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Diffstat (limited to '3rdparty/zlib/examples/zran.c')
-rw-r--r-- | 3rdparty/zlib/examples/zran.c | 740 |
1 files changed, 432 insertions, 308 deletions
diff --git a/3rdparty/zlib/examples/zran.c b/3rdparty/zlib/examples/zran.c index 4fec6594a66..d3135955b02 100644 --- a/3rdparty/zlib/examples/zran.c +++ b/3rdparty/zlib/examples/zran.c @@ -1,383 +1,503 @@ -/* zran.c -- example of zlib/gzip stream indexing and random access - * Copyright (C) 2005, 2012 Mark Adler +/* zran.c -- example of deflate stream indexing and random access + * Copyright (C) 2005, 2012, 2018, 2023 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h - Version 1.1 29 Sep 2012 Mark Adler */ + * Version 1.4 13 Apr 2023 Mark Adler */ /* Version History: 1.0 29 May 2005 First version 1.1 29 Sep 2012 Fix memory reallocation error + 1.2 14 Oct 2018 Handle gzip streams with multiple members + Add a header file to facilitate usage in applications + 1.3 18 Feb 2023 Permit raw deflate streams as well as zlib and gzip + Permit crossing gzip member boundaries when extracting + Support a size_t size when extracting (was an int) + Do a binary search over the index for an access point + Expose the access point type to enable save and load + 1.4 13 Apr 2023 Add a NOPRIME define to not use inflatePrime() */ -/* Illustrate the use of Z_BLOCK, inflatePrime(), and inflateSetDictionary() - for random access of a compressed file. A file containing a zlib or gzip - stream is provided on the command line. The compressed stream is decoded in - its entirety, and an index built with access points about every SPAN bytes - in the uncompressed output. The compressed file is left open, and can then - be read randomly, having to decompress on the average SPAN/2 uncompressed - bytes before getting to the desired block of data. - - An access point can be created at the start of any deflate block, by saving - the starting file offset and bit of that block, and the 32K bytes of - uncompressed data that precede that block. Also the uncompressed offset of - that block is saved to provide a referece for locating a desired starting - point in the uncompressed stream. build_index() works by decompressing the - input zlib or gzip stream a block at a time, and at the end of each block - deciding if enough uncompressed data has gone by to justify the creation of - a new access point. If so, that point is saved in a data structure that - grows as needed to accommodate the points. - - To use the index, an offset in the uncompressed data is provided, for which - the latest access point at or preceding that offset is located in the index. - The input file is positioned to the specified location in the index, and if - necessary the first few bits of the compressed data is read from the file. - inflate is initialized with those bits and the 32K of uncompressed data, and - the decompression then proceeds until the desired offset in the file is - reached. Then the decompression continues to read the desired uncompressed - data from the file. - - Another approach would be to generate the index on demand. In that case, - requests for random access reads from the compressed data would try to use - the index, but if a read far enough past the end of the index is required, - then further index entries would be generated and added. - - There is some fair bit of overhead to starting inflation for the random - access, mainly copying the 32K byte dictionary. So if small pieces of the - file are being accessed, it would make sense to implement a cache to hold - some lookahead and avoid many calls to extract() for small lengths. - - Another way to build an index would be to use inflateCopy(). That would - not be constrained to have access points at block boundaries, but requires - more memory per access point, and also cannot be saved to file due to the - use of pointers in the state. The approach here allows for storage of the - index in a file. - */ +// Illustrate the use of Z_BLOCK, inflatePrime(), and inflateSetDictionary() +// for random access of a compressed file. A file containing a raw deflate +// stream is provided on the command line. The compressed stream is decoded in +// its entirety, and an index built with access points about every SPAN bytes +// in the uncompressed output. The compressed file is left open, and can then +// be