From 8eb986df639f9ba7b3127619eabdb59e17612de4 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Wed, 26 Oct 2022 19:17:05 +0200
Subject: [PATCH] libc: Add program_invocation_name

This is a GNU extension, but I'm fine with adding it to libc.
It's guarded by the _GNU_SOURCE feature test macro anyways.
---
 libs/libc/include/errno.h | 5 +++++
 libs/libc/src/errno.cpp   | 3 ++-
 libs/libc/src/init.cpp    | 7 ++++++-
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/libs/libc/include/errno.h b/libs/libc/include/errno.h
index dca6d19e..239b0c42 100644
--- a/libs/libc/include/errno.h
+++ b/libs/libc/include/errno.h
@@ -28,4 +28,9 @@ extern int errno;
 #define ENOTSUP 95    // Operation not supported
 #define EOPNOTSUPP 95 // Operation not supported
 
+#ifdef _GNU_SOURCE // Give it only to programs that ask for it.
+/* Name used to invoke calling program. Same value as argv[0] in main(), but can be used globally. */
+extern char* program_invocation_name;
+#endif
+
 #endif
\ No newline at end of file
diff --git a/libs/libc/src/errno.cpp b/libs/libc/src/errno.cpp
index 434ba1ab..ccd33dd5 100644
--- a/libs/libc/src/errno.cpp
+++ b/libs/libc/src/errno.cpp
@@ -1,3 +1,4 @@
 #include <errno.h>
 
-int errno;
\ No newline at end of file
+int errno;
+char* program_invocation_name;
\ No newline at end of file
diff --git a/libs/libc/src/init.cpp b/libs/libc/src/init.cpp
index 330ca048..b2a92c25 100644
--- a/libs/libc/src/init.cpp
+++ b/libs/libc/src/init.cpp
@@ -51,12 +51,17 @@ static void check_for_file(int fd, FILE** target_stream, const char* path, const
     else { *target_stream = fdopen(fd, mode); }
 }
 
-extern "C" void initialize_libc()
+extern char* program_invocation_name;
+
+extern "C" void initialize_libc(int argc, char** argv)
 {
     check_for_file(STDIN_FILENO, &stdin, "/dev/kbd", "r");
     check_for_file(STDOUT_FILENO, &stdout, "/dev/console", "rw");
     check_for_file(STDERR_FILENO, &stderr, "/dev/console", "rw");
 
+    program_invocation_name =
+        argv[0]; // argv[0] should only be nullptr when being init, which shouldn't use program_invocation_name anyways.
+
     initialize_random();
     atexit(terminate_libc);
 }
\ No newline at end of file