Dear maintainer,

With glibc >= 2.44, <spawn.h> declares posix_spawn_file_actions_addchdir
as an asm redirection alias (__REDIRECT_NTH) to
posix_spawn_file_actions_addchdir_np according to POSIX.1-2024.

gnulib sets REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=1, compiling
spawn_faction_addchdir.c which returns posix_spawn_file_actions_addchdir_np.
Because asm redirection cannot be undone by #undef, gcc emits the function
definition as posix_spawn_file_actions_addchdir_np, calling itself in an
infinite recursion.

On i386, this causes an immediate SIGSEGV (exit code 139) during gnulib
tests. On amd64 and arm64, it hangs test-execute.sh and
test-posix_spawn-chdir, leading to FTBFS on Ubuntu stonking (LP: #2167365).

In glibc >= 2.44, posix_spawn_file_actions_addchdir is already provided
natively by libc. Guarding spawn_faction_addchdir.c when defined __GLIBC__
&& defined __USE_XOPEN2K24XSI prevents the recursive definition and allows
clean compilation and test suite execution.

Attached is the patch addressing this issue.

Thanks,
Viktor Pashaiev <w.paszajew@gmail.com>
--- a/gettext-tools/gnulib-lib/spawn_faction_addchdir.c
+++ b/gettext-tools/gnulib-lib/spawn_faction_addchdir.c
@@ -28,43 +28,58 @@

 /* Add an action to FILE-ACTIONS which tells the implementation to call
    'chdir' to the given directory during the 'spawn' call.  */
+#if !REPLACE_POSIX_SPAWN
+
+# if defined __GLIBC__ && defined __USE_XOPEN2K24XSI
+/* In glibc >= 2.44, <spawn.h> already defines posix_spawn_file_actions_addchdir
+   as an alias to posix_spawn_file_actions_addchdir_np. Defining it here would
+   create a recursive call to itself and shadow libc.so.6. */
+typedef int gl_posix_spawn_file_actions_addchdir_unused_t;
+# else
 int
 posix_spawn_file_actions_addchdir (posix_spawn_file_actions_t *file_actions,
                                    const char *path)
-#undef posix_spawn_file_actions_addchdir
+#  undef posix_spawn_file_actions_addchdir
 {
-#if !REPLACE_POSIX_SPAWN
   return posix_spawn_file_actions_addchdir_np (file_actions, path);
-#else
-  {
-    /* Copy PATH, because the caller may free it before calling posix_spawn()
-       or posix_spawnp().  */
-    char *path_copy = strdup (path);
-    if (path_copy == NULL)
-      return ENOMEM;
+}
+# endif
+
+#else
+
+int
+posix_spawn_file_actions_addchdir (posix_spawn_file_actions_t *file_actions,
+                                   const char *path)
+# undef posix_spawn_file_actions_addchdir
+{
+  /* Copy PATH, because the caller may free it before calling posix_spawn()
+     or posix_spawnp().  */
+  char *path_copy = strdup (path);
+  if (path_copy == NULL)
+    return ENOMEM;
+
+  /* Allocate more memory if needed.  */
+  if (file_actions->_used == file_actions->_allocated
+      && __posix_spawn_file_actions_realloc (file_actions) != 0)
+    {
+      /* This can only mean we ran out of memory.  */
+      free (path_copy);
+      return ENOMEM;
+    }
+
+  {
+    struct __spawn_action *rec;
+
+    /* Add the new value.  */
+    rec = &file_actions->_actions[file_actions->_used];
+    rec->tag = spawn_do_chdir;
+    rec->action.chdir_action.path = path_copy;
+
+    /* Account for the new entry.  */
+    ++file_actions->_used;
+
+    return 0;
+  }
 }
+
+#endif

severity 1149910 wishlist
thanks

Thanks for the report, but glibc 2.44-3, uploaded for experimental
today, has this change:

   [ Aurelien Jarno ]
   * debian/patches/git-updates.diff: update from upstream stable branch:
     - Remove POSIX aliases to some spawn functions added in the initial
       2.44 release.

and Aurelien confirms that such change is precisely to deal with the
kind of incompatibility reported here, so the proposed change should
not be necessary for now.

He also provided this link where the upstream issue is discussed:

https://sourceware.org/bugzilla/show_bug.cgi?id=34437

Thanks.

Makes sense, thanks for the update and upstream pointer.