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519 lines
16 KiB
C
519 lines
16 KiB
C
/* gzio.c -- IO on .gz files
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* Copyright (C) 1995-2005 Jean-loup Gailly.
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* For conditions of distribution and use, see copyright notice in zlib.h
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*
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* modified to use in EMILE by Laurent Vivier, 2005
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*
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*/
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/* @(#) $Id: gzio.c,v 1.1 2005/11/16 00:48:20 lvivier Exp $ */
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#include <stdio.h>
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#include "zutil.h"
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#ifndef NO_DUMMY_DECL
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struct internal_state {int dummy;}; /* for buggy compilers */
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#endif
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#ifndef Z_BUFSIZE
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# ifdef MAXSEG_64K
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# define Z_BUFSIZE 4096 /* minimize memory usage for 16-bit DOS */
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# else
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# define Z_BUFSIZE 16384
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# endif
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#endif
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#ifndef Z_PRINTF_BUFSIZE
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# define Z_PRINTF_BUFSIZE 4096
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#endif
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#ifndef STDC
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extern voidp malloc OF((uInt size));
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extern void free OF((voidpf ptr));
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#endif
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#define ALLOC(size) malloc(size)
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#define TRYFREE(p) {if (p) free(p);}
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static int const gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
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/* gzip flag byte */
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#define HEAD_CRC 0x02 /* bit 1 set: header CRC present */
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#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
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#define ORIG_NAME 0x08 /* bit 3 set: original file name present */
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#define COMMENT 0x10 /* bit 4 set: file comment present */
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#define RESERVED 0xE0 /* bits 5..7: reserved */
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typedef struct gz_stream {
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z_stream stream;
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int z_err; /* error code for last stream operation */
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int z_eof; /* set if end of input file */
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Byte *inbuf; /* input buffer */
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Byte *outbuf; /* output buffer */
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uLong crc; /* crc32 of uncompressed data */
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int transparent; /* 1 if input file is not a .gz file */
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z_off_t start; /* start of compressed data in file (header skipped) */
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z_off_t in; /* bytes into deflate or inflate */
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z_off_t out; /* bytes out of deflate or inflate */
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int back; /* one character push-back */
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int last; /* true if push-back is last character */
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void *file;
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size_t (*read)(void *, void * , size_t );
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int (*lseek)(void *, long , int );
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} gz_stream;
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local int get_byte OF((gz_stream *s));
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local void check_header OF((gz_stream *s));
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local int destroy OF((gz_stream *s));
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local uLong getLong OF((gz_stream *s));
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/* ===========================================================================
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Opens a gzip (.gz) file for reading or writing. The mode parameter
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is as in fopen ("rb" or "wb"). The file is given either by file descriptor
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or path name (if fd == -1).
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gz_open returns NULL if the file could not be opened or if there was
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insufficient memory to allocate the (de)compression state; errno
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can be checked to distinguish the two cases (if errno is zero, the
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zlib error is Z_MEM_ERROR).
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*/
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gzFile gzopen (file, read, lseek)
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void *file;
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size_t (*read)(void *, void *, size_t );
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int (*lseek)(void *, long , int );
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{
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int err;
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gz_stream *s;
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s = (gz_stream *)ALLOC(sizeof(gz_stream));
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if (!s) return Z_NULL;
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s->stream.zalloc = (alloc_func)0;
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s->stream.zfree = (free_func)0;
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s->stream.opaque = (voidpf)0;
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s->stream.next_in = s->inbuf = Z_NULL;
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s->stream.next_out = s->outbuf = Z_NULL;
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s->stream.avail_in = s->stream.avail_out = 0;
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s->file = file;
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s->read = read;
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s->lseek = lseek;
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s->z_err = Z_OK;
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s->z_eof = 0;
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s->in = 0;
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s->out = 0;
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s->back = EOF;
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s->crc = crc32(0L, Z_NULL, 0);
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s->transparent = 0;
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s->stream.next_in = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
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err = inflateInit2(&(s->stream), -MAX_WBITS);
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/* windowBits is passed < 0 to tell that there is no zlib header.