read randomly, having to decompress on the average SPAN/2 uncompressed +// bytes before getting to the desired block of data. +// +// An access point can be created at the start of any deflate block, by saving +// the starting file offset and bit of that block, and the 32K bytes of +// uncompressed data that precede that block. Also the uncompressed offset of +// that block is saved to provide a reference for locating a desired starting +// point in the uncompressed stream. deflate_index_build() decompresses the +// input raw deflate stream a block at a time, and at the end of each block +// decides if enough uncompressed data has gone by to justify the creation of a +// new access point. If so, that point is saved in a data structure that grows +// as needed to accommodate the points. +// +// To use the index, an offset in the uncompressed data is provided, for which +// the latest access point at or preceding that offset is located in the index. +// The input file is positioned to the specified location in the index, and if +// necessary the first few bits of the compressed data is read from the file. +// inflate is initialized with those bits and the 32K of uncompressed data, and +// decompression then proceeds until the desired offset in the file is reached. +// Then decompression continues to read the requested uncompressed data from +// the file. +// +// There is some fair bit of overhead to starting inflation for the random +// access, mainly copying the 32K byte dictionary. If small pieces of the file +// are being accessed, it would make sense to implement a cache to hold some +// lookahead to avoid many calls to deflate_index_extract() for small lengths. +// +// Another way to build an index would be to use inflateCopy(). That would not +// be constrained to have access points at block boundaries, but would require +// more memory per access point, and could not be saved to a file due to the +// use of pointers in the state. The approach here allows for storage of the +// index in a file. #include <stdio.h> #include <stdlib.h> #include <string.h> +#include <limits.h> #include "zlib.h" +#include "zran.h" + +#define WINSIZE 32768U // sliding window size +#define CHUNK 16384 // file input buffer size -#define local static - -#define SPAN 1048576L /* desired distance between access points */ -#define WINSIZE 32768U /* sliding window size */ -#define CHUNK 16384 /* file input buffer size */ - -/* access point entry */ -struct point { - off_t out; /* corresponding offset in uncompressed data */ - off_t in; /* offset in input file of first full byte */ - int bits; /* number of bits (1-7) from byte at in - 1, or 0 */ - unsigned char window[WINSIZE]; /* preceding 32K of uncompressed data */ -}; - -/* access point list */ -struct access { - int have; /* number of list entries filled in */ - int size; /* number of list entries allocated */ - struct point *list; /* allocated list */ -}; - -/* Deallocate an index built by build_index() */ -local void free_index(struct access *index) -{ +// See comments in zran.h. +void deflate_index_free(struct deflate_index *index) { if (index != NULL) { free(index->list); free(index); } } -/* Add an entry to the access point list. If out of memory, deallocate the - existing list and return NULL. */ -local struct access *addpoint(struct access *index, int bits, - off_t in, off_t out, unsigned left, unsigned char *window) -{ - struct point *next; - - /* if list is empty, create it (start with eight points) */ +// Add an access point to the list. If out of memory, deallocate the existing +// list and return NULL. index->mode is temporarily the allocated number of +// access points, until it is time for deflate_index_build() to return. Then +// index->mode is set to the mode of inflation. +static struct deflate_index *add_point(struct deflate_index *index, int bits, + off_t in, off_t out, unsigned left, + unsigned char *window) { if (index == NULL) { - index = malloc(sizeof(struct access)); - if (index == NULL) return NULL; - index->list = malloc(sizeof(struct point) << 3); + // The list is empty. Create it, starting with eight access points. + index = malloc(sizeof(struct deflate_index)); + if (index == NULL) + return NULL; + index->have = 0; + index->mode = 8; + index->list = malloc(sizeof(point_t) * index->mode); if (index->list == NULL) { free(index); return