Subject: static linux-user stubs
From: Michael Tokarev <mjt@tls.msk.ru>
Date: Thu, 25 Apr 2024 09:01:13 +0300
Forwarded: not-needed

When building a static linux-user binaries, ld complains:

/usr/bin/ld: libglib-2.0.a(gutils.c.o): in function `g_get_user_database_entry':
  warning: Using 'getpwuid' in statically linked applications requires...
  warning: Using 'getpwnam_r' in statically linked applications requires...
  warning: Using 'getpwuid_r' in statically linked applications requires...

This is because glib, in their "misc utils" unit (gutils.c), has functions
to return current user home directory and similar stuff, and this unit is
almost always included into the link, even if these particular functions
aren't used by the application.

Ideally this should be fixed on the glib side, by splitting gutils.c into
several files, so unused symbols wont be included in the link at all.
But this requires extra efforts from glib side, and static linkage with
glib is very rare.

So just stub-out a few getpw* symbols here, - this will eliminate the
warning and will make resulting binary quite a bit smaller.

It would be nice to eliminate whole dlopen() too.

diff --git a/linux-user/main.c b/linux-user/main.c
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -1025,3 +1025,23 @@ int main(int argc, char **argv, char **envp)
     /* never exits */
     return 0;
 }
+
+#ifdef PROVIDE_STUBS_FOR_STATIC
+
+struct passwd *getpwuid(uid_t uid) {
+  return NULL;
+}
+
+int getpwnam_r(const char *name, struct passwd *pwd,
+               char buf[], size_t buflen,
+               struct passwd **result) {
+  return -1;
+}
+
+int getpwuid_r(uid_t uid, struct passwd *pwd,
+               char buf[], size_t buflen,
+               struct passwd **result) {
+  return -1;
+}
+
+#endif