1 /*****************************************************************************
2 * RRDtool 1.4.3 Copyright by Tobi Oetiker, 1997-2010
3 *****************************************************************************
4 * rrd_open.c Open an RRD File
5 *****************************************************************************
6 * $Id$
7 *****************************************************************************/
9 #include "rrd_tool.h"
10 #include "unused.h"
12 #ifdef WIN32
13 #include <stdlib.h>
14 #include <fcntl.h>
15 #include <sys/stat.h>
16 #endif
19 #ifdef HAVE_BROKEN_MS_ASYNC
20 #include <sys/types.h>
21 #include <utime.h>
22 #endif
24 #define MEMBLK 8192
26 #ifdef WIN32
27 #define _LK_UNLCK 0 /* Unlock */
28 #define _LK_LOCK 1 /* Lock */
29 #define _LK_NBLCK 2 /* Non-blocking lock */
30 #define _LK_RLCK 3 /* Lock for read only */
31 #define _LK_NBRLCK 4 /* Non-blocking lock for read only */
34 #define LK_UNLCK _LK_UNLCK
35 #define LK_LOCK _LK_LOCK
36 #define LK_NBLCK _LK_NBLCK
37 #define LK_RLCK _LK_RLCK
38 #define LK_NBRLCK _LK_NBRLCK
39 #endif
41 /* DEBUG 2 prints information obtained via mincore(2) */
42 #define DEBUG 1
43 /* do not calculate exact madvise hints but assume 1 page for headers and
44 * set DONTNEED for the rest, which is assumed to be data */
45 /* Avoid calling madvise on areas that were already hinted. May be benefical if
46 * your syscalls are very slow */
48 #ifdef HAVE_MMAP
49 /* the cast to void* is there to avoid this warning seen on ia64 with certain
50 versions of gcc: 'cast increases required alignment of target type'
51 */
52 #define __rrd_read(dst, dst_t, cnt) { \
53 size_t wanted = sizeof(dst_t)*(cnt); \
54 if (offset + wanted > rrd_file->file_len) { \
55 rrd_set_error("reached EOF while loading header " #dst); \
56 goto out_nullify_head; \
57 } \
58 (dst) = (dst_t*)(void*) (data + offset); \
59 offset += wanted; \
60 }
61 #else
62 #define __rrd_read(dst, dst_t, cnt) { \
63 size_t wanted = sizeof(dst_t)*(cnt); \
64 size_t got; \
65 if ((dst = (dst_t*)malloc(wanted)) == NULL) { \
66 rrd_set_error(#dst " malloc"); \
67 goto out_nullify_head; \
68 } \
69 got = read (rrd_simple_file->fd, dst, wanted); \
70 if (got != wanted) { \
71 rrd_set_error("short read while reading header " #dst); \
72 goto out_nullify_head; \
73 } \
74 offset += got; \
75 }
76 #endif
78 /* get the address of the start of this page */
79 #if defined USE_MADVISE || defined HAVE_POSIX_FADVISE
80 #ifndef PAGE_START
81 #define PAGE_START(addr) ((addr)&(~(_page_size-1)))
82 #endif
83 #endif
85 /* Open a database file, return its header and an open filehandle,
86 * positioned to the first cdp in the first rra.
87 * In the error path of rrd_open, only rrd_free(&rrd) has to be called
88 * before returning an error. Do not call rrd_close upon failure of rrd_open.
89 * If creating a new file, the parameter rrd must be initialised with
90 * details of the file content.
