2 * Empire - A multi-player, client/server Internet based war game.
3 * Copyright (C) 1986-2011, Dave Pare, Jeff Bailey, Thomas Ruschak,
4 * Ken Stevens, Steve McClure, Markus Armbruster
6 * Empire is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 * See files README, COPYING and CREDITS in the root of the source
22 * tree for related information and legal notices. It is expected
23 * that future projects/authors will amend these files as needed.
27 * file.c: Operations on Empire tables (`files' for historical reasons)
29 * Known contributors to this file:
32 * Markus Armbruster, 2005-2011
40 #include <sys/types.h>
50 #include "prototypes.h"
52 static int open_locked(char *, int, mode_t);
53 static int ef_realloc_cache(struct empfile *, int);
54 static int fillcache(struct empfile *, int);
55 static int do_read(struct empfile *, void *, int, int);
56 static int do_write(struct empfile *, void *, int, int);
57 static unsigned get_seqno(struct empfile *, int);
58 static void new_seqno(struct empfile *, void *);
59 static void must_be_fresh(struct empfile *, void *);
60 static void do_blank(struct empfile *, void *, int, int);
61 static int ef_check(int);
63 static unsigned ef_generation;
66 * Open the file-backed table TYPE (EF_SECTOR, ...).
67 * HOW are flags to control operation. Naturally, immutable flags are
69 * If NELT is non-negative, the table must have that many elements.
70 * Return non-zero on success, zero on failure.
71 * You must call ef_close() before the next ef_open().
74 ef_open(int type, int how, int nelt)
77 int oflags, fd, fsiz, fids, nslots;
79 if (ef_check(type) < 0)
81 if (CANT_HAPPEN(how & EFF_IMMUTABLE))
82 how &= ~EFF_IMMUTABLE;
86 if (CANT_HAPPEN(ep->fd >= 0))
89 if (how & EFF_PRIVATE)
92 oflags |= O_CREAT | O_TRUNC;
93 fd = open_locked(ep->file, oflags, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
95 logerror("Can't open %s (%s)", ep->file, strerror(errno));
101 if (fsiz % ep->size) {
102 logerror("Can't open %s (file size not a multiple of record size %d)",
107 fids = fsiz / ep->size;
108 if (nelt >= 0 && nelt != fids) {
109 logerror("Can't open %s (got %d records instead of %d)",
110 ep->file, fids, nelt);
116 if (ep->flags & EFF_STATIC) {
117 /* ep->cache already points to space for ep->csize elements */
119 if (fids > ep->csize) {
120 logerror("Can't open %s (file larger than %d records)",
121 ep->file, ep->csize);
127 if (CANT_HAPPEN(ep->cache))
132 nslots = blksize(fd) / ep->size;
133 if (!ef_realloc_cache(ep, nslots)) {
134 logerror("Can't map %s (%s)", ep->file, strerror(errno));
142 ep->flags = (ep->flags & EFF_IMMUTABLE) | (how & ~EFF_CREATE);
145 /* map file into cache */
146 if ((how & EFF_MEM) && fids) {
147 if (fillcache(ep, 0) != fids) {
148 ep->cids = 0; /* prevent cache flush */
160 open_locked(char *name, int oflags, mode_t mode)
162 int rdlonly = (oflags & O_ACCMODE) == O_RDONLY;
166 fd = _sopen(name, oflags | O_BINARY, rdlonly ? SH_DENYNO : SH_DENYWR,
173 fd = open(name, oflags, mode);
177 lock.l_type = rdlonly ? F_RDLCK : F_WRLCK;
178 lock.l_whence = SEEK_SET;
179 lock.l_start = lock.l_len = 0;
180 if (fcntl(fd, F_SETLK, &lock) == -1) {
189 * Reallocate cache for table EP to hold COUNT slots.
190 * The table must not be allocated statically.
191 * The cache may still be unmapped.
