nss_files: Refactor gethostbyname3 multi case into separate function

This is in preparation of further cleanup work.

(cherry picked from commit 8ed70de2faceb4bd7b35bbdc2b7e8c83d9a297ba)

2 files changed, 208 insertions, 193 deletions

diff --git a/ChangeLog b/ChangeLog
index 513806b3b2..642f01fa18 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-10-10  Florian Weimer  <fweimer@redhat.com>
+
+	* nss/nss_files/files-hosts.c (gethostbyname3_multi): New
+	function.
+	(_nss_files_gethostbyname3_r): Call it.
+
 2017-04-21  Florian Weimer  <fweimer@redhat.com>
 
 	* malloc/Makefile (tests-internal): Add tst-alloc_buffer.
diff --git a/nss/nss_files/files-hosts.c b/nss/nss_files/files-hosts.c
index bccb6a5780..867c10c2ef 100644
--- a/nss/nss_files/files-hosts.c
+++ b/nss/nss_files/files-hosts.c
@@ -115,6 +115,206 @@ DB_LOOKUP (hostbyaddr, ,,,
 	   }, const void *addr, socklen_t len, int af)
 #undef EXTRA_ARGS_VALUE
 
+static enum nss_status
+gethostbyname3_multi (FILE * stream, const char *name, int af,
+		      struct hostent *result, char *buffer, size_t buflen,
+		      int *errnop, int *herrnop, int flags)
+{
+  /* We have to get all host entries from the file.  */
+  size_t tmp_buflen = MIN (buflen, 4096);
+  char tmp_buffer_stack[tmp_buflen]
+    __attribute__ ((__aligned__ (__alignof__ (struct hostent_data))));
+  char *tmp_buffer = tmp_buffer_stack;
+  struct hostent tmp_result_buf;
+  int naddrs = 1;
+  int naliases = 0;
+  char *bufferend;
+  bool tmp_buffer_malloced = false;
+  enum nss_status status;
+
+  while (result->h_aliases[naliases] != NULL)
+    ++naliases;
+
+  bufferend = (char *) &result->h_aliases[naliases + 1];
+
+ again:
+  while ((status = internal_getent (stream, &tmp_result_buf, tmp_buffer,
+				    tmp_buflen, errnop, herrnop, af,
+				    flags))
+	 == NSS_STATUS_SUCCESS)
+    {
+      int matches = 1;
+      struct hostent *old_result = result;
+      result = &tmp_result_buf;
+      /* The following piece is a bit clumsy but we want to use the
+	 `LOOKUP_NAME_CASE' value.  The optimizer should do its
+	 job.  */
+      do
+	{
+	  LOOKUP_NAME_CASE (h_name, h_aliases)
+	    result = old_result;
+	}
+      while ((matches = 0));
+
+      if (matches)
+	{
+	  /* We could be very clever and try to recycle a few bytes
+	     in the buffer instead of generating new arrays.  But
+	     we are not doing this here since it's more work than
+	     it's worth.  Simply let the user provide a bit bigger
+	     buffer.  */
+	  char **new_h_addr_list;
+	  char **new_h_aliases;
+	  int newaliases = 0;
+	  size_t newstrlen = 0;
+	  int cnt;
+
+	  /* Count the new aliases and the length of the strings.  */
+	  while (tmp_result_buf.h_aliases[newaliases] != NULL)
+	    {
+	      char *cp = tmp_result_buf.h_aliases[newaliases];
+	      ++newaliases;
+	      newstrlen += strlen (cp) + 1;
+	    }
+	  /* If the real name is different add it also to the
+	     aliases.  This means that there is a duplication
+	     in the alias list but this is really the user's
+	     problem.  */
+	  if (strcmp (old_result->h_name,
+		      tmp_result_buf.h_name) != 0)
+	    {
+	      ++newaliases;
+	      newstrlen += strlen (tmp_result_buf.h_name) + 1;
+	    }
+
+	  /* Make sure bufferend is aligned.  */
+	  assert ((bufferend - (char *) 0) % sizeof (char *) == 0);
+
+	  /* Now we can check whether the buffer is large enough.
+	     16 is the maximal size of the IP address.  */
