| 1 | /* |
| 2 | * gzlog.c |
| 3 | * Copyright (C) 2004, 2008, 2012, 2016, 2019 Mark Adler, all rights reserved |
| 4 | * For conditions of distribution and use, see copyright notice in gzlog.h |
| 5 | * version 2.3, 25 May 2019 |
| 6 | */ |
| 7 | |
| 8 | /* |
| 9 | gzlog provides a mechanism for frequently appending short strings to a gzip |
| 10 | file that is efficient both in execution time and compression ratio. The |
| 11 | strategy is to write the short strings in an uncompressed form to the end of |
| 12 | the gzip file, only compressing when the amount of uncompressed data has |
| 13 | reached a given threshold. |
| 14 | |
| 15 | gzlog also provides protection against interruptions in the process due to |
| 16 | system crashes. The status of the operation is recorded in an extra field |
| 17 | in the gzip file, and is only updated once the gzip file is brought to a |
| 18 | valid state. The last data to be appended or compressed is saved in an |
| 19 | auxiliary file, so that if the operation is interrupted, it can be completed |
| 20 | the next time an append operation is attempted. |
| 21 | |
| 22 | gzlog maintains another auxiliary file with the last 32K of data from the |
| 23 | compressed portion, which is preloaded for the compression of the subsequent |
| 24 | data. This minimizes the impact to the compression ratio of appending. |
| 25 | */ |
| 26 | |
| 27 | /* |
| 28 | Operations Concept: |
| 29 | |
| 30 | Files (log name "foo"): |
| 31 | foo.gz -- gzip file with the complete log |
| 32 | foo.add -- last message to append or last data to compress |
| 33 | foo.dict -- dictionary of the last 32K of data for next compression |
| 34 | foo.temp -- temporary dictionary file for compression after this one |
| 35 | foo.lock -- lock file for reading and writing the other files |
| 36 | foo.repairs -- log file for log file recovery operations (not compressed) |
| 37 | |
| 38 | gzip file structure: |
| 39 | - fixed-length (no file name) header with extra field (see below) |
| 40 | - compressed data ending initially with empty stored block |
| 41 | - uncompressed data filling out originally empty stored block and |
| 42 | subsequent stored blocks as needed (16K max each) |
| 43 | - gzip trailer |
| 44 | - no junk at end (no other gzip streams) |
| 45 | |
| 46 | When appending data, the information in the first three items above plus the |
| 47 | foo.add file are sufficient to recover an interrupted append operation. The |
| 48 | extra field has the necessary information to restore the start of the last |
| 49 | stored block and determine where to append the data in the foo.add file, as |
| 50 | well as the crc and length of the gzip data before the append operation. |
| 51 | |
| 52 | The foo.add file is created before the gzip file is marked for append, and |
| 53 | deleted after the gzip file is marked as complete. So if the append |
| 54 | operation is interrupted, the data to add will still be there. If due to |
| 55 | some external force, the foo.add file gets deleted between when the append |
| 56 | operation was interrupted and when recovery is attempted, the gzip file will |
| 57 | still be restored, but without the appended data. |
| 58 | |
| 59 | When compressing data, the information in the first two items above plus the |
| 60 | foo.add file are sufficient to recover an interrupted compress operation. |
| 61 | The extra field has the necessary information to find the end of the |
| 62 | compressed data, and contains both the crc and length of just the compressed |
| 63 | data and of the complete set of data including the contents of the foo.add |
| 64 | file. |
| 65 | |
| 66 | Again, the foo.add file is maintained during the compress operation in case |
| 67 | of an interruption. If in the unlikely event the foo.add file with the data |
| 68 | to be compressed is missing due to some external force, a gzip file with |
| 69 | just the previous compressed data will be reconstructed. In this case, all |
| 70 | of the data that was to be compressed is lost (approximately one megabyte). |
| 71 | This will not occur if all that happened was an interruption of the compress |
| 72 | operation. |
| 73 | |
| 74 | The third state that is marked is the replacement of the old dictionary with |
| 75 | the new dictionary after a compress operation. Once compression is |
| 76 | complete, the gzip file is marked as being in the replace state. This |
| 77 | completes the gzip file, so an interrupt after being so marked does not |
| 78 | result in recompression. Then the dictionary file is replaced, and the gzip |
| 79 | file is marked as completed. This state prevents the possibility of |
| 80 | restarting compression with the wrong dictionary file. |
| 81 | |
| 82 | All three operations are wrapped by a lock/unlock procedure. In order to |
| 83 | gain exclusive access to the log files, first a foo.lock file must be |
| 84 | exclusively created. When all operations are complete, the lock is |
| 85 | released by deleting the foo.lock file. If when attempting to create the |
| 86 | lock file, it already exists and the modify time of the lock file is more |
| 87 | than five minutes old (set by the PATIENCE define below), then the old |
| 88 | lock file is considered stale and deleted, and the exclusive creation of |
| 89 | the lock file is retried. To assure that there are no false assessments |
| 90 | of the staleness of the lock file, the operations periodically touch the |
| 91 | lock file to update the modified date. |
| 92 | |
| 93 | Following is the definition of the extra field with all of the information |
| 94 | required to enable the above append and compress operations and their |
| 95 | recovery if interrupted. Multi-byte values are stored little endian |
| 96 | (consistent with the gzip format). File pointers are eight bytes long. |