192 * If reallocation succeeds, any pointers obtained from ef_ptr()
194 * If it fails, the cache is unchanged, and errno is set.
195 * Return non-zero on success, zero on failure.
198 ef_realloc_cache(struct empfile *ep, int count)
202 if (CANT_HAPPEN(ep->flags & EFF_STATIC))
204 if (CANT_HAPPEN(count < 0))
208 * Avoid zero slots, because that can lead to null cache, which
209 * would be interpreted as unmapped cache.
213 cache = realloc(ep->cache, count * ep->size);
223 * Open the table TYPE as view of table BASE.
224 * Return non-zero on success, zero on failure.
225 * Beware: views work only as long as BASE doesn't change size!
226 * You must call ef_close(TYPE) before closing BASE.
229 ef_open_view(int type, int base)
233 if (CANT_HAPPEN(!EF_IS_VIEW(type)))
236 if (CANT_HAPPEN(!(ef_flags(base) & EFF_MEM)))
239 ep->cache = empfile[base].cache;
240 ep->csize = empfile[base].csize;
241 ep->flags |= EFF_MEM;
242 ep->baseid = empfile[base].baseid;
243 ep->cids = empfile[base].cids;
244 ep->fids = empfile[base].fids;
249 * Close the open table TYPE (EF_SECTOR, ...).
250 * Return non-zero on success, zero on failure.
258 if (ef_check(type) < 0)
262 if (EF_IS_VIEW(type)) {
268 if (!(ep->flags & EFF_STATIC)) {
273 if (close(ep->fd) < 0) {
274 logerror("Error closing %s (%s)", ep->file, strerror(errno));
279 ep->flags &= EFF_IMMUTABLE;
280 ep->baseid = ep->cids = ep->fids = 0;
287 * Flush file-backed table TYPE (EF_SECTOR, ...) to its backing file.
288 * Do nothing if the table is privately mapped.
289 * Update timestamps of written elements if table is EFF_TYPED.
290 * Return non-zero on success, zero on failure.
297 if (ef_check(type) < 0)
300 if (ep->flags & EFF_PRIVATE)
301 return 1; /* nothing to do */
302 if (CANT_HAPPEN(ep->fd < 0))
305 * We don't know which cache entries are dirty. ef_write() writes
306 * through, but direct updates through ef_ptr() don't. They are
307 * allowed only with EFF_MEM. Assume the whole cash is dirty
310 if (ep->flags & EFF_MEM) {
311 if (do_write(ep, ep->cache, ep->baseid, ep->cids) < 0)
319 * Return pointer to element ID in table TYPE if it exists, else NULL.
320 * The table must be fully cached, i.e. flags & EFF_MEM.
321 * The caller is responsible for flushing changes he makes.
324 ef_ptr(int type, int id)
328 if (ef_check(type) < 0)
331 if (CANT_HAPPEN(!(ep->flags & EFF_MEM) || !ep->cache))
333 if (id < 0 || id >= ep->fids)
335 return ep->cache + ep->size * id;
339 * Read element ID from table TYPE into buffer INTO.
340 * FIXME pass buffer size!
341 * INTO is marked fresh with ef_mark_fresh().
342 * Return non-zero on success, zero on failure.
345 ef_read(int type, int id, void *into)
350 if (ef_check(type) < 0)
353 if (CANT_HAPPEN(!ep->cache))
355 if (id < 0 || id >= ep->fids)
358 if (ep->flags & EFF_MEM) {
359 cachep = ep->cache + id * ep->size;
361 if (ep->baseid + ep->cids <= id || ep->baseid > id) {
362 if (fillcache(ep, id) < 1)
365 cachep = ep->cache + (id - ep->baseid) * ep->size;
367 memcpy(into, cachep, ep->size);
368 ef_mark_fresh(type, into);
371 ep->postread(id, into);
376 * Fill cache of file-backed EP with elements starting at ID.
377 * If any were read, return their number.
378 * Else return -1 and leave the cache unchanged.