91 * If opening an existing file, then use rrd must be initialised by
92 * rrd_init(rrd) prior to invoking rrd_open
93 */
95 rrd_file_t *rrd_open(
96 const char *const file_name,
97 rrd_t *rrd,
98 unsigned rdwr)
99 {
100 unsigned long ui;
101 int flags = 0;
102 int version;
104 #ifdef HAVE_MMAP
105 ssize_t _page_size = sysconf(_SC_PAGESIZE);
106 char *data = MAP_FAILED;
107 #endif
108 off_t offset = 0;
109 struct stat statb;
110 rrd_file_t *rrd_file = NULL;
111 rrd_simple_file_t *rrd_simple_file = NULL;
112 size_t newfile_size = 0;
113 size_t header_len, value_cnt, data_len;
115 /* Are we creating a new file? */
116 if((rdwr & RRD_CREAT) && (rrd->stat_head != NULL))
117 {
118 header_len = rrd_get_header_size(rrd);
120 value_cnt = 0;
121 for (ui = 0; ui < rrd->stat_head->rra_cnt; ui++)
122 value_cnt += rrd->stat_head->ds_cnt * rrd->rra_def[ui].row_cnt;
124 data_len = sizeof(rrd_value_t) * value_cnt;
126 newfile_size = header_len + data_len;
127 }
129 rrd_file = (rrd_file_t*)malloc(sizeof(rrd_file_t));
130 if (rrd_file == NULL) {
131 rrd_set_error("allocating rrd_file descriptor for '%s'", file_name);
132 return NULL;
133 }
134 memset(rrd_file, 0, sizeof(rrd_file_t));
136 rrd_file->pvt = malloc(sizeof(rrd_simple_file_t));
137 if(rrd_file->pvt == NULL) {
138 rrd_set_error("allocating rrd_simple_file for '%s'", file_name);
139 return NULL;
140 }
141 memset(rrd_file->pvt, 0, sizeof(rrd_simple_file_t));
142 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
144 #ifdef DEBUG
145 if ((rdwr & (RRD_READONLY | RRD_READWRITE)) ==
146 (RRD_READONLY | RRD_READWRITE)) {
147 /* Both READONLY and READWRITE were given, which is invalid. */
148 rrd_set_error("in read/write request mask");
149 exit(-1);
150 }
151 #endif
153 #ifdef HAVE_MMAP
154 rrd_simple_file->mm_prot = PROT_READ;
155 rrd_simple_file->mm_flags = 0;
156 #endif
158 if (rdwr & RRD_READONLY) {
159 flags |= O_RDONLY;
160 #ifdef HAVE_MMAP
161 # if !defined(AIX)
162 rrd_simple_file->mm_flags = MAP_PRIVATE;
163 # endif
164 # ifdef MAP_NORESERVE
165 rrd_simple_file->mm_flags |= MAP_NORESERVE; /* readonly, so no swap backing needed */
166 # endif
167 #endif
168 } else {
169 if (rdwr & RRD_READWRITE) {
170 flags |= O_RDWR;
171 #ifdef HAVE_MMAP
172 rrd_simple_file->mm_flags = MAP_SHARED;
173 rrd_simple_file->mm_prot |= PROT_WRITE;
174 #endif
175 }
176 if (rdwr & RRD_CREAT) {
177 flags |= (O_CREAT | O_TRUNC);
178 }
179 if (rdwr & RRD_EXCL) {
180 flags |= O_EXCL;
181 }
182 }
183 if (rdwr & RRD_READAHEAD) {
184 #ifdef MAP_POPULATE
185 rrd_simple_file->mm_flags |= MAP_POPULATE; /* populate ptes and data */
186 #endif
187 #if defined MAP_NONBLOCK
188 rrd_simple_file->mm_flags |= MAP_NONBLOCK; /* just populate ptes */
189 #endif
190 }
191 #if defined(_WIN32) && !defined(__CYGWIN__) && !defined(__CYGWIN32__)
192 flags |= O_BINARY;
193 #endif
195 if ((rrd_simple_file->fd = open(file_name, flags, 0666)) < 0) {
196 rrd_set_error("opening '%s': %s", file_name, rrd_strerror(errno));
197 goto out_free;
198 }
200 #ifdef HAVE_MMAP
201 #ifdef HAVE_BROKEN_MS_ASYNC
202 if (rdwr & RRD_READWRITE) {
203 /* some unices, the files mtime does not get update
204 on msync MS_ASYNC, in order to help them,
205 we update the the timestamp at this point.
206 The thing happens pretty 'close' to the open
207 call so the chances of a race should be minimal.