| 97 | The crc's and lengths for the gzip trailer are four bytes long. (Note that |
| 98 | the length at the end of a gzip file is used for error checking only, and |
| 99 | for large files is actually the length modulo 2^32.) The stored block |
| 100 | length is two bytes long. The gzip extra field two-byte identification is |
| 101 | "ap" for append. It is assumed that writing the extra field to the file is |
| 102 | an "atomic" operation. That is, either all of the extra field is written |
| 103 | to the file, or none of it is, if the operation is interrupted right at the |
| 104 | point of updating the extra field. This is a reasonable assumption, since |
| 105 | the extra field is within the first 52 bytes of the file, which is smaller |
| 106 | than any expected block size for a mass storage device (usually 512 bytes or |
| 107 | larger). |
| 108 | |
| 109 | Extra field (35 bytes): |
| 110 | - Pointer to first stored block length -- this points to the two-byte length |
| 111 | of the first stored block, which is followed by the two-byte, one's |
| 112 | complement of that length. The stored block length is preceded by the |
| 113 | three-bit header of the stored block, which is the actual start of the |
| 114 | stored block in the deflate format. See the bit offset field below. |
| 115 | - Pointer to the last stored block length. This is the same as above, but |
| 116 | for the last stored block of the uncompressed data in the gzip file. |
| 117 | Initially this is the same as the first stored block length pointer. |
| 118 | When the stored block gets to 16K (see the MAX_STORE define), then a new |
| 119 | stored block as added, at which point the last stored block length pointer |
| 120 | is different from the first stored block length pointer. When they are |
| 121 | different, the first bit of the last stored block header is eight bits, or |
| 122 | one byte back from the block length. |
| 123 | - Compressed data crc and length. This is the crc and length of the data |
| 124 | that is in the compressed portion of the deflate stream. These are used |
| 125 | only in the event that the foo.add file containing the data to compress is |
| 126 | lost after a compress operation is interrupted. |
| 127 | - Total data crc and length. This is the crc and length of all of the data |
| 128 | stored in the gzip file, compressed and uncompressed. It is used to |
| 129 | reconstruct the gzip trailer when compressing, as well as when recovering |
| 130 | interrupted operations. |
| 131 | - Final stored block length. This is used to quickly find where to append, |
| 132 | and allows the restoration of the original final stored block state when |
| 133 | an append operation is interrupted. |
| 134 | - First stored block start as the number of bits back from the final stored |
| 135 | block first length byte. This value is in the range of 3..10, and is |
| 136 | stored as the low three bits of the final byte of the extra field after |
| 137 | subtracting three (0..7). This allows the last-block bit of the stored |
| 138 | block header to be updated when a new stored block is added, for the case |
| 139 | when the first stored block and the last stored block are the same. (When |
| 140 | they are different, the numbers of bits back is known to be eight.) This |
| 141 | also allows for new compressed data to be appended to the old compressed |
| 142 | data in the compress operation, overwriting the previous first stored |
| 143 | block, or for the compressed data to be terminated and a valid gzip file |
| 144 | reconstructed on the off chance that a compression operation was |
| 145 | interrupted and the data to compress in the foo.add file was deleted. |
| 146 | - The operation in process. This is the next two bits in the last byte (the |
| 147 | bits under the mask 0x18). The are interpreted as 0: nothing in process, |
| 148 | 1: append in process, 2: compress in process, 3: replace in process. |
| 149 | - The top three bits of the last byte in the extra field are reserved and |
| 150 | are currently set to zero. |
| 151 | |
| 152 | Main procedure: |
| 153 | - Exclusively create the foo.lock file using the O_CREAT and O_EXCL modes of |
| 154 | the system open() call. If the modify time of an existing lock file is |
| 155 | more than PATIENCE seconds old, then the lock file is deleted and the |
| 156 | exclusive create is retried. |
| 157 | - Load the extra field from the foo.gz file, and see if an operation was in |
| 158 | progress but not completed. If so, apply the recovery procedure below. |
| 159 | - Perform the append procedure with the provided data. |
| 160 | - If the uncompressed data in the foo.gz file is 1MB or more, apply the |
| 161 | compress procedure. |
| 162 | - Delete the foo.lock file. |
| 163 | |
| 164 | Append procedure: |
| 165 | - Put what to append in the foo.add file so that the operation can be |
| 166 | restarted if this procedure is interrupted. |
| 167 | - Mark the foo.gz extra field with the append operation in progress. |
| 168 | + Restore the original last-block bit and stored block length of the last |
| 169 | stored block from the information in the extra field, in case a previous |
| 170 | append operation was interrupted. |
| 171 | - Append the provided data to the last stored block, creating new stored |
| 172 | blocks as needed and updating the stored blocks last-block bits and |
| 173 | lengths. |
| 174 | - Update the crc and length with the new data, and write the gzip trailer. |
| 175 | - Write over the extra field (with a single write operation) with the new |
| 176 | pointers, lengths, and crc's, and mark the gzip file as not in process. |
| 177 | Though there is still a foo.add file, it will be ignored since nothing |
| 178 | is in process. If a foo.add file is leftover from a previously |
