = 0;
- return 0;
- }
- /* Find minimum and maximum length, bound *m by those */
- l = *m;
- for (j = 1; j <= BMAX; j++)
- if (c[j])
- break;
- k = j; /* minimum code length */
- if ((unsigned) l < j)
- l = j;
- for (i = BMAX; i; i--)
- if (c[i])
- break;
- g = i; /* maximum code length */
- if ((unsigned) l > i)
- l = i;
- *m = l;
- /* Adjust last length count to fill out codes, if needed */
- for (y = 1 << j; j < i; j++, y <<= 1)
- if ((y -= c[j]) < 0)
- return 2; /* bad input: more codes than bits */
- if ((y -= c[i]) < 0)
- return 2;
- c[i] += y;
- /* Generate starting offsets into the value table for each length */
- x[1] = j = 0;
- p = c + 1;
- xp = x + 2;
- while (--i)
- { /* note that i == g from above */
- *xp++ = (j += *p++);
- }
- /* Make a table of values in order of bit lengths */
- p = b;
- i = 0;
- do
- {
- if ((j = *p++) != 0)
- v[x[j]++] = i;
- }
- while (++i < n);
- /* Generate the Huffman codes and for each, make the table entries */
- x[0] = i = 0; /* first Huffman code is zero */
- p = v; /* grab values in bit order */
- h = -1; /* no tables yet--level -1 */
- w = -l; /* bits decoded == (l * h) */
- u[0] = (struct huft *) NULL; /* just to keep compilers happy */
- q = (struct huft *) NULL; /* ditto */
- z = 0; /* ditto */
- /* go through the bit lengths (k already is bits in shortest code) */
- for (; k <= g; k++)
- {
- a = c[k];
- while (a--)
- {
- /* here i is the Huffman code of length k bits for value *p */
- /* make tables up to required level */
- while (k > w + l)
- {
- h++;
- w += l; /* previous table always l bits */
- /* compute minimum size table less than or equal to l bits */
- z = (z = (unsigned) (g - w)) > (unsigned) l ? (unsigned) l : z; /* upper limit on table size */
- if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */
- { /* too few codes for k-w bit table */
- f -= a + 1; /* deduct codes from patterns left */
- xp = c + k;
- while (++j < z) /* try smaller tables up to z bits */
- {
- if ((f <<= 1) <= *++xp)
- break; /* enough codes to use up j bits */
- f -= *xp; /* else deduct codes from patterns */
- }
- }
- z = 1 << j; /* table entries for j-bit table */
- /* allocate and link in new table */
- q = (struct huft *) grub_malloc ((z + 1) * sizeof (struct huft));
- if (! q)
- {
- if (h)
- huft_free (u[0]);
- return 3;
- }
- *t = q + 1; /* link to list for huft_free() */
- *(t = &(q->v.t)) = (struct huft *) NULL;
- u[h] = ++q; /* table starts after link */
- /* connect to last table, if there is one */
- if (h)
- {
- x[h] = i; /* save pattern for backing up */
- r.b = (uch) l; /* bits to dump before this table */
- r.e = (uch) (16 + j); /* bits in this table */
- r.v.t = q; /* pointer to this table */
- j = i >> (w - l); /* (get around Turbo C bug) */
- u[h - 1][j] = r; /* connect to last table */
- }
- }
- /* set up table entry in r */
- r.b = (uch) (k - w);
- if (p >= v + n)
- r.e = 99; /* out of values--invalid code */
- else if (*p < s)
- {
- r.e = (uch) (*p < 256 ? 16 : 15); /* 256 is end-of-block code */
- r.v.n = (ush) (*p); /* simple code is just the value */
- p++; /* one compiler does not like *p++ */
- }
- else
- {
- r.e = (uch) e[*p - s]; /* non-simple--look up in lists */
- r.v.n = d[*p++ - s];
- }
- /* fill code-like entries with r */
- f = 1 << (k - w);
- for (j = i >> w; j < z; j += f)
- q[j] = r;
- /* backwards increment the k-bit code i */
- for (j = 1 << (k - 1); i & j; j >>= 1)
- i ^= j;
- i ^= j;
- /* backup over finished tables */
- while ((i & ((1 << w) - 1)) != x[h])
- {
- h--; /* don't need to update q */
- w -= l;
- }
- }
- }
- /* Return true (1) if we were given an incomplete table */
- return y != 0 && g != 1;
- }
- /* Free the malloc'ed tables built by huft_build(), which makes a linked
- list of the tables it made, with the links in a dummy first entry of
- each table. */
- static int
- huft_free (struct huft *t)
- {
- register struct huft *p, *q;
- /* Go through linked list, freeing from the malloced (t[-1]) address. */
- p = t;
- while (p != (struct huft *) NULL)
- {
- q = (--p)->v.t;
- grub_free ((char *) p);
- p = q;
- }
- return 0;
- }
- /*
- * inflate (decompress) the codes in a deflated (compressed) block.
