+++ /dev/null
-/*
- * gzlog.c
- * Copyright (C) 2004, 2008, 2012 Mark Adler, all rights reserved
- * For conditions of distribution and use, see copyright notice in gzlog.h
- * version 2.2, 14 Aug 2012
- */
-
-/*
- 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 ((off_t)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 = (size_t)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))
- 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 = (size_t)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 = (size_t)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))
- 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 = (size_t)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;
-}
projects / ossec-hids.git / blobdiff