--- /dev/null
+/*
+ * Copyright 2007 David Gibson, IBM Corporation.
+ * Based on earlier work, Copyright (C) Paul Mackerras 1997.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <stddef.h>
+#include "string.h"
+#include "stdio.h"
+#include "ops.h"
+#include "gunzip_util.h"
+
+#define HEAD_CRC 2
+#define EXTRA_FIELD 4
+#define ORIG_NAME 8
+#define COMMENT 0x10
+#define RESERVED 0xe0
+
+/**
+ * gunzip_start - prepare to decompress gzip data
+ * @state: decompressor state structure to be initialized
+ * @src: buffer containing gzip compressed or uncompressed data
+ * @srclen: size in bytes of the buffer at src
+ *
+ * If the buffer at @src contains a gzip header, this function
+ * initializes zlib to decompress the data, storing the decompression
+ * state in @state. The other functions in this file can then be used
+ * to decompress data from the gzipped stream.
+ *
+ * If the buffer at @src does not contain a gzip header, it is assumed
+ * to contain uncompressed data. The buffer information is recorded
+ * in @state and the other functions in this file will simply copy
+ * data from the uncompressed data stream at @src.
+ *
+ * Any errors, such as bad compressed data, cause an error to be
+ * printed an the platform's exit() function to be called.
+ */
+void gunzip_start(struct gunzip_state *state, void *src, int srclen)
+{
+ char *hdr = src;
+ int hdrlen = 0;
+
+ memset(state, 0, sizeof(*state));
+
+ /* Check for gzip magic number */
+ if ((hdr[0] == 0x1f) && (hdr[1] == 0x8b)) {
+ /* gzip data, initialize zlib parameters */
+ int r, flags;
+
+ state->s.workspace = state->scratch;
+ if (zlib_inflate_workspacesize() > sizeof(state->scratch))
+ fatal("insufficient scratch space for gunzip\n\r");
+
+ /* skip header */
+ hdrlen = 10;
+ flags = hdr[3];
+ if (hdr[2] != Z_DEFLATED || (flags & RESERVED) != 0)
+ fatal("bad gzipped data\n\r");
+ if ((flags & EXTRA_FIELD) != 0)
+ hdrlen = 12 + hdr[10] + (hdr[11] << 8);
+ if ((flags & ORIG_NAME) != 0)
+ while (hdr[hdrlen++] != 0)
+ ;
+ if ((flags & COMMENT) != 0)
+ while (hdr[hdrlen++] != 0)
+ ;
+ if ((flags & HEAD_CRC) != 0)
+ hdrlen += 2;
+ if (hdrlen >= srclen)
+ fatal("gunzip_start: ran out of data in header\n\r");
+
+ r = zlib_inflateInit2(&state->s, -MAX_WBITS);
+ if (r != Z_OK)
+ fatal("inflateInit2 returned %d\n\r", r);
+ }
+
+ state->s.total_in = hdrlen;
+ state->s.next_in = src + hdrlen;
+ state->s.avail_in = srclen - hdrlen;
+}
+
+/**
+ * gunzip_partial - extract bytes from a gzip data stream
+ * @state: gzip state structure previously initialized by gunzip_start()
+ * @dst: buffer to store extracted data
+ * @dstlen: maximum number of bytes to extract
+ *
+ * This function extracts at most @dstlen bytes from the data stream
+ * previously associated with @state by gunzip_start(), decompressing
+ * if necessary. Exactly @dstlen bytes are extracted unless the data
+ * stream doesn't contain enough bytes, in which case the entire
+ * remainder of the stream is decompressed.
+ *
+ * Returns the actual number of bytes extracted. If any errors occur,
+ * such as a corrupted compressed stream, an error is printed an the
+ * platform's exit() function is called.
+ */
+int gunzip_partial(struct gunzip_state *state, void *dst, int dstlen)
+{
+ int len;
+
+ if (state->s.workspace) {
+ /* gunzipping */
+ int r;
+
+ state->s.next_out = dst;
+ state->s.avail_out = dstlen;
+ r = zlib_inflate(&state->s, Z_FULL_FLUSH);
+ if (r != Z_OK && r != Z_STREAM_END)
+ fatal("inflate returned %d msg: %s\n\r", r, state->s.msg);
+ len = state->s.next_out - (Byte *)dst;
+ } else {
+ /* uncompressed image */
+ len = min(state->s.avail_in, (uLong)dstlen);
+ memcpy(dst, state->s.next_in, len);
+ state->s.next_in += len;
+ state->s.avail_in -= len;
+ }
+ return len;
+}
+
+/**
+ * gunzip_exactly - extract a fixed number of bytes from a gzip data stream
+ * @state: gzip state structure previously initialized by gunzip_start()
+ * @dst: buffer to store extracted data
+ * @dstlen: number of bytes to extract
+ *
+ * This function extracts exactly @dstlen bytes from the data stream
+ * previously associated with @state by gunzip_start(), decompressing
+ * if necessary.
+ *
+ * If there are less @dstlen bytes available in the data stream, or if
+ * any other errors occur, such as a corrupted compressed stream, an
+ * error is printed an the platform's exit() function is called.
+ */
+void gunzip_exactly(struct gunzip_state *state, void *dst, int dstlen)
+{
+ int len;
+
+ len = gunzip_partial(state, dst, dstlen);
+ if (len < dstlen)
+ fatal("\n\rgunzip_exactly: ran out of data!"
+ " Wanted %d, got %d.\n\r", dstlen, len);
+}
+
+/**
+ * gunzip_discard - discard bytes from a gzip data stream
+ * @state: gzip state structure previously initialized by gunzip_start()
+ * @len: number of bytes to discard
+ *
+ * This function extracts, then discards exactly @len bytes from the
+ * data stream previously associated with @state by gunzip_start().
+ * Subsequent gunzip_partial(), gunzip_exactly() or gunzip_finish()
+ * calls will extract the data following the discarded bytes in the
+ * data stream.
+ *
+ * If there are less @len bytes available in the data stream, or if
+ * any other errors occur, such as a corrupted compressed stream, an
+ * error is printed an the platform's exit() function is called.
+ */
+void gunzip_discard(struct gunzip_state *state, int len)
+{
+ static char discard_buf[128];
+
+ while (len > sizeof(discard_buf)) {
+ gunzip_exactly(state, discard_buf, sizeof(discard_buf));
+ len -= sizeof(discard_buf);
+ }
+
+ if (len > 0)
+ gunzip_exactly(state, discard_buf, len);
+}
+
+/**
+ * gunzip_finish - extract all remaining bytes from a gzip data stream
+ * @state: gzip state structure previously initialized by gunzip_start()
+ * @dst: buffer to store extracted data
+ * @dstlen: maximum number of bytes to extract
+ *
+ * This function extracts all remaining data, or at most @dstlen
+ * bytes, from the stream previously associated with @state by
+ * gunzip_start(). zlib is then shut down, so it is an error to use
+ * any of the functions in this file on @state until it is
+ * re-initialized with another call to gunzip_start().
+ *
+ * If any errors occur, such as a corrupted compressed stream, an
+ * error is printed an the platform's exit() function is called.
+ */
+int gunzip_finish(struct gunzip_state *state, void *dst, int dstlen)
+{
+ int len;
+
+ len = gunzip_partial(state, dst, dstlen);
+
+ if (state->s.workspace) {
+ zlib_inflateEnd(&state->s);
+ }
+
+ return len;
+}
Code Review / kvmfornfv.git / blobdiff