CbC/CbC_gcc: zlib/examples/gzlog.c comparison

comparison zlib/examples/gzlog.c @ 111:04ced10e8804

gcc 7

author	kono
date	Fri, 27 Oct 2017 22:46:09 +0900
parents	ae3a4bfb450b
children

comparison

equal deleted inserted replaced

-:561a7518be6b
+:04ced10e8804
 /*
 * gzlog.c
-* Copyright (C) 2004 Mark Adler
+* Copyright (C) 2004, 2008, 2012, 2016 Mark Adler, all rights reserved
 * For conditions of distribution and use, see copyright notice in gzlog.h
-* version 1.0, 26 Nov 2004
+* version 2.2, 14 Aug 2012
-*
 */
-#include <string.h>             /* memcmp() */
+/*
-#include <stdlib.h>             /* malloc(), free(), NULL */
+gzlog provides a mechanism for frequently appending short strings to a gzip
-#include <sys/types.h>          /* size_t, off_t */
+file that is efficient both in execution time and compression ratio.  The
-#include <unistd.h>             /* read(), close(), sleep(), ftruncate(), */
+strategy is to write the short strings in an uncompressed form to the end of
-/* lseek() */
+the gzip file, only compressing when the amount of uncompressed data has
-#include <fcntl.h>              /* open() */
+reached a given threshold.
-#include <sys/file.h>           /* flock() */
-#include "zlib.h"               /* deflateInit2(), deflate(), deflateEnd() */
+gzlog also provides protection against interruptions in the process due to
+system crashes.  The status of the operation is recorded in an extra field
-#include "gzlog.h"              /* interface */
+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;
-/* log object structure */
+typedef unsigned long ulong;
-typedef struct {
-int id;                 /* object identifier */
+/* Macro for debugging to deterministically force recovery operations */
-int fd;                 /* log file descriptor */
+#ifdef GZLOG_DEBUG
-off_t extra;            /* offset of extra "ap" subfield */
+#include <setjmp.h>         /* longjmp */
-off_t mark_off;         /* offset of marked data */
+jmp_buf gzlog_jump;         /* where to go back to */
-off_t last_off;         /* offset of last block */
+int gzlog_bail = 0;         /* which point to bail at (1..8) */
-unsigned long crc;      /* uncompressed crc */
+int gzlog_count = -1;       /* number of times through to wait */
-unsigned long len;      /* uncompressed length (modulo 2^32) */
+#   define BAIL(n) do { if (n == gzlog_bail && gzlog_count-- == 0) \
-unsigned stored;        /* length of current stored block */
+longjmp(gzlog_jump, gzlog_bail); } while (0)
-} gz_log;
+#else
+#   define BAIL(n)
-#define GZLOGID 19334       /* gz_log object identifier */
+#endif
-#define LOCK_RETRY 1            /* retry lock once a second */
+/* how old the lock file can be in seconds before considering it stale */
-#define LOCK_PATIENCE 1200      /* try about twenty minutes before forcing */
+#define PATIENCE 300
-/* acquire a lock on a file */
+/* maximum stored block size in Kbytes -- must be in 1..63 */
-local int lock(int fd)
+#define MAX_STORE 16
-{
-int patience;
+/* number of stored Kbytes to trigger compression (must be >= 32 to allow
+dictionary construction, and <= 204 * MAX_STORE, in order for >> 10 to
-/* try to lock every LOCK_RETRY seconds for LOCK_PATIENCE seconds */
+discard the stored block headers contribution of five bytes each) */
-patience = LOCK_PATIENCE;
+#define TRIGGER 1024
-do {
-if (flock(fd, LOCK_EX + LOCK_NB) == 0)
+/* size of a deflate dictionary (this cannot be changed) */
-return 0;
+#define DICT 32768U
-(void)sleep(LOCK_RETRY);
-patience -= LOCK_RETRY;
+/* values for the operation (2 bits) */
-} while (patience > 0);
+#define NO_OP 0
+#define APPEND_OP 1
-/* we've run out of patience -- give up */
+#define COMPRESS_OP 2
-return -1;
+#define REPLACE_OP 3
-}
+/* macros to extract little-endian integers from an unsigned byte buffer */
-/* release lock */
+#define PULL2(p) ((p)[0]+((uint)((p)[1])<<8))
-local void unlock(int fd)
+#define PULL4(p) (PULL2(p)+((ulong)PULL2(p+2)<<16))
-{
+#define PULL8(p) (PULL4(p)+((off_t)PULL4(p+4)<<32))
-(void)flock(fd, LOCK_UN);
-}
