/*
* Empire - A multi-player, client/server Internet based war game.
* Copyright (C) 1986-2021, Dave Pare, Jeff Bailey, Thomas Ruschak,
* Ken Stevens, Steve McClure, Markus Armbruster
*
* Empire is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*
* ---
*
* See files README, COPYING and CREDITS in the root of the source
* tree for related information and legal notices. It is expected
* that future projects/authors will amend these files as needed.
*
* ---
*
* file.c: Operations on Empire tables (`files' for historical reasons)
*
* Known contributors to this file:
* Dave Pare, 1989
* Steve McClure, 2000
* Markus Armbruster, 2005-2014
*/
#include
#include
#include
#include
#include
#include
#include
#ifdef _WIN32
#include
#include
#endif
#include "file.h"
#include "match.h"
#include "misc.h"
#include "prototypes.h"
static int open_locked(char *, int, mode_t);
static int ef_realloc_cache(struct empfile *, int);
static int fillcache(struct empfile *, int);
static int do_read(struct empfile *, void *, int, int);
static int do_write(struct empfile *, void *, int, int);
static unsigned get_seqno(struct empfile *, int);
static void new_seqno(struct empfile *, void *);
static void must_be_fresh(struct empfile *, void *);
static int do_extend(struct empfile *, int);
static void do_blank(struct empfile *, void *, int, int);
static int ef_check(int);
static unsigned ef_generation;
/*
* Open the file-backed table @type (EF_SECTOR, ...).
* @how are flags to control operation. Naturally, immutable flags are
* not permitted.
* The table must not be already open.
* Return non-zero on success, zero on failure.
*/
int
ef_open(int type, int how)
{
struct empfile *ep;
int oflags, fd, fsiz, fids, nslots, fail;
if (ef_check(type) < 0)
return 0;
if (CANT_HAPPEN(how & EFF_IMMUTABLE))
how &= ~EFF_IMMUTABLE;
/* open file */
ep = &empfile[type];
if (CANT_HAPPEN(!ep->file || ep->base != EF_BAD || ep->fd >= 0))
return 0;
if (CANT_HAPPEN(ep->prewrite && !(how & EFF_MEM)))
return 0; /* not implemented */
oflags = O_RDWR;
if (how & EFF_PRIVATE)
oflags = O_RDONLY;
if (how & EFF_CREATE)
oflags |= O_CREAT | O_TRUNC;
fd = open_locked(ep->file, oflags, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
if (fd < 0) {
logerror("Can't open %s (%s)", ep->file, strerror(errno));
return 0;
}
/* get file size */
if (how & EFF_CREATE) {
fids = ep->nent >= 0 ? ep->nent : 0;
} else {
fsiz = fsize(fd);
if (fsiz % ep->size) {
logerror("Can't open %s (file size not a multiple of record size %d)",
ep->file, ep->size);
close(fd);
return 0;
}
fids = fsiz / ep->size;
if (ep->nent >= 0 && ep->nent != fids) {
logerror("Can't open %s (got %d records instead of %d)",
ep->file, fids, ep->nent);
close(fd);
return 0;
}
}
/* allocate cache */
if (ep->flags & EFF_STATIC) {
/* ep->cache already points to space for ep->csize elements */
if (how & EFF_MEM) {
if (fids > ep->csize) {
CANT_HAPPEN(ep->nent >= 0); /* insufficient static cache */
logerror("Can't open %s (file larger than %d records)",
ep->file, ep->csize);
close(fd);
return 0;
}
}
} else {
if (CANT_HAPPEN(ep->cache))
free(ep->cache);
if (how & EFF_MEM)
nslots = fids;
else
nslots = blksize(fd) / ep->size;
if (!ef_realloc_cache(ep, nslots)) {
logerror("Can't map %s (%s)", ep->file, strerror(errno));
close(fd);
return 0;
}
}
ep->baseid = 0;
ep->cids = 0;
ep->flags = (ep->flags & EFF_IMMUTABLE) | (how & ~EFF_CREATE);
ep->fd = fd;
if (how & EFF_CREATE) {
/* populate new file */
ep->fids = 0;
fail = !do_extend(ep, fids);
} else {
ep->fids = fids;
if ((how & EFF_MEM) && fids)
fail = fillcache(ep, 0) != fids;
else
fail = 0;
}
if (fail) {
ep->cids = 0; /* prevent cache flush */
ef_close(type);
return 0;
}
if (ep->onresize)
ep->onresize(type);
return 1;
}
static int
open_locked(char *name, int oflags, mode_t mode)
{
int rdlonly = (oflags & O_ACCMODE) == O_RDONLY;
int fd;
#ifdef _WIN32
fd = _sopen(name, oflags | O_BINARY, rdlonly ? SH_DENYNO : SH_DENYWR,
mode);
if (fd < 0)
return -1;
#else /* !_WIN32 */
struct flock lock;
fd = open(name, oflags, mode);
if (fd < 0)
return -1;
lock.l_type = rdlonly ? F_RDLCK : F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = lock.l_len = 0;
if (fcntl(fd, F_SETLK, &lock) == -1) {
close(fd);
return -1;
}
#endif /* !_WIN32 */
return fd;
}
/*
* Reallocate cache for table @ep to hold @count slots.
