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Diffstat (limited to 'cpukit/zlib/examples/gzlog.c')
| -rw-r--r-- | cpukit/zlib/examples/gzlog.c | 1058 |
1 files changed, 0 insertions, 1058 deletions
diff --git a/cpukit/zlib/examples/gzlog.c b/cpukit/zlib/examples/gzlog.c deleted file mode 100644 index d70aacabae..0000000000 --- a/cpukit/zlib/examples/gzlog.c +++ /dev/null @@ -1,1058 +0,0 @@ -/* - * gzlog.c - * Copyright (C) 2004, 2008 Mark Adler, all rights reserved - * For conditions of distribution and use, see copyright notice in gzlog.h - * version 2.0, 25 Apr 2008 - */ - -/* - gzlog provides a mechanism for frequently appending short strings to a gzip - file that is efficient both in execution time and compression ratio. The - strategy is to write the short strings in an uncompressed form to the end of - the gzip file, only compressing when the amount of uncompressed data has - reached a given threshold. - - gzlog also provides protection against interruptions in the process due to - system crashes. The status of the operation is recorded in an extra field - in the gzip file, and is only updated once the gzip file is brought to a - valid state. The last data to be appended or compressed is saved in an - auxiliary file, so that if the operation is interrupted, it can be completed - the next time an append operation is attempted. - - gzlog maintains another auxiliary file with the last 32K of data from the - compressed portion, which is preloaded for the compression of the subsequent - data. This minimizes the impact to the compression ratio of appending. - */ - -/* - Operations Concept: - - Files (log name "foo"): - foo.gz -- gzip file with the complete log - foo.add -- last message to append or last data to compress - foo.dict -- dictionary of the last 32K of data for next compression - foo.temp -- temporary dictionary file for compression after this one - foo.lock -- lock file for reading and writing the other files - foo.repairs -- log file for log file recovery operations (not compressed) - - gzip file structure: - - fixed-length (no file name) header with extra field (see below) - - compressed data ending initially with empty stored block - - uncompressed data filling out originally empty stored block and - subsequent stored blocks as needed (16K max each) - - gzip trailer - - no junk at end (no other gzip streams) - - When appending data, the information in the first three items above plus the - foo.add file are sufficient to recover an interrupted append operation. The - extra field has the necessary information to restore the start of the last - stored block and determine where to append the data in the foo.add file, as - well as the crc and length of the gzip data before the append operation. - - The foo.add file is created before the gzip file is marked for append, and - deleted after the gzip file is marked as complete. So if the append - operation is interrupted, the data to add will still be there. If due to - some external force, the foo.add file gets deleted between when the append - operation was interrupted and when recovery is attempted, the gzip file will - still be restored, but without the appended data. - - When compressing data, the information in the first two items above plus the - foo.add file are sufficient to recover an interrupted compress operation. - The extra field has the necessary information to find the end of the - compressed data, and contains both the crc and length of just the compressed - data and of the complete set of data including the contents of the foo.add - file. - - Again, the foo.add file is maintained during the compress operation in case - of an interruption. If in the unlikely event the foo.add file with the data - to be compressed is missing due to some external force, a gzip file with - just the previous compressed data will be reconstructed. In this case, all - of the data that was to be compressed is lost (approximately one megabyte). - This will not occur if all that happened was an interruption of the compress - operation. - - The third state that is marked is the replacement of the old dictionary with - the new dictionary after a compress operation. Once compression is - complete, the gzip file is marked as being in the replace state. This - completes the gzip file, so an interrupt after being so marked does not - result in recompression. Then the dictionary file is replaced, and the gzip - file is marked as completed. This state prevents the possibility of - restarting compression with the wrong dictionary file. - - All three operations are wrapped by a lock/unlock procedure. In order to - gain exclusive access to the log files, first a foo.lock file must be - exclusively created. When all operations are complete, the lock is - released by deleting the