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-rw-r--r--nss/nsswitch.c216
1 files changed, 107 insertions, 109 deletions
diff --git a/nss/nsswitch.c b/nss/nsswitch.c
index c748eb1bef..c92f33b45f 100644
--- a/nss/nsswitch.c
+++ b/nss/nsswitch.c
@@ -32,10 +32,6 @@ Boston, MA 02111-1307, USA. */
/* Prototypes for the local functions. */
static void nss_init (void);
static void *nss_lookup_function (service_user *ni, const char *fct_name);
-static int nss_find_entry (struct entry **knownp, const char *key,
- void **valp);
-static void nss_insert_entry (struct entry **knownp, const char *key,
- void *val);
static name_database *nss_parse_file (const char *fname);
static name_database_entry *nss_getline (char *line);
static service_user *nss_parse_service_list (const char *line);
@@ -191,131 +187,133 @@ nss_dlerror_run (void (*operate) (void))
static void *
nss_lookup_function (service_user *ni, const char *fct_name)
{
- void *result;
-
- /* Determine whether current function is loaded. */
- if (nss_find_entry (&ni->known, fct_name, &result) >= 0)
- return result;
+ /* Comparison function for searching NI->known tree. */
+ int known_compare (const void *p1, const void *p2)
+ {
+ return p1 == p2 ? 0 : strcmp (*(const char *const *) p1,
+ *(const char *const *) p2);
+ }
+ void **found, *result;
/* We now modify global data. Protect it. */
__libc_lock_lock (lock);
- if (ni->library == NULL)
- {
- /* This service has not yet been used. Fetch the service library
- for it, creating a new one if need be. If there is no service
- table from the file, this static variable holds the head of the
- service_library list made from the default configuration. */
- static name_database default_table;
- ni->library = nss_new_service (service_table ?: &default_table,
- ni->name);
- if (ni->library == NULL)
- {
- /* This only happens when out of memory. */
- __libc_lock_unlock (lock);
- return NULL;
- }
- }
-
- if (ni->library->lib_handle == NULL)
+ /* Search the tree of functions previously requested. Data in the
+ tree are `known_function' structures, whose first member is a
+ `const char *', the lookup key. The search returns a pointer to
+ the tree node structure; the first member of the is a pointer to
+ our structure (i.e. what will be a `known_function'); since the
+ first member of that is the lookup key string, &FCT_NAME is close
+ enough to a pointer to our structure to use as a lookup key that
+ will be passed to `known_compare' (above). */
+
+ found = __tsearch (&fct_name, (void **) &ni->known, &known_compare);
+ if (*found != &fct_name)
+ /* The search found an existing structure in the tree. */
+ result = ((known_function *) *found)->fct_ptr;
+ else
{
- /* Load the shared library. */
- size_t shlen = (7 + strlen (ni->library->name) + 3
- + sizeof (NSS_SHLIB_REVISION));
- char shlib_name[shlen];
+ /* This name was not known before. Now we have a node in the tree
+ (in the proper sorted position for FCT_NAME) that points to
+ &FCT_NAME instead of any real `known_function' structure.
+ Allocate a new structure and fill it in. */
- void do_open (void)
+ known_function *known = malloc (sizeof *known);
+ if (! known)
{
- /* Open and relocate the shared object. */
- ni->library->lib_handle = _dl_open (shlib_name, RTLD_LAZY);
+ remove_from_tree:
+ /* Oops. We can't instantiate this node properly.
