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rpm/zlib/gzio.c

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/* gzio.c -- IO on .gz files
* Copyright (C) 1995-2003 Jean-loup Gailly.
* For conditions of distribution and use, see copyright notice in zlib.h
*
* Compile this file with -DNO_DEFLATE to avoid the compression code.
*/
/* @(#) $Id: gzio.c,v 1.11 2003/03/08 23:18:09 jbj Exp $ */
#include <stdio.h>
#include "zutil.h"
struct internal_state {int dummy;}; /* for buggy compilers */
#ifndef Z_BUFSIZE
# ifdef MAXSEG_64K
# define Z_BUFSIZE 4096 /* minimize memory usage for 16-bit DOS */
# else
# define Z_BUFSIZE 16384
# endif
#endif
#ifndef Z_PRINTF_BUFSIZE
# define Z_PRINTF_BUFSIZE 4096
#endif
#ifndef STDC
extern voidp malloc OF((uInt size));
extern void free OF((voidpf ptr));
#endif
#define ALLOC(size) malloc(size)
#define TRYFREE(p) {if (p) free(p);}
/*@observer@*/ /*@unchecked@*/
static int const gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
/* 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 */
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 */
/*@null@*/
FILE *file; /*!< .gz file */
/*@null@*/
Byte *inbuf; /*!< input buffer */
/*@null@*/
Byte *outbuf; /*!< output buffer */
uLong crc; /*!< crc32 of uncompressed data */
/*@null@*/
char *msg; /*!< error message */
/*@null@*/
char *path; /*!< path name for debugging only */
int transparent; /*!< 1 if input file is not a .gz file */
char mode; /*!< 'w' or 'r' */
long startpos; /*!< start of compressed data in file (header skipped) */
} gz_stream;
local gzFile gz_open OF((const char *path, const char *mode, int fd))
/*@globals errno, fileSystem, internalState @*/
/*@modifies errno, fileSystem, internalState @*/;
local int do_flush OF((gzFile file, int flush))
/*@globals fileSystem @*/
/*@modifies fileSystem @*/;
local int get_byte OF((gz_stream *s))
/*@globals errno, fileSystem @*/
/*@modifies s, errno, fileSystem @*/;
local void check_header OF((gz_stream *s))
/*@globals fileSystem @*/
/*@modifies s, fileSystem @*/;
local int destroy OF((gz_stream *s))
/*@globals fileSystem @*/
/*@modifies s, fileSystem @*/;
local void putLong OF((FILE *file, uLong x))
/*@globals fileSystem @*/
/*@modifies file, fileSystem @*/;
local uLong getLong OF((gz_stream *s))
/*@globals fileSystem @*/
/*@modifies s, fileSystem @*/;
/* ========================================================================= */
/**
* 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 descriptor
* 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 (const char * path, const char * mode, int fd)
{
int err;
int level = Z_DEFAULT_COMPRESSION; /* compression level */
int strategy = Z_DEFAULT_STRATEGY; /* compression strategy */
char *p = (char*)mode;
gz_stream *s;
char fmode[80]; /* copy of mode, without the compression level */
char *m = fmode;
if (!path || !mode) return Z_NULL;
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.opaque = (voidpf)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' || *p == 'a') s->mode = 'w';
if (*p >= '0' && *p <= '9') {
level = *p - '0';
} else if (*p == 'f') {
strategy = Z_FILTERED;
} else if (*p == 'h') {
strategy = Z_HUFFMAN_ONLY;
} else if (*p == 'R') {
strategy = Z_RLE;
} else {
*m++ = *p; /* copy the mode */
}
} while (*p++ && m != fmode + sizeof(fmode));
if (s->mode == '\0') return destroy(s), (gzFile)Z_NULL;
if (s->mode == 'w') {
#ifdef NO_DEFLATE
err = Z_STREAM_ERROR;
#else
err = deflateInit2(&(s->stream), level,
Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, strategy);
/* windowBits is passed < 0 to suppress zlib header */
s->stream.next_out = s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
#endif
if (err != Z_OK || s->outbuf == Z_NULL) {
return destroy(s), (gzFile)Z_NULL;
}
} else {
s->stream.next_in = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
err = inflateInit2(&(s->stream), -MAX_WBITS);
/* windowBits is passed < 0 to tell that there is no zlib header.
* Note that in this case inflate *requires* an extra "dummy" byte
* after the compressed stream in order to complete decompression and
* return Z_STREAM_END. Here the gzip CRC32 ensures that 4 bytes are
* present after the compressed stream.
