524 lines
15 KiB
C
524 lines
15 KiB
C
/* gzio.c -- IO on .gz files
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* Copyright (C) 1995-1996 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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/* $Id: gzio.c,v 1.1.1.1 1996/09/12 15:33:09 gwr Exp $ */
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#include <stdio.h>
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#include "zutil.h"
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struct internal_state {int dummy;}; /* for buggy compilers */
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#define Z_BUFSIZE 4096
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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 gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
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/* gzip flag byte */
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#define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
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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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FILE *file; /* .gz 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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char *msg; /* error message */
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char *path; /* path name for debugging only */
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int transparent; /* 1 if input file is not a .gz file */
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char mode; /* 'w' or 'r' */
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} gz_stream;
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local gzFile gz_open OF((const char *path, const char *mode, int fd));
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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 void putLong OF((FILE *file, uLong x));
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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 return 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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local gzFile gz_open (path, mode, fd)
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const char *path;
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const char *mode;
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int fd;
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{
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int err;
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int level = Z_DEFAULT_COMPRESSION; /* compression level */
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char *p = (char*)mode;
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gz_stream *s;
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char fmode[80]; /* copy of mode, without the compression level */
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char *m = fmode;
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if (!path || !mode) return Z_NULL;
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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 = NULL;
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s->z_err = Z_OK;
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s->z_eof = 0;
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s->crc = crc32(0L, Z_NULL, 0);
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s->msg = NULL;
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s->transparent = 0;
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s->path = (char*)ALLOC(strlen(path)+1);
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if (s->path == NULL) {
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return destroy(s), (gzFile)Z_NULL;
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}
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strcpy(s->path, path); /* do this early for debugging */
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s->mode = '\0';
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do {
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if (*p == 'r') s->mode = 'r';
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if (*p == 'w' || *p == 'a') s->mode = 'w';
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if (*p >= '0' && *p <= '9') {
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level = *p - '0';
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} else {
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*m++ = *p; /* copy the mode */
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}
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} while (*p++ && m != fmode + sizeof(fmode));
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if (s->mode == '\0') return destroy(s), (gzFile)Z_NULL;
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if (s->mode == 'w') {
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err = deflateInit2(&(s->stream), level,
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Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, 0);
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/* windowBits is passed < 0 to suppress zlib header */
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s->stream.next_out = s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
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if (err != Z_OK || s->outbuf == Z_NULL) {
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return destroy(s), (gzFile)Z_NULL;
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}
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} else {
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err = inflateInit2(&(s->stream), -MAX_WBITS);
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s->stream.next_in = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
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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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}
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s->stream.avail_out = Z_BUFSIZE;
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errno = 0;
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s->file = fd < 0 ? FOPEN(path, fmode) : (FILE*)fdopen(fd, fmode);
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if (s->file == NULL) {
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return destroy(s), (gzFile)Z_NULL;
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}
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if (s->mode == 'w') {
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/* Write a very simple .gz header:
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*/
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fprintf(s->file, "%c%c%c%c%c%c%c%c%c%c", gz_magic[0], gz_magic[1],
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Z_DEFLATED, 0 /*flags*/, 0,0,0,0 /*time*/, 0 /*xflags*/, OS_CODE);
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} else {
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check_header(s); /* skip the .gz header */
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}
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return (gzFile)s;
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}
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/* ===========================================================================
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Opens a gzip (.gz) file for reading or writing.
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*/
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gzFile gzopen (path, mode)
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const char *path;
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const char *mode;
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{
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return gz_open (path, mode, -1);
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}
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/* ===========================================================================
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Associate a gzFile with the file descriptor fd. fd is not dup'ed here
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to mimic the behavio(u)r of fdopen.
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*/
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gzFile gzdopen (fd, mode)
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int fd;
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const char *mode;
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{
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char name[20];
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if (fd < 0) return (gzFile)Z_NULL;
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sprintf(name, "<fd:%d>", fd); /* for debugging */
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return gz_open (name, mode, fd);
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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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errno = 0;
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s->stream.avail_in = fread(s->inbuf, 1, Z_BUFSIZE, s->file);
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if (s->stream.avail_in == 0) {
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s->z_eof = 1;
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if (ferror(s->file)) s->z_err = Z_ERRNO;
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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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/* Check the gzip magic header */
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for (len = 0; len < 2; len++) {
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c = get_byte(s);
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if (c != gz_magic[len]) {
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s->transparent = 1;
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if (c != EOF) s->stream.avail_in++, s->stream.next_in--;
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s->z_err = s->stream.avail_in != 0 ? Z_OK : Z_STREAM_END;
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return;
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}
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}
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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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TRYFREE(s->msg);
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if (s->stream.state != NULL) {
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if (s->mode == 'w') {
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err = deflateEnd(&(s->stream));
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} else if (s->mode == 'r') {
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err = inflateEnd(&(s->stream));
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}
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}
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if (s->file != NULL && fclose(s->file)) {
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err = Z_ERRNO;
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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->path);
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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 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 = 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 || s->mode != 'r') return Z_STREAM_ERROR;
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if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) return -1;
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if (s->z_err == Z_STREAM_END) return 0; /* EOF */
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s->stream.next_out = next_out = buf;
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s->stream.avail_out = len;
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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 -= fread(next_out, 1, s->stream.avail_out,
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s->file);
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}
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return (int)(len - s->stream.avail_out);
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}
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if (s->stream.avail_in == 0 && !s->z_eof) {
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errno = 0;
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s->stream.avail_in = fread(s->inbuf, 1, Z_BUFSIZE, s->file);
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if (s->stream.avail_in == 0) {
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s->z_eof = 1;
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if (ferror(s->file)) {
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s->z_err = Z_ERRNO;
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break;
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}
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}
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s->stream.next_in = s->inbuf;
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}
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s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
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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 || getLong(s) != s->stream.total_out) {
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s->z_err = Z_DATA_ERROR;
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} else {
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/* Check for concatenated .gz files: */
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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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return (int)(len - s->stream.avail_out);
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}
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/* ===========================================================================
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Writes the given number of uncompressed bytes into the compressed file.
