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zlib/gzio.c

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/* gzio.c -- IO on .gz files
* Copyright (C) 1995 Jean-loup Gailly.
* For conditions of distribution and use, see copyright notice in zlib.h
*/
/* $Id: gzio.c,v 1.8 1995/05/03 17:27:09 jloup Exp $ */
#include <stdio.h>
#include "zutil.h"
struct internal_state {int dummy;}; /* for buggy compilers */
#define Z_BUFSIZE 4096
#define ALLOC(size) malloc(size)
#define TRYFREE(p) {if (p) free(p);}
#define GZ_MAGIC_1 0x1f
#define GZ_MAGIC_2 0x8b
/* gzip flag byte */
#define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
#define HEAD_CRC 0x02 /* bit 1 set: header CRC present */
#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 RESERVED 0xE0 /* bits 5..7: reserved */
#ifndef SEEK_CUR
# define SEEK_CUR 1
#endif
typedef struct gz_stream {
z_stream stream;
int z_err; /* error code for last stream operation */
int z_eof; /* set if end of input file */
FILE *file; /* .gz file */
Byte *inbuf; /* input buffer */
Byte *outbuf; /* output buffer */
uLong crc; /* crc32 of uncompressed data */
char *msg; /* error message */
char *path; /* path name for debugging only */
int transparent; /* 1 if input file is not a .gz file */
char mode; /* 'w' or 'r' */
} gz_stream;
local int destroy OF((gz_stream *s));
local gzFile gz_open OF((char *path, char *mode, int fd));
local void putLong OF((FILE *file, uLong x));
local uLong getLong OF((Bytef *buf));
/* ===========================================================================
* Cleanup then free the given gz_stream. Return a zlib error code.
*/
local int destroy (s)
gz_stream *s;
{
int err = Z_OK;
if (!s) return Z_STREAM_ERROR;
TRYFREE(s->inbuf);
TRYFREE(s->outbuf);
TRYFREE(s->path);
TRYFREE(s->msg);
if (s->stream.state != NULL) {
if (s->mode == 'w') {
err = deflateEnd(&(s->stream));
} else if (s->mode == 'r') {
err = inflateEnd(&(s->stream));
}
}
if (s->file != NULL && fclose(s->file)) {
err = Z_ERRNO;
}
if (s->z_err < 0) err = s->z_err;
TRYFREE(s);
return err;
}
/* ===========================================================================
Opens a gzip (.gz) file for reading or writing. The mode parameter
is as in fopen ("rb" or "wb"). The file is given either by file descritor
or path name (if fd == -1).
gz_open return NULL if the file could not be opened or if there was
insufficient memory to allocate the (de)compression state; errno
can be checked to distinguish the two cases (if errno is zero, the
zlib error is Z_MEM_ERROR).
*/
local gzFile gz_open (path, mode, fd)
char *path;
char *mode;
int fd;
{
int err;
int level = Z_DEFAULT_COMPRESSION; /* compression level */
char *p = mode;
gz_stream *s = (gz_stream *)ALLOC(sizeof(gz_stream));
if (!s) return Z_NULL;
s->stream.zalloc = (alloc_func)0;
s->stream.zfree = (free_func)0;
s->stream.next_in = s->inbuf = Z_NULL;
s->stream.next_out = s->outbuf = Z_NULL;
s->stream.avail_in = s->stream.avail_out = 0;
s->file = NULL;
s->z_err = Z_OK;
s->z_eof = 0;
s->crc = crc32(0L, Z_NULL, 0);
s->msg = NULL;
s->transparent = 0;
s->path = (char*)ALLOC(strlen(path)+1);
if (s->path == NULL) {
return destroy(s), (gzFile)Z_NULL;
}
strcpy(s->path, path); /* do this early for debugging */
s->mode = '\0';
do {
if (*p == 'r') s->mode = 'r';
if (*p == 'w') s->mode = 'w';
if (*p >= '1' && *p <= '9') level = *p - '0';
} while (*p++);
if (s->mode == '\0') return destroy(s), (gzFile)Z_NULL;
if (s->mode == 'w') {
err = deflateInit2(&(s->stream), level,
DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, 0);
/* windowBits is passed < 0 to suppress zlib header */
s->stream.next_out = s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
if (err != Z_OK || s->outbuf == Z_NULL) {
return destroy(s), (gzFile)Z_NULL;
}