381 fillcache(struct empfile *ep, int id)
385 if (CANT_HAPPEN(!ep->cache))
388 ret = do_read(ep, ep->cache, id, MIN(ep->csize, ep->fids - id));
398 do_read(struct empfile *ep, void *buf, int id, int count)
403 if (CANT_HAPPEN(ep->fd < 0 || id < 0 || count < 0))
406 if (lseek(ep->fd, id * ep->size, SEEK_SET) == (off_t)-1) {
407 logerror("Error seeking %s to elt %d (%s)",
408 ep->file, id, strerror(errno));
413 n = count * ep->size;
415 ret = read(ep->fd, p, n);
417 if (errno != EINTR) {
418 logerror("Error reading %s elt %d (%s)",
420 id + (int)((p - (char *)buf) / ep->size),
424 } else if (ret == 0) {
425 logerror("Unexpected EOF reading %s elt %d",
426 ep->file, id + (int)((p - (char *)buf) / ep->size));
434 return (p - (char *)buf) / ep->size;
438 * Write COUNT elements starting at ID from BUF to file-backed EP.
439 * Update the timestamp if the table is EFF_TYPED.
440 * Don't actually write if table is privately mapped.
441 * Return 0 on success, -1 on error (file may be corrupt then).
444 do_write(struct empfile *ep, void *buf, int id, int count)
448 struct emptypedstr *elt;
451 if (CANT_HAPPEN(ep->fd < 0 || id < 0 || count < 0))
454 if (ep->flags & EFF_TYPED) {
455 now = ep->flags & EFF_NOTIME ? (time_t)-1 : time(NULL);
456 for (i = 0; i < count; i++) {
458 * TODO Oopses here could be due to bad data corruption.
459 * Fail instead of attempting to recover?
461 elt = (struct emptypedstr *)((char *)buf + i * ep->size);
462 if (CANT_HAPPEN(elt->ef_type != ep->uid))
463 elt->ef_type = ep->uid;
464 if (CANT_HAPPEN(elt->uid != id + i))
466 if (now != (time_t)-1)
467 elt->timestamp = now;
471 if (ep->flags & EFF_PRIVATE)
474 if (lseek(ep->fd, id * ep->size, SEEK_SET) == (off_t)-1) {
475 logerror("Error seeking %s to elt %d (%s)",
476 ep->file, id, strerror(errno));
481 n = count * ep->size;
483 ret = write(ep->fd, p, n);
485 if (errno != EINTR) {
486 logerror("Error writing %s elt %d (%s)",
488 id + (int)((p - (char *)buf) / ep->size),
502 * Write element ID into table TYPE from buffer FROM.
503 * FIXME pass buffer size!
504 * Update timestamp in FROM if table is EFF_TYPED.
505 * If table is file-backed and not privately mapped, write through
506 * cache straight to disk.
507 * Cannot write beyond the end of fully cached table (flags & EFF_MEM).
508 * Can write at the end of partially cached table.
509 * FROM must be fresh; see ef_make_stale().
510 * Return non-zero on success, zero on failure.
513 ef_write(int type, int id, void *from)
518 if (ef_check(type) < 0)
521 if (CANT_HAPPEN((ep->flags & (EFF_MEM | EFF_PRIVATE)) == EFF_PRIVATE))
524 if (id >= ep->fids) {
525 /* beyond end of file */
526 if (CANT_HAPPEN((ep->flags & EFF_MEM) || id > ep->fids))
527 return 0; /* not implemented */
528 /* write at end of file extends it */
533 if (id >= ep->baseid && id < ep->baseid + ep->cids) {
534 cachep = ep->cache + (id - ep->baseid) * ep->size;
536 must_be_fresh(ep, from);
540 ep->prewrite(id, cachep, from);
542 if (do_write(ep, from, id, 1) < 0)
545 if (cachep && cachep != from) /* update the cache if necessary */
546 memcpy(cachep, from, ep->size);
552 * BUF is an element of table TYPE.