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* Note that in this case inflate *requires* an extra "dummy" byte
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* after the compressed stream in order to complete decompression and
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* return Z_STREAM_END. Here the gzip CRC32 ensures that 4 bytes are
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* present after the compressed stream.
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*/
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if (err != Z_OK || s->inbuf == Z_NULL) {
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return destroy(s), (gzFile)Z_NULL;
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}
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s->stream.avail_out = Z_BUFSIZE;
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check_header(s); /* skip the .gz header */
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s->start = s->lseek(s->file, 0, SEEK_CUR) - s->stream.avail_in;
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return (gzFile)s;
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}
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/* ===========================================================================
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Read a byte from a gz_stream; update next_in and avail_in. Return EOF
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for end of file.
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IN assertion: the stream s has been sucessfully opened for reading.
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*/
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local int get_byte(s)
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gz_stream *s;
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{
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if (s->z_eof) return EOF;
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if (s->stream.avail_in == 0) {
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s->stream.avail_in = (uInt)s->read(s->file, s->inbuf, Z_BUFSIZE);
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if (s->stream.avail_in == 0) {
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s->z_eof = 1;
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return EOF;
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}
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s->stream.next_in = s->inbuf;
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}
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s->stream.avail_in--;
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return *(s->stream.next_in)++;
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}
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/* ===========================================================================
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Check the gzip header of a gz_stream opened for reading. Set the stream
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mode to transparent if the gzip magic header is not present; set s->err
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to Z_DATA_ERROR if the magic header is present but the rest of the header
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is incorrect.
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IN assertion: the stream s has already been created sucessfully;
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s->stream.avail_in is zero for the first time, but may be non-zero
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for concatenated .gz files.
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*/
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local void check_header(s)
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gz_stream *s;
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{
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int method; /* method byte */
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int flags; /* flags byte */
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uInt len;
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int c;
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/* Assure two bytes in the buffer so we can peek ahead -- handle case
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where first byte of header is at the end of the buffer after the last
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gzip segment */
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len = s->stream.avail_in;
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if (len < 2) {
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if (len) s->inbuf[0] = s->stream.next_in[0];
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len = (uInt)s->read(s->file, s->inbuf + len, Z_BUFSIZE >> len);
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s->stream.avail_in += len;
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s->stream.next_in = s->inbuf;
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if (s->stream.avail_in < 2) {
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s->transparent = s->stream.avail_in;
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return;
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}
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}
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/* Peek ahead to check the gzip magic header */
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if (s->stream.next_in[0] != gz_magic[0] ||
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s->stream.next_in[1] != gz_magic[1]) {
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s->transparent = 1;
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return;
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}
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s->stream.avail_in -= 2;
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s->stream.next_in += 2;
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/* Check the rest of the gzip header */
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method = get_byte(s);
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flags = get_byte(s);
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if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
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s->z_err = Z_DATA_ERROR;
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return;
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}
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/* Discard time, xflags and OS code: */
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for (len = 0; len < 6; len++) (void)get_byte(s);
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if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
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len = (uInt)get_byte(s);
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len += ((uInt)get_byte(s))<<8;
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/* len is garbage if EOF but the loop below will quit anyway */
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while (len-- != 0 && get_byte(s) != EOF) ;
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}
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if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
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while ((c = get_byte(s)) != 0 && c != EOF) ;
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}
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if ((flags & COMMENT) != 0) { /* skip the .gz file comment */
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while ((c = get_byte(s)) != 0 && c != EOF) ;
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}
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if ((flags & HEAD_CRC) != 0) { /* skip the header crc */
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for (len = 0; len < 2; len++) (void)get_byte(s);
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}
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s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK;
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}
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/* ===========================================================================
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* Cleanup then free the given gz_stream. Return a zlib error code.
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Try freeing in the reverse order of allocations.
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*/
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local int destroy (s)
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gz_stream *s;
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{
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int err = Z_OK;
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if (!s) return Z_STREAM_ERROR;
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if (s->stream.state != NULL) {
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err = inflateEnd(&(s->stream));
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}
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if (s->z_err < 0) err = s->z_err;
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TRYFREE(s->inbuf);
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TRYFREE(s->outbuf);
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TRYFREE(s);
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return err;
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}
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/* ===========================================================================
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Reads the given number of uncompressed bytes from the compressed file.
