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// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
#include "pwcache.h"
#include "darray.h"
#include "trie.h"
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/** Represents cache hits for negative results. */
static void *MISSING = &MISSING;
/** Callback type for bfs_getent(). */
typedef void *bfs_getent_fn(const void *key, void *ent, void *buf, size_t bufsize);
/** Shared scaffolding for get{pw,gr}{nam,?id}_r(). */
static void *bfs_getent(struct trie_leaf *leaf, bfs_getent_fn *fn, const void *key, size_t entsize, size_t bufsize) {
if (leaf->value) {
errno = 0;
return leaf->value == MISSING ? NULL : leaf->value;
}
void *buf = NULL;
while (true) {
void *result = buf;
buf = realloc(buf, entsize + bufsize);
if (!buf) {
free(result);
return NULL;
}
result = fn(key, buf, (char *)buf + entsize, bufsize);
if (result) {
leaf->value = result;
return result;
} else if (errno == 0) {
free(buf);
leaf->value = MISSING;
return NULL;
} else if (errno == ERANGE) {
bufsize *= 2;
} else {
free(buf);
return NULL;
}
}
}
/** Flush a single cache. */
static void bfs_pwcache_flush(struct trie *trie) {
TRIE_FOR_EACH(trie, leaf) {
if (leaf->value != MISSING) {
free(leaf->value);
}
trie_remove(trie, leaf);
}
}
struct bfs_users {
/** Initial buffer size for getpw*_r(). */
size_t bufsize;
/** A map from usernames to entries. */
struct trie by_name;
/** A map from UIDs to entries. */
struct trie by_uid;
};
struct bfs_users *bfs_users_new(void) {
struct bfs_users *users = malloc(sizeof(*users));
if (!users) {
return NULL;
}
long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
if (bufsize > 0) {
users->bufsize = bufsize;
} else {
users->bufsize = 1024;
}
trie_init(&users->by_name);
trie_init(&users->by_uid);
return users;
}
/** bfs_getent() callback for getpwnam_r(). */
static void *bfs_getpwnam_impl(const void *key, void *ent, void *buf, size_t bufsize) {
struct passwd *result;
errno = getpwnam_r(key, ent, buf, bufsize, &result);
return result;
}
const struct passwd *bfs_getpwnam(struct bfs_users *users, const char *name) {
struct trie_leaf *leaf = trie_insert_str(&users->by_name, name);
if (!leaf) {
return NULL;
}
return bfs_getent(leaf, bfs_getpwnam_impl, name, sizeof(struct passwd), users->bufsize);
}
/** bfs_getent() callback for getpwuid_r(). */
static void *bfs_getpwuid_impl(const void *key, void *ent, void *buf, size_t bufsize) {
struct passwd *result;
errno = getpwuid_r(*(const uid_t *)key, ent, buf, bufsize, &result);
return result;
}
const struct passwd *bfs_getpwuid(struct bfs_users *users, uid_t uid) {
struct trie_leaf *leaf = trie_insert_mem(&users->by_uid, &uid, sizeof(uid));
if (!leaf) {
return NULL;
}
return bfs_getent(leaf, bfs_getpwuid_impl, &uid, sizeof(struct passwd), users->bufsize);
}
void bfs_users_flush(struct bfs_users *users) {
bfs_pwcache_flush(&users->by_name);
bfs_pwcache_flush(&users->by_uid);
}
void bfs_users_free(struct bfs_users *users) {
if (users) {
bfs_users_flush(users);
trie_destroy(&users->by_uid);
trie_destroy(&users->by_name);
free(users);
}
}
struct bfs_groups {
/** Initial buffer size for getgr*_r(). */
size_t bufsize;
/** A map from group names to entries. */
struct trie by_name;
/** A map from GIDs to entries. */
struct trie by_gid;
};
struct bfs_groups *bfs_groups_new(void) {
struct bfs_groups *groups = malloc(sizeof(*groups));
if (!groups) {
return NULL;
}
long bufsize = sysconf(_SC_GETGR_R_SIZE_MAX);
if (bufsize > 0) {
groups->bufsize = bufsize;
} else {
groups->bufsize = 1024;
}
trie_init(&groups->by_name);
trie_init(&groups->by_gid);
return groups;
}
/** bfs_getent() callback for getgrnam_r(). */
static void *bfs_getgrnam_impl(const void *key, void *ent, void *buf, size_t bufsize) {
struct group *result;
errno = getgrnam_r(key, ent, buf, bufsize, &result);
return result;
}
const struct group *bfs_getgrnam(struct bfs_groups *groups, const char *name) {
struct trie_leaf *leaf = trie_insert_str(&groups->by_name, name);
if (!leaf) {
return NULL;
}
return bfs_getent(leaf, bfs_getgrnam_impl, name, sizeof(struct group), groups->bufsize);
}
/** bfs_getent() callback for getgrgid_r(). */
static void *bfs_getgrgid_impl(const void *key, void *ent, void *buf, size_t bufsize) {
struct group *result;
errno = getgrgid_r(*(const gid_t *)key, ent, buf, bufsize, &result);
return result;
}
const struct group *bfs_getgrgid(struct bfs_groups *groups, gid_t gid) {
struct trie_leaf *leaf = trie_insert_mem(&groups->by_gid, &gid, sizeof(gid));
if (!leaf) {
return NULL;
}
return bfs_getent(leaf, bfs_getgrgid_impl, &gid, sizeof(struct group), groups->bufsize);
}
void bfs_groups_flush(struct bfs_groups *groups) {
bfs_pwcache_flush(&groups->by_name);
bfs_pwcache_flush(&groups->by_gid);
}
void bfs_groups_free(struct bfs_groups *groups) {
if (groups) {
bfs_groups_flush(groups);
trie_destroy(&groups->by_gid);
trie_destroy(&groups->by_name);
free(groups);
}
}
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