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/* gzlib.c -- zlib functions common to reading and writing gzip files
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* Copyright (C) 2004, 2010, 2011 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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#if defined(_WIN32) && !defined(__BORLANDC__)
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# define LSEEK _lseeki64
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#if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
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# define LSEEK lseek64
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local void gz_reset OF((gz_statep));
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local gzFile gz_open OF((const char *, int, const char *));
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/* Map the Windows error number in ERROR to a locale-dependent error message
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string and return a pointer to it. Typically, the values for ERROR come
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The string pointed to shall not be modified by the application, but may be
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overwritten by a subsequent call to gz_strwinerror
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The gz_strwinerror function does not change the current setting of
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char ZLIB_INTERNAL *gz_strwinerror (error)
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static char buf[1024];
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DWORD lasterr = GetLastError();
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DWORD chars = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM
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| FORMAT_MESSAGE_ALLOCATE_BUFFER,
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0, /* Default language */
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/* If there is an \r\n appended, zap it. */
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&& msgbuf[chars - 2] == '\r' && msgbuf[chars - 1] == '\n') {
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if (chars > sizeof (buf) - 1) {
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chars = sizeof (buf) - 1;
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wcstombs(buf, msgbuf, chars + 1);
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sprintf(buf, "unknown win32 error (%ld)", error);
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SetLastError(lasterr);
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/* Reset gzip file state */
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local void gz_reset(state)
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state->x.have = 0; /* no output data available */
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if (state->mode == GZ_READ) { /* for reading ... */
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state->eof = 0; /* not at end of file */
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state->past = 0; /* have not read past end yet */
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state->how = LOOK; /* look for gzip header */
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state->seek = 0; /* no seek request pending */
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gz_error(state, Z_OK, NULL); /* clear error */
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state->x.pos = 0; /* no uncompressed data yet */
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state->strm.avail_in = 0; /* no input data yet */
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/* Open a gzip file either by name or file descriptor. */
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local gzFile gz_open(path, fd, mode)
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/* allocate gzFile structure to return */
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state = malloc(sizeof(gz_state));
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state->size = 0; /* no buffers allocated yet */
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state->want = GZBUFSIZE; /* requested buffer size */
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state->msg = NULL; /* no error message yet */
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state->mode = GZ_NONE;
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state->level = Z_DEFAULT_COMPRESSION;
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state->strategy = Z_DEFAULT_STRATEGY;
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if (*mode >= '0' && *mode <= '9')
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state->level = *mode - '0';
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state->mode = GZ_READ;
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#ifndef NO_GZCOMPRESS
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state->mode = GZ_WRITE;
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state->mode = GZ_APPEND;
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case '+': /* can't read and write at the same time */
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case 'b': /* ignore -- will request binary anyway */
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state->strategy = Z_FILTERED;
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state->strategy = Z_HUFFMAN_ONLY;
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state->strategy = Z_RLE;
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state->strategy = Z_FIXED;
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default: /* could consider as an error, but just ignore */
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/* must provide an "r", "w", or "a" */
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if (state->mode == GZ_NONE) {
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/* can't force transparent read */
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if (state->mode == GZ_READ) {
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state->direct = 1; /* for empty file */
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/* save the path name for error messages */
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state->path = malloc(strlen(path) + 1);
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if (state->path == NULL) {
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strcpy(state->path, path);
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/* open the file with the appropriate mode (or just use fd) */
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state->fd = fd != -1 ? fd :
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(state->mode == GZ_READ ?
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(O_WRONLY | O_CREAT | (
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state->mode == GZ_WRITE ?
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if (state->fd == -1) {
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if (state->mode == GZ_APPEND)
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state->mode = GZ_WRITE; /* simplify later checks */
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/* save the current position for rewinding (only if reading) */
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if (state->mode == GZ_READ) {
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state->start = LSEEK(state->fd, 0, SEEK_CUR);
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if (state->start == -1) state->start = 0;
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/* initialize stream */
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return (gzFile)state;
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/* -- see zlib.h -- */
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gzFile ZEXPORT gzopen(path, mode)
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return gz_open(path, -1, mode);
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/* -- see zlib.h -- */
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gzFile ZEXPORT gzopen64(path, mode)
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return gz_open(path, -1, mode);
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/* -- see zlib.h -- */
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gzFile ZEXPORT gzdopen(fd, mode)
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char *path; /* identifier for error messages */
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if (fd == -1 || (path = malloc(7 + 3 * sizeof(int))) == NULL)
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sprintf(path, "<fd:%d>", fd); /* for debugging */
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gz = gz_open(path, fd, mode);
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/* -- see zlib.h -- */
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int ZEXPORT gzbuffer(file, size)
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/* get internal structure and check integrity */
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state = (gz_statep)file;
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if (state->mode != GZ_READ && state->mode != GZ_WRITE)
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/* make sure we haven't already allocated memory */
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if (state->size != 0)
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/* check and set requested size */
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size = 2; /* need two bytes to check magic header */
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/* -- see zlib.h -- */
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int ZEXPORT gzrewind(file)
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/* get internal structure */
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state = (gz_statep)file;
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/* check that we're reading and that there's no error */
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if (state->mode != GZ_READ ||
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(state->err != Z_OK && state->err != Z_BUF_ERROR))
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/* back up and start over */
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if (LSEEK(state->fd, state->start, SEEK_SET) == -1)
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/* -- see zlib.h -- */
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z_off64_t ZEXPORT gzseek64(file, offset, whence)
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/* get internal structure and check integrity */
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state = (gz_statep)file;
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if (state->mode != GZ_READ && state->mode != GZ_WRITE)
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/* check that there's no error */
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if (state->err != Z_OK && state->err != Z_BUF_ERROR)
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/* can only seek from start or relative to current position */
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if (whence != SEEK_SET && whence != SEEK_CUR)
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/* normalize offset to a SEEK_CUR specification */
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if (whence == SEEK_SET)
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offset -= state->x.pos;
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else if (state->seek)
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offset += state->skip;
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/* if within raw area while reading, just go there */
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if (state->mode == GZ_READ && state->how == COPY &&
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state->x.pos + offset >= 0) {
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ret = LSEEK(state->fd, offset - state->x.have, SEEK_CUR);
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gz_error(state, Z_OK, NULL);
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state->strm.avail_in = 0;
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state->x.pos += offset;
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/* calculate skip amount, rewinding if needed for back seek when reading */
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if (state->mode != GZ_READ) /* writing -- can't go backwards */
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offset += state->x.pos;
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if (offset < 0) /* before start of file! */
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if (gzrewind(file) == -1) /* rewind, then skip to offset */
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/* if reading, skip what's in output buffer (one less gzgetc() check) */
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if (state->mode == GZ_READ) {
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n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > offset ?