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gzread returns the number of bytes actually read (0 for end of file).
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*/
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int ZEXPORT gzread (file, buf, len)
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gzFile file;
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voidp buf;
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unsigned len;
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{
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gz_stream *s = (gz_stream*)file;
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Bytef *start = (Bytef*)buf; /* starting point for crc computation */
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Byte *next_out; /* == stream.next_out but not forced far (for MSDOS) */
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if (s == NULL) return Z_STREAM_ERROR;
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if (s->z_err == Z_DATA_ERROR) return -1;
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if (s->z_err == Z_STREAM_END) return 0; /* EOF */
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next_out = (Byte*)buf;
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s->stream.next_out = (Bytef*)buf;
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s->stream.avail_out = len;
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if (s->stream.avail_out && s->back != EOF) {
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*next_out++ = s->back;
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s->stream.next_out++;
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s->stream.avail_out--;
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s->back = EOF;
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s->out++;
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start++;
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if (s->last) {
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s->z_err = Z_STREAM_END;
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return 1;
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}
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}
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while (s->stream.avail_out != 0) {
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if (s->transparent) {
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/* Copy first the lookahead bytes: */
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uInt n = s->stream.avail_in;
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if (n > s->stream.avail_out) n = s->stream.avail_out;
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if (n > 0) {
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zmemcpy(s->stream.next_out, s->stream.next_in, n);
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next_out += n;
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s->stream.next_out = next_out;
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s->stream.next_in += n;
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s->stream.avail_out -= n;
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s->stream.avail_in -= n;
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}
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if (s->stream.avail_out > 0) {
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s->stream.avail_out -=
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(uInt)s->read(s->file, next_out, s->stream.avail_out);
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}
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len -= s->stream.avail_out;
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s->in += len;
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s->out += len;
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if (len == 0) s->z_eof = 1;
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return (int)len;
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}
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if (s->stream.avail_in == 0 && !s->z_eof) {
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s->stream.avail_in = (uInt)s->read(s->file, s->inbuf, Z_BUFSIZE);
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if (s->stream.avail_in == 0) {
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s->z_eof = 1;
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}
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s->stream.next_in = s->inbuf;
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}
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s->in += s->stream.avail_in;
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s->out += s->stream.avail_out;
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s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
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s->in -= s->stream.avail_in;
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s->out -= s->stream.avail_out;
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if (s->z_err == Z_STREAM_END) {
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/* Check CRC and original size */
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s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
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start = s->stream.next_out;
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if (getLong(s) != s->crc) {
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s->z_err = Z_DATA_ERROR;
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} else {
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(void)getLong(s);
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/* The uncompressed length returned by above getlong() may be
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* different from s->out in case of concatenated .gz files.
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* Check for such files:
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*/
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check_header(s);
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if (s->z_err == Z_OK) {
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inflateReset(&(s->stream));
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s->crc = crc32(0L, Z_NULL, 0);
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}
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}
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}
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if (s->z_err != Z_OK || s->z_eof) break;
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}
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s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
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if (len == s->stream.avail_out &&
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(s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO))
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return -1;
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return (int)(len - s->stream.avail_out);
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}
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/* ===========================================================================
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Sets the starting position for the next gzread or gzwrite on the given
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compressed file. The offset represents a number of bytes in the
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gzseek returns the resulting offset location as measured in bytes from
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the beginning of the uncompressed stream, or -1 in case of error.
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SEEK_END is not implemented, returns error.
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In this version of the library, gzseek can be extremely slow.
