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glibc/nss/nsswitch.c

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/* Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <ctype.h>
#include <dlfcn.h>
#include <errno.h>
#include <netdb.h>
#include <bits/libc-lock.h>
#include <search.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <elf/ldsodefs.h> /* We need some help from ld.so. */
#if !defined DO_STATIC_NSS || defined PIC
# include <gnu/lib-names.h>
#endif
#include "nsswitch.h"
/* Prototypes for the local functions. */
static name_database *nss_parse_file (const char *fname) internal_function;
static name_database_entry *nss_getline (char *line) internal_function;
static service_user *nss_parse_service_list (const char *line)
internal_function;
static service_library *nss_new_service (name_database *database,
const char *name) internal_function;
/* Declare external database variables. */
#define DEFINE_DATABASE(name) \
extern service_user *__nss_##name##_database; \
weak_extern (__nss_##name##_database)
#include "databases.def"
#undef DEFINE_DATABASE
/* Structure to map database name to variable. */
static struct
{
const char *name;
service_user **dbp;
} databases[] =
{
#define DEFINE_DATABASE(name) \
{ #name, &__nss_##name##_database },
#include "databases.def"
#undef DEFINE_DATABASE
};
__libc_lock_define_initialized (static, lock)
#if !defined DO_STATIC_NSS || defined PIC
/* String with revision number of the shared object files. */
static const char *const __nss_shlib_revision = LIBNSS_FILES_SO + 15;
#endif
/* The root of the whole data base. */
static name_database *service_table;
/* -1 == database not found
0 == database entry pointer stored */
int
__nss_database_lookup (const char *database, const char *alternate_name,
const char *defconfig, service_user **ni)
{
/* Prevent multiple threads to change the service table. */
__libc_lock_lock (lock);
/* Reconsider database variable in case some other thread called
`__nss_configure_lookup' while we waited for the lock. */
if (*ni != NULL)
{
__libc_lock_unlock (lock);
return 0;
}
/* Are we initialized yet? */
if (service_table == NULL)
/* Read config file. */
service_table = nss_parse_file (_PATH_NSSWITCH_CONF);
/* Test whether configuration data is available. */
if (service_table != NULL)
{
/* Return first `service_user' entry for DATABASE. */
name_database_entry *entry;
/* XXX Could use some faster mechanism here. But each database is
only requested once and so this might not be critical. */
for (entry = service_table->entry; entry != NULL; entry = entry->next)
if (strcmp (database, entry->name) == 0)
*ni = entry->service;
if (*ni == NULL && alternate_name != NULL)
/* We haven't found an entry so far. Try to find it with the
alternative name. */
for (entry = service_table->entry; entry != NULL; entry = entry->next)
if (strcmp (alternate_name, entry->name) == 0)
*ni = entry->service;
}
/* No configuration data is available, either because nsswitch.conf
doesn't exist or because it doesn't has a line for this database.
DEFCONFIG specifies the default service list for this database,
or null to use the most common default. */
if (*ni == NULL)
*ni = nss_parse_service_list (defconfig
?: "nis [NOTFOUND=return] files");
__libc_lock_unlock (lock);
return 0;
}
/* -1 == not found
0 == function found
1 == finished */
int
__nss_lookup (service_user **ni, const char *fct_name, void **fctp)
{
*fctp = __nss_lookup_function (*ni, fct_name);
while (*fctp == NULL
&& nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
&& (*ni)->next != NULL)
{
*ni = (*ni)->next;
*fctp = __nss_lookup_function (*ni, fct_name);
}
return *fctp != NULL ? 0 : (*ni)->next == NULL ? 1 : -1;
}
/* -1 == not found
0 == adjusted for next function
1 == finished */
int
__nss_next (service_user **ni, const char *fct_name, void **fctp, int status,
int all_values)
{
if (all_values)
{
if (nss_next_action (*ni, NSS_STATUS_TRYAGAIN) == NSS_ACTION_RETURN
&& nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_RETURN
&& nss_next_action (*ni, NSS_STATUS_NOTFOUND) == NSS_ACTION_RETURN
