1 files changed, 116 insertions, 0 deletions
diff --git a/nss/initgroups-fallback.c b/nss/initgroups-fallback.c
new file mode 100644
index 0000000000..9df940767b
--- /dev/null
+++ b/nss/initgroups-fallback.c
@@ -0,0 +1,116 @@
+/* Prototype for the setgrent functions we use here.  */
+typedef enum nss_status (*set_function) (void);
+
+/* Prototype for the endgrent functions we use here.  */
+typedef enum nss_status (*end_function) (void);
+
+/* Prototype for the setgrent functions we use here.  */
+typedef enum nss_status (*get_function) (struct group *, char *,
+					 size_t, int *);
+
+
+static enum nss_status
+compat_call (nss_action_list nip, const char *user, gid_t group, long int *start,
+	     long int *size, gid_t **groupsp, long int limit, int *errnop)
+{
+  struct group grpbuf;
+  enum nss_status status;
+  set_function setgrent_fct;
+  get_function getgrent_fct;
+  end_function endgrent_fct;
+  gid_t *groups = *groupsp;
+
+  getgrent_fct = __nss_lookup_function (nip, "getgrent_r");
+  if (getgrent_fct == NULL)
+    return NSS_STATUS_UNAVAIL;
+
+  setgrent_fct = __nss_lookup_function (nip, "setgrent");
+  if (setgrent_fct)
+    {
+      status = DL_CALL_FCT (setgrent_fct, ());
+      if (status != NSS_STATUS_SUCCESS)
+	return status;
+    }
+
+  endgrent_fct = __nss_lookup_function (nip, "endgrent");
+
+  struct scratch_buffer tmpbuf;
+  scratch_buffer_init (&tmpbuf);
+  enum nss_status result = NSS_STATUS_SUCCESS;
+
+  do
+    {
+      while ((status = DL_CALL_FCT (getgrent_fct,
+				     (&grpbuf, tmpbuf.data, tmpbuf.length,
+				      errnop)),
+	      status == NSS_STATUS_TRYAGAIN)
+	     && *errnop == ERANGE)
+        {
+	  if (!scratch_buffer_grow (&tmpbuf))
+	    {
+	      result = NSS_STATUS_TRYAGAIN;
+	      goto done;
+	    }
+        }
+
+      if (status != NSS_STATUS_SUCCESS)
+        goto done;
+
+      if (grpbuf.gr_gid != group)
+        {
+          char **m;
+
+          for (m = grpbuf.gr_mem; *m != NULL; ++m)
+            if (strcmp (*m, user) == 0)
+              {
+		/* Check whether the group is already on the list.  */
+		long int cnt;
+		for (cnt = 0; cnt < *start; ++cnt)
+		  if (groups[cnt] == grpbuf.gr_gid)
+		    break;
+
+		if (cnt == *start)
+		  {
+		    /* Matches user and not yet on the list.  Insert
+		       this group.  */
+		    if (__glibc_unlikely (*start == *size))
+		      {
+			/* Need a bigger buffer.  */
+			gid_t *newgroups;
+			long int newsize;
+
+			if (limit > 0 && *size == limit)
+			  /* We reached the maximum.  */
+			  goto done;
+
+			if (limit <= 0)
+			  newsize = 2 * *size;
+			else
+			  newsize = MIN (limit, 2 * *size);
+
+			newgroups = realloc (groups,
+					     newsize * sizeof (*groups));
+			if (newgroups == NULL)
+			  goto done;
+			*groupsp = groups = newgroups;
+			*size = newsize;
+		      }
+
+		    groups[*start] = grpbuf.gr_gid;
+		    *start += 1;
+		  }
+
+                break;
+              }
+        }
+    }
+  while (status == NSS_STATUS_SUCCESS);
+
+ done:
+  scratch_buffer_free (&tmpbuf);
+
+  if (endgrent_fct)
+    DL_CALL_FCT (endgrent_fct, ());
+
+  return result;
+}