| 179 | completed operation, it is truncated when writing new data to it. |
| 180 | - Delete the foo.add file. |
| 181 | |
| 182 | Compress and replace procedures: |
| 183 | - Read all of the uncompressed data in the stored blocks in foo.gz and write |
| 184 | it to foo.add. Also write foo.temp with the last 32K of that data to |
| 185 | provide a dictionary for the next invocation of this procedure. |
| 186 | - Rewrite the extra field marking foo.gz with a compression in process. |
| 187 | * If there is no data provided to compress (due to a missing foo.add file |
| 188 | when recovering), reconstruct and truncate the foo.gz file to contain |
| 189 | only the previous compressed data and proceed to the step after the next |
| 190 | one. Otherwise ... |
| 191 | - Compress the data with the dictionary in foo.dict, and write to the |
| 192 | foo.gz file starting at the bit immediately following the last previously |
| 193 | compressed block. If there is no foo.dict, proceed anyway with the |
| 194 | compression at slightly reduced efficiency. (For the foo.dict file to be |
| 195 | missing requires some external failure beyond simply the interruption of |
| 196 | a compress operation.) During this process, the foo.lock file is |
| 197 | periodically touched to assure that that file is not considered stale by |
| 198 | another process before we're done. The deflation is terminated with a |
| 199 | non-last empty static block (10 bits long), that is then located and |
| 200 | written over by a last-bit-set empty stored block. |
| 201 | - Append the crc and length of the data in the gzip file (previously |
| 202 | calculated during the append operations). |
| 203 | - Write over the extra field with the updated stored block offsets, bits |
| 204 | back, crc's, and lengths, and mark foo.gz as in process for a replacement |
| 205 | of the dictionary. |
| 206 | @ Delete the foo.add file. |
| 207 | - Replace foo.dict with foo.temp. |
| 208 | - Write over the extra field, marking foo.gz as complete. |
| 209 | |
| 210 | Recovery procedure: |
| 211 | - If not a replace recovery, read in the foo.add file, and provide that data |
| 212 | to the appropriate recovery below. If there is no foo.add file, provide |
| 213 | a zero data length to the recovery. In that case, the append recovery |
| 214 | restores the foo.gz to the previous compressed + uncompressed data state. |
| 215 | For the the compress recovery, a missing foo.add file results in foo.gz |
| 216 | being restored to the previous compressed-only data state. |
| 217 | - Append recovery: |
| 218 | - Pick up append at + step above |
| 219 | - Compress recovery: |
| 220 | - Pick up compress at * step above |
| 221 | - Replace recovery: |
| 222 | - Pick up compress at @ step above |
| 223 | - Log the repair with a date stamp in foo.repairs |
| 224 | */ |
| 225 | |
| 226 | #include <sys/types.h> |
| 227 | #include <stdio.h> /* rename, fopen, fprintf, fclose */ |
| 228 | #include <stdlib.h> /* malloc, free */ |
| 229 | #include <string.h> /* strlen, strrchr, strcpy, strncpy, strcmp */ |
| 230 | #include <fcntl.h> /* open */ |
| 231 | #include <unistd.h> /* lseek, read, write, close, unlink, sleep, */ |
| 232 | /* ftruncate, fsync */ |
| 233 | #include <errno.h> /* errno */ |
| 234 | #include <time.h> /* time, ctime */ |
| 235 | #include <sys/stat.h> /* stat */ |
| 236 | #include <sys/time.h> /* utimes */ |
| 237 | #include "zlib.h" /* crc32 */ |
| 238 | |
| 239 | #include "gzlog.h" /* header for external access */ |
| 240 | |
| 241 | #define local static |
| 242 | typedef unsigned int uint; |
| 243 | typedef unsigned long ulong; |
| 244 | |
| 245 | /* Macro for debugging to deterministically force recovery operations */ |
| 246 | #ifdef GZLOG_DEBUG |
| 247 | #include <setjmp.h> /* longjmp */ |
| 248 | jmp_buf gzlog_jump; /* where to go back to */ |
| 249 | int gzlog_bail = 0; /* which point to bail at (1..8) */ |
| 250 | int gzlog_count = -1; /* number of times through to wait */ |
| 251 | # define BAIL(n) do { if (n == gzlog_bail && gzlog_count-- == 0) \ |
| 252 | longjmp(gzlog_jump, gzlog_bail); } while (0) |
| 253 | #else |
| 254 | # define BAIL(n) |
| 255 | #endif |
| 256 | |
| 257 | /* how old the lock file can be in seconds before considering it stale */ |
| 258 | #define PATIENCE 300 |
| 259 | |
| 260 | /* maximum stored block size in Kbytes -- must be in 1..63 */ |
| 261 | #define MAX_STORE 16 |
| 262 | |
| 263 | /* number of stored Kbytes to trigger compression (must be >= 32 to allow |
| 264 | dictionary construction, and <= 204 * MAX_STORE, in order for >> 10 to |
| 265 | discard the stored block headers contribution of five bytes each) */ |
| 266 | #define TRIGGER 1024 |
| 267 | |
| 268 | /* size of a deflate dictionary (this cannot be changed) */ |
| 269 | #define DICT 32768U |
| 270 | |
| 271 | /* values for the operation (2 bits) */ |
| 272 | #define NO_OP 0 |
| 273 | #define APPEND_OP 1 |
| 274 | #define COMPRESS_OP 2 |
| 275 | #define REPLACE_OP 3 |
| 276 | |
| 277 | /* macros to extract little-endian integers from an unsigned byte buffer */ |
| 278 | #define PULL2(p) ((p)[0]+((uint)((p)[1])<<8)) |
| 279 | #define PULL4(p) (PULL2(p)+((ulong)PULL2(p+2)<<16)) |
| 280 | #define PULL8(p) (PULL4(p)+((off_t)PULL4(p+4)<<32)) |
| 281 | |
| 282 | /* macros to store integers into a byte buffer in little-endian order */ |
| 283 | #define PUT2(p,a) do {(p)[0]=a;(p)[1]=(a)>>8;} while(0) |
| 284 | #define PUT4(p,a) do {PUT2(p,a);PUT2(p+2,a>>16);} while(0) |
| 285 | #define PUT8(p,a) do {PUT4(p,a);PUT4(p+4,a>>32);} while(0) |
| 286 | |
| 287 | /* internal structure for log information */ |
| 288 | #define LOGID "\106\035\172" /* should be three non-zero characters */ |
| 289 | struct log { |
| 290 | char id[4]; /* contains LOGID to detect inadvertent overwrites */ |