&& nss_next_action (*ni, NSS_STATUS_SUCCESS) == NSS_ACTION_RETURN)
return 1;
}
else
{
/* This is really only for debugging. */
if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
__libc_fatal ("illegal status in " __FUNCTION__);
if (nss_next_action (*ni, status) == NSS_ACTION_RETURN)
return 1;
}
if ((*ni)->next == NULL)
return -1;
do
{
*ni = (*ni)->next;
*fctp = __nss_lookup_function (*ni, fct_name);
}
while (*fctp == NULL
&& nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
&& (*ni)->next != NULL);
return *fctp != NULL ? 0 : -1;
}
int
__nss_configure_lookup (const char *dbname, const char *service_line)
{
service_user *new_db;
size_t cnt;
for (cnt = 0; cnt < sizeof databases; ++cnt)
{
int cmp = strcmp (dbname, databases[cnt].name);
if (cmp == 0)
break;
if (cmp < 0)
{
__set_errno (EINVAL);
return -1;
}
}
if (cnt == sizeof databases)
{
__set_errno (EINVAL);
return -1;
}
/* Test whether it is really used. */
if (databases[cnt].dbp == NULL)
/* Nothing to do, but we could do. */
return 0;
/* Try to generate new data. */
new_db = nss_parse_service_list (service_line);
if (new_db == NULL)
{
/* Illegal service specification. */
__set_errno (EINVAL);
return -1;
}
/* Prevent multiple threads to change the service table. */
__libc_lock_lock (lock);
/* Install new rules. */
*databases[cnt].dbp = new_db;
__libc_lock_unlock (lock);
return 0;
}
#if !defined DO_STATIC_NSS || defined PIC
static int
nss_dlerror_run (void (*operate) (void *), void *args)
{
char *last_errstring = NULL;
int result;
(void) _dl_catch_error (&last_errstring, operate, args);
result = last_errstring != NULL;
if (result)
free (last_errstring);
return result;
}
struct do_open_args
{
/* Argument to do_open. */
char *shlib_name;
service_user *ni;
};
struct get_sym_args
{
/* Arguments to get_sym. */
struct link_map *map;
char *name;
/* Return values of get_sym. */
ElfW(Addr) loadbase;
const ElfW(Sym) *ref;
};
static void
do_open (void *a)
{
struct do_open_args *args = (struct do_open_args *) a;
/* Open and relocate the shared object. */
args->ni->library->lib_handle = _dl_open (args->shlib_name, RTLD_LAZY);
}
static void
get_sym (void *a)
{
struct get_sym_args *args = (struct get_sym_args *) a;
struct link_map *scope[2] = { args->map, NULL };
args->ref = NULL;
args->loadbase = _dl_lookup_symbol (args->name, &args->ref,
scope, args->map->l_name, 0);
}
#endif
/* Comparison function for searching NI->known tree. */
static int
known_compare (const void *p1, const void *p2)
{
return p1 == p2 ? 0 : strcmp (*(const char *const *) p1,
*(const char *const *) p2);
}
void *
__nss_lookup_function (service_user *ni, const char *fct_name)
{
void **found, *result;
/* We now modify global data. Protect it. */
__libc_lock_lock (lock);
/* 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
{
/* 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. */
known_function *known = malloc (sizeof *known);
if (! known)
{
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;
}
else
{
/* 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;
}
}
#if !defined DO_STATIC_NSS || defined PIC
if (ni->library->lib_handle == NULL)
{
/* Load the shared library. */
size_t shlen = (7 + strlen (ni->library->name) + 3
+ strlen (__nss_shlib_revision) + 1);
int saved_errno = errno;
struct do_open_args args;
args.shlib_name = __alloca (shlen);
args.ni = ni;
/* Construct shared object name. */
__stpcpy (__stpcpy (__stpcpy (__stpcpy (args.shlib_name,
"libnss_"),
ni->library->name),
".so"),
__nss_shlib_revision);
if (nss_dlerror_run (do_open, &args) != 0)
{
/* Failed to load the library. */
ni->library->lib_handle = (void *) -1l;
__set_errno (saved_errno);
}
}
if (ni->library->lib_handle == (void *) -1l)
/* 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);
struct get_sym_args args;
args.name = __alloca (namlen);
args.map = ni->library->lib_handle;
/* Construct the function name. */
__stpcpy (__stpcpy (__stpcpy (__stpcpy (args.name, "_nss_"),
ni->library->name),
"_"),
fct_name);
/* Look up the symbol. */
result = (nss_dlerror_run (get_sym, &args) ? NULL
: (void *) (args.loadbase + args.ref->st_value));
}
#else
