nss: Add __nss_fgetent_r

And helper functions __nss_readline, __nss_readline_seek,
 __nss_parse_line_result.

This consolidates common code for handling overlong lines and
parse files.  Use the new functionality in internal_getent
in nss/nss_files/files-XXX.c.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/nss/nss_fgetent_r.c b/nss/nss_fgetent_r.c
new file mode 100644
index 0000000000..8f7c5b5cc7
--- /dev/null
+++ b/nss/nss_fgetent_r.c
@@ -0,0 +1,55 @@
+/* Generic implementation of fget*ent_r.
+   Copyright (C) 2020 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 Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <nss_files.h>
+
+int
+__nss_fgetent_r (FILE *fp, void *result, char *buffer, size_t buffer_length,
+                 nss_files_parse_line parser)
+{
+  int ret;
+
+  _IO_flockfile (fp);
+
+  while (true)
+    {
+      off64_t original_offset;
+      ret = __nss_readline (fp, buffer, buffer_length, &original_offset);
+      if (ret == 0)
+        {
+          /* Parse the line into *RESULT.  */
+          ret = parser (buffer, result,
+                        (struct parser_data *) buffer, buffer_length, &errno);
+
+          /* Translate the result code from the parser into an errno
+             value.  Also seeks back to the start of the line if
+             necessary.  */
+          ret = __nss_parse_line_result (fp, original_offset, ret);
+
+          if (ret == EINVAL)
+            /* Skip over malformed lines.  */
+            continue;
+        }
+      break;
+    }
+
+  _IO_funlockfile (fp);
+
+  return ret;
+}