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gzwrite returns the number of bytes actually written (0 in case of error).
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*/
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int gzwrite (file, buf, len)
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gzFile file;
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const 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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if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
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s->stream.next_in = buf;
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s->stream.avail_in = len;
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while (s->stream.avail_in != 0) {
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if (s->stream.avail_out == 0) {
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s->stream.next_out = s->outbuf;
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if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
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s->z_err = Z_ERRNO;
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break;
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}
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s->stream.avail_out = Z_BUFSIZE;
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}
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s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
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if (s->z_err != Z_OK) break;
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}
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s->crc = crc32(s->crc, buf, len);
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return (int)(len - s->stream.avail_in);
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}
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/* ===========================================================================
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Flushes all pending output into the compressed file. The parameter
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flush is as in the deflate() function.
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gzflush should be called only when strictly necessary because it can
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degrade compression.
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*/
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int gzflush (file, flush)
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gzFile file;
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int flush;
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{
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uInt len;
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int done = 0;
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gz_stream *s = (gz_stream*)file;
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if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
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s->stream.avail_in = 0; /* should be zero already anyway */
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for (;;) {
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len = Z_BUFSIZE - s->stream.avail_out;
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if (len != 0) {
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if ((uInt)fwrite(s->outbuf, 1, len, s->file) != len) {
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s->z_err = Z_ERRNO;
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return Z_ERRNO;
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}
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s->stream.next_out = s->outbuf;
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s->stream.avail_out = Z_BUFSIZE;
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}
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if (done) break;
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s->z_err = deflate(&(s->stream), flush);
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/* deflate has finished flushing only when it hasn't used up
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* all the available space in the output buffer:
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*/
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done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
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if (s->z_err != Z_OK && s->z_err != Z_STREAM_END) break;
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}
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fflush(s->file);
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return s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
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}
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/* ===========================================================================
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Outputs a long in LSB order to the given file
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*/
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local void putLong (file, x)
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FILE *file;
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uLong x;
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{
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int n;
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for (n = 0; n < 4; n++) {
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fputc((int)(x & 0xff), file);
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x >>= 8;
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}
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}
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/* ===========================================================================
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Reads a long in LSB order from the given gz_stream. Sets
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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 gzclose (file)
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gzFile file;
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{
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int err;
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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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if (s->mode == 'w') {
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err = gzflush (file, Z_FINISH);
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if (err != Z_OK) return destroy(file);
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putLong (s->file, s->crc);
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putLong (s->file, s->stream.total_in);
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}
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return destroy(file);
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}
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/* ===========================================================================
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Returns the error message for the last error which occured on the
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given compressed file. errnum is set to zlib error number. If an
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error occured in the file system and not in the compression library,
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errnum is set to Z_ERRNO and the application may consult errno
|
|
to get the exact error code.
|
|
*/
|
|
const char* gzerror (file, errnum)
|
|
gzFile file;
|
|
int *errnum;
|
|
{
|
|
char *m;
|
|
gz_stream *s = (gz_stream*)file;
|
|
|
|
if (s == NULL) {
|
|
*errnum = Z_STREAM_ERROR;
|
|
return (const char*)ERR_MSG(Z_STREAM_ERROR);
|
|
}
|
|
*errnum = s->z_err;
|
|
if (*errnum == Z_OK) return (const char*)"";
|
|
|
|
m = (char*)(*errnum == Z_ERRNO ? zstrerror(errno) : s->stream.msg);
|
|
|
|
if (m == NULL || *m == '\0') m = (char*)ERR_MSG(s->z_err);
|
|
|
|
TRYFREE(s->msg);
|
|
s->msg = (char*)ALLOC(strlen(s->path) + strlen(m) + 3);
|
|
strcpy(s->msg, s->path);
|
|
strcat(s->msg, ": ");
|
|
strcat(s->msg, m);
|
|
return (const char*)s->msg;
|
|
}
|