*/
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 ? F_OPEN(path, fmode) : (FILE*)fdopen(fd, fmode);
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[0], gz_magic[1],
Z_DEFLATED, 0 /*flags*/, 0,0,0,0 /*time*/, 0 /*xflags*/, OS_CODE);
s->startpos = 10L;
/* We use 10L instead of ftell(s->file) to because ftell causes an
* fflush on some systems. This version of the library doesn't use
* startpos anyway in write mode, so this initialization is not
* necessary.
*/
} else {
check_header(s); /* skip the .gz header */
s->startpos = (ftell(s->file) - s->stream.avail_in);
}
return (gzFile)s;
}
/* ========================================================================= */
/**
* Opens a gzip (.gz) file for reading or writing.
*/
gzFile ZEXPORT gzopen (const char * path, const char * mode)
{
return gz_open (path, mode, -1);
}
/* ========================================================================= */
/**
* Associate a gzFile with the file descriptor fd. fd is not dup'ed here
* to mimic the behavio(u)r of fdopen.
*/
gzFile ZEXPORT gzdopen (int fd, const char * mode)
{
char name[20];
if (fd < 0) return (gzFile)Z_NULL;
sprintf(name, "<fd:%d>", fd); /* for debugging */
return gz_open (name, mode, fd);
}
/* ========================================================================= */
/**
* Update the compression level and strategy.
*/
int ZEXPORT gzsetparams (gzFile file, int level, int strategy)
{
gz_stream *s = (gz_stream*)file;
if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
/* Make room to allow flushing */
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;
}
s->stream.avail_out = Z_BUFSIZE;
}
return deflateParams (&(s->stream), level, strategy);
}
/* ========================================================================= */
/**
* Read a byte from a gz_stream; update next_in and avail_in. Return EOF
* for end of file.
* IN assertion: the stream s has been sucessfully opened for reading.
*/
local int get_byte(gz_stream * s)
{
if (s->z_eof) return EOF;
if (s->stream.avail_in == 0) {
errno = 0;
s->stream.avail_in = fread(s->inbuf, 1, Z_BUFSIZE, s->file);
if (s->stream.avail_in == 0) {
s->z_eof = 1;
if (ferror(s->file)) s->z_err = Z_ERRNO;
return EOF;
}
s->stream.next_in = s->inbuf;
}
s->stream.avail_in--;
return *(s->stream.next_in)++;
}
/* ========================================================================= */
/**
* Check the gzip header of a gz_stream opened for reading. Set the stream
* mode to transparent if the gzip magic header is not present; set s->err
* to Z_DATA_ERROR if the magic header is present but the rest of the header
* is incorrect.
* IN assertion: the stream s has already been created sucessfully;
* s->stream.avail_in is zero for the first time, but may be non-zero
* for concatenated .gz files.
*/
local void check_header(gz_stream * s)
{
int method; /* method byte */
int flags; /* flags byte */
uInt len;
int c;
/* Assure two bytes in the buffer so we can peek ahead -- handle case
where first byte of header is at the end of the buffer after the last
gzip segment */
len = s->stream.avail_in;
if (len < 2) {
if (len) s->inbuf[0] = s->stream.next_in[0];
errno = 0;
len = fread(s->inbuf + len, 1, Z_BUFSIZE >> len, s->file);
if (len == 0 && ferror(s->file)) s->z_err = Z_ERRNO;
s->stream.avail_in += len;
s->stream.next_in = s->inbuf;
if (s->stream.avail_in < 2) {
s->transparent = s->stream.avail_in;
return;
}
}
/* Peek ahead to check the gzip magic header */
if (s->stream.next_in[0] != gz_magic[0] ||
s->stream.next_in[1] != gz_magic[1]) {
s->transparent = 1;
return;
}
s->stream.avail_in -= 2;
s->stream.next_in += 2;
/* Check the rest of the gzip header */
method = get_byte(s);
flags = get_byte(s);
if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
s->z_err = Z_DATA_ERROR;
return;
}
/* Discard time, xflags and OS code: */
for (len = 0; len < 6; len++) (void)get_byte(s);
if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
len = (uInt)get_byte(s);
len += ((uInt)get_byte(s))<<8;
/* len is garbage if EOF but the loop below will quit anyway */
while (len-- != 0 && get_byte(s) != EOF) ;
}
if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
while ((c = get_byte(s)) != 0 && c != EOF) ;
}
if ((flags & COMMENT) != 0) { /* skip the .gz file comment */
while ((c = get_byte(s)) != 0 && c != EOF) ;
}
if ((flags & HEAD_CRC) != 0) { /* skip the header crc */
for (len = 0; len < 2; len++) (void)get_byte(s);
}
s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK;
}
/* ========================================================================= */
/**
* Cleanup then free the given gz_stream. Return a zlib error code.
