diff options
Diffstat (limited to 'usr.bin/csup/idcache.c')
| -rw-r--r-- | usr.bin/csup/idcache.c | 421 |
1 files changed, 421 insertions, 0 deletions
diff --git a/usr.bin/csup/idcache.c b/usr.bin/csup/idcache.c new file mode 100644 index 0000000..47a3e71 --- /dev/null +++ b/usr.bin/csup/idcache.c @@ -0,0 +1,421 @@ +/*- + * Copyright (c) 2006, Maxime Henrion <mux@FreeBSD.org> + * 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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. + * + * $FreeBSD$ + */ +#include <sys/types.h> + +#include <assert.h> +#include <grp.h> +#include <pthread.h> +#include <pwd.h> +#include <stdlib.h> +#include <string.h> + +#include "idcache.h" +#include "misc.h" + +/* + * Constants and data structures used to implement the thread-safe + * group and password file caches. Cache sizes must be prime. + */ +#define UIDTONAME_SZ 317 /* Size of uid -> user name cache */ +#define NAMETOUID_SZ 317 /* Size of user name -> uid cache */ +#define GIDTONAME_SZ 317 /* Size of gid -> group name cache */ +#define NAMETOGID_SZ 317 /* Size of group name -> gid cache */ + +/* Node structures used to cache lookups. */ +struct uidc { + char *name; /* user name */ + uid_t uid; /* cached uid */ + int valid; /* is this a valid or a miss entry */ + struct uidc *next; /* for collisions */ +}; + +struct gidc { + char *name; /* group name */ + gid_t gid; /* cached gid */ + int valid; /* is this a valid or a miss entry */ + struct gidc *next; /* for collisions */ +}; + +static struct uidc **uidtoname; /* uid to user name cache */ +static struct gidc **gidtoname; /* gid to group name cache */ +static struct uidc **nametouid; /* user name to uid cache */ +static struct gidc **nametogid; /* group name to gid cache */ + +static pthread_mutex_t uid_mtx; +static pthread_mutex_t gid_mtx; + +static void uid_lock(void); +static void uid_unlock(void); +static void gid_lock(void); +static void gid_unlock(void); + +static uint32_t hash(const char *); + +/* A 32-bit version of Peter Weinberger's (PJW) hash algorithm, + as used by ELF for hashing function names. */ +static uint32_t +hash(const char *name) +{ + uint32_t g, h; + + h = 0; + while(*name != '\0') { + h = (h << 4) + *name++; + if ((g = h & 0xF0000000)) { + h ^= g >> 24; + h &= 0x0FFFFFFF; + } + } + return (h); +} + +static void +uid_lock(void) +{ + int error; + + error = pthread_mutex_lock(&uid_mtx); + assert(!error); +} + +static void +uid_unlock(void) +{ + int error; + + error = pthread_mutex_unlock(&uid_mtx); + assert(!error); +} + +static void +gid_lock(void) +{ + int error; + + error = pthread_mutex_lock(&gid_mtx); + assert(!error); +} + +static void +gid_unlock(void) +{ + int error; + + error = pthread_mutex_unlock(&gid_mtx); + assert(!error); +} + +static void +uidc_insert(struct uidc **tbl, struct uidc *uidc, uint32_t key) +{ + + uidc->next = tbl[key]; + tbl[key] = uidc; +} + +static void +gidc_insert(struct gidc **tbl, struct gidc *gidc, uint32_t key) +{ + + gidc->next = tbl[key]; + tbl[key] = gidc; +} + +/* Return the user name for this uid, or NULL if it's not found. */ +char * +getuserbyid(uid_t uid) +{ + struct passwd *pw; + struct uidc *uidc, *uidc2; + uint32_t key, key2; + + key = uid % UIDTONAME_SZ; + uid_lock(); + uidc = uidtoname[key]; + while (uidc != NULL) { + if (uidc->uid == uid) + break; + uidc = uidc->next; + } + + if (uidc == NULL) { + /* We didn't find this uid, look it up and add it. */ + uidc = xmalloc(sizeof(struct uidc)); + uidc->uid = uid; + pw = getpwuid(uid); + if (pw != NULL) { + /* This uid is in the password file. */ + uidc->name = xstrdup(pw->pw_name); + uidc->valid = 1; + /* Also add it to the name -> gid table. */ + uidc2 = xmalloc(sizeof(struct uidc)); + uidc2->uid = uid; + uidc2->name = uidc->name; /* We reuse the pointer. */ + uidc2->valid = 1; + key2 = hash(uidc->name) % NAMETOUID_SZ; + uidc_insert(nametouid, uidc2, key2); + } else { + /* Add a miss entry for this uid. */ + uidc->name = NULL; + uidc->valid = 0; + } + uidc_insert(uidtoname, uidc, key); + } + /* It is safe to unlock here since the cache structure + is not going to get freed or changed. */ + uid_unlock(); + return (uidc->name); +} + +/* Return the group name for this gid, or NULL if it's not found. */ +char * +getgroupbyid(gid_t gid) +{ + struct group *gr; + struct gidc *gidc, *gidc2; + uint32_t key, key2; + + key = gid % GIDTONAME_SZ; + gid_lock(); + gidc = gidtoname[key]; + while (gidc != NULL) { + if (gidc->gid == gid) + break; + gidc = gidc->next; + } + + if (gidc == NULL) { + /* We didn't find this gid, look it up and add it. */ + gidc = xmalloc(sizeof(struct gidc)); + gidc->gid = gid; + gr = getgrgid(gid); + if (gr != NULL) { + /* This gid is in the group file. */ + gidc->name = xstrdup(gr->gr_name); + gidc->valid = 1; + /* Also add it to the name -> gid table. */ + gidc2 = xmalloc(sizeof(struct gidc)); + gidc2->gid = gid; + gidc2->name = gidc->name; /* We reuse the pointer. */ + gidc2->valid = 1; + key2 = hash(gidc->name) % NAMETOGID_SZ; + gidc_insert(nametogid, gidc2, key2); + } else { + /* Add a miss entry for this gid. */ + gidc->name = NULL; + gidc->valid = 0; + } + gidc_insert(gidtoname, gidc, key); + } + /* It is safe to unlock here since the cache structure + is not going to get freed or changed. */ + gid_unlock(); + return (gidc->name); +} + +/* Finds the uid for this user name. If it's found, the gid is stored + in *uid and 0 is returned. Otherwise, -1 is returned. */ +int +getuidbyname(const char *name, uid_t *uid) +{ + struct passwd *pw; + struct uidc *uidc, *uidc2; + uint32_t key, key2; + + uid_lock(); + key = hash(name) % NAMETOUID_SZ; + uidc = nametouid[key]; + while (uidc != NULL) { + if (strcmp(uidc->name, name) == 0) + break; + uidc = uidc->next; + } + + if (uidc == NULL) { + uidc = xmalloc(sizeof(struct uidc)); + uidc->name = xstrdup(name); + pw = getpwnam(name); + if (pw != NULL) { + /* This user name is in the password file. */ + uidc->valid = 1; + uidc->uid = pw->pw_uid; + /* Also add it to the uid -> name table. */ + uidc2 = xmalloc(sizeof(struct uidc)); + uidc2->name = uidc->name; /* We reuse the pointer. */ + uidc2->uid = uidc->uid; + uidc2->valid = 1; + key2 = uidc2->uid % UIDTONAME_SZ; + uidc_insert(uidtoname, uidc2, key2); + } else { + /* Add a miss entry for this user name. */ + uidc->valid = 0; + uidc->uid = (uid_t)-1; /* Should not be accessed. */ + } + uidc_insert(nametouid, uidc, key); + } + /* It is safe to unlock here since the cache structure + is not going to get freed or changed. */ + uid_unlock(); + if (!uidc->valid) + return (-1); + *uid = uidc->uid; + return (0); +} + +/* Finds the gid for this