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>

3 files changed, 33 insertions, 107 deletions

diff --git a/nss/nss_files/files-XXX.c b/nss/nss_files/files-XXX.c
index b4b989d..91553d7 100644
--- a/nss/nss_files/files-XXX.c
+++ b/nss/nss_files/files-XXX.c
@@ -45,10 +45,12 @@
 # include <netdb.h>
 # define H_ERRNO_PROTO	, int *herrnop
 # define H_ERRNO_ARG	, herrnop
+# define H_ERRNO_ARG_OR_NULL herrnop
 # define H_ERRNO_SET(val) (*herrnop = (val))
 #else
 # define H_ERRNO_PROTO
 # define H_ERRNO_ARG
+# define H_ERRNO_ARG_OR_NULL NULL
 # define H_ERRNO_SET(val) ((void) 0)
 #endif
 
@@ -58,15 +60,11 @@
 # define EXTRA_ARGS_VALUE
 #endif
 
-/* 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;
-
 /* Open database file if not already opened.  */
 static enum nss_status
 internal_setent (FILE **stream)
@@ -91,41 +89,13 @@ internal_setent (FILE **stream)
 enum nss_status
 CONCAT(_nss_files_set,ENTNAME) (int stayopen)
 {
-  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 (CONCAT (nss_file_, ENTNAME), DATAFILE);
 }
 
-
-/* Thread-safe, exported version of that.  */
 enum nss_status
 CONCAT(_nss_files_end,ENTNAME) (void)
 {
-  __libc_lock_lock (lock);
-
-  internal_endent (&stream);
-
-  __libc_lock_unlock (lock);
-
-  return NSS_STATUS_SUCCESS;
+  return __nss_files_data_endent (CONCAT (nss_file_, ENTNAME));
 }
 
 
@@ -194,26 +164,19 @@ CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
 				  size_t buflen, int *errnop H_ERRNO_PROTO)
 {
   /* Return next entry in host file.  */
-  enum nss_status status = NSS_STATUS_SUCCESS;
-
-  __libc_lock_lock (lock);
-
-  /* Be prepared that the set*ent function was not called before.  */
-  if (stream == NULL)
-    {
-      int save_errno = errno;
-
-      status = internal_setent (&stream);
-
-      __set_errno (save_errno);
-    }
 
-  if (status == NSS_STATUS_SUCCESS)
-    status = internal_getent (stream, result, buffer, buflen, errnop
-			      H_ERRNO_ARG EXTRA_ARGS_VALUE);
+  struct nss_files_per_file_data *data;
+  enum nss_status status = __nss_files_data_open (&data,
+						  CONCAT (nss_file_, ENTNAME),
+						  DATAFILE,
+						  errnop, H_ERRNO_ARG_OR_NULL);
+  if (status != NSS_STATUS_SUCCESS)
+    return status;
 
-  __libc_lock_unlock (lock);
+  status = internal_getent (data->stream, result, buffer, buflen, errnop
+			    H_ERRNO_ARG EXTRA_ARGS_VALUE);
 
+  __nss_files_data_put (data);
   return status;
 }
 
@@ -248,7 +211,7 @@ _nss_files_get##name##_r (proto,					      \
 	     == NSS_STATUS_SUCCESS)					      \
 	{ break_if_match }						      \
 									      \
-      internal_endent (&stream);					      \
+      fclose (stream);							      \
     }									      \
 									      \
   return status;							      \
diff --git a/nss/nss_files/files-alias.c b/nss/nss_files/files-alias.c
index 30971bf..9624b62 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;
 }
diff --git a/nss/nss_files/files-hosts.c b/nss/nss_files/files-hosts.c
index 2b47ec3..1dd51d1 100644
--- a/nss/nss_files/files-hosts.c
+++ b/nss/nss_files/files-hosts.c
@@ -349,7 +349,7 @@ _nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
 	status = gethostbyname3_multi
 	  (stream, name, af, result, buffer, buflen, errnop, herrnop);
 
-      internal_endent (&stream);
+      fclose (stream);
     }
 
   if (canonp && status == NSS_STATUS_SUCCESS)
@@ -475,7 +475,7 @@ _nss_files_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
 	  status = NSS_STATUS_SUCCESS;
 	}
 
-      internal_endent (&stream);
+      fclose (stream);
     }
   else if (status == NSS_STATUS_TRYAGAIN)
     {