209 Maybe ask your vendor to fix your OS ... */
210 utime(file_name,NULL);
211 }
212 #endif
213 #endif
215 /* Better try to avoid seeks as much as possible. stat may be heavy but
216 * many concurrent seeks are even worse. */
217 if (newfile_size == 0 && ((fstat(rrd_simple_file->fd, &statb)) < 0)) {
218 rrd_set_error("fstat '%s': %s", file_name, rrd_strerror(errno));
219 goto out_close;
220 }
221 if (newfile_size == 0) {
222 rrd_file->file_len = statb.st_size;
223 } else {
224 rrd_file->file_len = newfile_size;
225 #ifdef HAVE_POSIX_FALLOCATE
226 if (posix_fallocate(rrd_simple_file->fd, 0, newfile_size) == -1) {
227 rrd_set_error("posix_fallocate '%s': %s", file_name,
228 rrd_strerror(errno));
229 goto out_close;
230 }
231 #else
232 lseek(rrd_simple_file->fd, newfile_size - 1, SEEK_SET);
233 if ( write(rrd_simple_file->fd, "\0", 1) == -1){ /* poke */
234 rrd_set_error("write '%s': %s", file_name, rrd_strerror(errno));
235 goto out_close;
236 }
237 lseek(rrd_simple_file->fd, 0, SEEK_SET);
238 #endif
239 }
240 #ifdef HAVE_POSIX_FADVISE
241 /* In general we need no read-ahead when dealing with rrd_files.
242 When we stop reading, it is highly unlikely that we start up again.
243 In this manner we actually save time and diskaccess (and buffer cache).
244 Thanks to Dave Plonka for the Idea of using POSIX_FADV_RANDOM here. */
245 posix_fadvise(rrd_simple_file->fd, 0, 0, POSIX_FADV_RANDOM);
246 #endif
248 /*
249 if (rdwr & RRD_READWRITE)
250 {
251 if (setvbuf((rrd_simple_file->fd),NULL,_IONBF,2)) {
252 rrd_set_error("failed to disable the stream buffer\n");
253 return (-1);
254 }
255 }
256 */
258 #ifdef HAVE_MMAP
259 #ifndef HAVE_POSIX_FALLOCATE
260 /* force allocating the file on the underlaying filesystem to prevent any
261 * future bus error when the filesystem is full and attempting to write
262 * trough the file mapping. Filling the file using memset on the file
263 * mapping can also lead some bus error, so we use the old fashioned
264 * write().
265 */
266 if (rdwr & RRD_CREAT) {
267 char buf[4096];
268 unsigned i;
270 memset(buf, DNAN, sizeof buf);
271 lseek(rrd_simple_file->fd, offset, SEEK_SET);
273 for (i = 0; i < (newfile_size - 1) / sizeof buf; ++i)
274 {
275 if (write(rrd_simple_file->fd, buf, sizeof buf) == -1)
276 {
277 rrd_set_error("write '%s': %s", file_name, rrd_strerror(errno));
278 goto out_close;
279 }
280 }
282 if (write(rrd_simple_file->fd, buf,
283 (newfile_size - 1) % sizeof buf) == -1)
284 {
285 rrd_set_error("write '%s': %s", file_name, rrd_strerror(errno));
286 goto out_close;
287 }
289 lseek(rrd_simple_file->fd, 0, SEEK_SET);
290 }
291 #endif
293 data = mmap(0, rrd_file->file_len,
294 rrd_simple_file->mm_prot, rrd_simple_file->mm_flags,
295 rrd_simple_file->fd, offset);
297 /* lets see if the first read worked */
298 if (data == MAP_FAILED) {
299 rrd_set_error("mmaping file '%s': %s", file_name,
300 rrd_strerror(errno));
301 goto out_close;
302 }
303 rrd_simple_file->file_start = data;
304 if (rdwr & RRD_CREAT) {
305 goto out_done;
306 }
307 #endif
308 if (rdwr & RRD_CREAT)
309 goto out_done;
310 #ifdef USE_MADVISE
311 if (rdwr & RRD_COPY) {
312 /* We will read everything in a moment (copying) */
313 madvise(data, rrd_file->file_len, MADV_WILLNEED );
