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