* The table must not be allocated statically.
* The cache may still be unmapped.
* If reallocation succeeds, any pointers obtained from ef_ptr()
* become invalid.
* If it fails, the cache is unchanged, and errno is set.
* Return non-zero on success, zero on failure.
*/
static int
ef_realloc_cache(struct empfile *ep, int count)
{
void *cache;
if (CANT_HAPPEN(ep->flags & EFF_STATIC))
return 0;
if (CANT_HAPPEN(count < 0))
count = 0;
/*
* Avoid zero slots, because that can lead to null cache, which
* would be interpreted as unmapped cache.
*/
if (count == 0)
count++;
cache = realloc(ep->cache, count * ep->size);
if (!cache)
return 0;
ep->cache = cache;
ep->csize = count;
return 1;
}
/*
* Open the table @type, which is a view of a base table
* The table must not be already open.
* Return non-zero on success, zero on failure.
* Beware: views work only as long as the base table doesn't change size!
* You must close the view before closing its base table.
*/
int
ef_open_view(int type)
{
struct empfile *ep;
int base;
if (ef_check(type) < 0)
return 0;
ep = &empfile[type];
base = ep->base;
if (ef_check(base) < 0)
return 0;
if (CANT_HAPPEN(!(ef_flags(base) & EFF_MEM)
|| ep->file
|| ep->size != empfile[base].size
|| ep->nent != empfile[base].nent
|| ep->cache || ep->oninit || ep->postread
|| ep->prewrite || ep->onresize))
return -1;
ep->cache = empfile[base].cache;
ep->csize = empfile[base].csize;
ep->flags |= EFF_MEM;
ep->baseid = empfile[base].baseid;
ep->cids = empfile[base].cids;
ep->fids = empfile[base].fids;
return 0;
}
/*
* Close the open table @type (EF_SECTOR, ...).
* Return non-zero on success, zero on failure.
*/
int
ef_close(int type)
{
struct empfile *ep;
int retval = 1;
if (ef_check(type) < 0)
return 0;
ep = &empfile[type];
if (EF_IS_VIEW(type)) {
ep->cache = NULL;
ep->csize = 0;
} else {
if (!ef_flush(type))
retval = 0;
if (!(ep->flags & EFF_STATIC)) {
free(ep->cache);
ep->cache = NULL;
ep->csize = 0;
}
if (close(ep->fd) < 0) {
logerror("Error closing %s (%s)", ep->file, strerror(errno));
retval = 0;
}
ep->fd = -1;
}
ep->flags &= EFF_IMMUTABLE;
ep->baseid = ep->cids = ep->fids = 0;
if (ep->onresize)
ep->onresize(type);
return retval;
}
/*
* Flush file-backed table @type (EF_SECTOR, ...) to its backing file.
* Do nothing if the table is privately mapped.
* Update timestamps of written elements if table is EFF_TYPED.
* Return non-zero on success, zero on failure.
*/
int
ef_flush(int type)
{
struct empfile *ep;
if (ef_check(type) < 0)
return 0;
ep = &empfile[type];
if (ep->flags & EFF_PRIVATE)
return 1; /* nothing to do */
if (CANT_HAPPEN(ep->fd < 0))
return 0;
/*
* We don't know which cache entries are dirty. ef_write() writes
* through, but direct updates through ef_ptr() don't. They are
* allowed only with EFF_MEM. Assume the whole cash is dirty
* then.
*/
if (ep->flags & EFF_MEM) {
if (do_write(ep, ep->cache, ep->baseid, ep->cids) < 0)
return 0;
}
return 1;
}
/*
* Return pointer to element @id in table @type if it exists, else NULL.