foo.lock file. If when attempting to create the - lock file, it already exists and the modify time of the lock file is more - than five minutes old (set by the PATIENCE define below), then the old - lock file is considered stale and deleted, and the exclusive creation of - the lock file is retried. To assure that there are no false assessments - of the staleness of the lock file, the operations periodically touch the - lock file to update the modified date. - - Following is the definition of the extra field with all of the information - required to enable the above append and compress operations and their - recovery if interrupted. Multi-byte values are stored little endian - (consistent with the gzip format). File pointers are eight bytes long. - The crc's and lengths for the gzip trailer are four bytes long. (Note that - the length at the end of a gzip file is used for error checking only, and - for large files is actually the length modulo 2^32.) The stored block - length is two bytes long. The gzip extra field two-byte identification is - "ap" for append. It is assumed that writing the extra field to the file is - an "atomic" operation. That is, either all of the extra field is written - to the file, or none of it is, if the operation is interrupted right at the - point of updating the extra field. This is a reasonable assumption, since - the extra field is within the first 52 bytes of the file, which is smaller - than any expected block size for a mass storage device (usually 512 bytes or - larger). - - Extra field (35 bytes): - - Pointer to first stored block length -- this points to the two-byte length - of the first stored block, which is followed by the two-byte, one's - complement of that length. The stored block length is preceded by the - three-bit header of the stored block, which is the actual start of the - stored block in the deflate format. See the bit offset field below. - - Pointer to the last stored block length. This is the same as above, but - for the last stored block of the uncompressed data in the gzip file. - Initially this is the same as the first stored block length pointer. - When the stored block gets to 16K (see the MAX_STORE define), then a new - stored block as added, at which point the last stored block length pointer - is different from the first stored block length pointer. When they are - different, the first bit of the last stored block header is eight bits, or - one byte back from the block length. - - Compressed data crc and length. This is the crc and length of the data - that is in the compressed portion of the deflate stream. These are used - only in the event that the foo.add file containing the data to compress is - lost after a compress operation is interrupted. - - Total data crc and length. This is the crc and length of all of the data - stored in the gzip file, compressed and uncompressed. It is used to - reconstruct the gzip trailer when compressing, as well as when recovering - interrupted operations. - - Final stored block length. This is used to quickly find where to append, - and allows the restoration of the original final stored block state when - an append operation is interrupted. - - First stored block start as the number of bits back from the final stored - block first length byte. This value is in the range of 3..10, and is - stored as the low three bits of the final byte of the extra field after - subtracting three (0..7). This allows the last-block bit of the stored - block header to be updated when a new stored block is added, for the case - when the first stored block and the last stored block are the same. (When - they are different, the numbers of bits back is known to be eight.) This - also allows for new compressed data to be appended to the old compressed - data in the compress operation, overwriting the previous first stored - block, or for the compressed data to be terminated and a valid gzip file - reconstructed on the off chance that a compression operation was - interrupted and the data to compress in the foo.add file was deleted. - - The operation in process. This is the next two bits in the last byte (the - bits under the mask 0x18). The are interpreted as 0: nothing in process, - 1: append in process, 2: compress in process, 3: replace in process. - - The top three bits of the last byte in the extra field are reserved and - are currently set to zero. - - Main procedure: - - Exclusively create the foo.lock file using the O_CREAT and O_EXCL modes of - the system open() call. If the modify time of an existing lock file is - more than PATIENCE seconds old, then the lock file is deleted and the - exclusive create is retried. - - Load the extra field from the foo.gz file, and see if an operation was in - progress but not completed. If so, apply the recovery