nss_files: Add generic code for set*ent, end*ent and file open

This reduces RSS usage if nss_files is not actually used, and can
be used later to make NSS data thread-specific.  It also results in
a small code size reduction.

Before:

   text	   data	    bss	    dec	    hex	filename
   2288	      0	     72	   2360	    938	nss/files-alias.os
   1807	      0	     72	   1879	    757	nss/files-ethers.os
   1371	      0	     72	   1443	    5a3	nss/files-grp.os
   6246	      0	     72	   6318	   18ae	nss/files-hosts.os
    869	      0	      0	    869	    365	nss/files-initgroups.os
    666	      0	      0	    666	    29a	nss/files-init.os
   1934	      0	      0	   1934	    78e	nss/files-netgrp.os
   2353	      0	     72	   2425	    979	nss/files-network.os
   2130	      0	     72	   2202	    89a	nss/files-proto.os
   1372	      0	     72	   1444	    5a4	nss/files-pwd.os
   2124	      0	     72	   2196	    894	nss/files-rpc.os
   2265	      0	     72	   2337	    921	nss/files-service.os
   1125	      0	     72	   1197	    4ad	nss/files-sgrp.os
   1124	      0	     72	   1196	    4ac	nss/files-spwd.os

After:

   text	   data	    bss	    dec	    hex	filename
   2040	      0	      0	   2040	    7f8	nss/files-alias.os
   1599	      0	      0	   1599	    63f	nss/files-ethers.os
   1155	      0	      0	   1155	    483	nss/files-grp.os
   6010	      0	      0	   6010	   177a	nss/files-hosts.os
    869	      0	      0	    869	    365	nss/files-initgroups.os
    666	      0	      0	    666	    29a	nss/files-init.os
   1934	      0	      0	   1934	    78e	nss/files-netgrp.os
   2129	      0	      0	   2129	    851	nss/files-network.os
   1914	      0	      0	   1914	    77a	nss/files-proto.os
   1156	      0	      0	   1156	    484	nss/files-pwd.os
   1908	      0	      0	   1908	    774	nss/files-rpc.os
   2057	      0	      0	   2057	    809	nss/files-service.os
    909	      0	      0	    909	    38d	nss/files-sgrp.os
    908	      0	      0	    908	    38c	nss/files-spwd.os
   1090	      0	      8	   1098	    44a	nss/nss_files_data.os

27674 code bytes before, 26344 code bytes after, so it is an overall
win despite the extra initialization code.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 16 insertions, 53 deletions

diff --git a/nss/nss_files/files-alias.c b/nss/nss_files/files-alias.c
index 30971bfe56..9624b6224c 100644
--- a/nss/nss_files/files-alias.c
+++ b/nss/nss_files/files-alias.c
@@ -33,16 +33,11 @@
 
 NSS_DECLARE_MODULE_FUNCTIONS (files)
 
-/* Locks the static variables in this file.  */
-__libc_lock_define_initialized (static, lock)
 
 /* Maintenance of the stream open on the database file.  For getXXent
    operations the stream needs to be held open across calls, the other
    getXXbyYY operations all use their own stream.  */
 
-static FILE *stream;
-
-
 static enum nss_status
 internal_setent (FILE **stream)
 {
@@ -66,41 +61,13 @@ internal_setent (FILE **stream)
 enum nss_status
 _nss_files_setaliasent (void)
 {
-  enum nss_status status;
-
-  __libc_lock_lock (lock);
-
-  status = internal_setent (&stream);
-
-  __libc_lock_unlock (lock);
-
-  return status;
-}
-
-
-/* Close the database file.  */
-static void
-internal_endent (FILE **stream)
-{
-  if (*stream != NULL)
-    {
-      fclose (*stream);
-      *stream = NULL;
-    }
+  return __nss_files_data_setent (nss_file_aliasent, "/etc/aliases");
 }
 
-
-/* Thread-safe, exported version of that.  */
 enum nss_status
 _nss_files_endaliasent (void)
 {
-  __libc_lock_lock (lock);
-
-  internal_endent (&stream);
-
-  __libc_lock_unlock (lock);
-
-  return NSS_STATUS_SUCCESS;
+  return __nss_files_data_endent (nss_file_aliasent);
 }
 
 /* Parsing the database file into `struct aliasent' data structures.  */
@@ -369,26 +336,22 @@ _nss_files_getaliasent_r (struct aliasent *result, char *buffer, size_t buflen,
 			  int *errnop)
 {
   /* Return next entry in host file.  */
-  enum nss_status status = NSS_STATUS_SUCCESS;
 
-  __libc_lock_lock (lock);
+  struct nss_files_per_file_data *data;
+  enum nss_status status = __nss_files_data_open (&data, nss_file_aliasent,
+						  "/etc/aliases", errnop, NULL);
+  if (status != NSS_STATUS_SUCCESS)
+    return status;
 
-  /* Be prepared that the set*ent function was not called before.  */
-  if (stream == NULL)
-    status = internal_setent (&stream);
+  result->alias_local = 1;
 
-  if (status == NSS_STATUS_SUCCESS)
-    {
-      result->alias_local = 1;
-
-      /* Read lines until we get a definite result.  */
-      do
-	status = get_next_alias (stream, NULL, result, buffer, buflen, errnop);
-      while (status == NSS_STATUS_RETURN);
-    }
-
-  __libc_lock_unlock (lock);
+  /* Read lines until we get a definite result.  */
+  do
+    status = get_next_alias (data->stream, NULL, result, buffer, buflen,
+			     errnop);
+  while (status == NSS_STATUS_RETURN);
 
+  __nss_files_data_put (data);
   return status;
 }
 
@@ -418,9 +381,9 @@ _nss_files_getaliasbyname_r (const char *name, struct aliasent *result,
       do
 	status = get_next_alias (stream, name, result, buffer, buflen, errnop);
       while (status == NSS_STATUS_RETURN);
-    }
 
-  internal_endent (&stream);
+      fclose (stream);
+    }
 
   return status;
 }