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map_shared.c
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map_shared.c
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/* map_shared.c -- memory-mapping routines.
*
* Copyright (c) 1994-2008 Carnegie Mellon University. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The name "Carnegie Mellon University" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For permission or any legal
* details, please contact
* Carnegie Mellon University
* Center for Technology Transfer and Enterprise Creation
* 4615 Forbes Avenue
* Suite 302
* Pittsburgh, PA 15213
* (412) 268-7393, fax: (412) 268-7395
* innovation@andrew.cmu.edu
*
* 4. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Computing Services
* at Carnegie Mellon University (http://www.cmu.edu/computing/)."
*
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* $Id: map_shared.c,v 1.22 2008/03/24 17:43:09 murch Exp $
*/
#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <syslog.h>
#include "map.h"
#include "exitcodes.h"
#include "xmalloc.h"
#define SLOP (8*1024)
const char *map_method_desc = "shared";
/*
* Create/refresh mapping of file
*/
void
map_refresh(fd, onceonly, base, len, newlen, name, mboxname)
int fd;
int onceonly;
const char **base;
unsigned long *len;
unsigned long newlen;
const char *name;
const char *mboxname;
{
struct stat sbuf;
char buf[80];
if (newlen == MAP_UNKNOWN_LEN) {
if (fstat(fd, &sbuf) == -1) {
syslog(LOG_ERR, "IOERROR: fstating %s file%s%s: %m", name,
mboxname ? " for " : "", mboxname ? mboxname : "");
snprintf(buf, sizeof(buf), "failed to fstat %s file", name);
fatal(buf, EC_IOERR);
}
newlen = sbuf.st_size;
}
/* Already mapped in */
if (*len >= newlen) return;
if (*len) munmap((char *)*base, *len);
if (!onceonly) {
newlen = (newlen + 2*SLOP - 1) & ~(SLOP-1);
}
*base = (char *)mmap((caddr_t)0, newlen, PROT_READ, MAP_SHARED
#ifdef MAP_FILE
| MAP_FILE
#endif
#ifdef MAP_VARIABLE
| MAP_VARIABLE
#endif
, fd, 0L);
if (*base == (char *)-1) {
syslog(LOG_ERR, "IOERROR: mapping %s file%s%s: %m", name,
mboxname ? " for " : "", mboxname ? mboxname : "");
snprintf(buf, sizeof(buf), "failed to mmap %s file", name);
fatal(buf, EC_IOERR);
}
*len = newlen;
}
/*
* Destroy mapping of file
*/
void
map_free(base, len)
const char **base;
unsigned long *len;
{
if (*len) munmap((char *)*base, *len);
*base = 0;
*len = 0;
}

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