* Try freeing in the reverse order of allocations.
*/
local int destroy (gz_stream * s)
{
int err = Z_OK;
if (!s) return Z_STREAM_ERROR;
TRYFREE(s->msg);
if (s->stream.state != NULL) {
if (s->mode == 'w') {
#ifdef NO_DEFLATE
err = Z_STREAM_ERROR;
#else
err = deflateEnd(&(s->stream));
#endif
} else if (s->mode == 'r') {
err = inflateEnd(&(s->stream));
}
}
if (s->file != NULL && fclose(s->file)) {
#ifdef ESPIPE
if (errno != ESPIPE) /* fclose is broken for pipes in HP/UX */
#endif
err = Z_ERRNO;
}
if (s->z_err < 0) err = s->z_err;
TRYFREE(s->inbuf);
TRYFREE(s->outbuf);
TRYFREE(s->path);
TRYFREE(s);
return err;
}
/* ========================================================================= */
/**
* 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 ZEXPORT gzread (gzFile file, voidp buf, unsigned len)
{
gz_stream *s = (gz_stream*)file;
Bytef *start = (Bytef*)buf; /* starting point for crc computation */
Byte *next_out; /* == stream.next_out but not forced far (for MSDOS) */
if (s == NULL || s->mode != 'r') return Z_STREAM_ERROR;
if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) return -1;
if (s->z_err == Z_STREAM_END) return 0; /* EOF */
next_out = (Byte*)buf;
s->stream.next_out = (Bytef*)buf;
s->stream.avail_out = len;
while (s->stream.avail_out != 0) {
if (s->transparent) {
/* Copy first the lookahead bytes: */
uInt n = s->stream.avail_in;
if (n > s->stream.avail_out) n = s->stream.avail_out;
if (n > 0) {
zmemcpy(s->stream.next_out, s->stream.next_in, n);
next_out += n;
s->stream.next_out = next_out;
s->stream.next_in += n;
s->stream.avail_out -= n;
s->stream.avail_in -= n;
}
if (s->stream.avail_out > 0) {
s->stream.avail_out -= fread(next_out, 1, s->stream.avail_out,
s->file);
}
len -= s->stream.avail_out;
s->stream.total_in += (uLong)len;
s->stream.total_out += (uLong)len;
if (len == 0) s->z_eof = 1;
return (int)len;
}
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;
if (ferror(s->file)) {
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) {
/* Check CRC and original size */
s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
start = s->stream.next_out;
if (getLong(s) != s->crc) {
s->z_err = Z_DATA_ERROR;
} else {
(void)getLong(s);
/* The uncompressed length returned by above getlong() may
* be different from s->stream.total_out) in case of
* concatenated .gz files. Check for such files:
*/
check_header(s);
if (s->z_err == Z_OK) {
uLong total_in = s->stream.total_in;
uLong total_out = s->stream.total_out;
inflateReset(&(s->stream));
s->stream.total_in = total_in;
s->stream.total_out = total_out;
s->crc = crc32(0L, Z_NULL, 0);
}
}
}
if (s->z_err != Z_OK || s->z_eof) break;
}
s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
return (int)(len - s->stream.avail_out);
}
/* ========================================================================= */
/**
* Reads one byte from the compressed file. gzgetc returns this byte
* or -1 in case of end of file or error.
*/
int ZEXPORT gzgetc(gzFile file)
{
unsigned char c;
return gzread(file, &c, 1) == 1 ? c : -1;
}
/* ========================================================================= */
/**
* Reads bytes from the compressed file until len-1 characters are
* read, or a newline character is read and transferred to buf, or an
* end-of-file condition is encountered. The string is then terminated
* with a null character.
* gzgets returns buf, or Z_NULL in case of error.
*
* The current implementation is not optimized at all.