NULL; } - index->size = 8; - index->have = 0; } - /* if list is full, make it bigger */ - else if (index->have == index->size) { - index->size <<= 1; - next = realloc(index->list, sizeof(struct point) * index->size); + else if (index->have == index->mode) { + // The list is full. Make it bigger. + index->mode <<= 1; + point_t *next = realloc(index->list, sizeof(point_t) * index->mode); if (next == NULL) { - free_index(index); + deflate_index_free(index); return NULL; } index->list = next; } - /* fill in entry and increment how many we have */ - next = index->list + index->have; - next->bits = bits; - next->in = in; + // Fill in the access point and increment how many we have. + point_t *next = (point_t *)(index->list) + index->have++; + if (index->have < 0) { + // Overflowed the int! + deflate_index_free(index); + return NULL; + } next->out = out; + next->in = in; + next->bits = bits; if (left) memcpy(next->window, window + WINSIZE - left, left); if (left < WINSIZE) memcpy(next->window + left, window, WINSIZE - left); - index->have++; - /* return list, possibly reallocated */ + // Return the index, which may have been newly allocated or destroyed. return index; } -/* Make one entire pass through the compressed stream and build an index, with - access points about every span bytes of uncompressed output -- span is - chosen to balance the speed of random access against the memory requirements - of the list, about 32K bytes per access point. Note that data after the end - of the first zlib or gzip stream in the file is ignored. build_index() - returns the number of access points on success (>= 1), Z_MEM_ERROR for out - of memory, Z_DATA_ERROR for an error in the input file, or Z_ERRNO for a - file read error. On success, *built points to the resulting index. */ -local int build_index(FILE *in, off_t span, struct access **built) -{ - int ret; - off_t totin, totout; /* our own total counters to avoid 4GB limit */ - off_t last; /* totout value of last access point */ - struct access *index; /* access points being generated */ - z_stream strm; - unsigned char input[CHUNK]; - unsigned char window[WINSIZE]; - - /* initialize inflate */ - strm.zalloc = Z_NULL; - strm.zfree = Z_NULL; - strm.opaque = Z_NULL; - strm.avail_in = 0; - strm.next_in = Z_NULL; - ret = inflateInit2(&strm, 47); /* automatic zlib or gzip decoding */ - if (ret != Z_OK) - return ret; - - /* inflate the input, maintain a sliding window, and build an index -- this - also validates the integrity of the compressed data using the check - information at the end of the gzip or zlib stream */ - totin = totout = last = 0; - index = NULL; /* will be allocated by first addpoint() */ - strm.avail_out = 0; +// Decompression modes. These are the inflateInit2() windowBits parameter. +#define RAW -15 +#define ZLIB 15 +#define GZIP 31 + +// See comments in zran.h. +int deflate_index_build(FILE *in, off_t span, struct deflate_index **built) { + // Set up inflation state. + z_stream strm = {0}; // inflate engine (gets fired up later) + unsigned char buf[CHUNK]; // input buffer + unsigned char win[WINSIZE] = {0}; // output sliding window + off_t totin = 0; // total bytes read from input + off_t totout = 0; // total bytes uncompressed + int mode = 0; // mode: RAW, ZLIB, or GZIP (0 => not set yet) + + // Decompress from in, generating access points along the way. + int ret; // the return value from zlib, or Z_ERRNO + off_t last; // last access point uncompressed offset + struct deflate_index *index = NULL; // list of access points do { - /* get some compressed data from input file */ - strm.avail_in = fread(input, 1, CHUNK, in); - if (ferror(in)) { - ret = Z_ERRNO; - goto build_index_error; - } + // Assure available input, at least until reaching EOF. if (strm.avail_in == 0) { - ret = Z_DATA_ERROR; - goto build_index_error; - } - strm.next_in = input; - - /* process all of that, or until end of stream */ - do { - /* reset sliding window if necessary */ - if (strm.avail_out == 0) { - strm.avail_out = WINSIZE; - strm.next_out = window; - } - - /* inflate until out of input, output, or at end of block -- - update the total input and output counters */ + strm.avail_in = fread(buf, 1, sizeof(buf), in); totin += strm.avail_in; - totout += strm.avail_out; - ret = inflate(&strm, Z_BLOCK); /* return at end of block */ - totin -= strm.avail_in; - totout -= strm.avail_out; - if (ret == Z_NEED_DICT) - ret = Z_DATA_ERROR; - if (ret == Z_MEM_ERROR || ret == Z_DATA_ERROR) - goto build_index_error; - if (ret == Z_STREAM_END) + strm.next_in = buf; + if (strm.avail_in < sizeof(buf) && ferror(in)) { + ret = Z_ERRNO; break; + } - /* if at end of block, consider adding an index entry (note that if - data_type indicates an end-of-block, then all of the - uncompressed data from that block has been delivered, and none - of the compressed data after that block has been consumed, - except for up to seven bits) -- the totout == 0 provides an - entry point after the zlib or gzip header, and assures that the - index always has at least one access point; we avoid creating an - access point after the last block by checking bit 6 of data_type - */ - if ((strm.data_type & 128) && !(strm.data_type & 64) && - (totout == 0 || totout - last > span)) { - index = addpoint(index, strm.data_type & 7, totin, - totout, strm.avail_out, window); - if (index == NULL) { - ret = Z_MEM_ERROR; - goto build_index_error; - } - last = totout; + if (mode == 0) { + // At the start of the input -- determine the type. Assume raw + // if it is neither zlib nor gzip. This could in theory result + // in a false positive for zlib, but in practice the fill bits + // after a stored block are always zeros, so a raw stream won't + // start with an 8 in the low nybble. + mode = strm.avail_in == 0 ? RAW : // empty -- will fail + (strm.next_in[0] & 0xf) == 8 ? ZLIB : + strm.next_in[0] == 0x1f ? GZIP : + /* else */ RAW; + ret = inflateInit2(&strm, mode); + if (ret != Z_OK) + break; } - } while (strm.avail_in != 0); - } while (ret != Z_STREAM_END); + } - /* clean up and return index (release unused entries in list) */ - (void)inflateEnd(&strm); - index->list = realloc(index->list, sizeof(struct point) * index->have); - index->size = index->have; + // Assure available output. This rotates the output through, for use as + // a sliding window on the uncompressed data. + if (strm.avail_out == 0) { + strm.avail_out = sizeof(win); + strm.next_out = win; + } + + if (mode == RAW && index == NULL) + // We skip the inflate() call at the start of raw deflate data in + // order generate an access point there. Set data_type to imitate + // the end of a header. + strm.data_type = 0x80; + else { + // Inflate and update the number of uncompressed bytes. + unsigned before = strm.avail_out; + ret = inflate(&strm, Z_BLOCK); + totout += before - strm.avail_out; + } + + if ((strm.data_type & 0xc0) == 0x80 && + (index == NULL || totout - last >= span)) { + // We are at the end of a header or a non-last deflate block, so we + // can add an access point here. Furthermore, we are either at the + // very start for the first access point, or there has been span or + // more uncompressed bytes since the last access point, so we want + // to add an access point here. + index = add_point(index, strm.data_type & 7, totin - strm.avail_in, + totout, strm.avail_out, win); + if (index == NULL) { + ret = Z_MEM_ERROR; + break; + } + last = totout; + } + + if (ret == Z_STREAM_END && mode == GZIP && + (strm.avail_in || ungetc(getc(in), in) != EOF)) + // There is more input after the end of a gzip member. Reset the + // inflate state to read another gzip member. On success, this will + // set ret to Z_OK to continue decompressing. + ret = inflateReset2(&strm, GZIP); + + // Keep going until Z_STREAM_END or error. If the compressed data ends + // prematurely without a file read error, Z_BUF_ERROR is returned. + } while (ret == Z_OK); + inflateEnd(&strm); + + if (ret != Z_STREAM_END) { + // An error was encountered. Discard the index and return a negative + // error code. + deflate_index_free(index); + return ret == Z_NEED_DICT ? Z_DATA_ERROR : ret; + } + + // Shrink the index to only the occupied access points and return it. + index->mode = mode; + index->length = totout; + point_t *list = realloc(index->list, sizeof(point_t) * index->have); + if (list == NULL) { + // Seems like a realloc() to make something smaller should always work, + // but just in case. + deflate_index_free(index); + return Z_MEM_ERROR; + } + index->list = list; *built = index; - return index->size; - - /* return error */ - build_index_error: - (void)inflateEnd(&strm); - if (index != NULL) - free_index(index); - return ret; + return index->have; } -/* Use the index to read len bytes from offset into buf, return