cpython/Modules/zlib/gzlib.c at 3.3 · python/cpython · GitHub

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/* gzlib.c -- zlib functions common to reading and writing gzip files

* For conditions of distribution and use, see copyright notice in zlib.h

#include "gzguts.h"

#if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0

# define LSEEK lseek64

#else

# define LSEEK lseek

#endif

/* Local functions */

local void gz_reset OF((gz_statep));

local gzFile gz_open OF((const char *, int, const char *));

#if defined UNDER_CE

/* Map the Windows error number in ERROR to a locale-dependent error message

string and return a pointer to it. Typically, the values for ERROR come

from GetLastError.

The string pointed to shall not be modified by the application, but may be

overwritten by a subsequent call to gz_strwinerror

The gz_strwinerror function does not change the current setting of

GetLastError. */

char ZLIB_INTERNAL *gz_strwinerror (error)

DWORD error;

{

static char buf[1024];

wchar_t *msgbuf;

DWORD lasterr = GetLastError();

DWORD chars = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM

| FORMAT_MESSAGE_ALLOCATE_BUFFER,

NULL,

error,

0, /* Default language */

(LPVOID)&msgbuf,

NULL);

if (chars != 0) {

/* If there is an \r\n appended, zap it. */

if (chars >= 2

&& msgbuf[chars - 2] == '\r' && msgbuf[chars - 1] == '\n') {

chars -= 2;

msgbuf[chars] = 0;

}

if (chars > sizeof (buf) - 1) {

chars = sizeof (buf) - 1;

msgbuf[chars] = 0;

}

wcstombs(buf, msgbuf, chars + 1);

LocalFree(msgbuf);

}

else {

sprintf(buf, "unknown win32 error (%ld)", error);

}

SetLastError(lasterr);

return buf;

}

#endif /* UNDER_CE */

/* Reset gzip file state */

local void gz_reset(state)

gz_statep state;

{

if (state->mode == GZ_READ) { /* for reading ... */

state->have = 0; /* no output data available */

state->eof = 0; /* not at end of file */

state->how = LOOK; /* look for gzip header */

state->direct = 1; /* default for empty file */

}

state->seek = 0; /* no seek request pending */

gz_error(state, Z_OK, NULL); /* clear error */

state->pos = 0; /* no uncompressed data yet */

state->strm.avail_in = 0; /* no input data yet */

}

/* Open a gzip file either by name or file descriptor. */

local gzFile gz_open(path, fd, mode)

const char *path;

int fd;

const char *mode;

{

gz_statep state;

/* allocate gzFile structure to return */

state = malloc(sizeof(gz_state));

if (state == NULL)

return NULL;

state->size = 0; /* no buffers allocated yet */

state->want = GZBUFSIZE; /* requested buffer size */

state->msg = NULL; /* no error message yet */

/* interpret mode */

state->mode = GZ_NONE;

state->level = Z_DEFAULT_COMPRESSION;

state->strategy = Z_DEFAULT_STRATEGY;

while (*mode) {

if (*mode >= '0' && *mode <= '9')

state->level = *mode - '0';

else

switch (*mode) {

case 'r':

state->mode = GZ_READ;

break;

#ifndef NO_GZCOMPRESS

case 'w':

state->mode = GZ_WRITE;

break;

case 'a':

state->mode = GZ_APPEND;

break;

#endif

case '+': /* can't read and write at the same time */

free(state);

return NULL;

case 'b': /* ignore -- will request binary anyway */

break;

case 'f':

state->strategy = Z_FILTERED;

break;

case 'h':

state->strategy = Z_HUFFMAN_ONLY;

break;

case 'R':

state->strategy = Z_RLE;

break;

case 'F':

state->strategy = Z_FIXED;

default: /* could consider as an error, but just ignore */

;

}

mode++;

}

/* must provide an "r", "w", or "a" */

if (state->mode == GZ_NONE) {

free(state);

return NULL;

}

/* save the path name for error messages */

state->path = malloc(strlen(path) + 1);

if (state->path == NULL) {

free(state);

return NULL;

}

strcpy(state->path, path);

/* open the file with the appropriate mode (or just use fd) */

state->fd = fd != -1 ? fd :

open(path,

#ifdef O_LARGEFILE

O_LARGEFILE |

#endif

#ifdef O_BINARY

O_BINARY |

#endif

(state->mode == GZ_READ ?

O_RDONLY :

(O_WRONLY | O_CREAT | (

state->mode == GZ_WRITE ?

