bintools-wrapper: Init

Factor a bintools (i.e. binutils / cctools) wrapper out of cc-wrapper. While
only LD is wrapped, the setup hook defines environment variables on behalf of
other utilites.

pkgs/build-support/bintools-wrapper/setup-hook.sh

@@ -0,0 +1,67 @@
+# Binutils Wrapper hygiene
+#
+# See comments in cc-wrapper's setup hook. This works exactly the same way.
+
+bintoolsWrapper_addLDVars () {
+    case $depOffset in
+        -1) local role='BUILD_' ;;
+        0)  local role='' ;;
+        1)  local role='TARGET_' ;;
+        *)  echo "bintools-wrapper: Error: Cannot be used with $depOffset-offset deps, " >2;
+            return 1 ;;
+    esac
+
+    if [[ -d "$1/lib64" && ! -L "$1/lib64" ]]; then
+        export NIX_${role}LDFLAGS+=" -L$1/lib64"
+    fi
+
+    if [[ -d "$1/lib" ]]; then
+        export NIX_${role}LDFLAGS+=" -L$1/lib"
+    fi
+}
+
+if [ -n "${crossConfig:-}" ]; then
+    export NIX_BINTOOLS_WRAPPER_@infixSalt@_TARGET_BUILD=1
+    role_pre='BUILD_'
+    role_post='_FOR_BUILD'
+else
+    export NIX_BINTOOLS_WRAPPER_@infixSalt@_TARGET_HOST=1
+    role_pre=""
+    role_post=''
+fi
+
+envHooks+=(bintoolsWrapper_addLDVars)
+
+# shellcheck disable=SC2157
+if [ -n "@bintools_bin@" ]; then
+    addToSearchPath _PATH @bintools_bin@/bin
+fi
+
+# shellcheck disable=SC2157
+if [ -n "@libc_bin@" ]; then
+    addToSearchPath _PATH @libc_bin@/bin
+fi
+
+# shellcheck disable=SC2157
+if [ -n "@coreutils_bin@" ]; then
+    addToSearchPath _PATH @coreutils_bin@/bin
+fi
+
+# Export tool environment variables so various build systems use the right ones.
+
+export NIX_${role_pre}BINTOOLS=@out@
+
+for cmd in \
+    ar as ld nm objcopy objdump readelf ranlib strip strings size windres
+do
+    if
+        PATH=$_PATH type -p "@targetPrefix@${cmd}" > /dev/null
+    then
+        upper_case="$(echo "$cmd" | tr "[:lower:]" "[:upper:]")"
+        export "${role_pre}${upper_case}=@targetPrefix@${cmd}";
+        export "${upper_case}${role_post}=@targetPrefix@${cmd}";
+    fi
+done
+
+# No local scope in sourced file
+unset -v role_pre role_post cmd upper_case