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*/
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z_off_t ZEXPORT gzseek (file, offset, whence)
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gzFile file;
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z_off_t offset;
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int whence;
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{
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gz_stream *s = (gz_stream*)file;
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if (s == NULL || whence == SEEK_END ||
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s->z_err == Z_ERRNO || s->z_err == Z_DATA_ERROR) {
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return -1L;
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}
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/* Rest of function is for reading only */
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/* compute absolute position */
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if (whence == SEEK_CUR) {
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offset += s->out;
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}
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if (offset < 0) return -1L;
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if (s->transparent) {
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/* map to lseek */
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s->back = EOF;
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s->stream.avail_in = 0;
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s->stream.next_in = s->inbuf;
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if (s->lseek(s->file, offset, SEEK_SET) < 0) return -1L;
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s->in = s->out = offset;
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return offset;
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}
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/* For a negative seek, rewind and use positive seek */
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if (offset >= s->out) {
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offset -= s->out;
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} else if (gzrewind(file) < 0) {
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return -1L;
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}
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/* offset is now the number of bytes to skip. */
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if (offset != 0 && s->outbuf == Z_NULL) {
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s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
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if (s->outbuf == Z_NULL) return -1L;
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}
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if (offset && s->back != EOF) {
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s->back = EOF;
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s->out++;
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offset--;
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if (s->last) s->z_err = Z_STREAM_END;
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}
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while (offset > 0) {
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int size = Z_BUFSIZE;
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if (offset < Z_BUFSIZE) size = (int)offset;
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size = gzread(file, s->outbuf, (uInt)size);
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if (size <= 0) return -1L;
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offset -= size;
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}
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return s->out;
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}
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/* ===========================================================================
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Rewinds input file.
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*/
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int ZEXPORT gzrewind (file)
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gzFile file;
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{
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gz_stream *s = (gz_stream*)file;
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if (s == NULL) return -1;
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s->z_err = Z_OK;
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s->z_eof = 0;
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s->back = EOF;
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s->stream.avail_in = 0;
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s->stream.next_in = s->inbuf;
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s->crc = crc32(0L, Z_NULL, 0);
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if (!s->transparent) (void)inflateReset(&s->stream);
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s->in = 0;
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s->out = 0;
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return s->lseek(s->file, s->start, SEEK_SET);
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}
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/* ===========================================================================
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Returns 1 when EOF has previously been detected reading the given
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input stream, otherwise zero.
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*/
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int ZEXPORT gzeof (file)
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gzFile file;
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{
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gz_stream *s = (gz_stream*)file;
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/* With concatenated compressed files that can have embedded
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* crc trailers, z_eof is no longer the only/best indicator of EOF
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* on a gz_stream. Handle end-of-stream error explicitly here.
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*/
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if (s == NULL) return 0;
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if (s->z_eof) return 1;
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return s->z_err == Z_STREAM_END;
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}
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/* ===========================================================================
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Reads a long in LSB order from the given gz_stream. Sets z_err in case
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of error.
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*/
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local uLong getLong (s)
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gz_stream *s;
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{
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uLong x = (uLong)get_byte(s);
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int c;
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x += ((uLong)get_byte(s))<<8;
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x += ((uLong)get_byte(s))<<16;
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c = get_byte(s);
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if (c == EOF) s->z_err = Z_DATA_ERROR;
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x += ((uLong)c)<<24;
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return x;
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}
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/* ===========================================================================
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Flushes all pending output if necessary, closes the compressed file
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and deallocates all the (de)compression state.
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*/
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int ZEXPORT gzclose (file)
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gzFile file;
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{
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gz_stream *s = (gz_stream*)file;
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if (s == NULL) return Z_STREAM_ERROR;
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return destroy((gz_stream*)file);
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}
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#ifdef STDC
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# define zstrerror(errnum) strerror(errnum)
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#else
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# define zstrerror(errnum) ""
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#endif
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/* ===========================================================================
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Returns the error message for the last error which occurred on the
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given compressed file. errnum is set to zlib error number. If an
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error occurred in the file system and not in the compression library,
|
|
errnum is set to Z_ERRNO and the application may consult errno
|
|
to get the exact error code.
|
|
*/
|
|
const char * ZEXPORT gzerror (file, errnum)
|
|
gzFile file;
|
|
int *errnum;
|
|
{
|
|
return "Unknown error";
|
|
}
|
|
|
|
/* ===========================================================================
|
|
Clear the error and end-of-file flags, and do the same for the real file.
|
|
*/
|
|
void ZEXPORT gzclearerr (file)
|
|
gzFile file;
|
|
{
|
|
gz_stream *s = (gz_stream*)file;
|
|
|
|
if (s == NULL) return;
|
|
if (s->z_err != Z_STREAM_END) s->z_err = Z_OK;
|
|
s->z_eof = 0;
|
|
}
|