| 291 | int fd; /* file descriptor for .gz file, opened read/write */ |
| 292 | char *path; /* allocated path, e.g. "/var/log/foo" or "foo" */ |
| 293 | char *end; /* end of path, for appending suffices such as ".gz" */ |
| 294 | off_t first; /* offset of first stored block first length byte */ |
| 295 | int back; /* location of first block id in bits back from first */ |
| 296 | uint stored; /* bytes currently in last stored block */ |
| 297 | off_t last; /* offset of last stored block first length byte */ |
| 298 | ulong ccrc; /* crc of compressed data */ |
| 299 | ulong clen; /* length (modulo 2^32) of compressed data */ |
| 300 | ulong tcrc; /* crc of total data */ |
| 301 | ulong tlen; /* length (modulo 2^32) of total data */ |
| 302 | time_t lock; /* last modify time of our lock file */ |
| 303 | }; |
| 304 | |
| 305 | /* gzip header for gzlog */ |
| 306 | local unsigned char log_gzhead[] = { |
| 307 | 0x1f, 0x8b, /* magic gzip id */ |
| 308 | 8, /* compression method is deflate */ |
| 309 | 4, /* there is an extra field (no file name) */ |
| 310 | 0, 0, 0, 0, /* no modification time provided */ |
| 311 | 0, 0xff, /* no extra flags, no OS specified */ |
| 312 | 39, 0, 'a', 'p', 35, 0 /* extra field with "ap" subfield */ |
| 313 | /* 35 is EXTRA, 39 is EXTRA + 4 */ |
| 314 | }; |
| 315 | |
| 316 | #define HEAD sizeof(log_gzhead) /* should be 16 */ |
| 317 | |
| 318 | /* initial gzip extra field content (52 == HEAD + EXTRA + 1) */ |
| 319 | local unsigned char log_gzext[] = { |
| 320 | 52, 0, 0, 0, 0, 0, 0, 0, /* offset of first stored block length */ |
| 321 | 52, 0, 0, 0, 0, 0, 0, 0, /* offset of last stored block length */ |
| 322 | 0, 0, 0, 0, 0, 0, 0, 0, /* compressed data crc and length */ |
| 323 | 0, 0, 0, 0, 0, 0, 0, 0, /* total data crc and length */ |
| 324 | 0, 0, /* final stored block data length */ |
| 325 | 5 /* op is NO_OP, last bit 8 bits back */ |
| 326 | }; |
| 327 | |
| 328 | #define EXTRA sizeof(log_gzext) /* should be 35 */ |
| 329 | |
| 330 | /* initial gzip data and trailer */ |
| 331 | local unsigned char log_gzbody[] = { |
| 332 | 1, 0, 0, 0xff, 0xff, /* empty stored block (last) */ |
| 333 | 0, 0, 0, 0, /* crc */ |
| 334 | 0, 0, 0, 0 /* uncompressed length */ |
| 335 | }; |
| 336 | |
| 337 | #define BODY sizeof(log_gzbody) |
| 338 | |
| 339 | /* Exclusively create foo.lock in order to negotiate exclusive access to the |
| 340 | foo.* files. If the modify time of an existing lock file is greater than |
| 341 | PATIENCE seconds in the past, then consider the lock file to have been |
| 342 | abandoned, delete it, and try the exclusive create again. Save the lock |
| 343 | file modify time for verification of ownership. Return 0 on success, or -1 |
| 344 | on failure, usually due to an access restriction or invalid path. Note that |
| 345 | if stat() or unlink() fails, it may be due to another process noticing the |
| 346 | abandoned lock file a smidge sooner and deleting it, so those are not |
| 347 | flagged as an error. */ |
| 348 | local int log_lock(struct log *log) |
| 349 | { |
| 350 | int fd; |
| 351 | struct stat st; |
| 352 | |
| 353 | strcpy(log->end, ".lock"); |
| 354 | while ((fd = open(log->path, O_CREAT | O_EXCL, 0644)) < 0) { |
| 355 | if (errno != EEXIST) |
| 356 | return -1; |
| 357 | if (stat(log->path, &st) == 0 && time(NULL) - st.st_mtime > PATIENCE) { |
| 358 | unlink(log->path); |
| 359 | continue; |
| 360 | } |
| 361 | sleep(2); /* relinquish the CPU for two seconds while waiting */ |
| 362 | } |
| 363 | close(fd); |
| 364 | if (stat(log->path, &st) == 0) |
| 365 | log->lock = st.st_mtime; |
| 366 | return 0; |
| 367 | } |
| 368 | |
| 369 | /* Update the modify time of the lock file to now, in order to prevent another |
| 370 | task from thinking that the lock is stale. Save the lock file modify time |
| 371 | for verification of ownership. */ |
| 372 | local void log_touch(struct log *log) |
| 373 | { |
| 374 | struct stat st; |
| 375 | |
| 376 | strcpy(log->end, ".lock"); |
| 377 | utimes(log->path, NULL); |
| 378 | if (stat(log->path, &st) == 0) |
| 379 | log->lock = st.st_mtime; |
| 380 | } |
| 381 | |
| 382 | /* Check the log file modify time against what is expected. Return true if |
| 383 | this is not our lock. If it is our lock, touch it to keep it. */ |
| 384 | local int log_check(struct log *log) |
| 385 | { |
| 386 | struct stat st; |
| 387 | |
| 388 | strcpy(log->end, ".lock"); |
| 389 | if (stat(log->path, &st) || st.st_mtime != log->lock) |
| 390 | return 1; |
| 391 | log_touch(log); |
| 392 | return 0; |
| 393 | } |
| 394 | |
| 395 | /* Unlock a previously acquired lock, but only if it's ours. */ |
| 396 | local void log_unlock(struct log *log) |
| 397 | { |
| 398 | if (log_check(log)) |
| 399 | return; |
| 400 | strcpy(log->end, ".lock"); |
| 401 | unlink(log->path); |
| 402 | log->lock = 0; |
| 403 | } |
| 404 | |
| 405 | /* Check the gzip header and read in the extra field, filling in the values in |
| 406 | the log structure. Return op on success or -1 if the gzip header was not as |
| 407 | expected. op is the current operation in progress last written to the extra |
| 408 | field. This assumes that the gzip file has already been opened, with the |
| 409 | file descriptor log->fd. */ |
| 410 | local int log_head(struct log *log) |
| 411 | { |
| 412 | int op; |
| 413 | unsigned char buf[HEAD + EXTRA]; |
| 414 | |
| 415 | if (lseek(log->fd, 0, SEEK_SET) < 0 || |
| 416 | read(log->fd, buf, HEAD + EXTRA) != HEAD + EXTRA || |
| 417 | memcmp(buf, log_gzhead, HEAD)) { |
| 418 | return -1; |
| 419 | } |
| 420 | log->first = PULL8(buf + HEAD); |
| 421 | log->last = PULL8(buf + HEAD + 8); |
| 422 | log->ccrc = PULL4(buf + HEAD + 16); |
| 423 | log->clen = PULL4(buf + HEAD + 20); |
| 424 | log->tcrc = PULL4(buf + HEAD + 24); |
| 425 | log->tlen = PULL4(buf + HEAD + 28); |
| 426 | log->stored = PULL2(buf + HEAD + 32); |