553 * ID is its new element ID.
554 * If table is EFF_TYPED, change id and sequence number stored in BUF.
558 ef_set_uid(int type, void *buf, int uid)
560 struct emptypedstr *elt;
563 if (ef_check(type) < 0)
566 if (!(ep->flags & EFF_TYPED))
572 elt->seqno = get_seqno(ep, uid);
576 * Return sequence number of element ID in table EP.
577 * Return zero if table is not EFF_TYPED (it has no sequence number
581 get_seqno(struct empfile *ep, int id)
583 struct emptypedstr *elt;
585 if (!(ep->flags & EFF_TYPED))
587 if (id < 0 || id >= ep->fids)
589 if (id >= ep->baseid && id < ep->baseid + ep->cids)
590 elt = (void *)(ep->cache + (id - ep->baseid) * ep->size);
592 /* need a buffer, steal last cache slot */
593 if (ep->cids == ep->csize)
595 elt = (void *)(ep->cache + ep->cids * ep->size);
596 if (do_read(ep, elt, id, 1) < 0)
597 return 0; /* deep trouble */
603 * Increment sequence number in BUF, which is about to be written to EP.
604 * Do nothing if table is not EFF_TYPED (it has no sequence number
606 * Else, BUF's sequence number must match the one in EP's cache. If
607 * it doesn't, we're about to clobber a previous write.
610 new_seqno(struct empfile *ep, void *buf)
612 struct emptypedstr *elt = buf;
615 if (!(ep->flags & EFF_TYPED))
617 old_seqno = get_seqno(ep, elt->uid);
618 CANT_HAPPEN(old_seqno != elt->seqno);
619 elt->seqno = old_seqno + 1;
623 * Make all copies stale.
624 * Only fresh copies may be written back to the cache.
625 * To be called by functions that may yield the processor.
626 * Writing an copy when there has been a yield since it was read is
627 * unsafe, because we could clobber another thread's write then.
628 * Robust code must assume the that any function that may yield does
629 * yield. Marking copies stale there lets us catch unsafe writes.
637 /* Mark copy of an element of table TYPE in BUF fresh. */
639 ef_mark_fresh(int type, void *buf)
643 if (ef_check(type) < 0)
646 if (!(ep->flags & EFF_TYPED))
648 ((struct emptypedstr *)buf)->generation = ef_generation;
652 must_be_fresh(struct empfile *ep, void *buf)
654 struct emptypedstr *elt = buf;
656 if (!(ep->flags & EFF_TYPED))
658 CANT_HAPPEN(elt->generation != (ef_generation & 0xfff));
662 * Extend table TYPE by COUNT elements.
663 * Any pointers obtained from ef_ptr() become invalid.
664 * Return non-zero on success, zero on failure.
667 ef_extend(int type, int count)
671 int need_sentinel, i, id;
673 if (ef_check(type) < 0 || CANT_HAPPEN(EF_IS_VIEW(type)))
676 if (CANT_HAPPEN(count < 0))
680 if (ep->flags & EFF_MEM) {
681 need_sentinel = (ep->flags & EFF_SENTINEL) != 0;
682 if (id + count + need_sentinel > ep->csize) {
683 if (ep->flags & EFF_STATIC) {
684 logerror("Can't extend %s beyond %d elements",
685 ep->name, ep->csize - need_sentinel);
688 if (!ef_realloc_cache(ep, id + count + need_sentinel)) {
689 logerror("Can't extend %s to %d elements (%s)",
690 ep->name, id + count, strerror(errno));
694 p = ep->cache + id * ep->size;
695 do_blank(ep, p, id, count);
697 if (do_write(ep, p, id, count) < 0)
701 memset(ep->cache + (id + count) * ep->size, 0, ep->size);
702 ep->cids = id + count;
704 /* need a buffer, steal last cache slot */
705 if (ep->cids == ep->csize)
707 p = ep->cache + ep->cids * ep->size;
708 for (i = 0; i < count; i++) {
709 do_blank(ep, p, id + i, 1);
710 if (do_write(ep, p, id + i, 1) < 0)
714 ep->fids = id + count;
721 * Initialize element ID for table TYPE in BUF.