procedure below. - - Perform the append procedure with the provided data. - - If the uncompressed data in the foo.gz file is 1MB or more, apply the - compress procedure. - - Delete the foo.lock file. - - Append procedure: - - Put what to append in the foo.add file so that the operation can be - restarted if this procedure is interrupted. - - Mark the foo.gz extra field with the append operation in progress. - + Restore the original last-block bit and stored block length of the last - stored block from the information in the extra field, in case a previous - append operation was interrupted. - - Append the provided data to the last stored block, creating new stored - blocks as needed and updating the stored blocks last-block bits and - lengths. - - Update the crc and length with the new data, and write the gzip trailer. - - Write over the extra field (with a single write operation) with the new - pointers, lengths, and crc's, and mark the gzip file as not in process. - Though there is still a foo.add file, it will be ignored since nothing - is in process. If a foo.add file is leftover from a previously - completed operation, it is truncated when writing new data to it. - - Delete the foo.add file. - - Compress and replace procedures: - - Read all of the uncompressed data in the stored blocks in foo.gz and write - it to foo.add. Also write foo.temp with the last 32K of that data to - provide a dictionary for the next invocation of this procedure. - - Rewrite the extra field marking foo.gz with a compression in process. - * If there is no data provided to compress (due to a missing foo.add file - when recovering), reconstruct and truncate the foo.gz file to contain - only the previous compressed data and proceed to the step after the next - one. Otherwise ... - - Compress the data with the dictionary in foo.dict, and write to the - foo.gz file starting at the bit immediately following the last previously - compressed block. If there is no foo.dict, proceed anyway with the - compression at slightly reduced efficiency. (For the foo.dict file to be - missing requires some external failure beyond simply the interruption of - a compress operation.) During this process, the foo.lock file is - periodically touched to assure that that file is not considered stale by - another process before we're done. The deflation is terminated with a - non-last empty static block (10 bits long), that is then located and - written over by a last-bit-set empty stored block. - - Append the crc and length of the data in the gzip file (previously - calculated during the append operations). - - Write over the extra field with the updated stored block offsets, bits - back, crc's, and lengths, and mark foo.gz as in process for a replacement - of the dictionary. - @ Delete the foo.add file. - - Replace foo.dict with foo.temp. - - Write over the extra field, marking foo.gz as complete. - - Recovery procedure: - - If not a replace recovery, read in the foo.add file, and provide that data - to the appropriate recovery below. If there is no foo.add file, provide - a zero data length to the recovery. In that case, the append recovery - restores the foo.gz to the previous compressed + uncompressed data state. - For the the compress recovery, a missing foo.add file results in foo.gz - being restored to the previous compressed-only data state. - - Append recovery: - - Pick up append at + step above - - Compress recovery: - - Pick up compress at * step above - - Replace recovery: - - Pick up compress at @ step above - - Log the repair with a date stamp in foo.repairs - */ - -#include <sys/types.h> -#include <stdio.h> /* rename, fopen, fprintf, fclose */ -#include <stdlib.h> /* malloc, free */ -#include <string.h> /* strlen, strrchr, strcpy, strncpy, strcmp */ -#include <fcntl.h> /* open */ -#include <unistd.h> /* lseek, read, write, close, unlink, sleep, */ - /* ftruncate, fsync */ -#include <errno.h> /* errno */ -#include <time.h> /* time, ctime */ -#include <sys/stat.h> /* stat */ -#include <sys/time.h> /* utimes */ -#include "zlib.h" /* crc32 */ - -#include "gzlog.h" /* header for external access */ - -#define local static -typedef unsigned int uint; -typedef unsigned long ulong; - -/* Macro for debugging to deterministically force recovery operations */ -#ifdef DEBUG - #include <setjmp.h> /* longjmp */ - jmp_buf gzlog_jump; /* where to go back to */ - int gzlog_bail = 0; /* which point to bail at (1..8) */ - int gzlog_count = -1; /* number of times through to wait */ -# define BAIL(n) do { if (n == gzlog_bail && gzlog_count-- == 0) \ - longjmp(gzlog_jump, gzlog_bail); } while (0) -#else -# define BAIL(n) -#endif - -/* how old the lock file can be in seconds before considering it stale */ -#define PATIENCE 300 - -/* maximum stored block size in Kbytes -- must be