nscd_getgr_r: Use struct scratch_buffer instead of extend_alloca

The lack of alloca accounting means that the old code could run out of
stack space if multiple retries are needed.

diff --git a/ChangeLog b/ChangeLog
index 93583af..fd79b12 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,7 @@
        * nis/nss_compat/compat-initgroups.c (_nss_compat_initgroups_dyn):
        Rewrite to use struct scratch_buffer instead of extend_alloca.
        * inet/getnameinfo.c (nrl_domainname, getnameinfo): Likewise.
+       * nscd/nscd_getgr_r.c (nscd_getgr_r): Likewise.
 
 2015-04-08  Joseph Myers  <joseph@codesourcery.com>
 

diff --git a/nscd/nscd_getgr_r.c b/nscd/nscd_getgr_r.c
index 7e45ee5..d08b73f 100644 (file)
--- a/nscd/nscd_getgr_r.c
+++ b/nscd/nscd_getgr_r.c
@@ -31,6 +31,7 @@
 #include <sys/un.h>
 #include <not-cancel.h>
 #include <_itoa.h>
+#include <scratch_buffer.h>
 
 #include "nscd-client.h"
 #include "nscd_proto.h"
@@ -89,7 +90,8 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
   int gc_cycle;
   int nretries = 0;
   const uint32_t *len = NULL;
-  size_t lensize = 0;
+  struct scratch_buffer lenbuf;
+  scratch_buffer_init (&lenbuf);
 
   /* If the mapping is available, try to search there instead of
      communicating with the nscd.  */
@@ -200,14 +202,10 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
          else
            {
              /* Allocate array to store lengths.  */
-             if (lensize == 0)
-               {
-                 lensize = gr_resp.gr_mem_cnt * sizeof (uint32_t);
-                 len = (uint32_t *) alloca (lensize);
-               }
-             else if (gr_resp.gr_mem_cnt * sizeof (uint32_t) > lensize)
-               len = extend_alloca (len, lensize,
-                                    gr_resp.gr_mem_cnt * sizeof (uint32_t));
+             if (!scratch_buffer_set_array_size
+                 (&lenbuf, gr_resp.gr_mem_cnt, sizeof (uint32_t)))
+               goto out_close;
+             len = lenbuf.data;
 
              vec[0].iov_base = (void *) len;
              vec[0].iov_len = gr_resp.gr_mem_cnt * sizeof (uint32_t);
@@ -326,5 +324,7 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
        goto retry;
     }
 
+  scratch_buffer_free (&lenbuf);
+
   return retval;
 }