314 madvise(data, rrd_file->file_len, MADV_SEQUENTIAL );
315 } else {
316 /* We do not need to read anything in for the moment */
317 madvise(data, rrd_file->file_len, MADV_RANDOM);
318 /* the stat_head will be needed soonish, so hint accordingly */
319 madvise(data, sizeof(stat_head_t), MADV_WILLNEED);
320 madvise(data, sizeof(stat_head_t), MADV_RANDOM);
321 }
322 #endif
324 __rrd_read(rrd->stat_head, stat_head_t,
325 1);
327 /* lets do some test if we are on track ... */
328 if (memcmp(rrd->stat_head->cookie, RRD_COOKIE, sizeof(RRD_COOKIE)) != 0) {
329 rrd_set_error("'%s' is not an RRD file", file_name);
330 goto out_nullify_head;
331 }
333 if (rrd->stat_head->float_cookie != FLOAT_COOKIE) {
334 rrd_set_error("This RRD was created on another architecture");
335 goto out_nullify_head;
336 }
338 version = atoi(rrd->stat_head->version);
340 if (version > atoi(RRD_VERSION)) {
341 rrd_set_error("can't handle RRD file version %s",
342 rrd->stat_head->version);
343 goto out_nullify_head;
344 }
345 #if defined USE_MADVISE
346 /* the ds_def will be needed soonish, so hint accordingly */
347 madvise(data + PAGE_START(offset),
348 sizeof(ds_def_t) * rrd->stat_head->ds_cnt, MADV_WILLNEED);
349 #endif
350 __rrd_read(rrd->ds_def, ds_def_t,
351 rrd->stat_head->ds_cnt);
353 #if defined USE_MADVISE
354 /* the rra_def will be needed soonish, so hint accordingly */
355 madvise(data + PAGE_START(offset),
356 sizeof(rra_def_t) * rrd->stat_head->rra_cnt, MADV_WILLNEED);
357 #endif
358 __rrd_read(rrd->rra_def, rra_def_t,
359 rrd->stat_head->rra_cnt);
361 /* handle different format for the live_head */
362 if (version < 3) {
363 rrd->live_head = (live_head_t *) malloc(sizeof(live_head_t));
364 if (rrd->live_head == NULL) {
365 rrd_set_error("live_head_t malloc");
366 goto out_close;
367 }
368 #if defined USE_MADVISE
369 /* the live_head will be needed soonish, so hint accordingly */
370 madvise(data + PAGE_START(offset), sizeof(time_t), MADV_WILLNEED);
371 #endif
372 __rrd_read(rrd->legacy_last_up, time_t,
373 1);
375 rrd->live_head->last_up = *rrd->legacy_last_up;
376 rrd->live_head->last_up_usec = 0;
377 } else {
378 #if defined USE_MADVISE
379 /* the live_head will be needed soonish, so hint accordingly */
380 madvise(data + PAGE_START(offset),
381 sizeof(live_head_t), MADV_WILLNEED);
382 #endif
383 __rrd_read(rrd->live_head, live_head_t,
384 1);
385 }
386 __rrd_read(rrd->pdp_prep, pdp_prep_t,
387 rrd->stat_head->ds_cnt);
388 __rrd_read(rrd->cdp_prep, cdp_prep_t,
389 rrd->stat_head->rra_cnt * rrd->stat_head->ds_cnt);
390 __rrd_read(rrd->rra_ptr, rra_ptr_t,
391 rrd->stat_head->rra_cnt);
393 rrd_file->header_len = offset;
394 rrd_file->pos = offset;
396 {
397 unsigned long row_cnt = 0;
399 for (ui=0; ui<rrd->stat_head->rra_cnt; ui++)
400 row_cnt += rrd->rra_def[ui].row_cnt;
402 size_t correct_len = rrd_file->header_len +
403 sizeof(rrd_value_t) * row_cnt * rrd->stat_head->ds_cnt;
405 if (correct_len > rrd_file->file_len)
406 {
407 rrd_set_error("'%s' is too small (should be %ld bytes)",
408 file_name, (long long) correct_len);
409 goto out_nullify_head;
410 }
411 }
413 out_done:
414 return (rrd_file);
415 out_nullify_head:
416 rrd->stat_head = NULL;
417 out_close:
418 #ifdef HAVE_MMAP
419 if (data != MAP_FAILED)