in 1..63 */ -#define MAX_STORE 16 - -/* number of stored Kbytes to trigger compression (must be >= 32 to allow - dictionary construction, and <= 204 * MAX_STORE, in order for >> 10 to - discard the stored block headers contribution of five bytes each) */ -#define TRIGGER 1024 - -/* size of a deflate dictionary (this cannot be changed) */ -#define DICT 32768U - -/* values for the operation (2 bits) */ -#define NO_OP 0 -#define APPEND_OP 1 -#define COMPRESS_OP 2 -#define REPLACE_OP 3 - -/* macros to extract little-endian integers from an unsigned byte buffer */ -#define PULL2(p) ((p)[0]+((uint)((p)[1])<<8)) -#define PULL4(p) (PULL2(p)+((ulong)PULL2(p+2)<<16)) -#define PULL8(p) (PULL4(p)+((off_t)PULL4(p+4)<<32)) - -/* macros to store integers into a byte buffer in little-endian order */ -#define PUT2(p,a) do {(p)[0]=a;(p)[1]=(a)>>8;} while(0) -#define PUT4(p,a) do {PUT2(p,a);PUT2(p+2,a>>16);} while(0) -#define PUT8(p,a) do {PUT4(p,a);PUT4(p+4,a>>32);} while(0) - -/* internal structure for log information */ -#define LOGID "\106\035\172" /* should be three non-zero characters */ -struct log { - char id[4]; /* contains LOGID to detect inadvertent overwrites */ - int fd; /* file descriptor for .gz file, opened read/write */ - char *path; /* allocated path, e.g. "/var/log/foo" or "foo" */ - char *end; /* end of path, for appending suffices such as ".gz" */ - off_t first; /* offset of first stored block first length byte */ - int back; /* location of first block id in bits back from first */ - uint stored; /* bytes currently in last stored block */ - off_t last; /* offset of last stored block first length byte */ - ulong ccrc; /* crc of compressed data */ - ulong clen; /* length (modulo 2^32) of compressed data */ - ulong tcrc; /* crc of total data */ - ulong tlen; /* length (modulo 2^32) of total data */ - time_t lock; /* last modify time of our lock file */ -}; - -/* gzip header for gzlog */ -local unsigned char log_gzhead[] = { - 0x1f, 0x8b, /* magic gzip id */ - 8, /* compression method is deflate */ - 4, /* there is an extra field (no file name) */ - 0, 0, 0, 0, /* no modification time provided */ - 0, 0xff, /* no extra flags, no OS specified */ - 39, 0, 'a', 'p', 35, 0 /* extra field with "ap" subfield */ - /* 35 is EXTRA, 39 is EXTRA + 4 */ -}; - -#define HEAD sizeof(log_gzhead) /* should be 16 */ - -/* initial gzip extra field content (52 == HEAD + EXTRA + 1) */ -local unsigned char log_gzext[] = { - 52, 0, 0, 0, 0, 0, 0, 0, /* offset of first stored block length */ - 52, 0, 0, 0, 0, 0, 0, 0, /* offset of last stored block length */ - 0, 0, 0, 0, 0, 0, 0, 0, /* compressed data crc and length */ - 0, 0, 0, 0, 0, 0, 0, 0, /* total data crc and length */ - 0, 0, /* final stored block data length */ - 5 /* op is NO_OP, last bit 8 bits back */ -}; - -#define EXTRA sizeof(log_gzext) /* should be 35 */ - -/* initial gzip data and trailer */ -local unsigned char log_gzbody[] = { - 1, 0, 0, 0xff, 0xff, /* empty stored block (last) */ - 0, 0, 0, 0, /* crc */ - 0, 0, 0, 0 /* uncompressed length */ -}; - -#define BODY sizeof(log_gzbody) - -/* Exclusively create foo.lock in order to negotiate exclusive access to the - foo.* files. If the modify time of an existing lock file is greater than - PATIENCE seconds in the past, then consider the lock file to have been - abandoned, delete it, and try the exclusive create again. Save the lock - file modify time for verification of ownership. Return 0 on success, or -1 - on failure, usually due to an access restriction or invalid path. Note that - if stat() or unlink() fails, it may be due to another process noticing the - abandoned lock file a smidge sooner and deleting it, so those are not - flagged as an error. */ -local int log_lock(struct log *log) -{ - int fd; - struct stat st; - - strcpy(log->end, ".lock"); - while ((fd = open(log->path, O_CREAT | O_EXCL, 0644)) < 0) { - if (errno != EEXIST) - return -1; - if (stat(log->path, &st) == 0 && time(NULL) - st.st_mtime > PATIENCE) { - unlink(log->path); - continue; - } - sleep(2); /* relinquish the CPU for two seconds while waiting */ - } - close(fd); - if (stat(log->path, &st) == 0) - log->lock = st.st_mtime; - return 0; -} - -/* Update the modify time of the lock file to now, in order to prevent another - task from thinking that the lock is stale. Save the lock file modify time - for verification of ownership. */ -local void log_touch(struct log *log) -{ - struct stat st; - - strcpy(log->end, ".lock"); - utimes(log->path, NULL); - if (stat(log->path, &st) == 0) - log->lock = st.st_mtime; -} - -/* Check the log file modify time against what is expected. Return true if - this is not our lock. If it is our lock, touch it to keep it. */ -local int log_check(struct log *log) -{ - struct stat st; - - strcpy(log->end, ".lock"); - if (stat(log->path, &st) || st.st_mtime != log->lock) - return 1; - log_touch(log); - return 0; -} - -/* Unlock a previously acquired lock, but only if it's ours. */ -local void log_unlock(struct log *log) -{ - if (log_check(log)) - return; - strcpy(log->end, ".lock"); - unlink(log->path); - log->lock = 0; -} - -/* Check the gzip header and read in the extra field, filling in the values in - the log structure. Return op on success or -1 if the gzip header was not as - expected. op is the current operation in progress last written to the extra - field. This assumes that the gzip file has already been opened, with the - file descriptor log->fd. */ -local int log_head(struct log *log) -{ - int op; - unsigned char buf[HEAD + EXTRA]; - - if (lseek(log->fd, 0, SEEK_SET) < 0 || - read(log->fd, buf, HEAD + EXTRA) != HEAD + EXTRA || - memcmp(buf, log_gzhead, HEAD)) { - return -1; - } - log->first = PULL8(buf + HEAD); - log->last = PULL8(buf + HEAD + 8); - log->ccrc = PULL4(buf + HEAD + 16); - log->clen = PULL4(buf + HEAD + 20); - log->tcrc = PULL4(buf + HEAD + 24); - log->tlen = PULL4(buf + HEAD + 28); - log->stored = PULL2(buf + HEAD + 32); - log->back = 3 + (buf[HEAD + 34] & 7); - op = (buf[HEAD + 34] >> 3) & 3; - return op; -} - -/* Write over the extra field contents, marking the operation as op. Use fsync - to assure that the device is written to, and in the requested order. This - operation, and only this operation, is assumed to be atomic in order to - assure that the log is recoverable in the event of an interruption at any - point in the process. Return -1 if the write to foo.gz failed. */ -local int log_mark(struct log *log, int op) -{ - int ret; - unsigned char ext[EXTRA]; - - PUT8(ext, log->first); - PUT8(ext + 8, log->last); - PUT4(ext + 16, log->ccrc); - PUT4(ext + 20, log->clen); - PUT4(ext + 24, log->tcrc); - PUT4(ext + 28, log->tlen); - PUT2(ext + 32, log->stored); - ext[34] = log->back - 3 + (op << 3); - fsync(log->fd); - ret = lseek(log->fd, HEAD, SEEK_SET) < 0 || - write(log->fd, ext, EXTRA) != EXTRA ? -1 : 0; - fsync(log->fd); - return ret; -} - -/* Rewrite the last block header bits and subsequent zero bits to get to a byte - boundary, setting the last block bit if last is true, and then write the - remainder of the stored block header (length and one's complement). Leave - the file pointer after the end of the last stored block data. Return -1 if - there is a read or write failure on the foo.gz file */ -local int log_last(struct log *log, int last) -{ - int back, len, mask; - unsigned char buf[6]; - - /* determine the locations of the bytes and bits to modify */ - back = log->last == log->first ? log->back : 8; - len = back > 8 ? 2 : 1; /* bytes back from log->last */ - mask = 0x80 >> ((back - 1) & 7); /* mask for block last-bit */ - - /* get the byte to modify (one or two back) into buf[0] -- don't need to - read the byte if the last-bit is eight bits back, since in that case - the entire byte will be modified */ - buf[0] = 0; - if (back != 8 && (lseek(log->fd, log->last - len, SEEK_SET) < 0 || - read(log->fd, buf, 1) != 1)) - return -1; - - /* change the last-bit of the last stored block as requested -- note - that all bits above the last-bit are set to zero, per the type bits - of a stored block being 00 and per the convention that the bits to - bring the stream to a byte boundary are also zeros */ - buf[1] = 0; - buf[2 - len] = (*buf & (mask - 1)) + (last ? mask : 0); - - /* write the modified stored block header and lengths, move the file - pointer to after the last stored block data */ - PUT2(buf + 2, log->stored); - PUT2(buf + 4, log->stored ^ 0xffff); - return lseek(log->fd, log->last - len, SEEK_SET) < 0 || - write(log->fd, buf + 2 - len, len + 4) != len + 4 || - lseek(log->fd, log->stored, SEEK_CUR) < 0 ? -1 : 0; -} - -/* Append len bytes from data to the locked and open log file. len may be zero - if recovering and no .add file was found. In that case, the previous state - of the foo.gz file is restored. The data is appended uncompressed in - deflate stored blocks. Return -1 if there was an error reading or writing - the foo.gz file. */ -local int log_append(struct log *log, unsigned char *data, size_t len) -{ - uint put; - off_t end; - unsigned char buf[8]; - - /* set the last block last-bit and length, in case recovering an - interrupted append, then position the file pointer to append to the - block */ - if (log_last(log, 1)) - return -1; - - /* append, adding stored blocks and updating the offset of the last stored - block as needed, and update the total crc and length */ - while (len) { - /* append as much as we can to the last block */ - put = (MAX_STORE << 10) - log->stored; - if (put > len) - put = (uint)len; - if (put) { - if (write(log->fd, data, put) != put) - return -1; - BAIL(1); - log->tcrc = crc32(log->tcrc, data, put); - log->tlen += put; - log->stored += put; - data += put; - len -= put; - } - - /* if we need to, add a new empty stored block */ - if (len) { - /* mark current block as not last */ - if (log_last(log, 0)) - return -1; - - /* point to new, empty stored block */ - log->last += 4 + log->stored + 1; - log->stored = 0; - } - - /* mark last block as last, update its length */ - if (log_last(log, 1)) - return -1; - BAIL(2); - } - - /* write the new crc and length trailer, and truncate just in case (could - be recovering from partial append with a missing foo.add file) */ - PUT4(buf, log->tcrc); - PUT4(buf + 4, log->tlen); - if (write(log->fd, buf, 8) != 8 || - (end = lseek(log->fd, 0, SEEK_CUR)) < 0 || ftruncate(log->fd, end)) - return -1; - - /* write the extra field, marking the log file as done, delete .add file */ - if (log_mark(log, NO_OP)) - return -1; - strcpy(log->end, ".add"); - unlink(log->path); /* ignore error, since may not exist */ - return 0; -} - -/* Replace the foo.dict file with the foo.temp file. Also delete the foo.add - file, since the compress operation may have been interrupted before that was - done. Returns 1 if memory could not be allocated, or -1 if reading or - writing foo.gz fails, or if the rename fails for some reason other than - foo.temp not existing. foo.temp not existing is a permitted error, since - the replace operation may have been interrupted after the rename is done, - but before foo.gz is marked as complete. */ -local int log_replace(struct log *log) -{ - int ret; - char *dest; - - /* delete foo.add file */ - strcpy(log->end, ".add"); - unlink(log->path); /* ignore error, since may not exist */ - BAIL(3); - - /* rename foo.name to foo.dict, replacing foo.dict if it exists */ - strcpy(log->end, ".dict"); - dest = malloc(strlen(log->path) + 1); - if (dest == NULL) - return -2; - strcpy(dest, log->path); - strcpy(log->end, ".temp"); - ret = rename(log->path, dest); - free(dest); - if (ret && errno != ENOENT) - return -1; - BAIL(4); - - /* mark the foo.gz file as done */ - return log_mark(log, NO_OP); -} - -/* Compress the len bytes at data and append the compressed data to the - foo.gz deflate data immediately after the previous compressed data. This - overwrites the previous uncompressed data, which was stored in foo.add - and is the data provided in data[0..len-1]. If this operation is - interrupted, it picks up at the start of this routine, with the foo.add - file read in again. If there is no data to compress (len == 0), then we - simply terminate the foo.gz file after the previously compressed data, - appending a final empty stored block and the gzip trailer. Return -1 if - reading or writing the log.gz file failed, or -2 if there was a memory - allocation failure. */ -local int log_compress(struct log *log, unsigned char *data, size_t len) -{ - int fd; - uint got, max; - ssize_t dict; - off_t end; - z_stream strm; - unsigned char buf[DICT]; - - /* compress and append compressed data */ - if (len) { - /* set up for deflate, allocating memory */ - strm.zalloc = Z_NULL; - strm.zfree = Z_NULL; - strm.opaque = Z_NULL; - if (deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, -15, 8, - Z_DEFAULT_STRATEGY) != Z_OK) - return -2; - - /* read in dictionary (last 32K of data that was compressed) */ - strcpy(log->end, ".dict"); - fd = open(log->path, O_RDONLY, 0); - if (fd >= 0) { - dict = read(fd, buf, DICT); - close(fd); - if (dict < 0) { - deflateEnd(&strm); - return -1; - } - if (dict) - deflateSetDictionary(&strm, buf, (uint)dict); - } - log_touch(log); - - /* prime deflate with last bits of previous block, position write - pointer to write those bits and overwrite what follows */ - if (lseek(log->fd, log->first - (log->back > 8 ? 2 : 1), - SEEK_SET) < 0 || - read(log->fd, buf, 1) != 1 || lseek(log->fd, -1, SEEK_CUR) < 0) { - deflateEnd(&strm); - return -1; - } - deflatePrime(&strm, (8 - log->back) & 7, *buf); - - /* compress, finishing with a partial non-last empty static block */ - strm.next_in = data; - max = (((uint)0 - 1) >> 1) + 1; /* in case int smaller than size_t */ - do { - strm.avail_in = len > max ? max : (uint)len; - len -= strm.avail_in; - do { - strm.avail_out = DICT; - strm.next_out = buf; - deflate(&strm, len ? Z_NO_FLUSH : Z_PARTIAL_FLUSH); - got = DICT - strm.avail_out; - if (got && write(log->fd, buf, got) != got) { - deflateEnd(&strm); - return -1; - } - log_touch(log); - } while (strm.avail_out == 0); - } while (len); - deflateEnd(&strm); - BAIL(5); - - /* find start of empty static block -- scanning backwards the first one - bit is the second bit of the block, if the last byte is zero, then - we know the byte before that has a one in the top bit, since an - empty static block is ten bits long */ - if ((log->first = lseek(log->fd, -1, SEEK_CUR)) < 0 || - read(log->fd, buf, 1) != 1) - return -1; - log->first++; - if (*buf) { - log->back = 1; - while ((*buf & ((uint)1 << (8 - log->back++))) == 0) - ; /* guaranteed to terminate, since *buf != 0 */ - } - else - log->back = 10; - - /* update compressed crc and length */ - log->ccrc = log->tcrc; - log->clen = log->tlen; - } - else { - /* no data to compress -- fix up existing gzip stream */ - log->tcrc = log->ccrc; - log->tlen = log->clen; - } - - /* complete and truncate gzip stream */ - log->last = log->first; - log->stored = 0; - PUT4(buf, log->tcrc); - PUT4(buf + 4, log->tlen); - if (log_last(log, 1) || write(log->fd, buf, 8) != 8 || - (end = lseek(log->fd, 0, SEEK_CUR)) < 0 || ftruncate(log->fd, end)) - return -1; - BAIL(6); - - /* mark as being in the replace operation */ - if (log_mark(log, REPLACE_OP)) - return -1; - - /* execute the replace operation and mark the file as done */ - return log_replace(log); -} - -/* log a repair record to the .repairs file */ -local void log_log(struct log *log, int op, char *record) -{ - time_t now; - FILE *rec; - - now = time(NULL); - strcpy(log->end, ".repairs"); - rec = fopen(log->path, "a"); - if (rec == NULL) - return; - fprintf(rec, "%.24s %s recovery: %s\n", ctime(&now), op == APPEND_OP ? - "append" : (op == COMPRESS_OP ? "compress" : "replace"), record); - fclose(rec); - return; -} - -/* Recover the interrupted operation op. First read foo.add for recovering an - append or compress operation. Return -1 if there was an error reading or - writing foo.gz or reading an existing foo.add, or -2 if there was a memory - allocation failure. */ -local int log_recover(struct log *log, int op) -{ - int fd, ret = 0; - unsigned char *data = NULL; - size_t len = 0; - struct stat st; - - /* log recovery */ - log_log(log, op, "start"); - - /* load foo.add file if expected and present */ - if (op == APPEND_OP || op == COMPRESS_OP) { - strcpy(log->end, ".add"); - if (stat(log->path, &st) == 0 && st.st_size) { - len = (size_t)(st.st_size); - if (len != st.st_size || (data = malloc(st.st_size)) == NULL) { - log_log(log, op, "allocation failure"); - return -2; - } - if ((fd = open(log->path, O_RDONLY, 0)) < 0) { - log_log(log, op, ".add file read failure"); - return -1; - } - ret = read(fd, data, len) != len; - close(fd); - if (ret) { - log_log(log, op, ".add file read failure"); - return -1; - } - log_log(log, op, "loaded .add file"); - } - else - log_log(log, op, "missing .add file!"); - } - - /* recover the interrupted operation */ - switch (op) { - case APPEND_OP: - ret = log_append(log, data, len); - break; - case COMPRESS_OP: - ret = log_compress(log, data, len); - break; - case REPLACE_OP: - ret = log_replace(log); - } - - /* log status */ - log_log(log, op, ret ? "failure" : "complete"); - - /* clean up */ - if (data != NULL) - free(data); - return ret; -} - -/* Close the foo.gz file (if open) and release the lock. */ -local void log_close(struct log *log) -{ - if (log->fd >= 0) - close(log->fd); - log->fd = -1; - log_unlock(log); -} - -/* Open foo.gz, verify the header, and load the extra field contents, after - first creating the foo.lock file to gain exclusive access to the foo.* - files. If foo.gz does not exist or is empty, then write the initial header, - extra, and body content of an empty foo.gz log file. If there is an error - creating the lock file due to access restrictions, or an error reading or - writing the foo.gz file, or if the foo.gz file is not a proper log file for - this object (e.g. not a gzip file or does not contain the expected extra - field), then return true. If there is an error, the lock is released. - Otherwise, the lock is left in place. */ -local int log_open(struct log *log) -{ - int op; - - /* release open file resource if left over -- can occur if lock lost - between gzlog_open() and gzlog_write() */ - if (log->fd >= 0) - close(log->fd); - log->fd = -1; - - /* negotiate exclusive access */ - if (log_lock(log) < 0) - return -1; - - /* open the log file, foo.gz */ - strcpy(log->end, ".gz"); - log->fd = open(log->path, O_RDWR | O_CREAT, 0644); - if (log->fd < 0) { - log_close(log); - return -1; - } - - /* if new, initialize foo.gz with an empty log, delete old dictionary */ - if (lseek(log->fd, 0, SEEK_END) == 0) { - if (write(log->fd, log_gzhead, HEAD) != HEAD || - write(log->fd, log_gzext, EXTRA) != EXTRA || - write(log->fd, log_gzbody, BODY) != BODY) { - log_close(log); - return -1; - } - strcpy(log->end, ".dict"); - unlink(log->path); - } - - /* verify log file and load extra field information */ - if ((op = log_head(log)) < 0) { - log_close(log); - return -1; - } - - /* check for interrupted process and if so, recover */ - if (op != NO_OP && log_recover(log, op)) { - log_close(log); - return -1; - } - - /* touch the lock file to prevent another process from