| 427 | log->back = 3 + (buf[HEAD + 34] & 7); |
| 428 | op = (buf[HEAD + 34] >> 3) & 3; |
| 429 | return op; |
| 430 | } |
| 431 | |
| 432 | /* Write over the extra field contents, marking the operation as op. Use fsync |
| 433 | to assure that the device is written to, and in the requested order. This |
| 434 | operation, and only this operation, is assumed to be atomic in order to |
| 435 | assure that the log is recoverable in the event of an interruption at any |
| 436 | point in the process. Return -1 if the write to foo.gz failed. */ |
| 437 | local int log_mark(struct log *log, int op) |
| 438 | { |
| 439 | int ret; |
| 440 | unsigned char ext[EXTRA]; |
| 441 | |
| 442 | PUT8(ext, log->first); |
| 443 | PUT8(ext + 8, log->last); |
| 444 | PUT4(ext + 16, log->ccrc); |
| 445 | PUT4(ext + 20, log->clen); |
| 446 | PUT4(ext + 24, log->tcrc); |
| 447 | PUT4(ext + 28, log->tlen); |
| 448 | PUT2(ext + 32, log->stored); |
| 449 | ext[34] = log->back - 3 + (op << 3); |
| 450 | fsync(log->fd); |
| 451 | ret = lseek(log->fd, HEAD, SEEK_SET) < 0 || |
| 452 | write(log->fd, ext, EXTRA) != EXTRA ? -1 : 0; |
| 453 | fsync(log->fd); |
| 454 | return ret; |
| 455 | } |
| 456 | |
| 457 | /* Rewrite the last block header bits and subsequent zero bits to get to a byte |
| 458 | boundary, setting the last block bit if last is true, and then write the |
| 459 | remainder of the stored block header (length and one's complement). Leave |
| 460 | the file pointer after the end of the last stored block data. Return -1 if |
| 461 | there is a read or write failure on the foo.gz file */ |
| 462 | local int log_last(struct log *log, int last) |
| 463 | { |
| 464 | int back, len, mask; |
| 465 | unsigned char buf[6]; |
| 466 | |
| 467 | /* determine the locations of the bytes and bits to modify */ |
| 468 | back = log->last == log->first ? log->back : 8; |
| 469 | len = back > 8 ? 2 : 1; /* bytes back from log->last */ |
| 470 | mask = 0x80 >> ((back - 1) & 7); /* mask for block last-bit */ |
| 471 | |
| 472 | /* get the byte to modify (one or two back) into buf[0] -- don't need to |
| 473 | read the byte if the last-bit is eight bits back, since in that case |
| 474 | the entire byte will be modified */ |
| 475 | buf[0] = 0; |
| 476 | if (back != 8 && (lseek(log->fd, log->last - len, SEEK_SET) < 0 || |
| 477 | read(log->fd, buf, 1) != 1)) |
| 478 | return -1; |
| 479 | |
| 480 | /* change the last-bit of the last stored block as requested -- note |
| 481 | that all bits above the last-bit are set to zero, per the type bits |
| 482 | of a stored block being 00 and per the convention that the bits to |
| 483 | bring the stream to a byte boundary are also zeros */ |
| 484 | buf[1] = 0; |
| 485 | buf[2 - len] = (*buf & (mask - 1)) + (last ? mask : 0); |
| 486 | |
| 487 | /* write the modified stored block header and lengths, move the file |
| 488 | pointer to after the last stored block data */ |
| 489 | PUT2(buf + 2, log->stored); |
| 490 | PUT2(buf + 4, log->stored ^ 0xffff); |
| 491 | return lseek(log->fd, log->last - len, SEEK_SET) < 0 || |
| 492 | write(log->fd, buf + 2 - len, len + 4) != len + 4 || |
| 493 | lseek(log->fd, log->stored, SEEK_CUR) < 0 ? -1 : 0; |
| 494 | } |
| 495 | |
| 496 | /* Append len bytes from data to the locked and open log file. len may be zero |
| 497 | if recovering and no .add file was found. In that case, the previous state |
| 498 | of the foo.gz file is restored. The data is appended uncompressed in |
| 499 | deflate stored blocks. Return -1 if there was an error reading or writing |
| 500 | the foo.gz file. */ |
| 501 | local int log_append(struct log *log, unsigned char *data, size_t len) |
| 502 | { |
| 503 | uint put; |
| 504 | off_t end; |
| 505 | unsigned char buf[8]; |
| 506 | |
| 507 | /* set the last block last-bit and length, in case recovering an |
| 508 | interrupted append, then position the file pointer to append to the |
| 509 | block */ |
| 510 | if (log_last(log, 1)) |
| 511 | return -1; |
| 512 | |
| 513 | /* append, adding stored blocks and updating the offset of the last stored |
| 514 | block as needed, and update the total crc and length */ |
| 515 | while (len) { |
| 516 | /* append as much as we can to the last block */ |
| 517 | put = (MAX_STORE << 10) - log->stored; |
| 518 | if (put > len) |
| 519 | put = (uint)len; |
| 520 | if (put) { |
| 521 | if (write(log->fd, data, put) != put) |
| 522 | return -1; |
| 523 | BAIL(1); |
| 524 | log->tcrc = crc32(log->tcrc, data, put); |
| 525 | log->tlen += put; |
| 526 | log->stored += put; |
| 527 | data += put; |
| 528 | len -= put; |
| 529 | } |
| 530 | |
| 531 | /* if we need to, add a new empty stored block */ |
| 532 | if (len) { |
| 533 | /* mark current block as not last */ |
| 534 | if (log_last(log, 0)) |
| 535 | return -1; |
| 536 | |
| 537 | /* point to new, empty stored block */ |
| 538 | log->last += 4 + log->stored + 1; |
| 539 | log->stored = 0; |
| 540 | } |
| 541 | |
| 542 | /* mark last block as last, update its length */ |
| 543 | if (log_last(log, 1)) |
| 544 | return -1; |
| 545 | BAIL(2); |
| 546 | } |
| 547 | |
| 548 | /* write the new crc and length trailer, and truncate just in case (could |
| 549 | be recovering from partial append with a missing foo.add file) */ |
| 550 | PUT4(buf, log->tcrc); |
| 551 | PUT4(buf + 4, log->tlen); |
| 552 | if (write(log->fd, buf, 8) != 8 || |
| 553 | (end = lseek(log->fd, 0, SEEK_CUR)) < 0 || ftruncate(log->fd, end)) |
| 554 | return -1; |
| 555 | |
| 556 | /* write the extra field, marking the log file as done, delete .add file */ |
| 557 | if (log_mark(log, NO_OP)) |
| 558 | return -1; |
| 559 | strcpy(log->end, ".add"); |
| 560 | unlink(log->path); /* ignore error, since may not exist */ |
| 561 | return 0; |
| 562 | } |
| 563 | |
| 564 | /* Replace the foo.dict file with the foo.temp file. Also delete the foo.add |