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(unsigned)offset : state->x.have;
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/* request skip (if not zero) */
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state->skip = offset;
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return state->x.pos + offset;
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/* -- see zlib.h -- */
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z_off_t ZEXPORT gzseek(file, offset, whence)
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ret = gzseek64(file, (z_off64_t)offset, whence);
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return ret == (z_off_t)ret ? (z_off_t)ret : -1;
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/* -- see zlib.h -- */
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z_off64_t ZEXPORT gztell64(file)
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/* get internal structure and check integrity */
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state = (gz_statep)file;
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if (state->mode != GZ_READ && state->mode != GZ_WRITE)
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/* return position */
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return state->x.pos + (state->seek ? state->skip : 0);
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/* -- see zlib.h -- */
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z_off_t ZEXPORT gztell(file)
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ret = gztell64(file);
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return ret == (z_off_t)ret ? (z_off_t)ret : -1;
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/* -- see zlib.h -- */
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z_off64_t ZEXPORT gzoffset64(file)
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/* get internal structure and check integrity */
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state = (gz_statep)file;
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if (state->mode != GZ_READ && state->mode != GZ_WRITE)
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/* compute and return effective offset in file */
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offset = LSEEK(state->fd, 0, SEEK_CUR);
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if (state->mode == GZ_READ) /* reading */
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offset -= state->strm.avail_in; /* don't count buffered input */
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/* -- see zlib.h -- */
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z_off_t ZEXPORT gzoffset(file)
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ret = gzoffset64(file);
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return ret == (z_off_t)ret ? (z_off_t)ret : -1;
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/* -- see zlib.h -- */
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int ZEXPORT gzeof(file)
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/* get internal structure and check integrity */
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state = (gz_statep)file;
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if (state->mode != GZ_READ && state->mode != GZ_WRITE)
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/* return end-of-file state */
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return state->mode == GZ_READ ? state->past : 0;
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/* -- see zlib.h -- */
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const char * ZEXPORT gzerror(file, errnum)
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/* get internal structure and check integrity */
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state = (gz_statep)file;
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if (state->mode != GZ_READ && state->mode != GZ_WRITE)
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/* return error information */
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*errnum = state->err;
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return state->msg == NULL ? "" : state->msg;
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/* -- see zlib.h -- */
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void ZEXPORT gzclearerr(file)
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/* get internal structure and check integrity */
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state = (gz_statep)file;
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if (state->mode != GZ_READ && state->mode != GZ_WRITE)
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/* clear error and end-of-file */
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if (state->mode == GZ_READ) {
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gz_error(state, Z_OK, NULL);
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/* Create an error message in allocated memory and set state->err and
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state->msg accordingly. Free any previous error message already there. Do
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not try to free or allocate space if the error is Z_MEM_ERROR (out of
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memory). Simply save the error message as a static string. If there is an
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allocation failure constructing the error message, then convert the error to
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void ZLIB_INTERNAL gz_error(state, err, msg)
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/* free previously allocated message and clear */
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if (state->msg != NULL) {
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if (state->err != Z_MEM_ERROR)
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/* if fatal, set state->x.have to 0 so that the gzgetc() macro fails */
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if (err != Z_OK && err != Z_BUF_ERROR)
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/* set error code, and if no message, then done */
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/* for an out of memory error, save as static string */
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if (err == Z_MEM_ERROR) {
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state->msg = (char *)msg;
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/* construct error message with path */
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if ((state->msg = malloc(strlen(state->path) + strlen(msg) + 3)) == NULL) {
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state->err = Z_MEM_ERROR;
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state->msg = (char *)"out of memory";
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strcpy(state->msg, state->path);
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strcat(state->msg, ": ");
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strcat(state->msg, msg);
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/* portably return maximum value for an int (when limits.h presumed not
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available) -- we need to do this to cover cases where 2's complement not
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used, since C standard permits 1's complement and sign-bit representations,
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otherwise we could just use ((unsigned)-1) >> 1 */
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unsigned ZLIB_INTERNAL gz_intmax()