*/
char * ZEXPORT gzgets(gzFile file, char * buf, int len)
{
char *b = buf;
if (buf == Z_NULL || len <= 0) return Z_NULL;
while (--len > 0 && gzread(file, buf, 1) == 1 && *buf++ != '\n') ;
*buf = '\0';
return b == buf && len > 0 ? Z_NULL : b;
}
#ifndef NO_DEFLATE
/* ========================================================================= */
/**
* 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 ZEXPORT gzwrite (gzFile file, voidpc buf, unsigned len)
{
gz_stream *s = (gz_stream*)file;
if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
s->stream.next_in = (Bytef*)buf;
s->stream.avail_in = len;
/*@-infloops@*/
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;
}
/*@=infloops@*/
s->crc = crc32(s->crc, (const Bytef *)buf, len);
return (int)(len - s->stream.avail_in);
}
/* ========================================================================= */
/**
* Converts, formats, and writes the args to the compressed file under
* control of the format string, as in fprintf. gzprintf returns the number of
* uncompressed bytes actually written (0 in case of error).
*/
#ifdef STDC
#include <stdarg.h>
int ZEXPORTVA gzprintf (gzFile file, const char *format, /* args */ ...)
{
char buf[Z_PRINTF_BUFSIZE];
va_list va;
int len;
va_start(va, format);
#ifdef NO_vsnprintf
# ifdef HAS_vsprintf_void
(void)vsprintf(buf, format, va);
va_end(va);
len = strlen(buf); /* some *sprintf don't return the nb of bytes written */
if (len <= 0) return 0;
# else
len = vsprintf(buf, format, va);
va_end(va);
if (len <= 0 || len >= sizeof(buf))
return 0;
# endif
#else
# ifdef HAS_vsnprintf_void
(void)vsnprintf(buf, sizeof(buf), format, va);
va_end(va);
len = strlen(buf);
if (len <= 0)
return 0;
# else
len = vsnprintf(buf, sizeof(buf), format, va);
va_end(va);
if (len <= 0 || len >= sizeof(buf))
return 0;
# endif
#endif
return gzwrite(file, buf, (unsigned)len);
}
#else /* not ANSI C */
int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
gzFile file;
const char *format;
int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
a11, a12, a13, a14, a15, a16, a17, a18, a19, a20;
{
char buf[Z_PRINTF_BUFSIZE];
int len;
#ifdef NO_snprintf
# ifdef HAS_sprintf_void
sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
len = strlen(buf); /* old sprintf doesn't return the nb of bytes written */
if (len <= 0) return 0;
# else
len = sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
if (len <= 0 || len >= sizeof(buf))
return 0;
# endif
#else
# ifdef HAS_snprintf_void
snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
len = strlen(buf);
if (len <= 0)
return 0;
#else
len = snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
if (len <= 0 || len >= sizeof(buf))
return 0;
# endif
#endif
return gzwrite(file, buf, len);
}
#endif
/* ========================================================================= */
/**
* Writes c, converted to an unsigned char, into the compressed file.
* gzputc returns the value that was written, or -1 in case of error.
*/
int ZEXPORT gzputc(gzFile file, int c)
{
unsigned char cc = (unsigned char) c; /* required for big endian systems */
return gzwrite(file, &cc, 1) == 1 ? (int)cc : -1;
}
/* ========================================================================= */
/**
* Writes the given null-terminated string to the compressed file, excluding
* the terminating null character.
* gzputs returns the number of characters written, or -1 in case of error.
*/
int ZEXPORT gzputs(gzFile file, const char * s)
{
return gzwrite(file, (char*)s, (unsigned)strlen(s));
}
/* ========================================================================= */
/**
* Flushes all pending output into the compressed file. The parameter
* flush is as in the deflate() function.
*/
local int do_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 ((uInt)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);
/* Ignore the second of two consecutive flushes: */
if (len == 0 && s->z_err == Z_BUF_ERROR) s->z_err = Z_OK;
/* 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;
}
return s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
}
int ZEXPORT gzflush (gzFile file, int flush)
{
gz_stream *s = (gz_stream*)file;
int err = do_flush (file, flush);
if (err) return err;
fflush(s->file);
return s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
}
#endif /* NO_DEFLATE */
/* ========================================================================= */
/**
* Sets the starting position for the next gzread or gzwrite on the given
* compressed file. The offset represents a number of bytes in the
* gzseek returns the resulting offset location as measured in bytes from
* the beginning of the uncompressed stream, or -1 in case of error.
* SEEK_END is not implemented, returns error.
* In this version of the library, gzseek can be extremely slow.
