commit a3e230d1fa9a5ed773a029e2acc6eb4f3e849ea3
author Nick Kralevich <nnk@google.com> Mon Jul 02 12:24:42 2012 -0700
committer Nick Kralevich <nnk@google.com> Mon Jul 09 12:30:40 2012 -0700
tree 6f1dbd761142774dc7bed997d14ec4090c874880
parent 2ddf77b37731dff3a271c1312fc0bef2e7d41473

FORTIFY_SOURCE: Add openat, fix bug

Add fortify_source support for openat(). This change requires that
an argument be supplied when using O_CREAT.

Fix unnecessary call to __open_2. If, at compile time, we know that
"flags" is constant and DOESN'T contain O_CREAT, the call to __open_2
is useless.

Change-Id: Ifcd29c4fb25e25656961d7552d672e161f0cfdbd

libc/include/fcntl.h

diff --git a/libc/include/fcntl.h b/libc/include/fcntl.h
index 47151f4..77c92be 100644
--- a/libc/include/fcntl.h
+++ b/libc/include/fcntl.h
@@ -59,10 +59,10 @@
  * http://clang.llvm.org/docs/UsersManual.html#c_unimpl_gcc
  */
 
-extern void __open_creat_error()
-    __attribute__((__error__ ("open called with O_CREAT, but missing mode")));
-extern void __open_toomanyargs_error()
-    __attribute__((__error__ ("open called with too many arguments")));
+extern void __creat_error()
+    __attribute__((__error__ ("called with O_CREAT, but missing mode")));
+extern void __too_many_args_error()
+    __attribute__((__error__ ("too many arguments")));
 extern int __open_real(const char *pathname, int flags, ...)
     __asm__(__USER_LABEL_PREFIX__ "open");
 extern int __open_2(const char *, int);
@@ -71,21 +71,44 @@
 int open(const char *pathname, int flags, ...) {
     if (__builtin_constant_p(flags)) {
         if ((flags & O_CREAT) && __builtin_va_arg_pack_len() == 0) {
-            __open_creat_error();  // compile time error
+            __creat_error();  // compile time error
         }
     }
 
     if (__builtin_va_arg_pack_len() > 1) {
-        __open_toomanyargs_error();  // compile time error
+        __too_many_args_error();  // compile time error
     }
 
-    if (__builtin_va_arg_pack_len() == 0) {
+    if ((__builtin_va_arg_pack_len() == 0) && !__builtin_constant_p(flags)) {
         return __open_2(pathname, flags);
     }
 
     return __open_real(pathname, flags, __builtin_va_arg_pack());
 }
 
+extern int __openat_2(int, const char *, int);
+extern int __openat_real(int dirfd, const char *pathname, int flags, ...)
+    __asm__(__USER_LABEL_PREFIX__ "openat");
+
+__BIONIC_FORTIFY_INLINE
+int openat(int dirfd, const char *pathname, int flags, ...) {
+    if (__builtin_constant_p(flags)) {
+        if ((flags & O_CREAT) && __builtin_va_arg_pack_len() == 0) {
+            __creat_error();  // compile time error
+        }
+    }
+
+    if (__builtin_va_arg_pack_len() > 1) {
+        __too_many_args_error();  // compile time error
+    }
+
+    if ((__builtin_va_arg_pack_len() == 0) && !__builtin_constant_p(flags)) {
+        return __openat_2(dirfd, pathname, flags);
+    }
+
+    return __openat_real(dirfd, pathname, flags, __builtin_va_arg_pack());
+}
+
 #endif /* !defined(__clang__) */
 #endif /* defined(__BIONIC_FORTIFY_INLINE) */