* The table must be fully cached, i.e. flags & EFF_MEM.
* The caller is responsible for flushing changes he makes.
*/
void *
ef_ptr(int type, int id)
{
struct empfile *ep;
if (ef_check(type) < 0)
return NULL;
ep = &empfile[type];
if (CANT_HAPPEN(!(ep->flags & EFF_MEM) || !ep->cache))
return NULL;
if (id < 0 || id >= ep->fids)
return NULL;
return ep->cache + ep->size * id;
}
/*
* Read element @id from table @type into buffer @into.
* FIXME pass buffer size!
* @into is marked fresh with ef_mark_fresh().
* Return non-zero on success, zero on failure.
*/
int
ef_read(int type, int id, void *into)
{
struct empfile *ep;
void *cachep;
if (ef_check(type) < 0)
return 0;
ep = &empfile[type];
if (CANT_HAPPEN(!ep->cache))
return 0;
if (id < 0 || id >= ep->fids)
return 0;
if (ep->flags & EFF_MEM) {
cachep = ep->cache + id * ep->size;
} else {
if (ep->baseid + ep->cids <= id || ep->baseid > id) {
if (fillcache(ep, id) < 1)
return 0;
}
cachep = ep->cache + (id - ep->baseid) * ep->size;
}
memcpy(into, cachep, ep->size);
ef_mark_fresh(type, into);
if (ep->postread)
ep->postread(id, into);
return 1;
}
/*
* Fill cache of file-backed @ep with elements starting at @id.
* If any were read, return their number.
* Else return -1 and leave the cache unchanged.
*/
static int
fillcache(struct empfile *ep, int id)
{
int ret;
if (CANT_HAPPEN(!ep->cache))
return -1;
ret = do_read(ep, ep->cache, id, MIN(ep->csize, ep->fids - id));
if (ret >= 0) {
/* cache changed */
ep->baseid = id;
ep->cids = ret;
}
return ret;
}
static int
do_read(struct empfile *ep, void *buf, int id, int count)
{
int n, ret;
char *p;
if (CANT_HAPPEN(ep->fd < 0 || id < 0 || count < 0))
return -1;
if (lseek(ep->fd, id * ep->size, SEEK_SET) == (off_t)-1) {
logerror("Error seeking %s to elt %d (%s)",
ep->file, id, strerror(errno));
return -1;
}
p = buf;
n = count * ep->size;
while (n > 0) {
ret = read(ep->fd, p, n);
if (ret < 0) {
if (errno != EINTR) {
logerror("Error reading %s elt %d (%s)",
ep->file,
id + (int)((p - (char *)buf) / ep->size),
strerror(errno));
break;
}
} else if (ret == 0) {
logerror("Unexpected EOF reading %s elt %d",
ep->file, id + (int)((p - (char *)buf) / ep->size));
break;
} else {
p += ret;
n -= ret;
}
}
return (p - (char *)buf) / ep->size;
}
/*
* Write @count elements starting at @id from @buf to file-backed @ep.
* Update the timestamp if the table is EFF_TYPED.
* Don't actually write if table is privately mapped.
* Return 0 on success, -1 on error (file may be corrupt then).
*/
static int
do_write(struct empfile *ep, void *buf, int id, int count)
{
int i, n, ret;
char *p;
struct ef_typedstr *elt;
time_t now;
if (CANT_HAPPEN(ep->fd < 0 || id < 0 || count < 0))
return -1;
if (ep->flags & EFF_TYPED) {
now = ep->flags & EFF_NOTIME ? (time_t)-1 : time(NULL);
for (i = 0; i < count; i++) {
/*
* TODO Oopses here could be due to bad data corruption.
* Fail instead of attempting to recover?
*/
elt = (struct ef_typedstr *)((char *)buf + i * ep->size);
if (CANT_HAPPEN(elt->ef_type != ep->uid))
elt->ef_type = ep->uid;
if (CANT_HAPPEN(elt->uid != id + i))
elt->uid = id + i;
if (now != (time_t)-1)
elt->timestamp = now;
}
}
if (ep->flags & EFF_PRIVATE)
return 0;
if (lseek(ep->fd, id * ep->size, SEEK_SET) == (off_t)-1) {
logerror("Error seeking %s to elt %d (%s)",
ep->file, id, strerror(errno));
return -1;
}
p = buf;
n = count * ep->size;
while (n > 0) {
ret = write(ep->fd, p, n);
if (ret < 0) {
if (errno != EINTR) {
logerror("Error writing %s elt %d (%s)",
ep->file,
id + (int)((p - (char *)buf) / ep->size),
strerror(errno));
return -1;
}
} else {
p += ret;
n -= ret;
}
}
return 0;
}
/*
* Write element @id into table @type from buffer @from.