} else {
err = inflateInit2(&(s->stream), -MAX_WBITS);
s->stream.next_in = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
if (err != Z_OK || s->inbuf == Z_NULL) {
return destroy(s), (gzFile)Z_NULL;
}
}
s->stream.avail_out = Z_BUFSIZE;
errno = 0;
s->file = fd < 0 ? FOPEN(path, mode) : fdopen(fd, mode);
if (s->file == NULL) {
return destroy(s), (gzFile)Z_NULL;
}
if (s->mode == 'w') {
/* Write a very simple .gz header:
*/
fprintf(s->file, "%c%c%c%c%c%c%c%c%c%c", GZ_MAGIC_1, GZ_MAGIC_2,
DEFLATED, 0 /*flags*/, 0,0,0,0 /*time*/, 0 /*xflags*/, OS_CODE);
} else {
/* Check and skip the header:
*/
Byte c1 = 0, c2 = 0;
Byte method = 0;
Byte flags = 0;
Byte xflags = 0;
Byte time[4];
Byte osCode;
int c;
s->stream.avail_in = fread(s->inbuf, 1, 2, s->file);
if (s->stream.avail_in != 2 || s->inbuf[0] != GZ_MAGIC_1
|| s->inbuf[1] != GZ_MAGIC_2) {
s->transparent = 1;
return (gzFile)s;
}
s->stream.avail_in = 0;
fscanf(s->file,"%c%c%4c%c%c", &method, &flags, time, &xflags, &osCode);
if (method != DEFLATED || feof(s->file) || (flags & RESERVED) != 0) {
s->z_err = Z_DATA_ERROR;
return (gzFile)s;
}
if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
long len;
fscanf(s->file, "%c%c", &c1, &c2);
len = c1 + ((long)c2<<8);
fseek(s->file, len, SEEK_CUR);
}
if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
while ((c = getc(s->file)) != 0 && c != EOF) ;
}
if ((flags & COMMENT) != 0) { /* skip the .gz file comment */
while ((c = getc(s->file)) != 0 && c != EOF) ;
}
if ((flags & HEAD_CRC) != 0) { /* skip the header crc */
fscanf(s->file, "%c%c", &c1, &c2);
}
if (feof(s->file)) {
s->z_err = Z_DATA_ERROR;
}
}
return (gzFile)s;
}
/* ===========================================================================
Opens a gzip (.gz) file for reading or writing.
*/
gzFile gzopen (path, mode)
char *path;
char *mode;
{
return gz_open (path, mode, -1);
}
/* ===========================================================================
Associate a gzFile with the file descriptor fd.
*/
gzFile gzdopen (fd, mode)
int fd;
char *mode;
{
char name[20];
sprintf(name, "<fd:%d>", fd); /* for debugging */
return gz_open (name, mode, fd);
}
/* ===========================================================================
Reads the given number of uncompressed bytes from the compressed file.
gzread returns the number of bytes actually read (0 for end of file).
*/
int gzread (file, buf, len)
gzFile file;
voidp buf;
unsigned len;
{
gz_stream *s = (gz_stream*)file;
if (s == NULL || s->mode != 'r') return Z_STREAM_ERROR;
if (s->transparent) {
int n = 0;
Byte *b = (Byte*)buf;
/* Copy the first two (non-magic) bytes if not done already */
while (s->stream.avail_in > 0 && len > 0) {
*b++ = *s->stream.next_in++;
s->stream.avail_in--;
len--; n++;
}
if (len == 0) return n;
return n + fread(b, 1, len, s->file);
}
if (s->z_err == Z_DATA_ERROR) return -1; /* bad .gz file */
if (s->z_err == Z_STREAM_END) return 0; /* don't read crc as data */
s->stream.next_out = buf;
s->stream.avail_out = len;
while (s->stream.avail_out != 0) {
if (s->stream.avail_in == 0 && !s->z_eof) {
errno = 0;
s->stream.avail_in =
fread(s->inbuf, 1, Z_BUFSIZE, s->file);
if (s->stream.avail_in == 0) {
s->z_eof = 1;
} else if (s->stream.avail_in == (uInt)EOF) {
s->stream.avail_in = 0;
s->z_eof = 1;
s->z_err = Z_ERRNO;
break;
}
s->stream.next_in = s->inbuf;
}
s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
if (s->z_err == Z_STREAM_END ||
s->z_err != Z_OK || s->z_eof) break;
}
len -= s->stream.avail_out;
s->crc = crc32(s->crc, buf, len);
return (int)len;
}
/* ===========================================================================
Writes the given number of uncompressed bytes into the compressed file.
gzwrite returns the number of bytes actually written (0 in case of error).
