1 files changed, 98 insertions, 0 deletions
diff --git a/grp/compat-initgroups.c b/grp/compat-initgroups.c
new file mode 100644
index 0000000000..585c4aecbb
--- /dev/null
+++ b/grp/compat-initgroups.c
@@ -0,0 +1,98 @@
+/* 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 (service_user *nip, const char *user, gid_t group, long int *start,
+	     long int *size, gid_t **groupsp, long int limit, int *errnop)
+{
+  struct group grpbuf;
+  size_t buflen = __sysconf (_SC_GETGR_R_SIZE_MAX);
+  char *tmpbuf;
+  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");
+
+  tmpbuf = __alloca (buflen);
+
+  do
+    {
+      while ((status = DL_CALL_FCT (getgrent_fct,
+				     (&grpbuf, tmpbuf, buflen, errnop)),
+	      status == NSS_STATUS_TRYAGAIN)
+	     && *errnop == ERANGE)
+        {
+          buflen *= 2;
+          tmpbuf = __alloca (buflen);
+        }
+
+      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)
+              {
+                /* Matches user.  Insert this group.  */
+                if (__builtin_expect (*start == *size, 0))
+                  {
+                    /* 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:
+  if (endgrent_fct)
+    DL_CALL_FCT (endgrent_fct, ());
+
+  return NSS_STATUS_SUCCESS;
+}