Create sanitized response file instead of expanding arguments (#480)

The cc_wrapper.sh scripts inspects response files and sanitizes each
line within them. How the logic is structured currently causes all of
these arguments to the be directly used later in the script. This can
run into argument overflows. It can also run into problems where quoting
in response files and from args is treated differently.

This addresses some of the comments in #430, namely cleaning up files
and not overwriting the input files. I have not tried to apply a
threshold here as that is best left up to the tooling that previously
decided to use response files, which can cause difficult to debug
changes in behavior.

This conflicts with #479, but is trying to address the same underlying
problem of quoted arguments in response files as the result of golang's
link actions.

Fixes #421

Author: dfreese

toolchain/cc_wrapper.sh.tpl

@@ -29,6 +29,16 @@
 
 set -euo pipefail
 
+CLEANUP_FILES=()
+
+function cleanup() {
+  if [[ ${#CLEANUP_FILES[@]} -gt 0 ]]; then
+    rm -f "${CLEANUP_FILES[@]}"
+  fi
+}
+
+trap cleanup EXIT
+
 # See note in toolchain/internal/configure.bzl where we define
 # `wrapper_bin_prefix` for why this wrapper is needed.
 
@@ -60,14 +70,18 @@ function sanitize_option() {
 
 cmd=()
 for ((i = 0; i <= $#; i++)); do
-  if [[ ${!i} == @* ]]; then
+  if [[ ${!i} == @* && -r "${i:1}" ]]; then
+    # Create a new, sanitized file.
+    tmpfile=$(mktemp)
+    CLEANUP_FILES+=("${tmpfile}")
     while IFS= read -r opt; do
       opt="$(
         set -e
         sanitize_option "${opt}"
       )"
-      cmd+=("${opt}")
+      echo "${opt}" >>"${tmpfile}"
     done <"${!i:1}"
+    cmd+=("@${tmpfile}")
   else
     opt="$(
       set -e
@@ -78,4 +92,4 @@ for ((i = 0; i <= $#; i++)); do
 done
 
 # Call the C++ compiler.
-exec "${cmd[@]}"
+"${cmd[@]}"

toolchain/osx_cc_wrapper.sh.tpl

@@ -35,6 +35,15 @@ LIBS=
 LIB_DIRS=
 RPATHS=
 OUTPUT=
+CLEANUP_FILES=()
+
+function cleanup() {
+  if [[ ${#CLEANUP_FILES[@]} -gt 0 ]]; then
+    rm -f "${CLEANUP_FILES[@]}"
+  fi
+}
+
+trap cleanup EXIT
 
 function parse_option() {
   local -r opt="$1"
@@ -87,17 +96,19 @@ function sanitize_option() {
 cmd=()
 for ((i = 0; i <= $#; i++)); do
   if [[ ${!i} == @* && -r "${i:1}" ]]; then
+    tmpfile=$(mktemp)
+    CLEANUP_FILES+=("${tmpfile}")
     while IFS= read -r opt; do
       if [[ ${opt} == "-fuse-ld=ld64.lld" ]]; then
-        cmd+=("-fuse-ld=lld")
+        echo "-fuse-ld=lld" >>"${tmpfile}"
       fi
       opt="$(
         set -e
         sanitize_option "${opt}"
       )"
-      parse_option "${opt}"
-      cmd+=("${opt}")
+      parse_option "${opt}" >>"${tmpfile}"
     done <"${!i:1}"
+    cmd+=("@${tmpfile}")
   else
     opt="$(
       set -e