| 565 | file, since the compress operation may have been interrupted before that was |
| 566 | done. Returns 1 if memory could not be allocated, or -1 if reading or |
| 567 | writing foo.gz fails, or if the rename fails for some reason other than |
| 568 | foo.temp not existing. foo.temp not existing is a permitted error, since |
| 569 | the replace operation may have been interrupted after the rename is done, |
| 570 | but before foo.gz is marked as complete. */ |
| 571 | local int log_replace(struct log *log) |
| 572 | { |
| 573 | int ret; |
| 574 | char *dest; |
| 575 | |
| 576 | /* delete foo.add file */ |
| 577 | strcpy(log->end, ".add"); |
| 578 | unlink(log->path); /* ignore error, since may not exist */ |
| 579 | BAIL(3); |
| 580 | |
| 581 | /* rename foo.name to foo.dict, replacing foo.dict if it exists */ |
| 582 | strcpy(log->end, ".dict"); |
| 583 | dest = malloc(strlen(log->path) + 1); |
| 584 | if (dest == NULL) |
| 585 | return -2; |
| 586 | strcpy(dest, log->path); |
| 587 | strcpy(log->end, ".temp"); |
| 588 | ret = rename(log->path, dest); |
| 589 | free(dest); |
| 590 | if (ret && errno != ENOENT) |
| 591 | return -1; |
| 592 | BAIL(4); |
| 593 | |
| 594 | /* mark the foo.gz file as done */ |
| 595 | return log_mark(log, NO_OP); |
| 596 | } |
| 597 | |
| 598 | /* Compress the len bytes at data and append the compressed data to the |
| 599 | foo.gz deflate data immediately after the previous compressed data. This |
| 600 | overwrites the previous uncompressed data, which was stored in foo.add |
| 601 | and is the data provided in data[0..len-1]. If this operation is |
| 602 | interrupted, it picks up at the start of this routine, with the foo.add |
| 603 | file read in again. If there is no data to compress (len == 0), then we |
| 604 | simply terminate the foo.gz file after the previously compressed data, |
| 605 | appending a final empty stored block and the gzip trailer. Return -1 if |
| 606 | reading or writing the log.gz file failed, or -2 if there was a memory |
| 607 | allocation failure. */ |
| 608 | local int log_compress(struct log *log, unsigned char *data, size_t len) |
| 609 | { |
| 610 | int fd; |
| 611 | uint got, max; |
| 612 | ssize_t dict; |
| 613 | off_t end; |
| 614 | z_stream strm; |
| 615 | unsigned char buf[DICT]; |
| 616 | |
| 617 | /* compress and append compressed data */ |
| 618 | if (len) { |
| 619 | /* set up for deflate, allocating memory */ |
| 620 | strm.zalloc = Z_NULL; |
| 621 | strm.zfree = Z_NULL; |
| 622 | strm.opaque = Z_NULL; |
| 623 | if (deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, -15, 8, |
| 624 | Z_DEFAULT_STRATEGY) != Z_OK) |
| 625 | return -2; |
| 626 | |
| 627 | /* read in dictionary (last 32K of data that was compressed) */ |
| 628 | strcpy(log->end, ".dict"); |
| 629 | fd = open(log->path, O_RDONLY, 0); |
| 630 | if (fd >= 0) { |
| 631 | dict = read(fd, buf, DICT); |
| 632 | close(fd); |
| 633 | if (dict < 0) { |
| 634 | deflateEnd(&strm); |
| 635 | return -1; |
| 636 | } |
| 637 | if (dict) |
| 638 | deflateSetDictionary(&strm, buf, (uint)dict); |
| 639 | } |
| 640 | log_touch(log); |
| 641 | |
| 642 | /* prime deflate with last bits of previous block, position write |
| 643 | pointer to write those bits and overwrite what follows */ |
| 644 | if (lseek(log->fd, log->first - (log->back > 8 ? 2 : 1), |
| 645 | SEEK_SET) < 0 || |
| 646 | read(log->fd, buf, 1) != 1 || lseek(log->fd, -1, SEEK_CUR) < 0) { |
| 647 | deflateEnd(&strm); |
| 648 | return -1; |
| 649 | } |
| 650 | deflatePrime(&strm, (8 - log->back) & 7, *buf); |
| 651 | |
| 652 | /* compress, finishing with a partial non-last empty static block */ |
| 653 | strm.next_in = data; |
| 654 | max = (((uint)0 - 1) >> 1) + 1; /* in case int smaller than size_t */ |
| 655 | do { |
| 656 | strm.avail_in = len > max ? max : (uint)len; |
| 657 | len -= strm.avail_in; |
| 658 | do { |
| 659 | strm.avail_out = DICT; |
| 660 | strm.next_out = buf; |
| 661 | deflate(&strm, len ? Z_NO_FLUSH : Z_PARTIAL_FLUSH); |
| 662 | got = DICT - strm.avail_out; |
| 663 | if (got && write(log->fd, buf, got) != got) { |
| 664 | deflateEnd(&strm); |
| 665 | return -1; |
| 666 | } |
| 667 | log_touch(log); |
| 668 | } while (strm.avail_out == 0); |
| 669 | } while (len); |
| 670 | deflateEnd(&strm); |
| 671 | BAIL(5); |
| 672 | |
| 673 | /* find start of empty static block -- scanning backwards the first one |
| 674 | bit is the second bit of the block, if the last byte is zero, then |
| 675 | we know the byte before that has a one in the top bit, since an |
| 676 | empty static block is ten bits long */ |
| 677 | if ((log->first = lseek(log->fd, -1, SEEK_CUR)) < 0 || |
| 678 | read(log->fd, buf, 1) != 1) |
| 679 | return -1; |
| 680 | log->first++; |
| 681 | if (*buf) { |
| 682 | log->back = 1; |
| 683 | while ((*buf & ((uint)1 << (8 - log->back++))) == 0) |
| 684 | ; /* guaranteed to terminate, since *buf != 0 */ |
| 685 | } |
| 686 | else |
| 687 | log->back = 10; |
| 688 | |
| 689 | /* update compressed crc and length */ |
| 690 | log->ccrc = log->tcrc; |
| 691 | log->clen = log->tlen; |
| 692 | } |
| 693 | else { |
| 694 | /* no data to compress -- fix up existing gzip stream */ |
| 695 | log->tcrc = log->ccrc; |
| 696 | log->tlen = log->clen; |
| 697 | } |
| 698 | |
| 699 | /* complete and truncate gzip stream */ |
| 700 | log->last = log->first; |
| 701 | log->stored = 0; |
| 702 | PUT4(buf, log->tcrc); |
| 703 | PUT4(buf + 4, log->tlen); |
| 704 | if (log_last(log, 1) || write(log->fd, buf, 8) != 8 || |
| 705 | (end = lseek(log->fd, 0, SEEK_CUR)) < 0 || ftruncate(log->fd, end)) |
| 706 | return -1; |
| 707 | BAIL(6); |
| 708 | |
| 709 | /* mark as being in the replace operation */ |
| 710 | if (log_mark(log, REPLACE_OP)) |
| 711 | return -1; |
| 712 | |
| 713 | /* execute the replace operation and mark the file as done */ |