+/* 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)
-/* release a log object */
+#define PUT4(p,a) do {PUT2(p,a);PUT2(p+2,a>>16);} while(0)
-local void log_clean(gz_log *log)
+#define PUT8(p,a) do {PUT4(p,a);PUT4(p+4,a>>32);} while(0)
-{
-unlock(log->fd);
+/* internal structure for log information */
-(void)close(log->fd);
+#define LOGID "\106\035\172"    /* should be three non-zero characters */
-free(log);
+struct log {
-}
+char id[4];     /* contains LOGID to detect inadvertent overwrites */
+int fd;         /* file descriptor for .gz file, opened read/write */
-/* read an unsigned long from a byte buffer little-endian */
+char *path;     /* allocated path, e.g. "/var/log/foo" or "foo" */
-local unsigned long make_ulg(unsigned char *buf)
+char *end;      /* end of path, for appending suffices such as ".gz" */
-{
+off_t first;    /* offset of first stored block first length byte */
-int n;
+int back;       /* location of first block id in bits back from first */
-unsigned long val;
+uint stored;    /* bytes currently in last stored block */
+off_t last;     /* offset of last stored block first length byte */
-val = (unsigned long)(*buf++);
+ulong ccrc;     /* crc of compressed data */
-for (n = 8; n < 32; n += 8)
+ulong clen;     /* length (modulo 2^32) of compressed data */
-val += (unsigned long)(*buf++) << n;
+ulong tcrc;     /* crc of total data */
-return val;
+ulong tlen;     /* length (modulo 2^32) of total data */
-}
+time_t lock;    /* last modify time of our lock file */
+};
-/* read an off_t from a byte buffer little-endian */
-local off_t make_off(unsigned char *buf)
+/* gzip header for gzlog */
-{
+local unsigned char log_gzhead[] = {
-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 */
+4,                          /* there is an extra field (no file name) */
 0, 0, 0, 0,                 /* no modification time provided */
-0, 0xff,                    /* no extra flags, no OS */
+0, 0xff,                    /* no extra flags, no OS specified */
-20, 0, 'a', 'p', 16, 0,     /* extra field with "ap" subfield */
+39, 0, 'a', 'p', 35, 0      /* extra field with "ap" subfield */
-32, 0, 0, 0, 0, 0, 0, 0,    /* offset of uncompressed data */
+/* 35 is EXTRA, 39 is EXTRA + 4 */
-32, 0, 0, 0, 0, 0, 0, 0,    /* offset of last block */
+};
+#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 */
 };
-/* initialize a log object with locking */
+#define BODY sizeof(log_gzbody)
-void *gzlog_open(char *path)
-{
+/* Exclusively create foo.lock in order to negotiate exclusive access to the
-unsigned xlen;
+foo.* files.  If the modify time of an existing lock file is greater than
-unsigned char temp[20];
+PATIENCE seconds in the past, then consider the lock file to have been
-unsigned sub_len;
+abandoned, delete it, and try the exclusive create again.  Save the lock
-int good;
+file modify time for verification of ownership.  Return 0 on success, or -1
-gz_log *log;
+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
-/* allocate log structure */
+abandoned lock file a smidge sooner and deleting it, so those are not
-log = malloc(sizeof(gz_log));
+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;
-log->id = GZLOGID;
+strcpy(log->id, LOGID);
+log->fd = -1;
-/* open file, creating it if necessary, and locking it */
-log->fd = open(path, O_RDWR | O_CREAT, 0600);
+/* save path and end of path for name construction */
-if (log->fd < 0) {
+n = strlen(path);
+log->path = malloc(n + 9);              /* allow for ".repairs" */
+if (log->path == NULL) {
 free(log);
 return NULL;
 }
-if (lock(log->fd)) {
+strcpy(log->path, path);
-close(log->fd);
+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;
 }
-/* if file is empty, write new gzip stream */
+/* return pointer to log structure */
-if (lseek(log->fd, 0, SEEK_END) == 0) {
+return log;
-if (write(log->fd, empty_gz, sizeof(empty_gz)) != sizeof(empty_gz)) {
+}
-log_clean(log);
-return NULL;
+/* 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)
-/* 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];
+log_touch(log);
-sub_len += temp[3] << 8;