bytes read or - negative for error (Z_DATA_ERROR or Z_MEM_ERROR). If data is requested past - the end of the uncompressed data, then extract() will return a value less - than len, indicating how much as actually read into buf. This function - should not return a data error unless the file was modified since the index - was generated. extract() may also return Z_ERRNO if there is an error on - reading or seeking the input file. */ -local int extract(FILE *in, struct access *index, off_t offset, - unsigned char *buf, int len) -{ - int ret, skip; - z_stream strm; - struct point *here; - unsigned char input[CHUNK]; - unsigned char discard[WINSIZE]; +#ifdef NOPRIME +// Support zlib versions before 1.2.3 (July 2005), or incomplete zlib clones +// that do not have inflatePrime(). + +# define INFLATEPRIME inflatePreface + +// Append the low bits bits of value to in[] at bit position *have, updating +// *have. value must be zero above its low bits bits. bits must be positive. +// This assumes that any bits above the *have bits in the last byte are zeros. +// That assumption is preserved on return, as any bits above *have + bits in +// the last byte written will be set to zeros. +static inline void append_bits(unsigned value, int bits, + unsigned char *in, int *have) { + in += *have >> 3; // where the first bits from value will go + int k = *have & 7; // the number of bits already there + *have += bits; + if (k) + *in |= value << k; // write value above the low k bits + else + *in = value; + k = 8 - k; // the number of bits just appended + while (bits > k) { + value >>= k; // drop the bits appended + bits -= k; + k = 8; // now at a byte boundary + *++in = value; + } +} + +// Insert enough bits in the form of empty deflate blocks in front of the +// low bits bits of value, in order to bring the sequence to a byte boundary. +// Then feed that to inflate(). This does what inflatePrime() does, except that +// a negative value of bits is not supported. bits must be in 0..16. If the +// arguments are invalid, Z_STREAM_ERROR is returned. Otherwise the return +// value from inflate() is returned. +static int inflatePreface(z_stream *strm, int bits, int value) { + // Check input. + if (strm == Z_NULL || bits < 0 || bits > 16) + return Z_STREAM_ERROR; + if (bits == 0) + return Z_OK; + value &= (2 << (bits - 1)) - 1; + + // An empty dynamic block with an odd number of bits (95). The high bit of + // the last byte is unused. + static const unsigned char dyn[] = { + 4, 0xe0, 0x81, 8, 0, 0, 0, 0, 0x20, 0xa8, 0xab, 0x1f + }; + const int dynlen = 95; // number of bits in the block + + // Build an input buffer for inflate that is a multiple of eight bits in + // length, and that ends with the low bits bits of value. + unsigned char in[(dynlen + 3 * 10 + 16 + 7) / 8]; + int have = 0; + if (bits & 1) { + // Insert an empty dynamic block to get to an odd number of bits, so + // when bits bits from value are appended, we are at an even number of + // bits. + memcpy(in, dyn, sizeof(dyn)); + have = dynlen; + } + while ((have + bits) & 7) + // Insert empty fixed blocks until appending bits bits would put us on + // a byte boundary. This will insert at most three fixed blocks. + append_bits(2, 10, in, &have); + + // Append the bits bits from value, which takes us to a byte boundary. + append_bits(value, bits, in, &have); + + // Deliver the input to inflate(). There is no output space provided, but + // inflate() can't get stuck waiting on output not ingesting all of the + // provided input. The reason is that there will be at most 16 bits of + // input from value after the empty deflate blocks (which themselves + // generate no output). At least ten bits are needed to generate the first + // output byte from a fixed block. The last two bytes of the buffer have to + // be ingested in order to get ten bits, which is the most that value can + // occupy. + strm->avail_in = have >> 3; + strm->next_in = in; + strm->avail_out = 0; + strm->next_out = in; // not used, but can't be NULL + return inflate(strm, Z_NO_FLUSH); +} - /* proceed only if something reasonable to do */ - if (len < 0) +#else +# define INFLATEPRIME inflatePrime +#endif + +// See comments in zran.h. +ptrdiff_t deflate_index_extract(FILE *in, struct deflate_index *index, + off_t offset, unsigned char *buf, size_t len) { + // Do a quick sanity check on the index. + if (index == NULL || index->have < 1 || index->list[0].out != 0) + return Z_STREAM_ERROR; + + // If nothing to extract, return zero bytes extracted. + if (len == 0 || offset < 0 || offset >= index->length) return 0; - /* find where in stream to start */ - here = index->list; - ret = index->have; - while (--ret && here[1].out <= offset) - here++; - - /* initialize file and inflate state to start there */ - strm.zalloc = Z_NULL; - strm.zfree = Z_NULL; - strm.opaque = Z_NULL; - strm.avail_in = 0; - strm.next_in = Z_NULL; - ret = inflateInit2(&strm, -15); /* raw inflate */ + // Find the access point closest to but not after offset. + int lo = -1, hi = index->have; + point_t *point = index->list; + while (hi - lo > 1) { + int mid = (lo + hi) >> 1; + if (offset < point[mid].out) + hi = mid; + else + lo = mid; + } + point += lo; + + // Initialize the input file and prime the inflate engine to start there. + int ret = fseeko(in, point->in - (point->bits ? 1 : 0), SEEK_SET); + if (ret == -1) + return Z_ERRNO; + int ch = 0; + if (point->bits && (ch = getc(in)) == EOF) + return ferror(in) ? Z_ERRNO : Z_BUF_ERROR; + z_stream strm = {0}; + ret = inflateInit2(&strm, RAW); if (ret != Z_OK) return ret; - ret = fseeko(in, here->in - (here->bits ? 1 : 0), SEEK_SET); - if (ret == -1) - goto extract_ret; - if (here->bits) { - ret = getc(in); - if (ret == -1) { - ret = ferror(in) ? Z_ERRNO : Z_DATA_ERROR; - goto extract_ret; - } - (void)inflatePrime(&strm, here->bits, ret >> (8 - here->bits)); - } - (void)inflateSetDictionary(&strm, here->window, WINSIZE); + if (point->bits) + INFLATEPRIME(&strm, point->bits, ch >> (8 - point->bits)); + inflateSetDictionary(&strm, point->window, WINSIZE); - /* skip uncompressed bytes until offset reached, then satisfy request */ - offset -= here->out; - strm.avail_in = 0; - skip = 1; /* while skipping to offset */ + // Skip uncompressed bytes until offset reached, then satisfy request. + unsigned char input[CHUNK]; + unsigned char discard[WINSIZE]; + offset -= point->out; // number of bytes to skip to get to offset + size_t left = len; // number of bytes left to read after offset do { - /* define where to put uncompressed data, and how much */ - if (offset == 0 && skip) { /* at offset now */ - strm.avail_out = len; - strm.next_out = buf; - skip = 0; /* only do this once */ - } - if (offset > WINSIZE) { /* skip WINSIZE bytes */ - strm.avail_out = WINSIZE; + if (offset) { + // Discard up to offset uncompressed bytes. + strm.avail_out = offset < WINSIZE ? (unsigned)offset : WINSIZE; strm.next_out = discard; - offset -= WINSIZE; } - else if (offset != 0) { /* last skip */ - strm.avail_out = (unsigned)offset; - strm.next_out = discard; - offset = 0; + else { + // Uncompress up to left bytes into buf. + strm.avail_out = left < UINT_MAX ? (unsigned)left : UINT_MAX; + strm.next_out = buf + len - left; } - /* uncompress until avail_out filled, or end of stream */ - do { - if (strm.avail_in == 0) { - strm.avail_in = fread(input, 1, CHUNK, in); - if (ferror(in)) { - ret = Z_ERRNO; - goto extract_ret; - } - if (strm.avail_in == 0) { - ret = Z_DATA_ERROR; - goto extract_ret; - } - strm.next_in = input; - } - ret = inflate(&strm, Z_NO_FLUSH); /* normal inflate */ - if (ret == Z_NEED_DICT) - ret = Z_DATA_ERROR; - if (ret == Z_MEM_ERROR || ret == Z_DATA_ERROR) - goto extract_ret; - if (ret == Z_STREAM_END) + // Uncompress, setting got to the number of bytes uncompressed. + if (strm.avail_in == 0) { + // Assure available input. + strm.avail_in = fread(input, 1, CHUNK, in); + if (strm.avail_in < CHUNK && ferror(in)) { + ret = Z_ERRNO; break; - } while (strm.avail_out != 0); - - /* if reach end of stream, then don't keep trying to get more */ - if (ret == Z_STREAM_END) - break; + } + strm.next_in = input; + } + unsigned got = strm.avail_out; + ret = inflate(&strm, Z_NO_FLUSH); + got -= strm.avail_out; + + // Update the appropriate count. + if (offset) + offset -= got; + else + left -= got; + + // If we're at the end of a gzip member and there's more to read, + // continue to the next gzip member. + if (ret == Z_STREAM_END && index->mode == GZIP) { + // Discard the gzip trailer. + unsigned drop = 8; // length of gzip trailer + if (strm.avail_in >= drop) { + strm.avail_in -= drop; + strm.next_in += drop; + } + else { + // Read and discard the remainder of the gzip trailer. + drop -= strm.avail_in; + strm.avail_in = 