- * Return an error code or zero if it all goes ok.
- */
- static int
- inflate_codes_in_window (grub_file_t file)
- {
- register unsigned e; /* table entry flag/number of extra bits */
- unsigned n, d; /* length and index for copy */
- unsigned w; /* current window position */
- struct huft *t; /* pointer to table entry */
- unsigned ml, md; /* masks for bl and bd bits */
- register ulg b; /* bit buffer */
- register unsigned k; /* number of bits in bit buffer */
- grub_gzio_t gzio = file->data;
- /* make local copies of globals */
- d = gzio->inflate_d;
- n = gzio->inflate_n;
- b = gzio->bb; /* initialize bit buffer */
- k = gzio->bk;
- w = gzio->wp; /* initialize window position */
- /* inflate the coded data */
- ml = mask_bits[gzio->bl]; /* precompute masks for speed */
- md = mask_bits[gzio->bd];
- for (;;) /* do until end of block */
- {
- if (! gzio->code_state)
- {
- NEEDBITS ((unsigned) gzio->bl);
- if ((e = (t = gzio->tl + ((unsigned) b & ml))->e) > 16)
- do
- {
- if (e == 99)
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "an unused code found");
- return 1;
- }
- DUMPBITS (t->b);
- e -= 16;
- NEEDBITS (e);
- }
- while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
- DUMPBITS (t->b);
- if (e == 16) /* then it's a literal */
- {
- gzio->slide[w++] = (uch) t->v.n;
- if (w == WSIZE)
- break;
- }
- else
- /* it's an EOB or a length */
- {
- /* exit if end of block */
- if (e == 15)
- {
- gzio->block_len = 0;
- break;
- }
- /* get length of block to copy */
- NEEDBITS (e);
- n = t->v.n + ((unsigned) b & mask_bits[e]);
- DUMPBITS (e);
- /* decode distance of block to copy */
- NEEDBITS ((unsigned) gzio->bd);
- if ((e = (t = gzio->td + ((unsigned) b & md))->e) > 16)
- do
- {
- if (e == 99)
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "an unused code found");
- return 1;
- }
- DUMPBITS (t->b);
- e -= 16;
- NEEDBITS (e);
- }
- while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e)
- > 16);
- DUMPBITS (t->b);
- NEEDBITS (e);
- d = w - t->v.n - ((unsigned) b & mask_bits[e]);
- DUMPBITS (e);
- gzio->code_state++;
- }
- }
- if (gzio->code_state)
- {
- /* do the copy */
- do
- {
- n -= (e = (e = WSIZE - ((d &= WSIZE - 1) > w ? d : w)) > n ? n
- : e);
- if (w - d >= e)
- {
- grub_memmove (gzio->slide + w, gzio->slide + d, e);
- w += e;
- d += e;
- }
- else
- /* purposefully use the overlap for extra copies here!! */
- {
- while (e--)
- gzio->slide[w++] = gzio->slide[d++];
- }
- if (w == WSIZE)
- break;
- }
- while (n);
- if (! n)
- gzio->code_state--;
- /* did we break from the loop too soon? */
- if (w == WSIZE)
- break;
- }
- }
- /* restore the globals from the locals */
- gzio->inflate_d = d;
- gzio->inflate_n = n;
- gzio->wp = w; /* restore global window pointer */
- gzio->bb = b; /* restore global bit buffer */
- gzio->bk = k;
- return ! gzio->block_len;
- }
- /* get header for an inflated type 0 (stored) block. */
- static void
- init_stored_block (grub_file_t file)
- {
- register ulg b; /* bit buffer */
- register unsigned k; /* number of bits in bit buffer */
- grub_gzio_t gzio = file->data;
- /* make local copies of globals */
- b = gzio->bb; /* initialize bit buffer */
- k = gzio->bk;
- /* go to byte boundary */
- DUMPBITS (k & 7);
- /* get the length and its complement */
- NEEDBITS (16);
- gzio->block_len = ((unsigned) b & 0xffff);
- DUMPBITS (16);
- NEEDBITS (16);