420 munmap(data, rrd_file->file_len);
421 #endif
423 close(rrd_simple_file->fd);
424 out_free:
425 free(rrd_file->pvt);
426 free(rrd_file);
427 return NULL;
428 }
431 #if defined DEBUG && DEBUG > 1
432 /* Print list of in-core pages of a the current rrd_file. */
433 static
434 void mincore_print(
435 rrd_file_t *rrd_file,
436 char *mark)
437 {
438 rrd_simple_file_t *rrd_simple_file;
439 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
440 #ifdef HAVE_MMAP
441 /* pretty print blocks in core */
442 size_t off;
443 unsigned char *vec;
444 ssize_t _page_size = sysconf(_SC_PAGESIZE);
446 off = rrd_file->file_len +
447 ((rrd_file->file_len + _page_size - 1) / _page_size);
448 vec = malloc(off);
449 if (vec != NULL) {
450 memset(vec, 0, off);
451 if (mincore(rrd_simple_file->file_start, rrd_file->file_len, vec) == 0) {
452 int prev;
453 unsigned is_in = 0, was_in = 0;
455 for (off = 0, prev = 0; off < rrd_file->file_len; ++off) {
456 is_in = vec[off] & 1; /* if lsb set then is core resident */
457 if (off == 0)
458 was_in = is_in;
459 if (was_in != is_in) {
460 fprintf(stderr, "%s: %sin core: %p len %ld\n", mark,
461 was_in ? "" : "not ", vec + prev, off - prev);
462 was_in = is_in;
463 prev = off;
464 }
465 }
466 fprintf(stderr,
467 "%s: %sin core: %p len %ld\n", mark,
468 was_in ? "" : "not ", vec + prev, off - prev);
469 } else
470 fprintf(stderr, "mincore: %s", rrd_strerror(errno));
471 }
472 #else
473 fprintf(stderr, "sorry mincore only works with mmap");
474 #endif
475 }
476 #endif /* defined DEBUG && DEBUG > 1 */
478 /*
479 * get exclusive lock to whole file.
480 * lock gets removed when we close the file
481 *
482 * returns 0 on success
483 */
484 int rrd_lock(
485 rrd_file_t *rrd_file)
486 {
487 int rcstat;
488 rrd_simple_file_t *rrd_simple_file;
489 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
491 {
492 #if defined(_WIN32) && !defined(__CYGWIN__) && !defined(__CYGWIN32__)
493 struct _stat st;
495 if (_fstat(rrd_simple_file->fd, &st) == 0) {
496 rcstat = _locking(rrd_simple_file->fd, _LK_NBLCK, st.st_size);
497 } else {
498 rcstat = -1;
499 }
500 #else
501 struct flock lock;
503 lock.l_type = F_WRLCK; /* exclusive write lock */
504 lock.l_len = 0; /* whole file */
505 lock.l_start = 0; /* start of file */
506 lock.l_whence = SEEK_SET; /* end of file */
508 rcstat = fcntl(rrd_simple_file->fd, F_SETLK, &lock);
509 #endif
510 }
512 return (rcstat);
513 }
516 /* drop cache except for the header and the active pages */
517 void rrd_dontneed(
518 rrd_file_t *rrd_file,
519 rrd_t *rrd)
520 {
521 rrd_simple_file_t *rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
522 #if defined USE_MADVISE || defined HAVE_POSIX_FADVISE
523 size_t dontneed_start;
524 size_t rra_start;
525 size_t active_block;
526 size_t i;
527 ssize_t _page_size = sysconf(_SC_PAGESIZE);
529 if (rrd_file == NULL) {
530 #if defined DEBUG && DEBUG
531 fprintf (stderr, "rrd_dontneed: Argument 'rrd_file' is NULL.\n");
532 #endif
533 return;
534 }
536 #if defined DEBUG && DEBUG > 1
537 mincore_print(rrd_file, "before");
538 #endif
540 /* ignoring errors from RRDs that are smaller then the file_len+rounding */
541 rra_start = rrd_file->header_len;
542 dontneed_start = PAGE_START(rra_start) + _page_size;