0; + do { + if (getc(in) == EOF) + // The input does not have a complete trailer. + return ferror(in) ? Z_ERRNO : Z_BUF_ERROR; + } while (--drop); + } - /* do until offset reached and requested data read, or stream ends */ - } while (skip); + if (strm.avail_in || ungetc(getc(in), in) != EOF) { + // There's more after the gzip trailer. Use inflate to skip the + // gzip header and resume the raw inflate there. + inflateReset2(&strm, GZIP); + do { + if (strm.avail_in == 0) { + strm.avail_in = fread(input, 1, CHUNK, in); + if (strm.avail_in < CHUNK && ferror(in)) { + ret = Z_ERRNO; + break; + } + strm.next_in = input; + } + strm.avail_out = WINSIZE; + strm.next_out = discard; + ret = inflate(&strm, Z_BLOCK); // stop at end of header + } while (ret == Z_OK && (strm.data_type & 0x80) == 0); + if (ret != Z_OK) + break; + inflateReset2(&strm, RAW); + } + } - /* compute number of uncompressed bytes read after offset */ - ret = skip ? 0 : len - strm.avail_out; + // Continue until we have the requested data, the deflate data has + // ended, or an error is encountered. + } while (ret == Z_OK && left); + inflateEnd(&strm); - /* clean up and return bytes read or error */ - extract_ret: - (void)inflateEnd(&strm); - return ret; + // Return the number of uncompressed bytes read into buf, or the error. + return ret == Z_OK || ret == Z_STREAM_END ? len - left : ret; } -/* Demonstrate the use of build_index() and extract() by processing the file - provided on the command line, and the extracting 16K from about 2/3rds of - the way through the uncompressed output, and writing that to stdout. */ -int main(int argc, char **argv) -{ - int len; - off_t offset; - FILE *in; - struct access *index = NULL; - unsigned char buf[CHUNK]; - - /* open input file */ - if (argc != 2) { - fprintf(stderr, "usage: zran file.gz\n"); +#ifdef TEST + +#define SPAN 1048576L // desired distance between access points +#define LEN 16384 // number of bytes to extract + +// Demonstrate the use of deflate_index_build() and deflate_index_extract() by +// processing the file provided on the command line, and extracting LEN bytes +// from 2/3rds of the way through the uncompressed output, writing that to +// stdout. An offset can be provided as the second argument, in which case the +// data is extracted from there instead. +int main(int argc, char **argv) { + // Open the input file. + if (argc < 2 || argc > 3) { + fprintf(stderr, "usage: zran file.raw [offset]\n"); return 1; } - in = fopen(argv[1], "rb"); + FILE *in = fopen(argv[1], "rb"); if (in == NULL) { fprintf(stderr, "zran: could not open %s for reading\n", argv[1]); return 1; } - /* build index */ - len = build_index(in, SPAN, &index); + // Get optional offset. + off_t offset = -1; + if (argc == 3) { + char *end; + offset = strtoll(argv[2], &end, 10); + if (*end || offset < 0) { + fprintf(stderr, "zran: %s is not a valid offset\n", argv[2]); + return 1; + } + } + + // Build index. + struct deflate_index *index = NULL; + int len = deflate_index_build(in, SPAN, &index); if (len < 0) { fclose(in); switch (len) { case Z_MEM_ERROR: fprintf(stderr, "zran: out of memory\n"); break; + case Z_BUF_ERROR: + fprintf(stderr, "zran: %s ended prematurely\n", argv[1]); + break; case Z_DATA_ERROR: fprintf(stderr, "zran: compressed data error in %s\n", argv[1]); break; @@ -391,19 +511,23 @@ int main(int argc, char **argv) } fprintf(stderr, "zran: built index with %d access points\n", len); - /* use index by reading some bytes from an arbitrary offset */ - offset = (index->list[index->have - 1].out << 1) / 3; - len = extract(in, index, offset, buf, CHUNK); - if (len < 0) + // Use index by reading some bytes from an arbitrary offset. + unsigned char buf[LEN]; + if (offset == -1) + offset = ((index->length + 1) << 1) / 3; + ptrdiff_t got = deflate_index_extract(in, index, offset, buf, LEN); + if (got < 0) fprintf(stderr, "zran: extraction failed: %s error\n", - len == Z_MEM_ERROR ? "out of memory" : "input corrupted"); + got == Z_MEM_ERROR ? "out of memory" : "input corrupted"); else { - fwrite(buf, 1, len, stdout); - fprintf(stderr, "zran: extracted %d bytes at %llu\n", len, offset); + fwrite(buf, 1, got, stdout); + fprintf(stderr, "zran: extracted %ld bytes at %lld\n", got, offset); } - /* clean up and exit */ - free_index(index); + // Clean up and exit. + deflate_index_free(index); fclose(in); return 0; } + +#endif |