+	  if (bufferend + 16 + (naddrs + 2) * sizeof (char *)
+	      + roundup (newstrlen, sizeof (char *))
+	      + (naliases + newaliases + 1) * sizeof (char *)
+	      >= buffer + buflen)
+	    {
+	      *errnop = ERANGE;
+	      *herrnop = NETDB_INTERNAL;
+	      status = NSS_STATUS_TRYAGAIN;
+	      goto out;
+	    }
+
+	  new_h_addr_list =
+	    (char **) (bufferend
+		       + roundup (newstrlen, sizeof (char *))
+		       + 16);
+	  new_h_aliases =
+	    (char **) ((char *) new_h_addr_list
+		       + (naddrs + 2) * sizeof (char *));
+
+	  /* Copy the old data in the new arrays.  */
+	  for (cnt = 0; cnt < naddrs; ++cnt)
+	    new_h_addr_list[cnt] = old_result->h_addr_list[cnt];
+
+	  for (cnt = 0; cnt < naliases; ++cnt)
+	    new_h_aliases[cnt] = old_result->h_aliases[cnt];
+
+	  /* Store the new strings.  */
+	  cnt = 0;
+	  while (tmp_result_buf.h_aliases[cnt] != NULL)
+	    {
+	      new_h_aliases[naliases++] = bufferend;
+	      bufferend = (__stpcpy (bufferend,
+				     tmp_result_buf.h_aliases[cnt])
+			   + 1);
+	      ++cnt;
+	    }
+
+	  if (cnt < newaliases)
+	    {
+	      new_h_aliases[naliases++] = bufferend;
+	      bufferend = __stpcpy (bufferend,
+				    tmp_result_buf.h_name) + 1;
+	    }
+
+	  /* Final NULL pointer.  */
+	  new_h_aliases[naliases] = NULL;
+
+	  /* Round up the buffer end address.  */
+	  bufferend += (sizeof (char *)
+			- ((bufferend - (char *) 0)
+			   % sizeof (char *))) % sizeof (char *);
+
+	  /* Now the new address.  */
+	  new_h_addr_list[naddrs++] =
+	    memcpy (bufferend, tmp_result_buf.h_addr,
+		    tmp_result_buf.h_length);
+
+	  /* Also here a final NULL pointer.  */
+	  new_h_addr_list[naddrs] = NULL;
+
+	  /* Store the new array pointers.  */
+	  old_result->h_aliases = new_h_aliases;
+	  old_result->h_addr_list = new_h_addr_list;
+
+	  /* Compute the new buffer end.  */
+	  bufferend = (char *) &new_h_aliases[naliases + 1];
+	  assert (bufferend <= buffer + buflen);
+
+	  result = old_result;
+	}
+    }
+
+  if (status == NSS_STATUS_TRYAGAIN)
+    {
+      size_t newsize = 2 * tmp_buflen;
+      if (tmp_buffer_malloced)
+	{
+	  char *newp = realloc (tmp_buffer, newsize);
+	  if (newp != NULL)
+	    {
+	      assert ((((uintptr_t) newp)
+		       & (__alignof__ (struct hostent_data) - 1))
+		      == 0);
+	      tmp_buffer = newp;
+	      tmp_buflen = newsize;
+	      goto again;
+	    }
+	}
+      else if (!__libc_use_alloca (buflen + newsize))
+	{
+	  tmp_buffer = malloc (newsize);
+	  if (tmp_buffer != NULL)
+	    {
+	      assert ((((uintptr_t) tmp_buffer)
+		       & (__alignof__ (struct hostent_data) - 1))
+		      == 0);
+	      tmp_buffer_malloced = true;
+	      tmp_buflen = newsize;
+	      goto again;
+	    }
+	}
+      else
+	{
+	  tmp_buffer
+	    = extend_alloca (tmp_buffer, tmp_buflen,
+			     newsize
+			     + __alignof__ (struct hostent_data));
+	  tmp_buffer = (char *) (((uintptr_t) tmp_buffer
+				  + __alignof__ (struct hostent_data)
+				  - 1)
+				 & ~(__alignof__ (struct hostent_data)
+				     - 1));
+	  goto again;
+	}
+    }
+  else
+    status = NSS_STATUS_SUCCESS;
+ out:
+  if (tmp_buffer_malloced)
+    free (tmp_buffer);
+  return status;
+}
+
 enum nss_status
 _nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
 			     char *buffer, size_t buflen, int *errnop,
@@ -143,199 +343,8 @@ _nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
 
