Permalink
Fetching contributors…
Cannot retrieve contributors at this time
266 lines (241 sloc) 7.05 KB
/*-
* Copyright (c) 2003-2007 Tim Kientzle
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "archive_platform.h"
__FBSDID("$FreeBSD: head/lib/libarchive/archive_write_disk_set_standard_lookup.c 201083 2009-12-28 02:09:57Z kientzle $");
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_GRP_H
#include <grp.h>
#endif
#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include "archive.h"
#include "archive_private.h"
#include "archive_read_private.h"
#include "archive_write_disk_private.h"
struct bucket {
char *name;
int hash;
id_t id;
};
static const size_t cache_size = 127;
static unsigned int hash(const char *);
static int64_t lookup_gid(void *, const char *uname, int64_t);
static int64_t lookup_uid(void *, const char *uname, int64_t);
static void cleanup(void *);
/*
* Installs functions that use getpwnam()/getgrnam()---along with
* a simple cache to accelerate such lookups---into the archive_write_disk
* object. This is in a separate file because getpwnam()/getgrnam()
* can pull in a LOT of library code (including NIS/LDAP functions, which
* pull in DNS resolvers, etc). This can easily top 500kB, which makes
* it inappropriate for some space-constrained applications.
*
* Applications that are size-sensitive may want to just use the
* real default functions (defined in archive_write_disk.c) that just
* use the uid/gid without the lookup. Or define your own custom functions
* if you prefer.
*
* TODO: Replace these hash tables with simpler move-to-front LRU
* lists with a bounded size (128 items?). The hash is a bit faster,
* but has a bad pathology in which it thrashes a single bucket. Even
* walking a list of 128 items is a lot faster than calling
* getpwnam()!
*/
int
archive_write_disk_set_standard_lookup(struct archive *a)
{
struct bucket *ucache = calloc(cache_size, sizeof(struct bucket));
struct bucket *gcache = calloc(cache_size, sizeof(struct bucket));
if (ucache == NULL || gcache == NULL) {
free(ucache);
free(gcache);
return (ARCHIVE_FATAL);
}
archive_write_disk_set_group_lookup(a, gcache, lookup_gid, cleanup);
archive_write_disk_set_user_lookup(a, ucache, lookup_uid, cleanup);
return (ARCHIVE_OK);
}
static int64_t
lookup_gid(void *private_data, const char *gname, int64_t gid)
{
int h;
struct bucket *b;
struct bucket *gcache = (struct bucket *)private_data;
/* If no gname, just use the gid provided. */
if (gname == NULL || *gname == '\0')
return (gid);
/* Try to find gname in the cache. */
h = hash(gname);
b = &gcache[h % cache_size ];
if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0)
return ((gid_t)b->id);
/* Free the cache slot for a new entry. */
if (b->name != NULL)
free(b->name);
b->name = strdup(gname);
/* Note: If strdup fails, that's okay; we just won't cache. */
b->hash = h;
#if HAVE_GRP_H
# if HAVE_GETGRNAM_R
{
char _buffer[128];
size_t bufsize = 128;
char *buffer = _buffer;
char *allocated = NULL;
struct group grent, *result;
int r;
for (;;) {
result = &grent; /* Old getgrnam_r ignores last arg. */
r = getgrnam_r(gname, &grent, buffer, bufsize, &result);
if (r == 0)
break;
if (r != ERANGE)
break;
bufsize *= 2;
free(allocated);
allocated = malloc(bufsize);
if (allocated == NULL)
break;
buffer = allocated;
}
if (result != NULL)
gid = result->gr_gid;
free(allocated);
}
# else /* HAVE_GETGRNAM_R */
{
struct group *result;
result = getgrnam(gname);
if (result != NULL)
gid = result->gr_gid;
}
# endif /* HAVE_GETGRNAM_R */
#elif defined(_WIN32) && !defined(__CYGWIN__)
/* TODO: do a gname->gid lookup for Windows. */
#else
#error No way to perform gid lookups on this platform
#endif
b->id = (gid_t)gid;
return (gid);
}
static int64_t
lookup_uid(void *private_data, const char *uname, int64_t uid)
{
int h;
struct bucket *b;
struct bucket *ucache = (struct bucket *)private_data;
/* If no uname, just use the uid provided. */
if (uname == NULL || *uname == '\0')
return (uid);
/* Try to find uname in the cache. */
h = hash(uname);
b = &ucache[h % cache_size ];
if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0)
return ((uid_t)b->id);
/* Free the cache slot for a new entry. */
if (b->name != NULL)
free(b->name);
b->name = strdup(uname);
/* Note: If strdup fails, that's okay; we just won't cache. */
b->hash = h;
#if HAVE_PWD_H
# if HAVE_GETPWNAM_R
{
char _buffer[128];
size_t bufsize = 128;
char *buffer = _buffer;
char *allocated = NULL;
struct passwd pwent, *result;
int r;
for (;;) {
result = &pwent; /* Old getpwnam_r ignores last arg. */
r = getpwnam_r(uname, &pwent, buffer, bufsize, &result);
if (r == 0)
break;
if (r != ERANGE)
break;
bufsize *= 2;
free(allocated);
allocated = malloc(bufsize);
if (allocated == NULL)
break;
buffer = allocated;
}
if (result != NULL)
uid = result->pw_uid;
free(allocated);
}
# else /* HAVE_GETPWNAM_R */
{
struct passwd *result;
result = getpwnam(uname);
if (result != NULL)
uid = result->pw_uid;
}
#endif /* HAVE_GETPWNAM_R */
#elif defined(_WIN32) && !defined(__CYGWIN__)
/* TODO: do a uname->uid lookup for Windows. */
#else
#error No way to look up uids on this platform
#endif
b->id = (uid_t)uid;
return (uid);
}
static void
cleanup(void *private)
{
size_t i;
struct bucket *cache = (struct bucket *)private;
for (i = 0; i < cache_size; i++)
free(cache[i].name);
free(cache);
}
static unsigned int
hash(const char *p)
{
/* A 32-bit version of Peter Weinberger's (PJW) hash algorithm,
as used by ELF for hashing function names. */
unsigned g, h = 0;
while (*p != '\0') {
h = (h << 4) + *p++;
if ((g = h & 0xF0000000) != 0) {
h ^= g >> 24;
h &= 0x0FFFFFFF;
}
}
return h;
}