O_TRUNC :

O_APPEND))),

0666);

if (state->fd == -1) {

free(state->path);

free(state);

return NULL;

}

if (state->mode == GZ_APPEND)

state->mode = GZ_WRITE; /* simplify later checks */

/* save the current position for rewinding (only if reading) */

if (state->mode == GZ_READ) {

state->start = LSEEK(state->fd, 0, SEEK_CUR);

if (state->start == -1) state->start = 0;

}

/* initialize stream */

gz_reset(state);

/* return stream */

return (gzFile)state;

}

/* -- see zlib.h -- */

gzFile ZEXPORT gzopen(path, mode)

const char *path;

const char *mode;

{

return gz_open(path, -1, mode);

}

/* -- see zlib.h -- */

gzFile ZEXPORT gzopen64(path, mode)

const char *path;

const char *mode;

{

return gz_open(path, -1, mode);

}

/* -- see zlib.h -- */

gzFile ZEXPORT gzdopen(fd, mode)

int fd;

const char *mode;

{

char *path; /* identifier for error messages */

gzFile gz;

if (fd == -1 || (path = malloc(7 + 3 * sizeof(int))) == NULL)

return NULL;

sprintf(path, "<fd:%d>", fd); /* for debugging */

gz = gz_open(path, fd, mode);

free(path);

return gz;

}

/* -- see zlib.h -- */

int ZEXPORT gzbuffer(file, size)

gzFile file;

unsigned size;

{

gz_statep state;

/* get internal structure and check integrity */

if (file == NULL)

return -1;

state = (gz_statep)file;

if (state->mode != GZ_READ && state->mode != GZ_WRITE)

return -1;

/* make sure we haven't already allocated memory */

if (state->size != 0)

return -1;

/* check and set requested size */

if (size == 0)

return -1;

state->want = size;

return 0;

}

/* -- see zlib.h -- */

int ZEXPORT gzrewind(file)

gzFile file;

{

gz_statep state;

/* get internal structure */

if (file == NULL)

return -1;

state = (gz_statep)file;

/* check that we're reading and that there's no error */

if (state->mode != GZ_READ || state->err != Z_OK)

return -1;

/* back up and start over */

if (LSEEK(state->fd, state->start, SEEK_SET) == -1)

return -1;

gz_reset(state);

return 0;

}

/* -- see zlib.h -- */

z_off64_t ZEXPORT gzseek64(file, offset, whence)

gzFile file;

z_off64_t offset;

int whence;

{

unsigned n;

z_off64_t ret;

gz_statep state;

/* get internal structure and check integrity */

if (file == NULL)

return -1;

state = (gz_statep)file;

if (state->mode != GZ_READ && state->mode != GZ_WRITE)

return -1;

/* check that there's no error */

if (state->err != Z_OK)

return -1;

/* can only seek from start or relative to current position */

if (whence != SEEK_SET && whence != SEEK_CUR)

return -1;

/* normalize offset to a SEEK_CUR specification */

if (whence == SEEK_SET)

offset -= state->pos;

else if (state->seek)

offset += state->skip;

state->seek = 0;

/* if within raw area while reading, just go there */

if (state->mode == GZ_READ && state->how == COPY &&

state->pos + offset >= state->raw) {

ret = LSEEK(state->fd, offset - state->have, SEEK_CUR);

if (ret == -1)

return -1;

state->have = 0;

state->eof = 0;

state->seek = 0;

gz_error(state, Z_OK, NULL);

state->strm.avail_in = 0;

state->pos += offset;

return state->pos;

}

/* calculate skip amount, rewinding if needed for back seek when reading */

if (offset < 0) {

if (state->mode != GZ_READ) /* writing -- can't go backwards */

return -1;

offset += state->pos;

if (offset < 0) /* before start of file! */

return -1;

if (gzrewind(file) == -1) /* rewind, then skip to offset */

return -1;

}

/* if reading, skip what's in output buffer (one less gzgetc() check) */

if (state->mode == GZ_READ) {

n = GT_OFF(state->have) || (z_off64_t)state->have > offset ?