* FIXME pass buffer size!
* Update timestamp in @from if table is EFF_TYPED.
* If table is file-backed and not privately mapped, write through
* cache straight to disk.
* Cannot write beyond the end of fully cached table (flags & EFF_MEM).
* Can write at the end of partially cached table.
* @from must be fresh; see ef_make_stale().
* Return non-zero on success, zero on failure.
*/
int
ef_write(int type, int id, void *from)
{
struct empfile *ep;
char *cachep;
if (ef_check(type) < 0)
return 0;
ep = &empfile[type];
if (CANT_HAPPEN((ep->flags & (EFF_MEM | EFF_PRIVATE)) == EFF_PRIVATE))
return 0;
if (CANT_HAPPEN(id < 0))
return 0;
if (CANT_HAPPEN(ep->nent >= 0 && id >= ep->nent))
return 0; /* beyond fixed size */
new_seqno(ep, from);
if (id >= ep->fids) {
/* beyond end of file */
if (CANT_HAPPEN((ep->flags & EFF_MEM) || id > ep->fids))
return 0; /* not implemented */
/* write at end of file extends it */
ep->fids = id + 1;
if (ep->onresize)
ep->onresize(type);
}
if (id >= ep->baseid && id < ep->baseid + ep->cids) {
cachep = ep->cache + (id - ep->baseid) * ep->size;
if (cachep != from)
must_be_fresh(ep, from);
} else
cachep = NULL;
if (ep->prewrite)
ep->prewrite(id, cachep, from);
if (ep->fd >= 0) {
if (do_write(ep, from, id, 1) < 0)
return 0;
}
if (cachep && cachep != from) /* update the cache if necessary */
memcpy(cachep, from, ep->size);
return 1;
}
/*
* Change element ID.
* @buf is an element of table @type.
* @id is its new element ID.
* If table is EFF_TYPED, change ID and sequence number stored in @buf.
* Else do nothing.
*/
void
ef_set_uid(int type, void *buf, int uid)
{
struct ef_typedstr *elt;
struct empfile *ep;
if (ef_check(type) < 0)
return;
ep = &empfile[type];
if (!(ep->flags & EFF_TYPED))
return;
elt = buf;
if (elt->uid == uid)
return;
elt->uid = uid;
elt->seqno = get_seqno(ep, uid);
}
/*
* Are *@a and *@b equal, except for timestamps and such?
*/
int
ef_typedstr_eq(struct ef_typedstr *a, struct ef_typedstr *b)
{
return a->ef_type == b->ef_type
&& a->seqno == b->seqno
&& a->uid == b->uid
&& !memcmp((char *)a + sizeof(*a), (char *)b + sizeof(*a),
empfile[a->ef_type].size - sizeof(*a));
}
/*
* Return sequence number of element @id in table @ep.
* Return zero if table is not EFF_TYPED (it has no sequence number
* then).
*/
static unsigned
get_seqno(struct empfile *ep, int id)
{
struct ef_typedstr *elt;
if (!(ep->flags & EFF_TYPED))
return 0;
if (id < 0 || id >= ep->fids)
return 0;
if (id >= ep->baseid && id < ep->baseid + ep->cids)
elt = (void *)(ep->cache + (id - ep->baseid) * ep->size);
else {
/* need a buffer, steal last cache slot */
if (ep->cids == ep->csize)
ep->cids--;
elt = (void *)(ep->cache + ep->cids * ep->size);
if (do_read(ep, elt, id, 1) < 0)
return 0; /* deep trouble */
}
return elt->seqno;
}
/*
* Increment sequence number in @buf, which is about to be written to @ep.
* Do nothing if table is not EFF_TYPED (it has no sequence number
* then).
* Else, @buf's sequence number must match the one in @ep's cache. If
* it doesn't, we're about to clobber a previous write.