| 714 | return log_replace(log); |
| 715 | } |
| 716 | |
| 717 | /* log a repair record to the .repairs file */ |
| 718 | local void log_log(struct log *log, int op, char *record) |
| 719 | { |
| 720 | time_t now; |
| 721 | FILE *rec; |
| 722 | |
| 723 | now = time(NULL); |
| 724 | strcpy(log->end, ".repairs"); |
| 725 | rec = fopen(log->path, "a"); |
| 726 | if (rec == NULL) |
| 727 | return; |
| 728 | fprintf(rec, "%.24s %s recovery: %s\n", ctime(&now), op == APPEND_OP ? |
| 729 | "append" : (op == COMPRESS_OP ? "compress" : "replace"), record); |
| 730 | fclose(rec); |
| 731 | return; |
| 732 | } |
| 733 | |
| 734 | /* Recover the interrupted operation op. First read foo.add for recovering an |
| 735 | append or compress operation. Return -1 if there was an error reading or |
| 736 | writing foo.gz or reading an existing foo.add, or -2 if there was a memory |
| 737 | allocation failure. */ |
| 738 | local int log_recover(struct log *log, int op) |
| 739 | { |
| 740 | int fd, ret = 0; |
| 741 | unsigned char *data = NULL; |
| 742 | size_t len = 0; |
| 743 | struct stat st; |
| 744 | |
| 745 | /* log recovery */ |
| 746 | log_log(log, op, "start"); |
| 747 | |
| 748 | /* load foo.add file if expected and present */ |
| 749 | if (op == APPEND_OP || op == COMPRESS_OP) { |
| 750 | strcpy(log->end, ".add"); |
| 751 | if (stat(log->path, &st) == 0 && st.st_size) { |
| 752 | len = (size_t)(st.st_size); |
| 753 | if ((off_t)len != st.st_size || |
| 754 | (data = malloc(st.st_size)) == NULL) { |
| 755 | log_log(log, op, "allocation failure"); |
| 756 | return -2; |
| 757 | } |
| 758 | if ((fd = open(log->path, O_RDONLY, 0)) < 0) { |
| 759 | free(data); |
| 760 | log_log(log, op, ".add file read failure"); |
| 761 | return -1; |
| 762 | } |
| 763 | ret = (size_t)read(fd, data, len) != len; |
| 764 | close(fd); |
| 765 | if (ret) { |
| 766 | free(data); |
| 767 | log_log(log, op, ".add file read failure"); |
| 768 | return -1; |
| 769 | } |
| 770 | log_log(log, op, "loaded .add file"); |
| 771 | } |
| 772 | else |
| 773 | log_log(log, op, "missing .add file!"); |
| 774 | } |
| 775 | |
| 776 | /* recover the interrupted operation */ |
| 777 | switch (op) { |
| 778 | case APPEND_OP: |
| 779 | ret = log_append(log, data, len); |
| 780 | break; |
| 781 | case COMPRESS_OP: |
| 782 | ret = log_compress(log, data, len); |
| 783 | break; |
| 784 | case REPLACE_OP: |
| 785 | ret = log_replace(log); |
| 786 | } |
| 787 | |
| 788 | /* log status */ |
| 789 | log_log(log, op, ret ? "failure" : "complete"); |
| 790 | |
| 791 | /* clean up */ |
| 792 | if (data != NULL) |
| 793 | free(data); |
| 794 | return ret; |
| 795 | } |
| 796 | |
| 797 | /* Close the foo.gz file (if open) and release the lock. */ |
| 798 | local void log_close(struct log *log) |
| 799 | { |
| 800 | if (log->fd >= 0) |
| 801 | close(log->fd); |
| 802 | log->fd = -1; |
| 803 | log_unlock(log); |
| 804 | } |
| 805 | |
| 806 | /* Open foo.gz, verify the header, and load the extra field contents, after |
| 807 | first creating the foo.lock file to gain exclusive access to the foo.* |
| 808 | files. If foo.gz does not exist or is empty, then write the initial header, |
| 809 | extra, and body content of an empty foo.gz log file. If there is an error |
| 810 | creating the lock file due to access restrictions, or an error reading or |
| 811 | writing the foo.gz file, or if the foo.gz file is not a proper log file for |
| 812 | this object (e.g. not a gzip file or does not contain the expected extra |
| 813 | field), then return true. If there is an error, the lock is released. |
| 814 | Otherwise, the lock is left in place. */ |
| 815 | local int log_open(struct log *log) |
| 816 | { |
| 817 | int op; |
| 818 | |
| 819 | /* release open file resource if left over -- can occur if lock lost |
| 820 | between gzlog_open() and gzlog_write() */ |
| 821 | if (log->fd >= 0) |
| 822 | close(log->fd); |
| 823 | log->fd = -1; |
| 824 | |
| 825 | /* negotiate exclusive access */ |
| 826 | if (log_lock(log) < 0) |
| 827 | return -1; |
| 828 | |
| 829 | /* open the log file, foo.gz */ |
| 830 | strcpy(log->end, ".gz"); |
| 831 | log->fd = open(log->path, O_RDWR | O_CREAT, 0644); |
| 832 | if (log->fd < 0) { |
| 833 | log_close(log); |
| 834 | return -1; |
| 835 | } |
| 836 | |
| 837 | /* if new, initialize foo.gz with an empty log, delete old dictionary */ |
| 838 | if (lseek(log->fd, 0, SEEK_END) == 0) { |
| 839 | if (write(log->fd, log_gzhead, HEAD) != HEAD || |
| 840 | write(log->fd, log_gzext, EXTRA) != EXTRA || |
| 841 | write(log->fd, log_gzbody, BODY) != BODY) { |
| 842 | log_close(log); |
| 843 | return -1; |
| 844 | } |
| 845 | strcpy(log->end, ".dict"); |
| 846 | unlink(log->path); |
| 847 | } |
| 848 | |
| 849 | /* verify log file and load extra field information */ |
| 850 | if ((op = log_head(log)) < 0) { |
| 851 | log_close(log); |
| 852 | return -1; |
| 853 | } |
| 854 | |
| 855 | /* check for interrupted process and if so, recover */ |
| 856 | if (op != NO_OP && log_recover(log, op)) { |
| 857 | log_close(log); |
| 858 | return -1; |
| 859 | } |
| 860 | |
| 861 | /* touch the lock file to prevent another process from grabbing it */ |
| 862 | log_touch(log); |
| 863 | return 0; |
| 864 | } |
| 865 | |
| 866 | /* See gzlog.h for the description of the external methods below */ |
| 867 | gzlog *gzlog_open(char *path) |
| 868 | { |
| 869 | size_t n; |
| 870 | struct log *log; |
| 871 | |
| 872 | /* check arguments */ |
| 873 | if (path == NULL || *path == 0) |
| 874 | return NULL; |
| 875 | |
| 876 | /* allocate and initialize log structure */ |
| 877 | log = malloc(sizeof(struct log)); |
| 878 | if (log == NULL) |
| 879 | return NULL; |
| 880 | strcpy(log->id, LOGID); |
| 881 | log->fd = -1; |
| 882 | |
| 883 | /* save path and end of path for name construction */ |
