static int gz_decomp(gz_statep);
static int gz_fetch(gz_statep);
static int gz_skip(gz_statep, z_off64_t);
+static size_t gz_read(gz_statep, void *, size_t);
/* Use read() to load a buffer -- return -1 on error, otherwise 0. Read from
state->fd, and update state->eof, state->err, and state->msg as appropriate.
return 0;
}
-/* -- see zlib.h -- */
-int ZEXPORT gzread(gzFile file, void *buf, unsigned len) {
- unsigned got, n;
- gz_statep state;
- z_stream *strm;
-
- /* get internal structure */
- if (file == NULL)
- return -1;
- state = (gz_statep)file;
- strm = &(state->strm);
-
- /* check that we're reading and that there's no (serious) error */
- if (state->mode != GZ_READ || (state->err != Z_OK && state->err != Z_BUF_ERROR))
- return -1;
-
- /* since an int is returned, make sure len fits in one, otherwise return
- with an error (this avoids the flaw in the interface) */
- if ((int)len < 0) {
- gz_error(state, Z_DATA_ERROR, "requested length does not fit in int");
- return -1;
- }
+/* Read len bytes into buf from file, or less than len up to the end of the
+ input. Return the number of bytes read. If zero is returned, either the
+ end of file was reached, or there was an error. state->err must be
+ consulted in that case to determine which. */
+static size_t gz_read(gz_statep state, void *buf, size_t len) {
+ size_t got;
+ unsigned n;
/* if len is zero, avoid unnecessary operations */
if (len == 0)
if (state->seek) {
state->seek = 0;
if (gz_skip(state, state->skip) == -1)
- return -1;
+ return 0;
}
/* get len bytes to buf, or less than len if at the end */
got = 0;
do {
+ /* set n to the maximum amount of len that fits in an unsigned int */
+ n = -1;
+ if (n > len)
+ n = len;
+
/* first just try copying data from the output buffer */
if (state->x.have) {
- n = state->x.have > len ? len : state->x.have;
+ if (state->x.have < n)
+ n = state->x.have;
memcpy(buf, state->x.next, n);
state->x.next += n;
state->x.have -= n;
- } else if (state->eof && strm->avail_in == 0) {
- /* output buffer empty -- return if we're at the end of the input */
+ }
+
+ /* output buffer empty -- return if we're at the end of the input */
+ else if (state->eof && state->strm.avail_in == 0) {
state->past = 1; /* tried to read past end */
break;
- } else if (state->how == LOOK || len < (state->size << 1)) {
- /* need output data -- for small len or new stream load up our output buffer */
+ }
+
+ /* need output data -- for small len or new stream load up our output
+ buffer */
+ else if (state->how == LOOK || n < (state->size << 1)) {
/* get more output, looking for header if required */
if (gz_fetch(state) == -1)
- return -1;
+ return 0;
continue; /* no progress yet -- go back to copy above */
/* the copy above assures that we will leave with space in the
output buffer, allowing at least one gzungetc() to succeed */
- } else if (state->how == COPY) { /* read directly */
- /* large len -- read directly into user buffer */
- if (gz_load(state, (unsigned char *)buf, len, &n) == -1)
- return -1;
- } else { /* state->how == GZIP */
- /* large len -- decompress directly into user buffer */
- strm->avail_out = len;
- strm->next_out = (unsigned char *)buf;
+ }
+
+ /* large len -- read directly into user buffer */
+ else if (state->how == COPY) { /* read directly */
+ if (gz_load(state, (unsigned char *)buf, n, &n) == -1)
+ return 0;
+ }
+
+ /* large len -- decompress directly into user buffer */
+ else { /* state->how == GZIP */
+ state->strm.avail_out = n;
+ state->strm.next_out = (unsigned char *)buf;
if (gz_decomp(state) == -1)
- return -1;
+ return 0;
n = state->x.have;
state->x.have = 0;
}
state->x.pos += n;
} while (len);
- /* return number of bytes read into user buffer (will fit in int) */
- return (int)got;
+ /* return number of bytes read into user buffer */
+ return got;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzread(gzFile file, void *buf, unsigned len) {
+ 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 (serious) error */
+ if (state->mode != GZ_READ ||
+ (state->err != Z_OK && state->err != Z_BUF_ERROR))
+ return -1;
+
+ /* since an int is returned, make sure len fits in one, otherwise return
+ with an error (this avoids a flaw in the interface) */
+ if ((int)len < 0) {
+ gz_error(state, Z_STREAM_ERROR, "request does not fit in an int");
+ return -1;
+ }
+
+ /* read len or fewer bytes to buf */
+ len = gz_read(state, buf, len);
+
+ /* check for an error */
+ if (len == 0 && state->err != Z_OK && state->err != Z_BUF_ERROR)
+ return -1;
+
+ /* return the number of bytes read (this is assured to fit in an int) */
+ return (int)len;
+}
+
+/* -- see zlib.h -- */
+size_t ZEXPORT gzfread(void *buf, size_t size, size_t nitems, gzFile file) {
+ size_t len;
+ gz_statep state;
+
+ /* get internal structure */
+ if (file == NULL)
+ return 0;
+ state = (gz_statep)file;
+
+ /* check that we're reading and that there's no (serious) error */
+ if (state->mode != GZ_READ ||
+ (state->err != Z_OK && state->err != Z_BUF_ERROR))
+ return 0;
+
+ /* compute bytes to read -- error on overflow */
+ len = nitems * size;
+ if (size && len / size != nitems) {
+ gz_error(state, Z_STREAM_ERROR, "request does not fit in a size_t");
+ return 0;
+ }
+
+ /* read len or fewer bytes to buf, return the number of full items read */
+ return len ? gz_read(state, buf, len) / size : 0;
}
/* -- see zlib.h -- */
return *(state->x.next)++;
}
- /* nothing there -- try gzread() */
- ret = gzread(file, buf, 1);
+ /* nothing there -- try gz_read() */
+ ret = gz_read(state, buf, 1);
return ret < 1 ? -1 : buf[0];
}
case.
gzread returns the number of uncompressed bytes actually read, less than
- len for end of file, or -1 for error.
+ len for end of file, or -1 for error. If len is too large to fit in an int,
+ then nothing is read, -1 is returned, and the error state is set to
+ Z_STREAM_ERROR.
+*/
+
+ZEXTERN size_t ZEXPORT gzfread (void *buf, size_t size, size_t nitems, gzFile file);
+/*
+ Read up to nitems items of size size from file to buf, otherwise operating
+ as gzread() does. This duplicates the interface of stdio's fread(), with
+ size_t request and return types.
+
+ gzfread() returns the number of full items read of size size, or zero if
+ the end of the file was reached and a full item could not be read, or if
+ there was an error. gzerror() must be consulted if zero is returned in
+ order to determine if there was an error. If the multiplication of size and
+ nitems overflows, i.e. the product does not fit in a size_t, then nothing
+ is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
+
+ In the event that the end of file is reached and only a partial item is
+ available at the end, i.e. the remaining uncompressed data length is not a
+ multiple of size, then the final partial item is nevertheless read into buf
+ and the end-of-file flag is set. The length of the partial item read is not
+ provided, but could be inferred from the result of gztell(). This behavior
+ is the same as the behavior of fread() implementations in common libraries,
+ but it prevents the direct use of gzfread() to read a concurrently written
+ file, reseting and retrying on end-of-file, when size is not 1.
*/
ZEXTERN int ZEXPORT gzwrite(gzFile file, void const *buf, unsigned len);
projects / thirdparty / zlib-ng.git / commitdiff