- if (gzio->block_len != (int) ((~b) & 0xffff))
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "the length of a stored block does not match");
- DUMPBITS (16);
- /* restore global variables */
- gzio->bb = b;
- gzio->bk = k;
- }
- /* get header for an inflated type 1 (fixed Huffman codes) block. We should
- either replace this with a custom decoder, or at least precompute the
- Huffman tables. */
- static void
- init_fixed_block (grub_file_t file)
- {
- int i; /* temporary variable */
- unsigned l[288]; /* length list for huft_build */
- grub_gzio_t gzio = file->data;
- /* set up literal table */
- for (i = 0; i < 144; i++)
- l[i] = 8;
- for (; i < 256; i++)
- l[i] = 9;
- for (; i < 280; i++)
- l[i] = 7;
- for (; i < 288; i++) /* make a complete, but wrong code set */
- l[i] = 8;
- gzio->bl = 7;
- if (huft_build (l, 288, 257, cplens, cplext, &gzio->tl, &gzio->bl) != 0)
- {
- if (grub_errno == GRUB_ERR_NONE)
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "failed in building a Huffman code table");
- return;
- }
- /* set up distance table */
- for (i = 0; i < 30; i++) /* make an incomplete code set */
- l[i] = 5;
- gzio->bd = 5;
- if (huft_build (l, 30, 0, cpdist, cpdext, &gzio->td, &gzio->bd) > 1)
- {
- if (grub_errno == GRUB_ERR_NONE)
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "failed in building a Huffman code table");
- huft_free (gzio->tl);
- gzio->tl = 0;
- return;
- }
- /* indicate we're now working on a block */
- gzio->code_state = 0;
- gzio->block_len++;
- }
- /* get header for an inflated type 2 (dynamic Huffman codes) block. */
- static void
- init_dynamic_block (grub_file_t file)
- {
- int i; /* temporary variables */
- unsigned j;
- unsigned l; /* last length */
- unsigned m; /* mask for bit lengths table */
- unsigned n; /* number of lengths to get */
- unsigned nb; /* number of bit length codes */
- unsigned nl; /* number of literal/length codes */
- unsigned nd; /* number of distance codes */
- unsigned ll[286 + 30]; /* literal/length and distance code lengths */
- register ulg b; /* bit buffer */
- register unsigned k; /* number of bits in bit buffer */
- grub_gzio_t gzio = file->data;
- /* make local bit buffer */
- b = gzio->bb;
- k = gzio->bk;
- /* read in table lengths */
- NEEDBITS (5);
- nl = 257 + ((unsigned) b & 0x1f); /* number of literal/length codes */
- DUMPBITS (5);
- NEEDBITS (5);
- nd = 1 + ((unsigned) b & 0x1f); /* number of distance codes */
- DUMPBITS (5);
- NEEDBITS (4);
- nb = 4 + ((unsigned) b & 0xf); /* number of bit length codes */
- DUMPBITS (4);
- if (nl > 286 || nd > 30)
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA, "too much data");
- return;
- }
- /* read in bit-length-code lengths */
- for (j = 0; j < nb; j++)
- {
- NEEDBITS (3);
- ll[bitorder[j]] = (unsigned) b & 7;
- DUMPBITS (3);
- }
- for (; j < 19; j++)
- ll[bitorder[j]] = 0;
- /* build decoding table for trees--single level, 7 bit lookup */
- gzio->bl = 7;
- if (huft_build (ll, 19, 19, NULL, NULL, &gzio->tl, &gzio->bl) != 0)
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "failed in building a Huffman code table");
- return;
- }
- /* read in literal and distance code lengths */
- n = nl + nd;
- m = mask_bits[gzio->bl];
- i = l = 0;
- while ((unsigned) i < n)
- {
- NEEDBITS ((unsigned) gzio->bl);
- j = (gzio->td = gzio->tl + ((unsigned) b & m))->b;
- DUMPBITS (j);