/* We can't get function address dynamically in static linking. */
{
# define DEFINE_ENT(h,nm) \
extern void _nss_##h##_get##nm##ent_r (void); \
extern void _nss_##h##_end##nm##ent (void); \
extern void _nss_##h##_set##nm##ent (void);
# define DEFINE_GET(h,nm) \
extern void _nss_##h##_get##nm##_r (void);
# define DEFINE_GETBY(h,nm,ky) \
extern void _nss_##h##_get##nm##by##ky##_r (void);
# include "function.def"
# undef DEFINE_ENT
# undef DEFINE_GET
# undef DEFINE_GETBY
# define DEFINE_ENT(h,nm) \
{ #h"_get"#nm"ent_r", _nss_##h##_get##nm##ent_r }, \
{ #h"_end"#nm"ent", _nss_##h##_end##nm##ent }, \
{ #h"_set"#nm"ent", _nss_##h##_set##nm##ent },
# define DEFINE_GET(h,nm) \
{ #h"_get"#nm"_r", _nss_##h##_get##nm##_r },
# define DEFINE_GETBY(h,nm,ky) \
{ #h"_get"#nm"by"#ky"_r", _nss_##h##_get##nm##by##ky##_r },
static struct fct_tbl { const char *fname; void *fp; } *tp, tbl[] =
{
# include "function.def"
{ NULL, NULL }
};
size_t namlen = (5 + strlen (ni->library->name) + 1
+ strlen (fct_name) + 1);
char name[namlen];
/* Construct the function name. */
__stpcpy (__stpcpy (__stpcpy (name, ni->library->name),
"_"),
fct_name);
result = NULL;
for (tp = &tbl[0]; tp->fname; tp++)
if (strcmp (tp->fname, name) == 0)
{
result = tp->fp;
break;
}
}
#endif
/* 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;
}
}
/* Remove the lock. */
__libc_lock_unlock (lock);
return result;
}
static name_database *
internal_function
nss_parse_file (const char *fname)
{
FILE *fp;
name_database *result;
name_database_entry *last;
char *line;
size_t len;
/* Open the configuration file. */
fp = fopen (fname, "r");
if (fp == NULL)
return NULL;
result = (name_database *) malloc (sizeof (name_database));
if (result == NULL)
return NULL;
result->entry = NULL;
result->library = NULL;
last = NULL;
line = NULL;
len = 0;
do
{
name_database_entry *this;
ssize_t n;
char *cp;
n = __getline (&line, &len, fp);
if (n < 0)
break;
if (line[n - 1] == '\n')
line[n - 1] = '\0';
/* Because the file format does not know any form of quoting we
can search forward for the next '#' character and if found
make it terminating the line. */
cp = strchr (line, '#');
if (cp != NULL)
*cp = '\0';
/* If the line is blank it is ignored. */
if (line[0] == '\0')
continue;
/* Each line completely specifies the actions for a database. */
this = nss_getline (line);
if (this != NULL)
{
if (last != NULL)
last->next = this;
else
result->entry = this;
last = this;
}
}
while (!feof (fp));
/* Free the buffer. */
free (line);
/* Close configuration file. */
fclose (fp);
return result;
}
/* Read the source names:
`( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
*/
static service_user *
internal_function
nss_parse_service_list (const char *line)
{
service_user *result = NULL, **nextp = &result;
while (1)
{
service_user *new_service;
const char *name;
while (isspace (line[0]))
++line;
if (line[0] == '\0')
/* No source specified. */
return result;
/* Read <source> identifier. */
name = line;
while (line[0] != '\0' && !isspace (line[0]) && line[0] != '[')
++line;
if (name == line)
return result;
new_service = (service_user *) malloc (sizeof (service_user));
if (new_service == NULL)
return result;
else
{
char *source = (char *) malloc (line - name + 1);
if (source == NULL)
{
free (new_service);
return result;
}
*((char *) __mempcpy (source, name, line - name)) = '\0';
new_service->name = source;
}
/* Set default actions. */
new_service->actions[2 + NSS_STATUS_TRYAGAIN] = NSS_ACTION_CONTINUE;
new_service->actions[2 + NSS_STATUS_UNAVAIL] = NSS_ACTION_CONTINUE;
new_service->actions[2 + NSS_STATUS_NOTFOUND] = NSS_ACTION_CONTINUE;
new_service->actions[2 + NSS_STATUS_SUCCESS] = NSS_ACTION_RETURN;
new_service->actions[2 + NSS_STATUS_RETURN] = NSS_ACTION_RETURN;
new_service->library = NULL;
new_service->known = NULL;
new_service->next = NULL;
while (isspace (line[0]))
++line;
if (line[0] == '[')
{
/* Read criterions. */
do
++line;
while (line[0] != '\0' && isspace (line[0]));
do
{
int not;
enum nss_status status;
lookup_actions action;
/* Grok ! before name to mean all statii but that one. */
if (not = line[0] == '!')
