From e1b80a5a99a3013c6556ec2e2e73ef6ca8e8b80b Mon Sep 17 00:00:00 2001
From: Florian Klink <flokli@flokli.de>
Date: Fri, 16 Aug 2019 15:48:11 +0200
Subject: [PATCH] setup.sh introduce isELFExec, isELFDyn

These can be used to determine whether a ELF file with ELF header is an
executable or shared library.

We can't implement it in pure bash, as bash has problems with null
bytes.
---
 pkgs/stdenv/generic/setup.sh | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index ebcedce60b8..311292169ec 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -212,6 +212,18 @@ isELF() {
     if [ "$magic" = $'\177ELF' ]; then return 0; else return 1; fi
 }
 
+# Return success if the specified file is an ELF object
+# and its e_type is ET_EXEC (executable file)
+isELFExec() {
+    grep -ao -P '^\177ELF.{11}\x00\x02' "$1" >/dev/null
+}
+
+# Return success if the specified file is an ELF object
+# and its e_type is ET_DYN (shared object file)
+isELFDyn() {
+    grep -ao -P '^\177ELF.{11}\x00\x03' "$1" >/dev/null
+}
+
 # Return success if the specified file is a script (i.e. starts with
 # "#!").
 isScript() {