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Diffstat (limited to 'arch/powerpc/boot/gunzip_util.c')
| -rw-r--r-- | arch/powerpc/boot/gunzip_util.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/arch/powerpc/boot/gunzip_util.c b/arch/powerpc/boot/gunzip_util.c new file mode 100644 index 000000000000..df8ab07e9ff4 --- /dev/null +++ b/arch/powerpc/boot/gunzip_util.c @@ -0,0 +1,206 @@ +/* + * 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.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 - (unsigned char *)dst; + } else { + /* uncompressed image */ + len = min(state->s.avail_in, (unsigned)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; + + if (state->s.workspace) { + len = gunzip_partial(state, dst, dstlen); + zlib_inflateEnd(&state->s); + } else { + /* uncompressed image */ + len = min(state->s.avail_in, (unsigned)dstlen); + memcpy(dst, state->s.next_in, len); + } + + return len; +} |