- j = gzio->td->v.n;
- if (j < 16) /* length of code in bits (0..15) */
- ll[i++] = l = j; /* save last length in l */
- else if (j == 16) /* repeat last length 3 to 6 times */
- {
- NEEDBITS (2);
- j = 3 + ((unsigned) b & 3);
- DUMPBITS (2);
- if ((unsigned) i + j > n)
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA, "too many codes found");
- return;
- }
- while (j--)
- ll[i++] = l;
- }
- else if (j == 17) /* 3 to 10 zero length codes */
- {
- NEEDBITS (3);
- j = 3 + ((unsigned) b & 7);
- DUMPBITS (3);
- if ((unsigned) i + j > n)
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA, "too many codes found");
- return;
- }
- while (j--)
- ll[i++] = 0;
- l = 0;
- }
- else
- /* j == 18: 11 to 138 zero length codes */
- {
- NEEDBITS (7);
- j = 11 + ((unsigned) b & 0x7f);
- DUMPBITS (7);
- if ((unsigned) i + j > n)
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA, "too many codes found");
- return;
- }
- while (j--)
- ll[i++] = 0;
- l = 0;
- }
- }
- /* free decoding table for trees */
- huft_free (gzio->tl);
- gzio->td = 0;
- gzio->tl = 0;
- /* restore the global bit buffer */
- gzio->bb = b;
- gzio->bk = k;
- /* build the decoding tables for literal/length and distance codes */
- gzio->bl = lbits;
- if (huft_build (ll, nl, 257, cplens, cplext, &gzio->tl, &gzio->bl) != 0)
- {
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "failed in building a Huffman code table");
- return;
- }
- gzio->bd = dbits;
- if (huft_build (ll + nl, nd, 0, cpdist, cpdext, &gzio->td, &gzio->bd) != 0)
- {
- huft_free (gzio->tl);
- gzio->tl = 0;
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "failed in building a Huffman code table");
- return;
- }
- /* indicate we're now working on a block */
- gzio->code_state = 0;
- gzio->block_len++;
- }
- static void
- get_new_block (grub_file_t file)
- {
- register ulg b; /* bit buffer */
- register unsigned k; /* number of bits in bit buffer */
- grub_gzio_t gzio = file->data;
- /* make local bit buffer */
- b = gzio->bb;
- k = gzio->bk;
- /* read in last block bit */
- NEEDBITS (1);
- gzio->last_block = (int) b & 1;
- DUMPBITS (1);
- /* read in block type */
- NEEDBITS (2);
- gzio->block_type = (unsigned) b & 3;
- DUMPBITS (2);
- /* restore the global bit buffer */
- gzio->bb = b;
- gzio->bk = k;
- switch (gzio->block_type)
- {
- case INFLATE_STORED:
- init_stored_block (file);
- break;
- case INFLATE_FIXED:
- init_fixed_block (file);
- break;
- case INFLATE_DYNAMIC:
- init_dynamic_block (file);
- break;
- default:
- break;
- }
- }
- static void
- inflate_window (grub_file_t file)
- {
- grub_gzio_t gzio = file->data;
- /* initialize window */
- gzio->wp = 0;
- /*
- * Main decompression loop.
- */
- while (gzio->wp < WSIZE && grub_errno == GRUB_ERR_NONE)
- {
- if (! gzio->block_len)
- {
- if (gzio->last_block)
- break;
- get_new_block (file);
- }
- if (gzio->block_type > INFLATE_DYNAMIC)
- grub_error (GRUB_ERR_BAD_GZIP_DATA,
- "unknown block type %d", gzio->block_type);
- if (grub_errno != GRUB_ERR_NONE)
- return;
- /*
- * Expand stored block here.
- */
- if (gzio->block_type == INFLATE_STORED)
- {
- int w = gzio->wp;
- /*
- * This is basically a glorified pass-through
- */
- while (gzio->block_len && w < WSIZE && grub_errno == GRUB_ERR_NONE)
- {
- gzio->slide[w++] = get_byte (file);
- gzio->block_len--;
- }
- gzio->wp = w;
- continue;
- }
- /*
- * Expand other kind of block.