*/
static void
new_seqno(struct empfile *ep, void *buf)
{
struct ef_typedstr *elt = buf;
unsigned old_seqno;
if (!(ep->flags & EFF_TYPED))
return;
old_seqno = get_seqno(ep, elt->uid);
CANT_HAPPEN(old_seqno != elt->seqno);
elt->seqno = old_seqno + 1;
}
/*
* Make all copies stale.
* Only fresh copies may be written back to the cache.
* To be called by functions that may yield the processor.
* Writing an copy when there has been a yield since it was read is
* unsafe, because we could clobber another thread's write then.
* Robust code must assume the that any function that may yield does
* yield. Marking copies stale there lets us catch unsafe writes.
*/
void
ef_make_stale(void)
{
ef_generation++;
}
/* Mark copy of an element of table @type in @buf fresh. */
void
ef_mark_fresh(int type, void *buf)
{
struct empfile *ep;
if (ef_check(type) < 0)
return;
ep = &empfile[type];
if (!(ep->flags & EFF_TYPED))
return;
((struct ef_typedstr *)buf)->generation = ef_generation;
}
static void
must_be_fresh(struct empfile *ep, void *buf)
{
struct ef_typedstr *elt = buf;
if (!(ep->flags & EFF_TYPED))
return;
CANT_HAPPEN(elt->generation != (ef_generation & 0xfff));
}
/*
* Extend table @type by @count elements.
* Any pointers obtained from ef_ptr() become invalid.
* Return non-zero on success, zero on failure.
*/
int
ef_extend(int type, int count)
{
struct empfile *ep;
if (ef_check(type) < 0)
return 0;
ep = &empfile[type];
if (ep->nent >= 0) {
logerror("Can't extend %s, its size is fixed", ep->name);
return 0;
}
if (!do_extend(ep, count))
return 0;
if (ep->onresize)
ep->onresize(type);
return 1;
}
static int
do_extend(struct empfile *ep, int count)
{
char *p;
int need_sentinel, i, id;
if (CANT_HAPPEN(EF_IS_VIEW(ep->uid)) || count < 0)
return 0;
id = ep->fids;
if (ep->flags & EFF_MEM) {
need_sentinel = (ep->flags & EFF_SENTINEL) != 0;
if (id + count + need_sentinel > ep->csize) {
if (ep->flags & EFF_STATIC) {
logerror("Can't extend %s beyond %d elements",
ep->name, ep->csize - need_sentinel);
return 0;
}
if (!ef_realloc_cache(ep, id + count + need_sentinel)) {
logerror("Can't extend %s to %d elements (%s)",
ep->name, id + count, strerror(errno));
return 0;
}
}
p = ep->cache + id * ep->size;
do_blank(ep, p, id, count);
if (ep->fd >= 0) {
if (do_write(ep, p, id, count) < 0)
return 0;
}
if (need_sentinel)
memset(ep->cache + (id + count) * ep->size, 0, ep->size);
ep->cids = id + count;
} else {
/* need a buffer, steal last cache slot */
if (ep->cids == ep->csize)
ep->cids--;
p = ep->cache + ep->cids * ep->size;
for (i = 0; i < count; i++) {
do_blank(ep, p, id + i, 1);
if (do_write(ep, p, id + i, 1) < 0)
return 0;
}
}
ep->fids = id + count;
return 1;
}
/*
* Initialize element @id for table @type in @buf.
* FIXME pass buffer size!
* @buf is marked fresh with ef_mark_fresh().
*/
void
ef_blank(int type, int id, void *buf)
{
struct empfile *ep;
struct ef_typedstr *elt;
if (ef_check(type) < 0)
return;
ep = &empfile[type];
do_blank(ep, buf, id, 1);
if (ep->flags & EFF_TYPED) {
elt = buf;
elt->seqno = get_seqno(ep, elt->uid);
}
ef_mark_fresh(type, buf);
}
/*
* Initialize @count elements of @ep in @buf, starting with element @id.
*/
static void
do_blank(struct empfile *ep, void *buf, int id, int count)
{
int i;
struct ef_typedstr *elt;
memset(buf, 0, count * ep->size);
for (i = 0; i < count; i++) {
elt = (struct ef_typedstr *)((char *)buf + i * ep->size);
if (ep->flags & EFF_TYPED) {
elt->ef_type = ep->uid;
elt->uid = id + i;
}
if (ep->oninit)
ep->oninit(elt);
}
}
/*
* Truncate table @type to @count elements.
* Any pointers obtained from ef_ptr() become invalid.
* Return non-zero on success, zero on failure.