group name. If it's found, the gid is stored + in *gid and 0 is returned. Otherwise, -1 is returned. */ +int +getgidbyname(const char *name, gid_t *gid) +{ + struct group *gr; + struct gidc *gidc, *gidc2; + uint32_t key, key2; + + gid_lock(); + key = hash(name) % NAMETOGID_SZ; + gidc = nametogid[key]; + while (gidc != NULL) { + if (strcmp(gidc->name, name) == 0) + break; + gidc = gidc->next; + } + + if (gidc == NULL) { + gidc = xmalloc(sizeof(struct gidc)); + gidc->name = xstrdup(name); + gr = getgrnam(name); + if (gr != NULL) { + /* This group name is in the group file. */ + gidc->gid = gr->gr_gid; + gidc->valid = 1; + /* Also add it to the gid -> name table. */ + gidc2 = xmalloc(sizeof(struct gidc)); + gidc2->name = gidc->name; /* We reuse the pointer. */ + gidc2->gid = gidc->gid; + gidc2->valid = 1; + key2 = gidc2->gid % GIDTONAME_SZ; + gidc_insert(gidtoname, gidc2, key2); + } else { + /* Add a miss entry for this group name. */ + gidc->gid = (gid_t)-1; /* Should not be accessed. */ + gidc->valid = 0; + } + gidc_insert(nametogid, gidc, key); + } + /* It is safe to unlock here since the cache structure + is not going to get freed or changed. */ + gid_unlock(); + if (!gidc->valid) + return (-1); + *gid = gidc->gid; + return (0); +} + +/* Initialize the cache structures. */ +void +idcache_init(void) +{ + + pthread_mutex_init(&uid_mtx, NULL); + pthread_mutex_init(&gid_mtx, NULL); + uidtoname = xmalloc(UIDTONAME_SZ * sizeof(struct uidc *)); + gidtoname = xmalloc(GIDTONAME_SZ * sizeof(struct gidc *)); + nametouid = xmalloc(NAMETOUID_SZ * sizeof(struct uidc *)); + nametogid = xmalloc(NAMETOGID_SZ * sizeof(struct gidc *)); + memset(uidtoname, 0, UIDTONAME_SZ * sizeof(struct uidc *)); + memset(gidtoname, 0, GIDTONAME_SZ * sizeof(struct gidc *)); + memset(nametouid, 0, NAMETOUID_SZ * sizeof(struct uidc *)); + memset(nametogid, 0, NAMETOGID_SZ * sizeof(struct gidc *)); +} + +/* Cleanup the cache structures. */ +void +idcache_fini(void) +{ + struct uidc *uidc, *uidc2; + struct gidc *gidc, *gidc2; + size_t i; + + for (i = 0; i < UIDTONAME_SZ; i++) { + uidc = uidtoname[i]; + while (uidc != NULL) { + if (uidc->name != NULL) { + assert(uidc->valid); + free(uidc->name); + } + uidc2 = uidc->next; + free(uidc); + uidc = uidc2; + } + } + free(uidtoname); + for (i = 0; i < NAMETOUID_SZ; i++) { + uidc = nametouid[i]; + while (uidc != NULL) { + assert(uidc->name != NULL); + /* If it's a valid entry, it has been added to both the + uidtoname and nametouid tables, and the name pointer + has been reused for both entries. Thus, the name + pointer has already been freed in the loop above. */ + if (!uidc->valid) + free(uidc->name); + uidc2 = uidc->next; + free(uidc); + uidc = uidc2; + } + } + free(nametouid); + for (i = 0; i < GIDTONAME_SZ; i++) { + gidc = gidtoname[i]; + while (gidc != NULL) { + if (gidc->name != NULL) { + assert(gidc->valid); + free(gidc->name); + } + gidc2 = gidc->next; + free(gidc); + gidc = gidc2; + } + } + free(gidtoname); + for (i = 0; i < NAMETOGID_SZ; i++) { + gidc = nametogid[i]; + while (gidc != NULL) { + assert(gidc->name != NULL); + /* See above comment. */ + if (!gidc->valid) + free(gidc->name); + gidc2 = gidc->next; + free(gidc); + gidc = gidc2; + } + } + free(nametogid); + pthread_mutex_destroy(&uid_mtx); + pthread_mutex_destroy(&gid_mtx); +} |
