GN: Avoid nontrivial shell commands in gcc_toolchain tools

build/toolchain/gcc_toolchain.gni

Index: build/toolchain/gcc_toolchain.gni
diff --git a/build/toolchain/gcc_toolchain.gni b/build/toolchain/gcc_toolchain.gni
index 3960acb1f342de9437a7cb4fedfa688ddf49f996..6746f5e0db9ffe5bd5c804553d99c2ad20aadce4 100644
--- a/build/toolchain/gcc_toolchain.gni
+++ b/build/toolchain/gcc_toolchain.gni
@@ -214,7 +214,11 @@ template("gcc_toolchain") {
                 root_build_dir)
         arflags = "--plugin $gold_plugin_path"
       }
-      command = "rm -f {{output}} && $ar rcs $arflags {{output}} @$rspfile"
+
+      # This needs a Python script to avoid using simple sh features in this
+      # command, in case the host does not use a POSIX shell (e.g. Windows).
+      ar_wrapper = rebase_path("//build/toolchain/gcc_ar_wrapper.py")
+      command = "$python_path $ar_wrapper --output={{output}} --ar=$ar $arflags rcs @$rspfile"
       description = "AR {{output}}"
       rspfile_content = "{{inputs}}"
       outputs = [
@@ -237,25 +241,27 @@ template("gcc_toolchain") {
         unstripped_sofile = "{{root_out_dir}}/lib.unstripped/$soname"
       }
 
-      # These variables are not built into GN but are helpers that implement
-      # (1) linking to produce a .so, (2) extracting the symbols from that file
-      # to a temporary file, (3) if the temporary file has differences from the
-      # existing .TOC file, overwrite it, otherwise, don't change it.
+      # These variables are not built into GN but are helpers that
+      # implement (1) linking to produce a .so, (2) extracting the symbols
+      # from that file (3) if the extracted list differs from the existing
+      # .TOC file, overwrite it, otherwise, don't change it.
       tocfile = sofile + ".TOC"
-      temporary_tocname = sofile + ".tmp"
 
       link_command = "$ld -shared {{ldflags}} -o $unstripped_sofile -Wl,-soname=$soname @$rspfile"
+
       assert(defined(readelf), "to solink you must have a readelf")
       assert(defined(nm), "to solink you must have an nm")
-      toc_command = "{ $readelf -d $unstripped_sofile | grep SONAME ; $nm -gD -f p $unstripped_sofile | cut -f1-2 -d' '; } > $temporary_tocname"
-      replace_command = "if ! cmp -s $temporary_tocname $tocfile; then mv $temporary_tocname $tocfile; fi"
-
-      command = "$link_command && $toc_command && $replace_command"
+      strip_switch = ""
       if (defined(invoker.strip)) {
-        strip_command =
-            "${invoker.strip} --strip-unneeded -o $sofile $unstripped_sofile"
-        command += " && " + strip_command
+        strip_switch = "--strip=${invoker.strip}"
       }
+
+      # This needs a Python script to avoid using a complex shell command
+      # requiring sh control structures, pipelines, and POSIX utilities.
+      # The host might not have a POSIX shell and utilities (e.g. Windows).
+      solink_wrapper = rebase_path("//build/toolchain/gcc_solink_wrapper.py")
+      command = "$python_path $solink_wrapper --readelf=$readelf --nm=$nm $strip_switch --sofile=$unstripped_sofile --tocfile=$tocfile --output=$sofile -- $link_command"
+
       rspfile_content = "-Wl,--whole-archive {{inputs}} {{solibs}} -Wl,--no-whole-archive $solink_libs_section_prefix {{libs}} $solink_libs_section_postfix"
 
       description = "SOLINK $sofile"