diff options
Diffstat (limited to 'Build/source/libs/zlib/zlib-1.2.3/examples/gzlog.c')
-rw-r--r-- | Build/source/libs/zlib/zlib-1.2.3/examples/gzlog.c | 413 |
1 files changed, 413 insertions, 0 deletions
diff --git a/Build/source/libs/zlib/zlib-1.2.3/examples/gzlog.c b/Build/source/libs/zlib/zlib-1.2.3/examples/gzlog.c new file mode 100644 index 00000000000..f71f817c8b6 --- /dev/null +++ b/Build/source/libs/zlib/zlib-1.2.3/examples/gzlog.c @@ -0,0 +1,413 @@ +/* + * gzlog.c + * Copyright (C) 2004 Mark Adler + * For conditions of distribution and use, see copyright notice in gzlog.h + * version 1.0, 26 Nov 2004 + * + */ + +#include <string.h> /* memcmp() */ +#include <stdlib.h> /* malloc(), free(), NULL */ +#include <sys/types.h> /* size_t, off_t */ +#include <unistd.h> /* read(), close(), sleep(), ftruncate(), */ + /* lseek() */ +#include <fcntl.h> /* open() */ +#include <sys/file.h> /* flock() */ +#include "zlib.h" /* deflateInit2(), deflate(), deflateEnd() */ + +#include "gzlog.h" /* interface */ +#define local static + +/* log object structure */ +typedef struct { + int id; /* object identifier */ + int fd; /* log file descriptor */ + off_t extra; /* offset of extra "ap" subfield */ + off_t mark_off; /* offset of marked data */ + off_t last_off; /* offset of last block */ + unsigned long crc; /* uncompressed crc */ + unsigned long len; /* uncompressed length (modulo 2^32) */ + unsigned stored; /* length of current stored block */ +} gz_log; + +#define GZLOGID 19334 /* gz_log object identifier */ + +#define LOCK_RETRY 1 /* retry lock once a second */ +#define LOCK_PATIENCE 1200 /* try about twenty minutes before forcing */ + +/* acquire a lock on a file */ +local int lock(int fd) +{ + int patience; + + /* try to lock every LOCK_RETRY seconds for LOCK_PATIENCE seconds */ + patience = LOCK_PATIENCE; + do { + if (flock(fd, LOCK_EX + LOCK_NB) == 0) + return 0; + (void)sleep(LOCK_RETRY); + patience -= LOCK_RETRY; + } while (patience > 0); + + /* we've run out of patience -- give up */ + return -1; +} + +/* release lock */ +local void unlock(int fd) +{ + (void)flock(fd, LOCK_UN); +} + +/* release a log object */ +local void log_clean(gz_log *log) +{ + unlock(log->fd); + (void)close(log->fd); + free(log); +} + +/* read an unsigned long from a byte buffer little-endian */ +local unsigned long make_ulg(unsigned char *buf) +{ + int n; + unsigned long val; + + val = (unsigned long)(*buf++); + for (n = 8; n < 32; n += 8) + val += (unsigned long)(*buf++) << n; + return val; +} + +/* read an off_t from a byte buffer little-endian */ +local off_t make_off(unsigned char *buf) +{ + int n; + off_t val; + + val = (off_t)(*buf++); + for (n = 8; n < 64; n += 8) + val += (off_t)(*buf++) << n; + return val; +} + +/* write an unsigned long little-endian to byte buffer */ +local void dice_ulg(unsigned long val, unsigned char *buf) +{ + int n; + + for (n = 0; n < 4; n++) { + *buf++ = val & 0xff; + val >>= 8; + } +} + +/* write an off_t little-endian to byte buffer */ +local void dice_off(off_t val, unsigned char *buf) +{ + int n; + + for (n = 0; n < 8; n++) { + *buf++ = val & 0xff; + val >>= 8; + } +} + +/* initial, empty gzip file for appending */ +local char empty_gz[] = { + 0x1f, 0x8b, /* magic gzip id */ + 8, /* compression method is deflate */ + 4, /* there is an extra field */ + 0, 0, 0, 0, /* no modification time provided */ + 0, 0xff, /* no extra flags, no OS */ + 20, 0, 'a', 'p', 16, 0, /* extra field with "ap" subfield */ + 32, 0, 0, 0, 0, 0, 0, 0, /* offset of uncompressed data */ + 32, 0, 0, 0, 0, 0, 0, 0, /* offset of last block */ + 1, 0, 0, 0xff, 0xff, /* empty stored block (last) */ + 0, 0, 0, 0, /* crc */ + 0, 0, 0, 0 /* uncompressed length */ +}; + +/* initialize a log object with locking */ +void *gzlog_open(char *path) +{ + unsigned xlen; + unsigned char temp[20]; + unsigned sub_len; + int good; + gz_log *log; + + /* allocate log structure */ + log = malloc(sizeof(gz_log)); + if (log == NULL) + return NULL; + log->id = GZLOGID; + + /* open file, creating it if necessary, and locking it */ + log->fd = open(path, O_RDWR | O_CREAT, 0600); + if (log->fd < 0) { + free(log); + return NULL; + } + if (lock(log->fd)) { + close(log->fd); + free(log); + return NULL; + } + + /* if file is empty, write new gzip stream */ + if (lseek(log->fd, 0, SEEK_END) == 0) { + if (write(log->fd, empty_gz, sizeof(empty_gz)) != sizeof(empty_gz)) { + log_clean(log); + return NULL; + } + } + + /* check gzip header */ + (void)lseek(log->fd, 0, SEEK_SET); + if (read(log->fd, temp, 12) != 12 || temp[0] != 0x1f || + temp[1] != 0x8b || temp[2] != 8 || (temp[3] & 4) == 0) { + log_clean(log); + return NULL; + } + + /* process extra field to find "ap" sub-field */ + xlen = temp[10] + (temp[11] << 8); + good = 0; + while (xlen) { + if (xlen < 4 || read(log->fd, temp, 4) != 4) + break; + sub_len = temp[2]; + sub_len += temp[3] << 8; + xlen -= 4; + if (memcmp(temp, "ap", 2) == 0 && sub_len == 16) { + good = 1; + break; + } + if (xlen < sub_len) + break; + (void)lseek(log->fd, sub_len, SEEK_CUR); + xlen -= sub_len; + } + if (!good) { + log_clean(log); + return NULL; + } + + /* read in "ap" sub-field */ + log->extra = lseek(log->fd, 0, SEEK_CUR); + if (read(log->fd, temp, 16) != 16) { + log_clean(log); + return NULL; + } + log->mark_off = make_off(temp); + log->last_off = make_off(temp + 8); + + /* get crc, length of gzip file */ + (void)lseek(log->fd, log->last_off, SEEK_SET); + if (read(log->fd, temp, 13) != 13 || + memcmp(temp, "\001\000\000\377\377", 5) != 0) { + log_clean(log); + return NULL; + } + log->crc = make_ulg(temp + 5); + log->len = make_ulg(temp + 9); + + /* set up to write over empty last block */ + (void)lseek(log->fd, log->last_off + 5, SEEK_SET); + log->stored = 0; + return (void *)log; +} + +/* maximum amount to put in a stored block before starting a new one */ +#define MAX_BLOCK 16384 + +/* write a block to a log object */ +int gzlog_write(void *obj, char *data, size_t len) +{ + size_t some; + unsigned char temp[5]; + gz_log *log; + + /* check object */ + log = (gz_log *)obj; + if (log == NULL || log->id != GZLOGID) + return 1; + + /* write stored blocks until all of the input is written */ + do { + some = MAX_BLOCK - log->stored; + if (some > len) + some = len; + if (write(log->fd, data, some) != some) + return 1; + log->crc = crc32(log->crc, data, some); + log->len += some; + len -= some; + data += some; + log->stored += some; + + /* if the stored block is full, end it and start another */ + if (log->stored == MAX_BLOCK) { + (void)lseek(log->fd, log->last_off, SEEK_SET); + temp[0] = 0; + dice_ulg(log->stored + ((unsigned long)(~log->stored) << 16), + temp + 1); + if (write(log->fd, temp, 5) != 5) + return 1; + log->last_off = lseek(log->fd, log->stored, SEEK_CUR); + (void)lseek(log->fd, 5, SEEK_CUR); + log->stored = 0; + } + } while (len); + return 0; +} + +/* recompress the remaining stored deflate data in place */ +local int recomp(gz_log *log) +{ + z_stream strm; + size_t len, max; + unsigned char *in; + unsigned char *out; + unsigned char