*/
z_off_t ZEXPORT gzseek (gzFile file, z_off_t offset, int whence)
{
gz_stream *s = (gz_stream*)file;
if (s == NULL || whence == SEEK_END ||
s->z_err == Z_ERRNO || s->z_err == Z_DATA_ERROR) {
return -1L;
}
if (s->mode == 'w') {
#ifdef NO_DEFLATE
return -1L;
#else
if (whence == SEEK_SET) {
offset -= s->stream.total_in;
}
if (offset < 0) return -1L;
/* At this point, offset is the number of zero bytes to write. */
if (s->inbuf == Z_NULL) {
s->inbuf = (Byte*)ALLOC(Z_BUFSIZE); /* for seeking */
if (s->inbuf == Z_NULL) return -1L;
zmemzero(s->inbuf, Z_BUFSIZE);
}
while (offset > 0) {
uInt size = Z_BUFSIZE;
if (offset < Z_BUFSIZE) size = (uInt)offset;
size = gzwrite(file, s->inbuf, size);
if (size == 0) return -1L;
offset -= size;
}
return (z_off_t)s->stream.total_in;
#endif
}
/* Rest of function is for reading only */
/* compute absolute position */
if (whence == SEEK_CUR) {
offset += s->stream.total_out;
}
if (offset < 0) return -1L;
if (s->transparent) {
/* map to fseek */
s->stream.avail_in = 0;
s->stream.next_in = s->inbuf;
if (fseek(s->file, offset, SEEK_SET) < 0) return -1L;
s->stream.total_in = s->stream.total_out = (uLong)offset;
return offset;
}
/* For a negative seek, rewind and use positive seek */
if ((uLong)offset >= s->stream.total_out) {
offset -= s->stream.total_out;
} else if (gzrewind(file) < 0) {
return -1L;
}
/* offset is now the number of bytes to skip. */
if (offset != 0 && s->outbuf == Z_NULL) {
s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
if (s->outbuf == Z_NULL) return -1L;
}
while (offset > 0) {
int size = Z_BUFSIZE;
if (offset < Z_BUFSIZE) size = (int)offset;
size = gzread(file, s->outbuf, (uInt)size);
if (size <= 0) return -1L;
offset -= size;
}
return (z_off_t)s->stream.total_out;
}
/* ========================================================================= */
/**
* Rewinds input file.
*/
int ZEXPORT gzrewind (gzFile file)
{
gz_stream *s = (gz_stream*)file;
if (s == NULL || s->mode != 'r') return -1;
s->z_err = Z_OK;
s->z_eof = 0;
s->stream.avail_in = 0;
s->stream.next_in = s->inbuf;
s->crc = crc32(0L, Z_NULL, 0);
if (s->startpos == 0) { /* not a compressed file */
rewind(s->file);
return 0;
}
(void) inflateReset(&s->stream);
return fseek(s->file, s->startpos, SEEK_SET);
}
/* ========================================================================= */
/**
* Returns the starting position for the next gzread or gzwrite on the
* given compressed file. This position represents a number of bytes in the
* uncompressed data stream.
*/
z_off_t ZEXPORT gztell (gzFile file)
{
return gzseek(file, 0L, SEEK_CUR);
}
/* ========================================================================= */
/**
* Returns 1 when EOF has previously been detected reading the given
* input stream, otherwise zero.
*/
int ZEXPORT gzeof (gzFile file)
{
gz_stream *s = (gz_stream*)file;
return (s == NULL || s->mode != 'r') ? 0 : s->z_eof;
}
/* ========================================================================= */
/**
* Outputs a long in LSB order to the given file
*/
local void putLong (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 gz_stream. Sets z_err in case
* of error.
*/
local uLong getLong (gz_stream * s)
{
uLong x = (uLong)get_byte(s);
int c;
x += ((uLong)get_byte(s))<<8;
x += ((uLong)get_byte(s))<<16;
c = get_byte(s);
if (c == EOF) s->z_err = Z_DATA_ERROR;
x += ((uLong)c)<<24;
return x;
}
/* ========================================================================= */
/**
* Flushes all pending output if necessary, closes the compressed file
* and deallocates all the (de)compression state.
*/
int ZEXPORT gzclose (gzFile file)
{
int err;
gz_stream *s = (gz_stream*)file;
if (s == NULL) return Z_STREAM_ERROR;
if (s->mode == 'w') {
#ifdef NO_DEFLATE
return Z_STREAM_ERROR;
#else
err = do_flush (file, Z_FINISH);
if (err != Z_OK) return destroy((gz_stream*)file);
putLong (s->file, s->crc);
putLong (s->file, s->stream.total_in);
#endif
}
return destroy((gz_stream*)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.
*/
const char* ZEXPORT gzerror (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);
if (s->msg == Z_NULL) return (const char*)ERR_MSG(Z_MEM_ERROR);
strcpy(s->msg, s->path);
strcat(s->msg, ": ");
strcat(s->msg, m);
return (const char*)s->msg;
}
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