*/
int
ef_truncate(int type, int count)
{
struct empfile *ep;
int need_sentinel;
if (ef_check(type) < 0 || CANT_HAPPEN(EF_IS_VIEW(type)))
return 0;
ep = &empfile[type];
if (ep->nent >= 0) {
logerror("Can't truncate %s, its size is fixed", ep->name);
return 0;
}
if (CANT_HAPPEN(count < 0 || count > ep->fids))
return 0;
if (ep->fd >= 0 && !(ep->flags & EFF_PRIVATE)) {
if (ftruncate(ep->fd, count * ep->size) < 0) {
logerror("Can't truncate %s to %d elements (%s)",
ep->file, count, strerror(errno));
return 0;
}
}
ep->fids = count;
if (ep->flags & EFF_MEM) {
need_sentinel = (ep->flags & EFF_SENTINEL) != 0;
if (!(ep->flags & EFF_STATIC)) {
if (!ef_realloc_cache(ep, count + need_sentinel)) {
logerror("Can't shrink %s cache after truncate (%s)",
ep->name, strerror(errno));
/* continue with unshrunk cache */
}
}
if (need_sentinel)
memset(ep->cache + count * ep->size, 0, ep->size);
ep->cids = count;
} else {
if (ep->baseid >= count)
ep->cids = 0;
else if (ep->cids > count - ep->baseid)
ep->cids = count - ep->baseid;
}
if (ep->onresize)
ep->onresize(type);
return 1;
}
struct castr *
ef_cadef(int type)
{
if (ef_check(type) < 0)
return NULL;
return empfile[type].cadef;
}
int
ef_nelem(int type)
{
if (ef_check(type) < 0)
return 0;
return empfile[type].fids;
}
int
ef_flags(int type)
{
if (ef_check(type) < 0)
return 0;
return empfile[type].flags;
}
time_t
ef_mtime(int type)
{
if (ef_check(type) < 0)
return 0;
if (empfile[type].fd <= 0)
return 0;
return fdate(empfile[type].fd);
}
/*
* Search for a table matching @name, return its table type.
* Return M_NOTFOUND if there are no matches, M_NOTUNIQUE if there are
* several.
*/
int
ef_byname(char *name)
{
return stmtch(name, empfile, offsetof(struct empfile, name),
sizeof(empfile[0]));
}
/*
* Search @choices[] for a table type matching @name, return it.
* Return M_NOTFOUND if there are no matches, M_NOTUNIQUE if there are
* several.
* @choices[] must be terminated with a negative value.
*/
int
ef_byname_from(char *name, int choices[])
{
int res;
int *p;
res = M_NOTFOUND;
for (p = choices; *p >= 0; p++) {
if (ef_check(*p) < 0)
continue;
switch (mineq(name, empfile[*p].name)) {
case ME_MISMATCH:
break;
case ME_PARTIAL:
if (res >= 0)
return M_NOTUNIQUE;
res = *p;
break;
case ME_EXACT:
return *p;
}
}
return res;
}
/*
* Return name of table @type. Always a single, short word.
*/
char *
ef_nameof(int type)
{
if (ef_check(type) < 0)
return "bad";
return empfile[type].name;
}
/*
* Return "pretty" name of table @type.
*/
char *
ef_nameof_pretty(int type)
{
if (ef_check(type) < 0)
return "bad";
return empfile[type].pretty_name;
}
static int
ef_check(int type)
{
if (CANT_HAPPEN((unsigned)type >= EF_MAX))
return -1;
return 0;
}
/*
* Ensure table @type contains element @id.
* If necessary, extend it in steps of @count elements.
* Return non-zero on success, zero on failure.
*/
int
ef_ensure_space(int type, int id, int count)
{
if (ef_check(type) < 0 || CANT_HAPPEN(id < 0))
return 0;
while (id >= empfile[type].fids) {
if (!ef_extend(type, count))
return 0;
}
return 1;
}
/*
* Return maximum ID acceptable for table @type.
* Assuming infinite memory and disk space.
*/
int
ef_id_limit(int type)
{
struct empfile *ep;
if (ef_check(type) < 0)
return -1;
ep = &empfile[type];
if (ep->nent >= 0)
return ep->nent - 1;
if (ep->flags & EFF_MEM) {
if (ep->flags & EFF_STATIC)
return ep->csize - 1 - ((ep->flags & EFF_SENTINEL) != 0);
}
return INT_MAX;
}