-xlen -= 4;
+/* write the uncompressed data to the .add file */
-if (memcmp(temp, "ap", 2) == 0 && sub_len == 16) {
+strcpy(log->end, ".add");
-good = 1;
+fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+if (fd < 0)
 break;
-}
+ret = (size_t)write(fd, data, len) != len;
-if (xlen < sub_len)
+if (ret | close(fd))
 break;
-(void)lseek(log->fd, sub_len, SEEK_CUR);
+log_touch(log);
-xlen -= sub_len;
-}
+/* write the dictionary for the next compress to the .temp file */
-if (!good) {
+strcpy(log->end, ".temp");
-log_clean(log);
+fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
-return NULL;
+if (fd < 0)
-}
+break;
+next = DICT > len ? len : DICT;
-/* read in "ap" sub-field */
+ret = (size_t)write(fd, (char *)data + len - next, next) != next;
-log->extra = lseek(log->fd, 0, SEEK_CUR);
+if (ret | close(fd))
-if (read(log->fd, temp, 16) != 16) {
+break;
-log_clean(log);
+log_touch(log);
-return NULL;
-}
+/* roll back to compressed data, mark the compress in progress */
-log->mark_off = make_off(temp);
+log->last = log->first;
-log->last_off = make_off(temp + 8);
+log->stored = 0;
+if (log_mark(log, COMPRESS_OP))
-/* get crc, length of gzip file */
+break;
-(void)lseek(log->fd, log->last_off, SEEK_SET);
+BAIL(7);
-if (read(log->fd, temp, 13) != 13 ||
-memcmp(temp, "\001\000\000\377\377", 5) != 0) {
+/* compress and append the data (clears mark) */
-log_clean(log);
+ret = log_compress(log, data, len);
-return NULL;
+free(data);
-}
+return ret;
-log->crc = make_ulg(temp + 5);
+} while (0);
-log->len = make_ulg(temp + 9);
+/* broke out of do above on i/o error */
-/* set up to write over empty last block */
+free(data);
-(void)lseek(log->fd, log->last_off + 5, SEEK_SET);
+return -1;
-log->stored = 0;
+}
-return (void *)log;
-}
+/* gzlog_write() return values:
+0: all good
-/* maximum amount to put in a stored block before starting a new one */
+-1: file i/o error (usually access issue)
-#define MAX_BLOCK 16384
+-2: memory allocation failure
+-3: invalid log pointer argument */
-/* write a block to a log object */
+int gzlog_write(gzlog *logd, void *data, size_t len)
-int gzlog_write(void *obj, char *data, size_t len)
+{
-{
+int fd, ret;
-size_t some;
+struct log *log = logd;
-unsigned char temp[5];
-gz_log *log;
+/* check arguments */
+if (log == NULL || strcmp(log->id, LOGID))
-/* check object */
+return -3;
-log = (gz_log *)obj;
+if (data == NULL || len <= 0)
-if (log == NULL || log->id != GZLOGID)
+return 0;
-return 1;
+/* see if we lost the lock -- if so get it again and reload the extra
-/* write stored blocks until all of the input is written */
+field information (it probably changed), recover last operation if
-do {
+necessary */
-some = MAX_BLOCK - log->stored;
+if (log_check(log) && log_open(log))
-if (some > len)
+return -1;
-some = len;
-if (write(log->fd, data, some) != some)
+/* create and write .add file */
-return 1;
+strcpy(log->end, ".add");
-log->crc = crc32(log->crc, data, some);
+fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
-log->len += some;
+if (fd < 0)
-len -= some;
+return -1;
-data += some;
+ret = (size_t)write(fd, data, len) != len;
-log->stored += some;
+if (ret | close(fd))
+return -1;
-/* if the stored block is full, end it and start another */
+log_touch(log);
-if (log->stored == MAX_BLOCK) {
-(void)lseek(log->fd, log->last_off, SEEK_SET);
+/* mark log file with append in progress */
-temp[0] = 0;
+if (log_mark(log, APPEND_OP))
-dice_ulg(log->stored + ((unsigned long)(~log->stored) << 16),
+return -1;
-temp + 1);
+BAIL(8);
-if (write(log->fd, temp, 5) != 5)
-return 1;
+/* append data (clears mark) */
-log->last_off = lseek(log->fd, log->stored, SEEK_CUR);
+if (log_append(log, data, len))
-(void)lseek(log->fd, 5, SEEK_CUR);
+return -1;
-log->stored = 0;
-}
+/* check to see if it's time to compress -- if not, then done */
-} while (len);
+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;
 }
-/* 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;
-}

Mercurial > hg > CbC > CbC_gcc

comparison zlib/examples/gzlog.c @ 111:04ced10e8804