0009-scratchbox2-Add-ld.so-argv0-STRING-to-use-STRING-as-.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Bidar?= <bjorn.bidar@jolla.com>
Date: Tue, 31 Aug 2021 01:56:22 +0300
Subject: [PATCH] (scratchbox2) Add ld.so --argv0 <STRING> to use <STRING> as
 argv0

A small patch for the dynamic linker/loader ("ld.so", also known as
"ld-linux.so"). The dynamic linker is part of the "glibc" package.

This patch adds one command line option which is only used
when the dynamic linker is started as an ordinary program,
which is a seldom used way to start dynamically linked
programs. SB2 uses that option to preserve semantics of the
exec* calls

[SB2 starts the dynamic linker as an ordinary program,
to be able to get full control of the execution environment -
this is somewhat complex system. Study the implementation
of SB2's exec-related functions for full details]

Note that this patch causes no harm in the default case, i.e.
when the dynamic linker is started "automatically" by the kernel.
---
 elf/rtld.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/elf/rtld.c b/elf/rtld.c
index 38b56eb380e035202b978c786f7fcac5730d5d5e..c2022d5bf7cafba0fe3fa3cfaf7cf6470ab23320 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1119,6 +1119,7 @@ dl_main (const ElfW(Phdr) *phdr,
 
   if (*user_entry == (ElfW(Addr)) ENTRY_POINT)
     {
+      char *forced_argv0 = NULL;
       /* Ho ho.  We are not the program interpreter!  We are the program
 	 itself!  This means someone ran ld.so as a command.  Well, that
 	 might be convenient to do sometimes.  We support it by
@@ -1202,6 +1203,14 @@ dl_main (const ElfW(Phdr) *phdr,
 	else if (! strcmp (_dl_argv[1], "--preload") && _dl_argc > 2)
 	  {
 	    preloadarg = _dl_argv[2];
+	    _dl_skip_args += 2;
+	    _dl_argc -= 2;
+	    _dl_argv += 2;
+	  }
+	else if (! strcmp (_dl_argv[1], "--argv0") && _dl_argc > 2)
+	  {
+	    forced_argv0 = _dl_argv[2];
+
 	    _dl_skip_args += 2;
 	    _dl_argc -= 2;
 	    _dl_argv += 2;
@@ -1235,6 +1244,7 @@ of this helper program; chances are you did not intend to run this program.\n\
 			variable LD_LIBRARY_PATH\n\
   --inhibit-rpath LIST  ignore RUNPATH and RPATH information in object names\n\
 			in LIST\n\
+  --argv0 STRING        use STRING as argv[0]\n\
   --audit LIST          use objects named in LIST as auditors\n\
   --preload LIST        preload objects named in LIST\n");
 
@@ -1287,6 +1297,8 @@ of this helper program; chances are you did not intend to run this program.\n\
 	  rtld_timer_stop (&load_time, start);
 	}
 
+      if (forced_argv0 != NULL) _dl_argv[0] = forced_argv0;
+
       /* Now the map for the main executable is available.  */
       main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;