Permalink
Switch branches/tags
Nothing to show
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
240 lines (195 sloc) 5.51 KB
/*
* AUTHOR
*
* Rob Mueller <cpan@robm.fastmail.fm>
*
* COPYRIGHT AND LICENSE
*
* Copyright (C) 2003 by FastMail IP Partners
*
* This library is free software; you can redistribute it and/or modify
* it under the same terms as Perl itself.
*
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <errno.h>
#include <stdarg.h>
#include "mmap_cache.h"
#include "mmap_cache_internals.h"
char* _mmc_get_def_share_filename(mmap_cache * cache)
{
return def_share_file;
}
int mmc_open_cache_file(mmap_cache* cache, int * do_init) {
int res, i, fh;
void * tmp;
struct stat statbuf;
/* Check if file exists */
res = stat(cache->share_file, &statbuf);
/* Remove if different size or remove requested */
if (!res &&
(cache->init_file || (statbuf.st_size != cache->c_size))) {
res = remove(cache->share_file);
if (res == -1 && errno != ENOENT) {
_mmc_set_error(cache, errno, "Unlink of existing share file %s failed", cache->share_file);
return -1;
}
}
/* Create file if it doesn't exist */
*do_init = 0;
res = stat(cache->share_file, &statbuf);
if (res == -1) {
mode_t permissions = (mode_t)cache->permissions;
res = open(cache->share_file, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC | O_APPEND, permissions);
if (res == -1) {
_mmc_set_error(cache, errno, "Create of share file %s failed", cache->share_file);
return -1;
}
/* Fill file with 0's */
tmp = malloc(cache->c_page_size);
if (!tmp) {
_mmc_set_error(cache, errno, "Malloc of tmp space failed");
return -1;
}
memset(tmp, 0, cache->c_page_size);
for (i = 0; i < cache->c_num_pages; i++) {
int written = write(res, tmp, cache->c_page_size);
if (written < 0) {
_mmc_set_error(cache, errno, "Write to share file %s failed", cache->share_file);
return -1;
}
if (written < cache->c_page_size) {
_mmc_set_error(cache, errno, "Write to share file %s failed; short write (%d of %d bytes written)", cache->share_file, written, cache->c_page_size);
return -1;
}
}
free(tmp);
/* Later on initialise page structures */
*do_init = 1;
close(res);
}
/* Open for reading/writing */
fh = open(cache->share_file, O_RDWR);
if (fh == -1) {
_mmc_set_error(cache, errno, "Open of share file %s failed", cache->share_file);
return -1;
}
/* Automatically close cache fd on exec */
fcntl(fh, F_SETFD, FD_CLOEXEC);
cache->fh = fh;
return 0;
}
/*
* mmc_map_memory(mmap_cache * cache)
*
* maps the cache file into memory, and sets cache->mm_var as needed.
*/
int mmc_map_memory(mmap_cache* cache) {
/* Map file into memory */
cache->mm_var = mmap(0, cache->c_size, PROT_READ | PROT_WRITE, MAP_SHARED, cache->fh, 0);
if (cache->mm_var == (void *)MAP_FAILED) {
mmc_close_fh(cache);
_mmc_set_error(cache, errno, "Mmap of shared file %s failed", cache->share_file);
return -1;
}
return 0;
}
/*
* mmc_unmap_memory(mmap_cache * cache)
*
* Unmaps cache->mm_var
*/
int mmc_unmap_memory(mmap_cache* cache) {
int res = munmap(cache->mm_var, cache->c_size);
if (res == -1) {
_mmc_set_error(cache, errno, "Munmap of shared file %s failed", cache->share_file);
return -1;
}
return res;
}
int mmc_close_fh(mmap_cache* cache) {
int res = close(cache->fh);
return res;
}
int mmc_lock_page(mmap_cache* cache, MU32 p_offset) {
struct flock lock;
int old_alarm, alarm_left = 10;
int lock_res = -1;
/* Setup fcntl locking structure */
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = p_offset;
lock.l_len = cache->c_page_size;
if (cache->catch_deadlocks)
old_alarm = alarm(alarm_left);
while (lock_res != 0) {
/* Lock the page (block till done, signal, or timeout) */
lock_res = fcntl(cache->fh, F_SETLKW, &lock);
/* Continue immediately if success */
if (lock_res == 0) {
if (cache->catch_deadlocks)
alarm(old_alarm);
break;
}
/* Turn off alarm for a moment */
if (cache->catch_deadlocks)
alarm_left = alarm(0);
/* Some signal interrupted, and it wasn't the alarm? Rerun lock */
if (lock_res == -1 && errno == EINTR && alarm_left) {
if (cache->catch_deadlocks)
alarm(alarm_left);
continue;
}
/* Lock failed? */
_mmc_set_error(cache, errno, "Lock failed");
if (cache->catch_deadlocks)
alarm(old_alarm);
return -1;
}
return 0;
}
int mmc_unlock_page(mmap_cache * cache) {
struct flock lock;
/* Setup fcntl locking structure */
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
lock.l_start = cache->p_offset;
lock.l_len = cache->c_page_size;
/* And unlock page */
fcntl(cache->fh, F_SETLKW, &lock);
/* Set to bad value while page not locked */
cache->p_cur = -1;
return 0;
}
/*
* int _mmc_set_error(mmap_cache *cache, int err, char * error_string, ...)
*
* Set internal error string/state
*
*/
int _mmc_set_error(mmap_cache *cache, int err, char * error_string, ...) {
va_list ap;
static char errbuf[1024];
va_start(ap, error_string);
/* Make sure it's terminated */
errbuf[1023] = '\0';
/* Start with error string passed */
vsnprintf(errbuf, 1023, error_string, ap);
/* Add system error code if passed */
if (err) {
strncat(errbuf, ": ", 1024);
strncat(errbuf, strerror(err), 1023);
}
/* Save in cache object */
cache->last_error = errbuf;
va_end(ap);
return 0;
}