temp[16]; + + /* allocate space and read it all in (it's around 1 MB) */ + len = log->last_off - log->mark_off; + max = len + (len >> 12) + (len >> 14) + 11; + out = malloc(max); + if (out == NULL) + return 1; + in = malloc(len); + if (in == NULL) { + free(out); + return 1; + } + (void)lseek(log->fd, log->mark_off, SEEK_SET); + if (read(log->fd, in, len) != len) { + free(in); + free(out); + return 1; + } + + /* recompress in memory, decoding stored data as we go */ + /* note: this assumes that unsigned is four bytes or more */ + /* consider not making that assumption */ + strm.zalloc = Z_NULL; + strm.zfree = Z_NULL; + strm.opaque = Z_NULL; + if (deflateInit2(&strm, Z_BEST_COMPRESSION, Z_DEFLATED, -15, 8, + Z_DEFAULT_STRATEGY) != Z_OK) { + free(in); + free(out); + return 1; + } + strm.next_in = in; + strm.avail_out = max; + strm.next_out = out; + while (len >= 5) { + if (strm.next_in[0] != 0) + break; + strm.avail_in = strm.next_in[1] + (strm.next_in[2] << 8); + strm.next_in += 5; + len -= 5; + if (strm.avail_in != 0) { + if (len < strm.avail_in) + break; + len -= strm.avail_in; + (void)deflate(&strm, Z_NO_FLUSH); + if (strm.avail_in != 0 || strm.avail_out == 0) + break; + } + } + (void)deflate(&strm, Z_SYNC_FLUSH); + (void)deflateEnd(&strm); + free(in); + if (len != 0 || strm.avail_out == 0) { + free(out); + return 1; + } + + /* overwrite stored data with compressed data */ + (void)lseek(log->fd, log->mark_off, SEEK_SET); + len = max - strm.avail_out; + if (write(log->fd, out, len) != len) { + free(out); + return 1; + } + free(out); + + /* write last empty block, crc, and length */ + log->mark_off = log->last_off = lseek(log->fd, 0, SEEK_CUR); + temp[0] = 1; + dice_ulg(0xffffL << 16, temp + 1); + dice_ulg(log->crc, temp + 5); + dice_ulg(log->len, temp + 9); + if (write(log->fd, temp, 13) != 13) + return 1; + + /* truncate file to discard remaining stored data and old trailer */ + ftruncate(log->fd, lseek(log->fd, 0, SEEK_CUR)); + + /* update extra field to point to new last empty block */ + (void)lseek(log->fd, log->extra, SEEK_SET); + dice_off(log->mark_off, temp); + dice_off(log->last_off, temp + 8); + if (write(log->fd, temp, 16) != 16) + return 1; + return 0; +} + +/* maximum accumulation of stored blocks before compressing */ +#define MAX_STORED 1048576 + +/* close log object */ +int gzlog_close(void *obj) +{ + unsigned char temp[8]; + gz_log *log; + + /* check object */ + log = (gz_log *)obj; + if (log == NULL || log->id != GZLOGID) + return 1; + + /* go to start of most recent block being written */ + (void)lseek(log->fd, log->last_off, SEEK_SET); + + /* if some stuff was put there, update block */ + if (log->stored) { + temp[0] = 0; + dice_ulg(log->stored + ((unsigned long)(~log->stored) << 16), + temp + 1); + if (write(log->fd, temp, 5) != 5) + return 1; + log->last_off = lseek(log->fd, log->stored, SEEK_CUR); + } + + /* write last block (empty) */ + if (write(log->fd, "\001\000\000\377\377", 5) != 5) + return 1; + + /* write updated crc and uncompressed length */ + dice_ulg(log->crc, temp); + dice_ulg(log->len, temp + 4); + if (write(log->fd, temp, 8) != 8) + return 1; + + /* put offset of that last block in gzip extra block */ + (void)lseek(log->fd, log->extra + 8, SEEK_SET); + dice_off(log->last_off, temp); + if (write(log->fd, temp, 8) != 8) + return 1; + + /* if more than 1 MB stored, then time to compress it */ + if (log->last_off - log->mark_off > MAX_STORED) { + if (recomp(log)) + return 1; + } + + /* unlock and close file */ + log_clean(log); + return 0; +} |