nss_files: Use struct scratch_buffer instead of extend_alloca [BZ #18023]

diff --git a/ChangeLog b/ChangeLog
index b0159351952c6b97bb86180fabc01e5f57e064af..f8d28b496ec3668f71712c5171c0abceece3e945 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2018-06-25  Florian Weimer  <fweimer@redhat.com>
+
+       [BZ #18023]
+       * nss/nss_files/files-initgroups.c (_nss_files_initgroups_dyn):
+       Use struct scratch_buffer instead of extend_alloca.
+
 2018-06-25  Florian Weimer  <fweimer@redhat.com>
 
        [BZ #18023]

diff --git a/nss/nss_files/files-initgroups.c b/nss/nss_files/files-initgroups.c
index 8af0d4d36a400f0e325e537e6817724d4cf09154..b441d8345f8a7a247eb5989b0f2abd788f0dfd6b 100644 (file)
--- a/nss/nss_files/files-initgroups.c
+++ b/nss/nss_files/files-initgroups.c
@@ -16,7 +16,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <alloca.h>
 #include <errno.h>
 #include <grp.h>
 #include <nss.h>
@@ -25,6 +24,7 @@
 #include <sys/param.h>
 #include <stdbool.h>
 #include <stdlib.h>
+#include <scratch_buffer.h>
 
 enum nss_status
 _nss_files_initgroups_dyn (const char *user, gid_t group, long int *start,
@@ -46,9 +46,8 @@ _nss_files_initgroups_dyn (const char *user, gid_t group, long int *start,
   enum nss_status status = NSS_STATUS_SUCCESS;
   bool any = false;
 
-  size_t buflen = 1024;
-  void *buffer = alloca (buflen);
-  bool buffer_use_malloc = false;
+  struct scratch_buffer tmpbuf;
+  scratch_buffer_init (&tmpbuf);
 
   gid_t *groups = *groupsp;
 
@@ -67,26 +66,16 @@ _nss_files_initgroups_dyn (const char *user, gid_t group, long int *start,
        }
 
       struct group grp;
-      int res = _nss_files_parse_grent (line, &grp, buffer, buflen, errnop);
+      int res = _nss_files_parse_grent (line, &grp,
+                                       tmpbuf.data, tmpbuf.length, errnop);
       if (res == -1)
        {
-         size_t newbuflen = 2 * buflen;
-         if (buffer_use_malloc || ! __libc_use_alloca (buflen + newbuflen))
+         if (!scratch_buffer_grow (&tmpbuf))
            {
-             void *newbuf = realloc (buffer_use_malloc ? buffer : NULL,
-                                     newbuflen);
-             if (newbuf == NULL)
-               {
-                 *errnop = ENOMEM;
-                 status = NSS_STATUS_TRYAGAIN;
-                 goto out;
-               }
-             buffer = newbuf;
-             buflen = newbuflen;
-             buffer_use_malloc = true;
+             *errnop = ENOMEM;
+             status = NSS_STATUS_TRYAGAIN;
+             goto out;
            }
-         else
-           buffer = extend_alloca (buffer, buflen, newbuflen);
          /* Reread current line, the parser has clobbered it.  */
          fsetpos (stream, &pos);
          continue;
@@ -132,8 +121,7 @@ _nss_files_initgroups_dyn (const char *user, gid_t group, long int *start,
 
  out:
   /* Free memory.  */
-  if (buffer_use_malloc)
-    free (buffer);
+  scratch_buffer_free (&tmpbuf);
   free (line);
 
   fclose (stream);