+ Remove it from the tree. */
+ __tdelete (&fct_name, (void **) &ni->known, &known_compare);
+ result = NULL;
}
-
- /* Construct name. */
- __stpcpy (__stpcpy (__stpcpy (shlib_name, "libnss_"), ni->library->name),
- ".so" NSS_SHLIB_REVISION);
-
- if (nss_dlerror_run (do_open) != 0)
- /* Failed to load the library. */
- ni->library->lib_handle = (void *) -1;
- }
-
- if (ni->library->lib_handle == (void *) -1)
- /* Library not found => function not found. */
- result = NULL;
- else
- {
- /* Get the desired function. Again, GNU ld.so magic ahead. */
- size_t namlen = (5 + strlen (ni->library->name) + 1
- + strlen (fct_name) + 1);
- char name[namlen];
- struct link_map *map = ni->library->lib_handle;
- ElfW(Addr) loadbase;
- const ElfW(Sym) *ref = NULL;
- void get_sym (void)
+ else
{
- struct link_map *scope[2] = { map, NULL };
- loadbase = _dl_lookup_symbol (name, &ref, scope, map->l_name, 0, 0);
- }
-
- __stpcpy (__stpcpy (__stpcpy (__stpcpy (name, "_nss_"),
- ni->library->name),
- "_"),
- fct_name);
-
- result = (nss_dlerror_run (get_sym)
- ? NULL : (void *) (loadbase + ref->st_value));
- }
-
- /* Remember function pointer for the usage. */
- nss_insert_entry (&ni->known, fct_name, result);
-
- /* Remove the lock. */
- __libc_lock_unlock (lock);
-
- return result;
-}
-
-
-static int
-known_compare (const void *p1, const void *p2)
-{
- known_function *v1 = (known_function *) p1;
- known_function *v2 = (known_function *) p2;
-
- return strcmp (v1->fct_name, v2->fct_name);
-}
+ /* Point the tree node at this new structure. */
+ *found = known;
+ known->fct_name = fct_name;
+ if (ni->library == NULL)
+ {
+ /* This service has not yet been used. Fetch the service
+ library for it, creating a new one if need be. If there
+ is no service table from the file, this static variable
+ holds the head of the service_library list made from the
+ default configuration. */
+ static name_database default_table;
+ ni->library = nss_new_service (service_table ?: &default_table,
+ ni->name);
+ if (ni->library == NULL)
+ {
+ /* This only happens when out of memory. */
+ free (known);
+ goto remove_from_tree;
+ }
+ }
-static int
-nss_find_entry (struct entry **knownp, const char *key, void **valp)
-{
- known_function looking_for = { fct_name: key };
- struct entry **found;
+ if (ni->library->lib_handle == NULL)
+ {
+ /* Load the shared library. */
+ size_t shlen = (7 + strlen (ni->library->name) + 3
+ + sizeof (NSS_SHLIB_REVISION));
+ char shlib_name[shlen];
- found = __tfind (&looking_for, (const void **) knownp, known_compare);
+ void do_open (void)
+ {
+ /* Open and relocate the shared object. */
+ ni->library->lib_handle = _dl_open (shlib_name, RTLD_LAZY);
+ }
- if (found == NULL)
- return -1;
+ /* Construct shared object name. */
+ __stpcpy (__stpcpy (__stpcpy (shlib_name, "libnss_"),
+ ni->library->name),
+ ".so" NSS_SHLIB_REVISION);
- *valp = ((known_function *) (*found)->key)->fct_ptr;
+ if (nss_dlerror_run (do_open) != 0)
+ /* Failed to load the library. */
+ ni->library->lib_handle = (void *) -1;
+ }
- return 0;
-}
+ if (ni->library->lib_handle == (void *) -1)
+ /* Library not found => function not found. */
+ result = NULL;
+ else
+ {
+ /* Get the desired function. Again, GNU ld.so magic ahead. */
+ size_t namlen = (5 + strlen (ni->library->name) + 1
+ + strlen (fct_name) + 1);
+ char name[namlen];
+ struct link_map *map = ni->library->lib_handle;
+ ElfW(Addr) loadbase;
+ const ElfW(Sym) *ref = NULL;
+ void get_sym (void)
+ {
+ struct link_map *scope[2] = { map, NULL };
+ loadbase = _dl_lookup_symbol (name, &ref,
+ scope, map->l_name, 0, 0);
+ }
+ /* Construct the function name. */
+ __stpcpy (__stpcpy (__stpcpy (__stpcpy (name, "_nss_"),
+ ni->library->name),
+ "_"),
+ fct_name);
-static void
-nss_insert_entry (struct entry **knownp, const char *key, void *val)
-{
- known_function *to_insert;
+ /* Look up the symbol. */
+ result = (nss_dlerror_run (get_sym)
+ ? NULL : (void *) (loadbase + ref->st_value));
+ }
- to_insert = (known_function *) malloc (sizeof (known_function));
- if (to_insert == NULL)
- return;
+ /* Remember function pointer for later calls. Even if null, we
+ record it so a second try needn't search the library again. */
+ known->fct_ptr = result;
+ }
+ }
- to_insert->fct_name = key;
- to_insert->fct_ptr = val;
+ /* Remove the lock. */
+ __libc_lock_unlock (lock);
- __tsearch (to_insert, (void **) knownp, known_compare);
+ return result;
}
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