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// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
#include "prelude.h"
#include "pwcache.h"
#include "alloc.h"
#include "trie.h"
#include <errno.h>
#include <grp.h>
#include <pwd.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 *ptr, size_t bufsize);
/** Shared scaffolding for get{pw,gr}{nam,?id}_r(). */
static void *bfs_getent(bfs_getent_fn *fn, const void *key, struct trie_leaf *leaf, struct varena *varena) {
if (leaf->value) {
errno = 0;
return leaf->value == MISSING ? NULL : leaf->value;
}
// _SC_GET{PW,GR}_R_SIZE_MAX tend to be fairly large (~1K). That's okay
// for temporary allocations, but for these long-lived ones, let's start
// with a smaller buffer.
size_t bufsize = 128;
void *ptr = varena_alloc(varena, bufsize);
if (!ptr) {
return NULL;
}
while (true) {
void *ret = fn(key, ptr, bufsize);
if (ret) {
leaf->value = ret;
return ret;
} else if (errno == 0) {
leaf->value = MISSING;
break;
} else if (errno == ERANGE) {
void *next = varena_grow(varena, ptr, &bufsize);
if (!next) {
break;
}
ptr = next;
} else {
break;
}
}
varena_free(varena, ptr, bufsize);
return NULL;
}
/**
* An arena-allocated struct passwd.
*/
struct bfs_passwd {
struct passwd pwd;
char buf[];
};
struct bfs_users {
/** bfs_passwd arena. */
struct varena varena;
/** 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 = ALLOC(struct bfs_users);
if (!users) {
return NULL;
}
VARENA_INIT(&users->varena, struct bfs_passwd, buf);
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 *ptr, size_t bufsize) {
struct bfs_passwd *storage = ptr;
struct passwd *ret = NULL;
errno = getpwnam_r(key, &storage->pwd, storage->buf, bufsize, &ret);
return ret;
}
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(bfs_getpwnam_impl, name, leaf, &users->varena);
}
/** bfs_getent() callback for getpwuid_r(). */
static void *bfs_getpwuid_impl(const void *key, void *ptr, size_t bufsize) {
const uid_t *uid = key;
struct bfs_passwd *storage = ptr;
struct passwd *ret = NULL;
errno = getpwuid_r(*uid, &storage->pwd, storage->buf, bufsize, &ret);
return ret;
}
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(bfs_getpwuid_impl, &uid, leaf, &users->varena);
}
void bfs_users_flush(struct bfs_users *users) {
trie_clear(&users->by_uid);
trie_clear(&users->by_name);
varena_clear(&users->varena);
}
void bfs_users_free(struct bfs_users *users) {
if (users) {
trie_destroy(&users->by_uid);
trie_destroy(&users->by_name);
varena_destroy(&users->varena);
free(users);
}
}
/**
* An arena-allocated struct group.
*/
struct bfs_group {
struct group grp;
char buf[];
};
struct bfs_groups {
/** bfs_group arena. */
struct varena varena;
/** 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 = ALLOC(struct bfs_groups);
if (!groups) {
return NULL;
}
VARENA_INIT(&groups->varena, struct bfs_group, buf);
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 *ptr, size_t bufsize) {
struct bfs_group *storage = ptr;
struct group *ret = NULL;
errno = getgrnam_r(key, &storage->grp, storage->buf, bufsize, &ret);
return ret;
}
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(bfs_getgrnam_impl, name, leaf, &groups->varena);
}
/** bfs_getent() callback for getgrgid_r(). */
static void *bfs_getgrgid_impl(const void *key, void *ptr, size_t bufsize) {
const gid_t *gid = key;
struct bfs_group *storage = ptr;
struct group *ret = NULL;
errno = getgrgid_r(*gid, &storage->grp, storage->buf, bufsize, &ret);
return ret;
}
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(bfs_getgrgid_impl, &gid, leaf, &groups->varena);
}
void bfs_groups_flush(struct bfs_groups *groups) {
trie_clear(&groups->by_gid);
trie_clear(&groups->by_name);
varena_clear(&groups->varena);
}
void bfs_groups_free(struct bfs_groups *groups) {
if (groups) {
trie_destroy(&groups->by_gid);
trie_destroy(&groups->by_name);
varena_destroy(&groups->varena);
free(groups);
}
}
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