722 * FIXME pass buffer size!
723 * BUF is marked fresh with ef_mark_fresh().
726 ef_blank(int type, int id, void *buf)
729 struct emptypedstr *elt;
731 if (ef_check(type) < 0)
734 do_blank(ep, buf, id, 1);
735 if (ep->flags & EFF_TYPED) {
737 elt->seqno = get_seqno(ep, elt->uid);
739 ef_mark_fresh(type, buf);
743 * Initialize COUNT elements of EP in BUF, starting with element ID.
746 do_blank(struct empfile *ep, void *buf, int id, int count)
749 struct emptypedstr *elt;
751 memset(buf, 0, count * ep->size);
752 for (i = 0; i < count; i++) {
753 elt = (struct emptypedstr *)((char *)buf + i * ep->size);
754 if (ep->flags & EFF_TYPED) {
755 elt->ef_type = ep->uid;
764 * Truncate table TYPE to COUNT elements.
765 * Any pointers obtained from ef_ptr() become invalid.
766 * Return non-zero on success, zero on failure.
769 ef_truncate(int type, int count)
774 if (ef_check(type) < 0 || CANT_HAPPEN(EF_IS_VIEW(type)))
777 if (CANT_HAPPEN(count < 0 || count > ep->fids))
780 if (ep->fd >= 0 && !(ep->flags & EFF_PRIVATE)) {
781 if (ftruncate(ep->fd, count * ep->size) < 0) {
782 logerror("Can't truncate %s to %d elements (%s)",
783 ep->file, count, strerror(errno));
789 if (ep->flags & EFF_MEM) {
790 need_sentinel = (ep->flags & EFF_SENTINEL) != 0;
791 if (!(ep->flags & EFF_STATIC)) {
792 if (!ef_realloc_cache(ep, count + need_sentinel)) {
793 logerror("Can't shrink %s cache after truncate (%s)",
794 ep->name, strerror(errno));
795 /* continue with unshrunk cache */
799 memset(ep->cache + count * ep->size, 0, ep->size);
802 if (ep->baseid >= count)
804 else if (ep->cids > count - ep->baseid)
805 ep->cids = count - ep->baseid;
816 if (ef_check(type) < 0)
818 return empfile[type].cadef;
824 if (ef_check(type) < 0)
826 return empfile[type].fids;
832 if (ef_check(type) < 0)
834 return empfile[type].flags;
840 if (ef_check(type) < 0)
842 if (empfile[type].fd <= 0)
844 return fdate(empfile[type].fd);
848 * Search for a table matching NAME, return its table type.
849 * Return M_NOTFOUND if there are no matches, M_NOTUNIQUE if there are
853 ef_byname(char *name)
855 return stmtch(name, empfile, offsetof(struct empfile, name),
860 * Search CHOICES[] for a table type matching NAME, return it.
861 * Return M_NOTFOUND if there are no matches, M_NOTUNIQUE if there are
863 * CHOICES[] must be terminated with a negative value.
866 ef_byname_from(char *name, int choices[])
872 for (p = choices; *p >= 0; p++) {
873 if (ef_check(*p) < 0)
875 switch (mineq(name, empfile[*p].name)) {
893 if (ef_check(type) < 0)
894 return "bad ef_type";
895 return empfile[type].name;
901 if (CANT_HAPPEN((unsigned)type >= EF_MAX))
907 * Ensure table contains element ID.
908 * If necessary, extend it in steps of COUNT elements.
909 * Return non-zero on success, zero on failure.
912 ef_ensure_space(int type, int id, int count)
914 if (ef_check(type) < 0)
918 while (id >= empfile[type].fids) {
919 if (!ef_extend(type, count))