| 884 | n = strlen(path); |
| 885 | log->path = malloc(n + 9); /* allow for ".repairs" */ |
| 886 | if (log->path == NULL) { |
| 887 | free(log); |
| 888 | return NULL; |
| 889 | } |
| 890 | strcpy(log->path, path); |
| 891 | log->end = log->path + n; |
| 892 | |
| 893 | /* gain exclusive access and verify log file -- may perform a |
| 894 | recovery operation if needed */ |
| 895 | if (log_open(log)) { |
| 896 | free(log->path); |
| 897 | free(log); |
| 898 | return NULL; |
| 899 | } |
| 900 | |
| 901 | /* return pointer to log structure */ |
| 902 | return log; |
| 903 | } |
| 904 | |
| 905 | /* gzlog_compress() return values: |
| 906 | 0: all good |
| 907 | -1: file i/o error (usually access issue) |
| 908 | -2: memory allocation failure |
| 909 | -3: invalid log pointer argument */ |
| 910 | int gzlog_compress(gzlog *logd) |
| 911 | { |
| 912 | int fd, ret; |
| 913 | uint block; |
| 914 | size_t len, next; |
| 915 | unsigned char *data, buf[5]; |
| 916 | struct log *log = logd; |
| 917 | |
| 918 | /* check arguments */ |
| 919 | if (log == NULL || strcmp(log->id, LOGID)) |
| 920 | return -3; |
| 921 | |
| 922 | /* see if we lost the lock -- if so get it again and reload the extra |
| 923 | field information (it probably changed), recover last operation if |
| 924 | necessary */ |
| 925 | if (log_check(log) && log_open(log)) |
| 926 | return -1; |
| 927 | |
| 928 | /* create space for uncompressed data */ |
| 929 | len = ((size_t)(log->last - log->first) & ~(((size_t)1 << 10) - 1)) + |
| 930 | log->stored; |
| 931 | if ((data = malloc(len)) == NULL) |
| 932 | return -2; |
| 933 | |
| 934 | /* do statement here is just a cheap trick for error handling */ |
| 935 | do { |
| 936 | /* read in the uncompressed data */ |
| 937 | if (lseek(log->fd, log->first - 1, SEEK_SET) < 0) |
| 938 | break; |
| 939 | next = 0; |
| 940 | while (next < len) { |
| 941 | if (read(log->fd, buf, 5) != 5) |
| 942 | break; |
| 943 | block = PULL2(buf + 1); |
| 944 | if (next + block > len || |
| 945 | read(log->fd, (char *)data + next, block) != block) |
| 946 | break; |
| 947 | next += block; |
| 948 | } |
| 949 | if (lseek(log->fd, 0, SEEK_CUR) != log->last + 4 + log->stored) |
| 950 | break; |
| 951 | log_touch(log); |
| 952 | |
| 953 | /* write the uncompressed data to the .add file */ |
| 954 | strcpy(log->end, ".add"); |
| 955 | fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); |
| 956 | if (fd < 0) |
| 957 | break; |
| 958 | ret = (size_t)write(fd, data, len) != len; |
| 959 | if (ret | close(fd)) |
| 960 | break; |
| 961 | log_touch(log); |
| 962 | |
| 963 | /* write the dictionary for the next compress to the .temp file */ |
| 964 | strcpy(log->end, ".temp"); |
| 965 | fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); |
| 966 | if (fd < 0) |
| 967 | break; |
| 968 | next = DICT > len ? len : DICT; |
| 969 | ret = (size_t)write(fd, (char *)data + len - next, next) != next; |
| 970 | if (ret | close(fd)) |
| 971 | break; |
| 972 | log_touch(log); |
| 973 | |
| 974 | /* roll back to compressed data, mark the compress in progress */ |
| 975 | log->last = log->first; |
| 976 | log->stored = 0; |
| 977 | if (log_mark(log, COMPRESS_OP)) |
| 978 | break; |
| 979 | BAIL(7); |
| 980 | |
| 981 | /* compress and append the data (clears mark) */ |
| 982 | ret = log_compress(log, data, len); |
| 983 | free(data); |
| 984 | return ret; |
| 985 | } while (0); |
| 986 | |
| 987 | /* broke out of do above on i/o error */ |
| 988 | free(data); |
| 989 | return -1; |
| 990 | } |
| 991 | |
| 992 | /* gzlog_write() return values: |
| 993 | 0: all good |
| 994 | -1: file i/o error (usually access issue) |
| 995 | -2: memory allocation failure |
| 996 | -3: invalid log pointer argument */ |
| 997 | int gzlog_write(gzlog *logd, void *data, size_t len) |
| 998 | { |
| 999 | int fd, ret; |
| 1000 | struct log *log = logd; |
| 1001 | |
| 1002 | /* check arguments */ |
| 1003 | if (log == NULL || strcmp(log->id, LOGID)) |
| 1004 | return -3; |
| 1005 | if (data == NULL || len <= 0) |
| 1006 | return 0; |
| 1007 | |
| 1008 | /* see if we lost the lock -- if so get it again and reload the extra |
| 1009 | field information (it probably changed), recover last operation if |
| 1010 | necessary */ |
| 1011 | if (log_check(log) && log_open(log)) |
| 1012 | return -1; |
| 1013 | |
| 1014 | /* create and write .add file */ |
| 1015 | strcpy(log->end, ".add"); |
| 1016 | fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); |
| 1017 | if (fd < 0) |
| 1018 | return -1; |
| 1019 | ret = (size_t)write(fd, data, len) != len; |
| 1020 | if (ret | close(fd)) |
| 1021 | return -1; |
| 1022 | log_touch(log); |
| 1023 | |
| 1024 | /* mark log file with append in progress */ |
| 1025 | if (log_mark(log, APPEND_OP)) |
| 1026 | return -1; |
| 1027 | BAIL(8); |
| 1028 | |
| 1029 | /* append data (clears mark) */ |
| 1030 | if (log_append(log, data, len)) |
| 1031 | return -1; |
| 1032 | |
| 1033 | /* check to see if it's time to compress -- if not, then done */ |
| 1034 | if (((log->last - log->first) >> 10) + (log->stored >> 10) < TRIGGER) |
| 1035 | return 0; |
| 1036 | |
| 1037 | /* time to compress */ |
| 1038 | return gzlog_compress(log); |
| 1039 | } |
| 1040 | |
| 1041 | /* gzlog_close() return values: |
| 1042 | 0: ok |
| 1043 | -3: invalid log pointer argument */ |
| 1044 | int gzlog_close(gzlog *logd) |
| 1045 | { |
| 1046 | struct log *log = logd; |
| 1047 | |
| 1048 | /* check arguments */ |
| 1049 | if (log == NULL || strcmp(log->id, LOGID)) |
| 1050 | return -3; |
| 1051 | |
| 1052 | /* close the log file and release the lock */ |
| 1053 | log_close(log); |
| 1054 | |
| 1055 | /* free structure and return */ |
| 1056 | if (log->path != NULL) |
| 1057 | free(log->path); |
| 1058 | strcpy(log->id, "bad"); |
| 1059 | free(log); |
| 1060 | return 0; |
| 1061 | } |