*/
int gzwrite (file, buf, len)
gzFile file;
voidp buf;
unsigned len;
{
gz_stream *s = (gz_stream*)file;
if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
s->stream.next_in = buf;
s->stream.avail_in = len;
while (s->stream.avail_in != 0) {
if (s->stream.avail_out == 0) {
s->stream.next_out = s->outbuf;
if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
s->z_err = Z_ERRNO;
break;
}
s->stream.avail_out = Z_BUFSIZE;
}
s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
if (s->z_err != Z_OK) break;
}
s->crc = crc32(s->crc, buf, len);
return (int)(len - s->stream.avail_in);
}
/* ===========================================================================
Flushes all pending output into the compressed file. The parameter
flush is as in the deflate() function.
gzflush should be called only when strictly necessary because it can
degrade compression.
*/
int gzflush (file, flush)
gzFile file;
int flush;
{
uInt len;
int done = 0;
gz_stream *s = (gz_stream*)file;
if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
s->stream.avail_in = 0; /* should be zero already anyway */
for (;;) {
len = Z_BUFSIZE - s->stream.avail_out;
if (len != 0) {
if (fwrite(s->outbuf, 1, len, s->file) != len) {
s->z_err = Z_ERRNO;
return Z_ERRNO;
}
s->stream.next_out = s->outbuf;
s->stream.avail_out = Z_BUFSIZE;
}
if (done) break;
s->z_err = deflate(&(s->stream), flush);
/* deflate has finished flushing only when it hasn't used up
* all the available space in the output buffer:
*/
done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
if (s->z_err != Z_OK && s->z_err != Z_STREAM_END) break;
}
fflush(s->file);
return s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
}
/* ===========================================================================
Outputs a long in LSB order to the given file
*/
local void putLong (file, x)
FILE *file;
uLong x;
{
int n;
for (n = 0; n < 4; n++) {
fputc((int)(x & 0xff), file);
x >>= 8;
}
}
/* ===========================================================================
Reads a long in LSB order from the given buffer
*/
local uLong getLong (buf)
Bytef *buf;
{
uLong x = 0;
Bytef *p = buf+4;
do {
x <<= 8;
x |= *--p;
} while (p != buf);
return x;
}
/* ===========================================================================
Flushes all pending output if necessary, closes the compressed file
and deallocates all the (de)compression state.
*/
int gzclose (file)
gzFile file;
{
uInt n;
int err;
gz_stream *s = (gz_stream*)file;
if (s == NULL) return Z_STREAM_ERROR;
if (s->mode == 'w') {
err = gzflush (file, Z_FINISH);
if (err != Z_OK) return destroy(file);
putLong (s->file, s->crc);
putLong (s->file, s->stream.total_in);
} else if (s->mode == 'r' && s->z_err == Z_STREAM_END) {
/* slide CRC and original size if they are at the end of inbuf */
if ((n = s->stream.avail_in) < 8 && !s->z_eof) {
Byte *p = s->inbuf;
Bytef *q = s->stream.next_in;
while (n--) { *p++ = *q++; };
n = s->stream.avail_in;
n += fread(p, 1, 8, s->file);
s->stream.next_in = s->inbuf;
}
/* check CRC and original size */
if (n < 8 ||
getLong(s->stream.next_in) != s->crc ||
getLong(s->stream.next_in + 4) != s->stream.total_out) {
s->z_err = Z_DATA_ERROR;
}
}
return destroy(file);
}
/* ===========================================================================
Returns the error message for the last error which occured on the
given compressed file. errnum is set to zlib error number. If an
error occured 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.
*/
char* gzerror (file, errnum)
gzFile file;
int *errnum;
{
char *m;
gz_stream *s = (gz_stream*)file;
if (s == NULL) {
*errnum = Z_STREAM_ERROR;
return z_errmsg[1-Z_STREAM_ERROR];
}
*errnum = s->z_err;
if (*errnum == Z_OK) return "";
m = *errnum == Z_ERRNO ? zstrerror(errno) : s->stream.msg;
if (m == NULL || *m == '\0') m = z_errmsg[1-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 s->msg;
}
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