(unsigned)offset : state->have;

state->have -= n;

state->next += n;

state->pos += n;

offset -= n;

}

/* request skip (if not zero) */

if (offset) {

state->seek = 1;

state->skip = offset;

}

return state->pos + offset;

}

/* -- see zlib.h -- */

z_off_t ZEXPORT gzseek(file, offset, whence)

gzFile file;

z_off_t offset;

int whence;

{

z_off64_t ret;

ret = gzseek64(file, (z_off64_t)offset, whence);

return ret == (z_off_t)ret ? (z_off_t)ret : -1;

}

/* -- see zlib.h -- */

z_off64_t ZEXPORT gztell64(file)

gzFile file;

{

gz_statep state;

/* get internal structure and check integrity */

if (file == NULL)

return -1;

state = (gz_statep)file;

if (state->mode != GZ_READ && state->mode != GZ_WRITE)

return -1;

/* return position */

return state->pos + (state->seek ? state->skip : 0);

}

/* -- see zlib.h -- */

z_off_t ZEXPORT gztell(file)

gzFile file;

{

z_off64_t ret;

ret = gztell64(file);

return ret == (z_off_t)ret ? (z_off_t)ret : -1;

}

/* -- see zlib.h -- */

z_off64_t ZEXPORT gzoffset64(file)

gzFile file;

{

z_off64_t offset;

gz_statep state;

/* get internal structure and check integrity */

if (file == NULL)

return -1;

state = (gz_statep)file;

if (state->mode != GZ_READ && state->mode != GZ_WRITE)

return -1;

/* compute and return effective offset in file */

offset = LSEEK(state->fd, 0, SEEK_CUR);

if (offset == -1)

return -1;

if (state->mode == GZ_READ) /* reading */

offset -= state->strm.avail_in; /* don't count buffered input */

return offset;

}

/* -- see zlib.h -- */

z_off_t ZEXPORT gzoffset(file)

gzFile file;

{

z_off64_t ret;

ret = gzoffset64(file);

return ret == (z_off_t)ret ? (z_off_t)ret : -1;

}

/* -- see zlib.h -- */

int ZEXPORT gzeof(file)

gzFile file;

{

gz_statep state;

/* get internal structure and check integrity */

if (file == NULL)

return 0;

state = (gz_statep)file;

if (state->mode != GZ_READ && state->mode != GZ_WRITE)

return 0;

/* return end-of-file state */

return state->mode == GZ_READ ?

(state->eof && state->strm.avail_in == 0 && state->have == 0) : 0;

}

/* -- see zlib.h -- */

const char * ZEXPORT gzerror(file, errnum)

gzFile file;

int *errnum;

{

gz_statep state;

/* get internal structure and check integrity */

if (file == NULL)

return NULL;

state = (gz_statep)file;

if (state->mode != GZ_READ && state->mode != GZ_WRITE)

return NULL;

/* return error information */

if (errnum != NULL)

*errnum = state->err;

return state->msg == NULL ? "" : state->msg;

}

/* -- see zlib.h -- */

void ZEXPORT gzclearerr(file)

gzFile file;

{

gz_statep state;

/* get internal structure and check integrity */

if (file == NULL)

return;

state = (gz_statep)file;

if (state->mode != GZ_READ && state->mode != GZ_WRITE)

return;

/* clear error and end-of-file */

if (state->mode == GZ_READ)

state->eof = 0;

gz_error(state, Z_OK, NULL);

}

/* Create an error message in allocated memory and set state->err and

state->msg accordingly. Free any previous error message already there. Do

not try to free or allocate space if the error is Z_MEM_ERROR (out of

memory). Simply save the error message as a static string. If there is an

allocation failure constructing the error message, then convert the error to

out of memory. */

void ZLIB_INTERNAL gz_error(state, err, msg)

gz_statep state;

int err;

const char *msg;

{

/* free previously allocated message and clear */

if (state->msg != NULL) {

if (state->err != Z_MEM_ERROR)

free(state->msg);

state->msg = NULL;

}

/* set error code, and if no message, then done */

state->err = err;

if (msg == NULL)

return;

/* for an out of memory error, save as static string */

if (err == Z_MEM_ERROR) {

state->msg = (char *)msg;

return;

}

/* construct error message with path */

if ((state->msg = malloc(strlen(state->path) + strlen(msg) + 3)) == NULL) {

state->err = Z_MEM_ERROR;

state->msg = (char *)"out of memory";

return;

}

strcpy(state->msg, state->path);

strcat(state->msg, ": ");

strcat(state->msg, msg);

return;

}

#ifndef INT_MAX

/* portably return maximum value for an int (when limits.h presumed not

available) -- we need to do this to cover cases where 2's complement not

used, since C standard permits 1's complement and sign-bit representations,

otherwise we could just use ((unsigned)-1) >> 1 */

unsigned ZLIB_INTERNAL gz_intmax()

{

unsigned p, q;

p = 1;

do {

q = p;

p <<= 1;

p++;

} while (p > q);

return q >> 1;

}

#endif

cpython/Modules/zlib/gzlib.c at 3.3 · python/cpython · GitHub

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