Last minute change. cvs/libc-ud-960811-2

Mon Aug 12 04:33:09 1996  Ulrich Drepper  <drepper@cygnus.com>

	* nss/nsswitch.c (__nss_database_lookup): Always release locks
 	before returning.  Reported by Miles Bader.

	(distributes): Add databases.def.

6 files changed, 182 insertions, 50 deletions

diff --git a/nss/Makefile b/nss/Makefile
index f23f5f3fbb..5dcae4d40e 100644
--- a/nss/Makefile
+++ b/nss/Makefile
@@ -21,13 +21,16 @@
 #
 subdir	:= nss
 
+headers			:= nss.h
 distribute		:= nsswitch.h XXX-lookup.c getXXbyYY.c getXXbyYY_r.c \
-			   getXXent.c getXXent_r.c
+			   getXXent.c getXXent_r.c databases.def
 
 # This is the trivial part which goes into libc itself.
 routines		= nsswitch $(addsuffix -lookup,$(databases))
 
 # These are the databases that go through nss dispatch.
+# Caution: if you add a database here, you must add its real name
+# in databases.def, too.
 databases		= proto service hosts network grp pwd rpc ethers \
 			  spwd
 
diff --git a/nss/XXX-lookup.c b/nss/XXX-lookup.c
index 4a2d25cb42..1b43018d47 100644
--- a/nss/XXX-lookup.c
+++ b/nss/XXX-lookup.c
@@ -35,25 +35,26 @@ Boston, MA 02111-1307, USA.  */
 #define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
 #define CONCAT3_2(Pre, Name, Post) Pre##Name##Post
 
+#define DATABASE_NAME_SYMBOL CONCAT3_1 (__nss_, DATABASE_NAME, _database)
 #define DATABASE_NAME_STRING STRINGIFY1 (DATABASE_NAME)
 #define STRINGIFY1(Name) STRINGIFY2 (Name)
 #define STRINGIFY2(Name) #Name
 
 #ifndef DEFAULT_CONFIG
-#define DEFAULT_CONFIG 0
+#define DEFAULT_CONFIG NULL
 #endif
 
-static service_user *database = NULL;
+service_user *DATABASE_NAME_SYMBOL = NULL;
 
 int
 DB_LOOKUP_FCT (service_user **ni, const char *fct_name, void **fctp)
 {
-  if (database == NULL
+  if (DATABASE_NAME_SYMBOL == NULL
       && __nss_database_lookup (DATABASE_NAME_STRING, DEFAULT_CONFIG,
-				&database) < 0)
+				&DATABASE_NAME_SYMBOL) < 0)
     return -1;
 
-  *ni = database;
+  *ni = DATABASE_NAME_SYMBOL;
 
   return __nss_lookup (ni, fct_name, fctp);
 }
diff --git a/nss/databases.def b/nss/databases.def
new file mode 100644
index 0000000000..98772bac76
--- /dev/null
+++ b/nss/databases.def
@@ -0,0 +1,31 @@
+/* List of all databases defined for the NSS in GNU C Library.
+Copyright (C) 1996 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.  */
+
+/* This list must be kept sorted!!!  */
+
+DEFINE_DATABASE (ethers)
+DEFINE_DATABASE (group)
+DEFINE_DATABASE (hosts)
+DEFINE_DATABASE (networks)
+DEFINE_DATABASE (passwd)
+DEFINE_DATABASE (protocols)
+DEFINE_DATABASE (rpc)
+DEFINE_DATABASE (services)
+DEFINE_DATABASE (shadow)
diff --git a/nss/nss.h b/nss/nss.h
new file mode 100644
index 0000000000..e9acb93bcc
--- /dev/null
+++ b/nss/nss.h
@@ -0,0 +1,54 @@
+/* Copyright (C) 1996 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+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.  */
+
+/* Define interface to NSS.  This is meant for the interface functions
+   and for implementors of new services.  */
+
+#ifndef _NSS_H
+
+#define _NSS_H	1
+#include <features.h>
+
+/* Revision number of NSS interface (must be a string).  */
+#define NSS_SHLIB_REVISION ".1"
+
+
+__BEGIN_DECLS
+
+/* Possible results of lookup using a nss_* function.  */
+enum nss_status
+{
+  NSS_STATUS_TRYAGAIN = -2,
+  NSS_STATUS_UNAVAIL,
+  NSS_STATUS_NOTFOUND,
+  NSS_STATUS_SUCCESS,
+};
+
+
+/* Overwrite service selection for database DBNAME using specification
+   in STRING.
+   This function should only be used by system programs which have to
+   work around non-existing services (e.e., while booting).
+   Attention: Using this function repeatedly will slowly eat up the
+   whole memory since previous selection data cannot be freed.  */
+extern int __nss_configure_lookup __P ((__const char *__dbname,
+					__const char *__string));
+
+__END_DECLS
+
+#endif /* nss.h */
diff --git a/nss/nsswitch.c b/nss/nsswitch.c
index 1349e0ca08..0a4c9482d2 100644
--- a/nss/nsswitch.c
+++ b/nss/nsswitch.c
@@ -19,6 +19,7 @@ Boston, MA 02111-1307, USA.  */
 