       if (status == NSS_STATUS_SUCCESS
 	  && _res_hconf.flags & HCONF_FLAG_MULTI)
-	{
-	  /* We have to get all host entries from the file.  */
-	  size_t tmp_buflen = MIN (buflen, 4096);
-	  char tmp_buffer_stack[tmp_buflen]
-	    __attribute__ ((__aligned__ (__alignof__ (struct hostent_data))));
-	  char *tmp_buffer = tmp_buffer_stack;
-	  struct hostent tmp_result_buf;
-	  int naddrs = 1;
-	  int naliases = 0;
-	  char *bufferend;
-	  bool tmp_buffer_malloced = false;
-
-	  while (result->h_aliases[naliases] != NULL)
-	    ++naliases;
-
-	  bufferend = (char *) &result->h_aliases[naliases + 1];
-
-	again:
-	  while ((status = internal_getent (stream, &tmp_result_buf, tmp_buffer,
-					    tmp_buflen, errnop, herrnop, af,
-					    flags))
-		 == NSS_STATUS_SUCCESS)
-	    {
-	      int matches = 1;
-	      struct hostent *old_result = result;
-	      result = &tmp_result_buf;
-	      /* The following piece is a bit clumsy but we want to use the
-		 `LOOKUP_NAME_CASE' value.  The optimizer should do its
-		 job.  */
-	      do
-		{
-		  LOOKUP_NAME_CASE (h_name, h_aliases)
-		  result = old_result;
-		}
-	      while ((matches = 0));
-
-	      if (matches)
-		{
-		  /* We could be very clever and try to recycle a few bytes
-		     in the buffer instead of generating new arrays.  But
-		     we are not doing this here since it's more work than
-		     it's worth.  Simply let the user provide a bit bigger
-		     buffer.  */
-		  char **new_h_addr_list;
-		  char **new_h_aliases;
-		  int newaliases = 0;
-		  size_t newstrlen = 0;
-		  int cnt;
-
-		  /* Count the new aliases and the length of the strings.  */
-		  while (tmp_result_buf.h_aliases[newaliases] != NULL)
-		    {
-		      char *cp = tmp_result_buf.h_aliases[newaliases];
-		      ++newaliases;
-		      newstrlen += strlen (cp) + 1;
-		    }
-		  /* If the real name is different add it also to the
-		     aliases.  This means that there is a duplication
-		     in the alias list but this is really the user's
-		     problem.  */
-		  if (strcmp (old_result->h_name,
-			      tmp_result_buf.h_name) != 0)
-		    {
-		      ++newaliases;
-		      newstrlen += strlen (tmp_result_buf.h_name) + 1;
-		    }
-
-		  /* Make sure bufferend is aligned.  */
-		  assert ((bufferend - (char *) 0) % sizeof (char *) == 0);
-
-		  /* Now we can check whether the buffer is large enough.
-		     16 is the maximal size of the IP address.  */
-		  if (bufferend + 16 + (naddrs + 2) * sizeof (char *)
-		      + roundup (newstrlen, sizeof (char *))
-		      + (naliases + newaliases + 1) * sizeof (char *)
-		      >= buffer + buflen)
-		    {
-		      *errnop = ERANGE;
-		      *herrnop = NETDB_INTERNAL;
-		      status = NSS_STATUS_TRYAGAIN;
-		      goto out;
-		    }
-
-		  new_h_addr_list =
-		    (char **) (bufferend
-			       + roundup (newstrlen, sizeof (char *))
-			       + 16);
-		  new_h_aliases =
-		    (char **) ((char *) new_h_addr_list