++line;
/* Read status name. */
name = line;
while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
&& line[0] != ']')
++line;
/* Compare with known statii. */
if (line - name == 7)
{
if (__strncasecmp (name, "SUCCESS", 7) == 0)
status = NSS_STATUS_SUCCESS;
else if (__strncasecmp (name, "UNAVAIL", 7) == 0)
status = NSS_STATUS_UNAVAIL;
else
return result;
}
else if (line - name == 8)
{
if (__strncasecmp (name, "NOTFOUND", 8) == 0)
status = NSS_STATUS_NOTFOUND;
else if (__strncasecmp (name, "TRYAGAIN", 8) == 0)
status = NSS_STATUS_TRYAGAIN;
else
return result;
}
else
return result;
while (isspace (line[0]))
++line;
if (line[0] != '=')
return result;
do
++line;
while (isspace (line[0]));
name = line;
while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
&& line[0] != ']')
++line;
if (line - name == 6 && __strncasecmp (name, "RETURN", 6) == 0)
action = NSS_ACTION_RETURN;
else if (line - name == 8
&& __strncasecmp (name, "CONTINUE", 8) == 0)
action = NSS_ACTION_CONTINUE;
else
return result;
if (not)
{
/* Save the current action setting for this status,
set them all to the given action, and reset this one. */
const lookup_actions save = new_service->actions[2 + status];
new_service->actions[2 + NSS_STATUS_TRYAGAIN] = action;
new_service->actions[2 + NSS_STATUS_UNAVAIL] = action;
new_service->actions[2 + NSS_STATUS_NOTFOUND] = action;
new_service->actions[2 + NSS_STATUS_SUCCESS] = action;
new_service->actions[2 + status] = save;
}
else
new_service->actions[2 + status] = action;
/* Skip white spaces. */
while (isspace (line[0]))
++line;
}
while (line[0] != ']');
/* Skip the ']'. */
++line;
}
*nextp = new_service;
nextp = &new_service->next;
}
}
static name_database_entry *
internal_function
nss_getline (char *line)
{
const char *name;
name_database_entry *result;
/* Ignore leading white spaces. ATTENTION: this is different from
what is implemented in Solaris. The Solaris man page says a line
beginning with a white space character is ignored. We regard
this as just another misfeature in Solaris. */
while (isspace (line[0]))
++line;
/* Recognize `<database> ":"'. */
name = line;
while (line[0] != '\0' && !isspace (line[0]) && line[0] != ':')
++line;
if (line[0] == '\0' || name == line)
/* Syntax error. */
return NULL;
*line++ = '\0';
result = (name_database_entry *) malloc (sizeof (name_database_entry));
if (result == NULL)
return NULL;
/* Save the database name. */
{
const size_t len = strlen (name) + 1;
char *new = malloc (len);
if (new == NULL)
{
free (result);
return NULL;
}
result->name = memcpy (new, name, len);
}
/* Parse the list of services. */
result->service = nss_parse_service_list (line);
result->next = NULL;
return result;
}
static service_library *
internal_function
nss_new_service (name_database *database, const char *name)
{
service_library **currentp = &database->library;
while (*currentp != NULL)
{
if (strcmp ((*currentp)->name, name) == 0)
return *currentp;
currentp = &(*currentp)->next;
}
/* We have to add the new service. */
*currentp = (service_library *) malloc (sizeof (service_library));
if (*currentp == NULL)
return NULL;
(*currentp)->name = name;
(*currentp)->lib_handle = NULL;
(*currentp)->next = NULL;
return *currentp;
}
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