 #include <ctype.h>
 #include <dlfcn.h>
+#include <errno.h>
 #include <netdb.h>
 #include <libc-lock.h>
 #include <search.h>
@@ -30,7 +31,6 @@ Boston, MA 02111-1307, USA.  */
 #include "../elf/link.h"	/* We need some help from ld.so.  */
 
 /* Prototypes for the local functions.  */
-static void nss_init (void);
 static void *nss_lookup_function (service_user *ni, const char *fct_name);
 static name_database *nss_parse_file (const char *fname);
 static name_database_entry *nss_getline (char *line);
@@ -39,6 +39,27 @@ static service_library *nss_new_service (name_database *database,
 					 const char *name);
 
 
+/* 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)
 
 
@@ -50,35 +71,29 @@ static int nss_initialized;
 static name_database *service_table;
 
 
-static void
-nss_init (void)
-{
-  /* Prevent multiple threads to change the service table.  */
-  __libc_lock_lock (lock);
-
-  if (service_table == NULL)
-    service_table = nss_parse_file (_PATH_NSSWITCH_CONF);
-
-  __libc_lock_unlock (lock);
-}
-
-
 /* -1 == database not found
     0 == database entry pointer stored */
 int
 __nss_database_lookup (const char *database, const char *defconfig,
 		       service_user **ni)
 {
-  name_database_entry *entry;
+  /* Prevent multiple threads to change the service table.  */
+  __libc_lock_lock (lock);
 
-  if (nss_initialized == 0)
-    nss_init ();
+  /* Reconsider database variable in case some other thread called
+     `__nss_configure_lookup' while we waited for the lock.  */
+  if (*ni != NULL)
+    return 0;
+
+  if (nss_initialized == 0 && service_table == NULL)
+    /* Read config file.  */
+    service_table = nss_parse_file (_PATH_NSSWITCH_CONF);
 
   /* Test whether configuration data is available.  */
-  if (service_table)
+  if (service_table != NULL)
     {
-      /* Return first `service_user' entry for DATABASE.
-	 XXX Will use perfect hashing function for known databases.  */
+      /* 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.  */
@@ -91,17 +106,14 @@ __nss_database_lookup (const char *database, const char *defconfig,
     }
 
   /* No configuration data is available, either because nsswitch.conf
-     doesn't exist or because it doesn't have a line for this database.  */
-  entry = malloc (sizeof *entry);
-  if (entry == NULL)
-    return -1;
-  entry->name = database;
-  /* DEFCONFIG specifies the default service list for this database,
+     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.  */
-  entry->service = nss_parse_service_list (defconfig ?:
-					   "compat [NOTFOUND=return] files");
+  *ni = nss_parse_service_list (defconfig ?: "compat [NOTFOUND=return] files");
+
+  __libc_lock_unlock (lock);
 
-  *ni = entry->service;
   return 0;
 }
 
@@ -168,6 +180,48 @@ __nss_next (service_user **ni, const char *fct_name, void **fctp, int status,
 }
 
 
+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)
+    if (strcmp (dbname, databases[cnt].name) == 0)
+      break;
+
+  if (cnt == sizeof databases)
+    {
+      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.  */
+      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;
+}
+
+
 static int
 nss_dlerror_run (void (*operate) (void))
 {
@@ -385,7 +439,9 @@ nss_parse_file (const char *fname)
 }
 
 
-/* Read the source names: `<source> ( "[" <status> "=" <action> "]" )*'.  */
+/* Read the source names:
+	`( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
+   */
 static service_user *
 nss_parse_service_list (const char *line)
 {
diff --git a/nss/nsswitch.h b/nss/nsswitch.h
index c4d4d11193..0c99f147fd 100644
--- a/nss/nsswitch.h
+++ b/nss/nsswitch.h
@@ -23,24 +23,11 @@ Boston, MA 02111-1307, USA.  */
 
 #include <arpa/nameser.h>
 #include <netinet/in.h>
+#include <nss.h>
 #include <resolv.h>
 #include <search.h>
 
 
-/* Revision number of NSS interface (must be a string).  */
-#define NSS_SHLIB_REVISION ".1"
-
-
-/* Possible results of lookup using a nss_* function.  */
-enum nss_status
-{
-  NSS_STATUS_TRYAGAIN = -2,
-  NSS_STATUS_UNAVAIL,
-  NSS_STATUS_NOTFOUND,
-  NSS_STATUS_SUCCESS,
-};
-
-
 /* Actions performed after lookup finished.  */
 typedef enum
 {