grabbing it */ - log_touch(log); - return 0; -} - -/* See gzlog.h for the description of the external methods below */ -gzlog *gzlog_open(char *path) -{ - size_t n; - struct log *log; - - /* check arguments */ - if (path == NULL || *path == 0) - return NULL; - - /* allocate and initialize log structure */ - log = malloc(sizeof(struct log)); - if (log == NULL) - return NULL; - strcpy(log->id, LOGID); - log->fd = -1; - - /* save path and end of path for name construction */ - n = strlen(path); - log->path = malloc(n + 9); /* allow for ".repairs" */ - if (log->path == NULL) { - free(log); - return NULL; - } - strcpy(log->path, path); - log->end = log->path + n; - - /* gain exclusive access and verify log file -- may perform a - recovery operation if needed */ - if (log_open(log)) { - free(log->path); - free(log); - return NULL; - } - - /* return pointer to log structure */ - return log; -} - -/* gzlog_compress() return values: - 0: all good - -1: file i/o error (usually access issue) - -2: memory allocation failure - -3: invalid log pointer argument */ -int gzlog_compress(gzlog *logd) -{ - int fd, ret; - uint block; - size_t len, next; - unsigned char *data, buf[5]; - struct log *log = logd; - - /* check arguments */ - if (log == NULL || strcmp(log->id, LOGID) || len < 0) - return -3; - - /* see if we lost the lock -- if so get it again and reload the extra - field information (it probably changed), recover last operation if - necessary */ - if (log_check(log) && log_open(log)) - return -1; - - /* create space for uncompressed data */ - len = ((size_t)(log->last - log->first) & ~(((size_t)1 << 10) - 1)) + - log->stored; - if ((data = malloc(len)) == NULL) - return -2; - - /* do statement here is just a cheap trick for error handling */ - do { - /* read in the uncompressed data */ - if (lseek(log->fd, log->first - 1, SEEK_SET) < 0) - break; - next = 0; - while (next < len) { - if (read(log->fd, buf, 5) != 5) - break; - block = PULL2(buf + 1); - if (next + block > len || - read(log->fd, (char *)data + next, block) != block) - break; - next += block; - } - if (lseek(log->fd, 0, SEEK_CUR) != log->last + 4 + log->stored) - break; - log_touch(log); - - /* write the uncompressed data to the .add file */ - strcpy(log->end, ".add"); - fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); - if (fd < 0) - break; - ret = write(fd, data, len) != len; - if (ret | close(fd)) - break; - log_touch(log); - - /* write the dictionary for the next compress to the .temp file */ - strcpy(log->end, ".temp"); - fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); - if (fd < 0) - break; - next = DICT > len ? len : DICT; - ret = write(fd, (char *)data + len - next, next) != next; - if (ret | close(fd)) - break; - log_touch(log); - - /* roll back to compressed data, mark the compress in progress */ - log->last = log->first; - log->stored = 0; - if (log_mark(log, COMPRESS_OP)) - break; - BAIL(7); - - /* compress and append the data (clears mark) */ - ret = log_compress(log, data, len); - free(data); - return ret; - } while (0); - - /* broke out of do above on i/o error */ - free(data); - return -1; -} - -/* gzlog_write() return values: - 0: all good - -1: file i/o error (usually access issue) - -2: memory allocation failure - -3: invalid log pointer argument */ -int gzlog_write(gzlog *logd, void *data, size_t len) -{ - int fd, ret; - struct log *log = logd; - - /* check arguments */ - if (log == NULL || strcmp(log->id, LOGID) || len < 0) - return -3; - if (data == NULL || len == 0) - return 0; - - /* see if we lost the lock -- if so get it again and reload the extra - field information (it probably changed), recover last operation if - necessary */ - if (log_check(log) && log_open(log)) - return -1; - - /* create and write .add file */ - strcpy(log->end, ".add"); - fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); - if (fd < 0) - return -1; - ret = write(fd, data, len) != len; - if (ret | close(fd)) - return -1; - log_touch(log); - - /* mark log file with append in progress */ - if (log_mark(log, APPEND_OP)) - return -1; - BAIL(8); - - /* append data (clears mark) */ - if (log_append(log, data, len)) - return -1; - - /* check to see if it's time to compress -- if not, then done */ - if (((log->last - log->first) >> 10) + (log->stored >> 10) < TRIGGER) - return 0; - - /* time to compress */ - return gzlog_compress(log); -} - -/* gzlog_close() return values: - 0: ok - -3: invalid log pointer argument */ -int gzlog_close(gzlog *logd) -{ - struct log *log = logd; - - /* check arguments */ - if (log == NULL || strcmp(log->id, LOGID)) - return -3; - - /* close the log file and release the lock */ - log_close(log); - - /* free structure and return */ - if (log->path != NULL) - free(log->path); - strcpy(log->id, "bad"); - free(log); - return 0; -} |