From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Dmitry Muhomor <muhomor.dmitry@gmail.com>
Date: Tue, 2 May 2023 16:45:26 +0300
Subject: [PATCH] support assigning ID to path of current executable

---
 libc/bionic/libc_init_dynamic.cpp | 27 ++++++++++++++++++++++++++-
 libc/include/stdlib.h             |  3 +++
 libc/libc.map.txt                 |  1 +
 libc/private/bionic_globals.h     |  1 +
 4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/libc/bionic/libc_init_dynamic.cpp b/libc/bionic/libc_init_dynamic.cpp
index 1180a513e..1135b805c 100644
--- a/libc/bionic/libc_init_dynamic.cpp
+++ b/libc/bionic/libc_init_dynamic.cpp
@@ -78,6 +78,28 @@ extern "C" __attribute__((weak)) void __hwasan_library_unloaded(ElfW(Addr) base,
                                                                 const ElfW(Phdr)* phdr,
                                                                 ElfW(Half) phnum);
 
+static void init_prog_id(libc_globals* globals) {
+  char exe_path[500];
+  ssize_t readlink_res = readlink("/proc/self/exe", exe_path, sizeof(exe_path) - 1 /* space for NUL terminator */);
+  if (readlink_res <= 0) {
+    return;
+  }
+  exe_path[readlink_res] = '\0';
+
+  int prog_id = 0;
+
+#define IS(prog) (!strcmp(exe_path, prog))
+
+#undef IS
+
+  // libc_globals struct is write-protected
+  globals->prog_id = prog_id;
+}
+
+int get_prog_id() {
+  return __libc_globals->prog_id;
+}
+
 // We need a helper function for __libc_preinit because compiling with LTO may
 // inline functions requiring a stack protector check, but __stack_chk_guard is
 // not initialized at the start of __libc_preinit. __libc_preinit_impl will run
@@ -109,7 +131,10 @@ static void __libc_preinit_impl() {
 #endif
 
   // Hooks for various libraries to let them know that we're starting up.
-  __libc_globals.mutate(__libc_init_malloc);
+  __libc_globals.mutate([](libc_globals* globals) {
+    init_prog_id(globals);
+    __libc_init_malloc(globals);
+  });
 
   // Install reserved signal handlers for assisting the platform's profilers.
   __libc_init_profiling_handlers();
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 2830a493d..5ce8f9103 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -210,6 +210,9 @@ long strtol_l(const char* _Nonnull __s, char* _Nullable * _Nullable __end_ptr, i
 // Implemented as static inlines before 26.
 #endif
 
+int get_prog_id();
+#define is_prog(id) (get_prog_id() == id)
+
 __END_DECLS
 
 #include <android/legacy_stdlib_inlines.h>
diff --git a/libc/libc.map.txt b/libc/libc.map.txt
index 2c8ec0796..f5340c172 100644
--- a/libc/libc.map.txt
+++ b/libc/libc.map.txt
@@ -420,6 +420,7 @@ LIBC {
     get_nprocs; # introduced=23
     get_nprocs_conf; # introduced=23
     get_phys_pages; # introduced=23
+    get_prog_id;
     getaddrinfo;
     getauxval; # introduced-arm=18 introduced-arm64=21 introduced-x86=18 introduced-x86_64=21
     getc;
diff --git a/libc/private/bionic_globals.h b/libc/private/bionic_globals.h
index 6f1e3895e..598918f09 100644
--- a/libc/private/bionic_globals.h
+++ b/libc/private/bionic_globals.h
@@ -66,6 +66,7 @@ struct libc_globals {
   // limit is enabled and some other hook is enabled at the same time.
   _Atomic(const MallocDispatch*) default_dispatch_table;
   MallocDispatch malloc_dispatch_table;
+  int prog_id;
 };
 
 struct memtag_dynamic_entries_t {