543 for (i = 0; i < rrd->stat_head->rra_cnt; ++i) {
544 active_block =
545 PAGE_START(rra_start
546 + rrd->rra_ptr[i].cur_row
547 * rrd->stat_head->ds_cnt * sizeof(rrd_value_t));
548 if (active_block > dontneed_start) {
549 #ifdef USE_MADVISE
550 madvise(rrd_simple_file->file_start + dontneed_start,
551 active_block - dontneed_start - 1, MADV_DONTNEED);
552 #endif
553 /* in linux at least only fadvise DONTNEED seems to purge pages from cache */
554 #ifdef HAVE_POSIX_FADVISE
555 posix_fadvise(rrd_simple_file->fd, dontneed_start,
556 active_block - dontneed_start - 1,
557 POSIX_FADV_DONTNEED);
558 #endif
559 }
560 dontneed_start = active_block;
561 /* do not release 'hot' block if update for this RAA will occur
562 * within 10 minutes */
563 if (rrd->stat_head->pdp_step * rrd->rra_def[i].pdp_cnt -
564 rrd->live_head->last_up % (rrd->stat_head->pdp_step *
565 rrd->rra_def[i].pdp_cnt) < 10 * 60) {
566 dontneed_start += _page_size;
567 }
568 rra_start +=
569 rrd->rra_def[i].row_cnt * rrd->stat_head->ds_cnt *
570 sizeof(rrd_value_t);
571 }
573 if (dontneed_start < rrd_file->file_len) {
574 #ifdef USE_MADVISE
575 madvise(rrd_simple_file->file_start + dontneed_start,
576 rrd_file->file_len - dontneed_start, MADV_DONTNEED);
577 #endif
578 #ifdef HAVE_POSIX_FADVISE
579 posix_fadvise(rrd_simple_file->fd, dontneed_start,
580 rrd_file->file_len - dontneed_start,
581 POSIX_FADV_DONTNEED);
582 #endif
583 }
585 #if defined DEBUG && DEBUG > 1
586 mincore_print(rrd_file, "after");
587 #endif
588 #endif /* without madvise and posix_fadvise it does not make much sense todo anything */
589 }
595 int rrd_close(
596 rrd_file_t *rrd_file)
597 {
598 rrd_simple_file_t *rrd_simple_file;
599 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
600 int ret;
602 #ifdef HAVE_MMAP
603 ret = msync(rrd_simple_file->file_start, rrd_file->file_len, MS_ASYNC);
604 if (ret != 0)
605 rrd_set_error("msync rrd_file: %s", rrd_strerror(errno));
606 ret = munmap(rrd_simple_file->file_start, rrd_file->file_len);
607 if (ret != 0)
608 rrd_set_error("munmap rrd_file: %s", rrd_strerror(errno));
609 #endif
610 ret = close(rrd_simple_file->fd);
611 if (ret != 0)
612 rrd_set_error("closing file: %s", rrd_strerror(errno));
613 free(rrd_file->pvt);
614 free(rrd_file);
615 rrd_file = NULL;
616 return ret;
617 }
620 /* Set position of rrd_file. */
622 off_t rrd_seek(
623 rrd_file_t *rrd_file,
624 off_t off,
625 int whence)
626 {
627 off_t ret = 0;
628 rrd_simple_file_t *rrd_simple_file;
629 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
631 #ifdef HAVE_MMAP
632 if (whence == SEEK_SET)
633 rrd_file->pos = off;
634 else if (whence == SEEK_CUR)
635 rrd_file->pos += off;
636 else if (whence == SEEK_END)
637 rrd_file->pos = rrd_file->file_len + off;
638 #else
639 ret = lseek(rrd_simple_file->fd, off, whence);
640 if (ret < 0)
641 rrd_set_error("lseek: %s", rrd_strerror(errno));
642 rrd_file->pos = ret;
643 #endif
644 /* mimic fseek, which returns 0 upon success */
645 return ret < 0; /*XXX: or just ret to mimic lseek */
646 }
649 /* Get current position in rrd_file. */
651 off_t rrd_tell(
652 rrd_file_t *rrd_file)
653 {
654 return rrd_file->pos;
655 }
658 /* Read count bytes into buffer buf, starting at rrd_file->pos.