-			       + (naddrs + 2) * sizeof (char *));
-
-		  /* Copy the old data in the new arrays.  */
-		  for (cnt = 0; cnt < naddrs; ++cnt)
-		    new_h_addr_list[cnt] = old_result->h_addr_list[cnt];
-
-		  for (cnt = 0; cnt < naliases; ++cnt)
-		    new_h_aliases[cnt] = old_result->h_aliases[cnt];
-
-		  /* Store the new strings.  */
-		  cnt = 0;
-		  while (tmp_result_buf.h_aliases[cnt] != NULL)
-		    {
-		      new_h_aliases[naliases++] = bufferend;
-		      bufferend = (__stpcpy (bufferend,
-					     tmp_result_buf.h_aliases[cnt])
-				   + 1);
-		      ++cnt;
-		    }
-
-		  if (cnt < newaliases)
-		    {
-		      new_h_aliases[naliases++] = bufferend;
-		      bufferend = __stpcpy (bufferend,
-					    tmp_result_buf.h_name) + 1;
-		    }
-
-		  /* Final NULL pointer.  */
-		  new_h_aliases[naliases] = NULL;
-
-		  /* Round up the buffer end address.  */
-		  bufferend += (sizeof (char *)
-				- ((bufferend - (char *) 0)
-				   % sizeof (char *))) % sizeof (char *);
-
-		  /* Now the new address.  */
-		  new_h_addr_list[naddrs++] =
-		    memcpy (bufferend, tmp_result_buf.h_addr,
-			    tmp_result_buf.h_length);
-
-		  /* Also here a final NULL pointer.  */
-		  new_h_addr_list[naddrs] = NULL;
-
-		  /* Store the new array pointers.  */
-		  old_result->h_aliases = new_h_aliases;
-		  old_result->h_addr_list = new_h_addr_list;
-
-		  /* Compute the new buffer end.  */
-		  bufferend = (char *) &new_h_aliases[naliases + 1];
-		  assert (bufferend <= buffer + buflen);
-
-		  result = old_result;
-		}
-	    }
-
-	  if (status == NSS_STATUS_TRYAGAIN)
-	    {
-	      size_t newsize = 2 * tmp_buflen;
-	      if (tmp_buffer_malloced)
-		{
-		  char *newp = realloc (tmp_buffer, newsize);
-		  if (newp != NULL)
-		    {
-		      assert ((((uintptr_t) newp)
-			       & (__alignof__ (struct hostent_data) - 1))
-			      == 0);
-		      tmp_buffer = newp;
-		      tmp_buflen = newsize;
-		      goto again;
-		    }
-		}
-	      else if (!__libc_use_alloca (buflen + newsize))
-		{
-		  tmp_buffer = malloc (newsize);
-		  if (tmp_buffer != NULL)
-		    {
-		      assert ((((uintptr_t) tmp_buffer)
-			       & (__alignof__ (struct hostent_data) - 1))
-			      == 0);
-		      tmp_buffer_malloced = true;
-		      tmp_buflen = newsize;
-		      goto again;
-		    }
-		}
-	      else
-		{
-		  tmp_buffer
-		    = extend_alloca (tmp_buffer, tmp_buflen,
-				     newsize
-				     + __alignof__ (struct hostent_data));
-		  tmp_buffer = (char *) (((uintptr_t) tmp_buffer
-					  + __alignof__ (struct hostent_data)
-					  - 1)
-					 & ~(__alignof__ (struct hostent_data)
-					     - 1));
-		  goto again;
-		}
-	    }
-	  else
-	    status = NSS_STATUS_SUCCESS;
-	out:
-	  if (tmp_buffer_malloced)
-	    free (tmp_buffer);
-	}
+	status = gethostbyname3_multi
+	  (stream, name, af, result, buffer, buflen, errnop, herrnop, flags);
 
       internal_endent (&stream);
     }