- */
- if (inflate_codes_in_window (file))
- {
- huft_free (gzio->tl);
- huft_free (gzio->td);
- gzio->tl = 0;
- gzio->td = 0;
- }
- }
- gzio->saved_offset += WSIZE;
- /* XXX do CRC calculation here! */
- }
- static void
- initialize_tables (grub_file_t file)
- {
- grub_gzio_t gzio = file->data;
- gzio->saved_offset = 0;
- grub_file_seek (gzio->file, gzio->data_offset);
- /* Initialize the bit buffer. */
- gzio->bk = 0;
- gzio->bb = 0;
- /* Reset partial decompression code. */
- gzio->last_block = 0;
- gzio->block_len = 0;
- /* Reset memory allocation stuff. */
- huft_free (gzio->tl);
- huft_free (gzio->td);
- }
- /* Open a new decompressing object on the top of IO. If TRANSPARENT is true,
- even if IO does not contain data compressed by gzip, return a valid file
- object. Note that this function won't close IO, even if an error occurs. */
- grub_file_t
- grub_gzio_open (grub_file_t io, int transparent)
- {
- grub_file_t file;
- grub_gzio_t gzio = 0;
- file = (grub_file_t) grub_malloc (sizeof (*file));
- if (! file)
- return 0;
- gzio = grub_zalloc (sizeof (*gzio));
- if (! gzio)
- {
- grub_free (file);
- return 0;
- }
- gzio->file = io;
- file->device = io->device;
- file->offset = 0;
- file->data = gzio;
- file->read_hook = 0;
- file->fs = &grub_gzio_fs;
- if (! test_header (file))
- {
- grub_free (gzio);
- grub_free (file);
- grub_file_seek (io, 0);
- if (grub_errno == GRUB_ERR_BAD_FILE_TYPE && transparent)
- {
- grub_errno = GRUB_ERR_NONE;
- return io;
- }
- else
- return 0;
- }
- return file;
- }
- /* This is similar to grub_gzio_open, but takes a file name as an argument. */
- grub_file_t
- grub_gzfile_open (const char *name, int transparent)
- {
- grub_file_t io, file;
- io = grub_file_open (name);
- if (! io)
- return 0;
- file = grub_gzio_open (io, transparent);
- if (! file)
- {
- grub_file_close (io);
- return 0;
- }
- return file;
- }
- static grub_ssize_t
- grub_gzio_read (grub_file_t file, char *buf, grub_size_t len)
- {
- grub_ssize_t ret = 0;
- grub_gzio_t gzio = file->data;
- grub_off_t offset;
- /* Do we reset decompression to the beginning of the file? */
- if (gzio->saved_offset > file->offset + WSIZE)
- initialize_tables (file);
- /*
- * This loop operates upon uncompressed data only. The only
- * special thing it does is to make sure the decompression
- * window is within the range of data it needs.
- */
- offset = file->offset;
- while (len > 0 && grub_errno == GRUB_ERR_NONE)
- {
- register grub_size_t size;
- register char *srcaddr;
- while (offset >= gzio->saved_offset)
- inflate_window (file);
- srcaddr = (char *) ((offset & (WSIZE - 1)) + gzio->slide);
- size = gzio->saved_offset - offset;
- if (size > len)
- size = len;
- grub_memmove (buf, srcaddr, size);
- buf += size;
- len -= size;
- ret += size;
- offset += size;
- }
- if (grub_errno != GRUB_ERR_NONE)
- ret = -1;
- return ret;
- }
- /* Release everything, including the underlying file object. */
- static grub_err_t
- grub_gzio_close (grub_file_t file)
- {
- grub_gzio_t gzio = file->data;
- grub_file_close (gzio->file);
- huft_free (gzio->tl);
- huft_free (gzio->td);
- grub_free (gzio);
- /* No need to close the same device twice. */
- file->device = 0;
- return grub_errno;
- }
- static struct grub_fs grub_gzio_fs =
- {
- .name = "gzio",
- .dir = 0,
- .open = 0,
- .read = grub_gzio_read,
- .close = grub_gzio_close,
- .label = 0,
- .next = 0
- };
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