659 * Returns the number of bytes read or <0 on error. */
661 ssize_t rrd_read(
662 rrd_file_t *rrd_file,
663 void *buf,
664 size_t count)
665 {
666 rrd_simple_file_t *rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
667 #ifdef HAVE_MMAP
668 size_t _cnt = count;
669 ssize_t _surplus;
671 if (rrd_file->pos > rrd_file->file_len || _cnt == 0) /* EOF */
672 return 0;
673 if (buf == NULL)
674 return -1; /* EINVAL */
675 _surplus = rrd_file->pos + _cnt - rrd_file->file_len;
676 if (_surplus > 0) { /* short read */
677 _cnt -= _surplus;
678 }
679 if (_cnt == 0)
680 return 0; /* EOF */
681 buf = memcpy(buf, rrd_simple_file->file_start + rrd_file->pos, _cnt);
683 rrd_file->pos += _cnt; /* mimmic read() semantics */
684 return _cnt;
685 #else
686 ssize_t ret;
688 ret = read(rrd_simple_file->fd, buf, count);
689 if (ret > 0)
690 rrd_file->pos += ret; /* mimmic read() semantics */
691 return ret;
692 #endif
693 }
696 /* Write count bytes from buffer buf to the current position
697 * rrd_file->pos of rrd_simple_file->fd.
698 * Returns the number of bytes written or <0 on error. */
700 ssize_t rrd_write(
701 rrd_file_t *rrd_file,
702 const void *buf,
703 size_t count)
704 {
705 rrd_simple_file_t *rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
706 #ifdef HAVE_MMAP
707 size_t old_size = rrd_file->file_len;
708 if (count == 0)
709 return 0;
710 if (buf == NULL)
711 return -1; /* EINVAL */
713 if((rrd_file->pos + count) > old_size)
714 {
715 rrd_set_error("attempting to write beyond end of file (%ld + %ld > %ld)",rrd_file->pos, count, old_size);
716 return -1;
717 }
718 memcpy(rrd_simple_file->file_start + rrd_file->pos, buf, count);
719 rrd_file->pos += count;
720 return count; /* mimmic write() semantics */
721 #else
722 ssize_t _sz = write(rrd_simple_file->fd, buf, count);
724 if (_sz > 0)
725 rrd_file->pos += _sz;
726 return _sz;
727 #endif
728 }
731 /* this is a leftover from the old days, it serves no purpose
732 and is therefore turned into a no-op */
733 void rrd_flush(
734 rrd_file_t UNUSED(*rrd_file))
735 {
736 }
738 /* Initialize RRD header. */
740 void rrd_init(
741 rrd_t *rrd)
742 {
743 rrd->stat_head = NULL;
744 rrd->ds_def = NULL;
745 rrd->rra_def = NULL;
746 rrd->live_head = NULL;
747 rrd->legacy_last_up = NULL;
748 rrd->rra_ptr = NULL;
749 rrd->pdp_prep = NULL;
750 rrd->cdp_prep = NULL;
751 rrd->rrd_value = NULL;
752 }
755 /* free RRD header data. */
757 #ifdef HAVE_MMAP
758 void rrd_free(
759 rrd_t *rrd)
760 {
761 if (rrd->legacy_last_up) { /* this gets set for version < 3 only */
762 free(rrd->live_head);
763 }
764 }
765 #else
766 void rrd_free(
767 rrd_t *rrd)
768 {
769 free(rrd->live_head);
770 free(rrd->stat_head);
771 free(rrd->ds_def);
772 free(rrd->rra_def);
773 free(rrd->rra_ptr);
774 free(rrd->pdp_prep);
775 free(rrd->cdp_prep);
776 free(rrd->rrd_value);
777 }
778 #endif
781 /* routine used by external libraries to free memory allocated by
782 * rrd library */
784 void rrd_freemem(
785 void *mem)
786 {
787 free(mem);
788 }
790 /*
791 * rra_update informs us about the RRAs being updated
792 * The low level storage API may use this information for
793 * aligning RRAs within stripes, or other performance enhancements
794 */
795 void rrd_notify_row(
796 rrd_file_t UNUSED(*rrd_file),
797 int UNUSED(rra_idx),
798 unsigned long UNUSED(rra_row),
799 time_t UNUSED(rra_time))
800 {
801 }
803 /*
804 * This function is called when creating a new RRD
805 * The storage implementation can use this opportunity to select
806 * a sensible starting row within the file.
807 * The default implementation is random, to ensure that all RRAs
808 * don't change to a new disk block at the same time
809 */
810 unsigned long rrd_select_initial_row(
811 rrd_file_t UNUSED(*rrd_file),
812 int UNUSED(rra_idx),
813 rra_def_t *rra
814 )
815 {
816 return rrd_random() % rra->row_cnt;
817 }