From d6faad7de2bdbff18da4c5379e97871ec3839e7f Mon Sep 17 00:00:00 2001
From: Nathaniel Wesley Filardo <nwfilardo@gmail.com>
Date: Sat, 22 Nov 2025 15:32:08 +0000
Subject: [PATCH] test/getrandom-fallbacks: fix open shim types
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In C, functions taking a variable number of arguments are not guaranteed to have
the same calling convention as functions taking a fixed number of arguments
[^0].  Since `open()` and `open64()` are defined as taking a variable number of
arguments, the `__wrap_open()` and `__wrap_open64()` mocks must be as well.

[^0]: C23 §6.7.7.4¶14 says: "For two function types to be compatible, both shall
specify compatible return types. Moreover, the parameter type lists shall agree
in the number of parameters and in use of the final ellipsis; corresponding
parameters shall have compatible types."

This fixes the test on my powerpc64el machine building nixpkgs a8d610af3f1.
---
 test/getrandom-fallbacks.c | 46 +++++++++++++++++++++++++++++++++-----
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/test/getrandom-fallbacks.c b/test/getrandom-fallbacks.c
index b124c181..4048ae29 100644
--- a/test/getrandom-fallbacks.c
+++ b/test/getrandom-fallbacks.c
@@ -151,13 +151,38 @@ __wrap_syscall(long number, ...)
    there's no way to _clear_ that flag again.  This test chooses to
    exercise the read-failure path, not the open-failure path.  */
 #if defined HAVE_SYS_STAT_H && defined HAVE_FCNTL_H && defined HAVE_UNISTD_H
+
+static bool open_needs_mode(int flags)
+{
+  if (flags & O_CREAT)
+  {
+    return true;
+  }
+#if defined(O_TMPFILE)
+  if ((flags & O_TMPFILE) == O_TMPFILE)
+  {
+    return true;
+  }
+#endif
+  return false;
+}
+
 static bool urandom_should_fail = false;
 static int urandom_fd = -1;
-extern int __wrap_open (const char *, int, mode_t);
-extern int __real_open (const char *, int, mode_t);
+extern int __wrap_open (const char *, int, ...);
+extern int __real_open (const char *, int, ...);
 int
-__wrap_open (const char *path, int flags, mode_t mode)
+__wrap_open (const char *path, int flags, ...)
 {
+  int mode = 0;
+  if (open_needs_mode(flags))
+  {
+    va_list args;
+    va_start(args, flags);
+    mode = va_arg(args, int);
+    va_end(args);
+  }
+
   int ret = __real_open (path, flags, mode);
   if (ret == -1)
     return ret;
@@ -167,11 +192,20 @@ __wrap_open (const char *path, int flags, mode_t mode)
 }
 
 #ifdef HAVE_OPEN64
-extern int __wrap_open64 (const char *, int, mode_t);
-extern int __real_open64 (const char *, int, mode_t);
+extern int __wrap_open64 (const char *, int, ...);
+extern int __real_open64 (const char *, int, ...);
 int
-__wrap_open64 (const char *path, int flags, mode_t mode)
+__wrap_open64 (const char *path, int flags, ...)
 {
+  int mode = 0;
+  if (open_needs_mode(flags))
+  {
+    va_list args;
+    va_start(args, flags);
+    mode = va_arg(args, int);
+    va_end(args);
+  }
+
   int ret = __real_open64 (path, flags, mode);
   if (ret == -1)
     return ret;