[ios/mac] Use clonefile instead of hardlink to populate bundles

Use `cp -c` to copy file into the bundle which uses clonefile instead
of hardlink. This is as efficient in speed and disk usage. This also
ensures that files in the bundle are distinct from any other files
(which is important when running EG2 tests via Xcode as it tries to
overwrite some files with `ditto` which fails if source and target
are hardlinked together).

Bug: 1042182
Change-Id: I53c08a0ee2200355b3c4249465f78189d6e294d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2133930
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756765}

build/toolchain/mac/BUILD.gn

@@ -421,27 +421,16 @@ template("mac_toolchain") {
 
     tool("copy_bundle_data") {
       # copy_command use hardlink if possible but this does not work with
-      # directories. If source is a directory, instead use "pax" to create
-      # the same tree structure using hardlinks to individual files (this
-      # preserve symbolic links too) as recommended in the replies to the
-      # question at http://serverfault.com/q/209888/43689 ("cp -al" isn't
-      # available on macOS).
+      # directories. Also when running EG2 tests from Xcode, Xcode tries to
+      # copy some files into the application bundle which fails if source
+      # and destination are hardlinked together.
       #
-      # According to the man page for pax, the commands to use to clone
-      # olddir to newdir using pax are the following:
-      #
-      #   $ mkdir newdir
-      #   $ cd olddir
-      #   $ pax -rwl . ../newdir
-      #
-      # The _copydir command does exactly that but use an absolute path
-      # constructed using shell variable $OLDPWD (automatically set when
-      # cd is used) as computing the relative path is a bit complex and
-      # using pwd would requires a sub-shell to be created.
-      _copydir = "mkdir -p {{output}} && cd {{source}} && " +
-                 "pax -rwl . \"\$OLDPWD\"/{{output}}"
-      command = "rm -rf {{output}} && if [[ -d {{source}} ]]; then " +
-                _copydir + "; else " + copy_command + "; fi"
+      # Instead use clonefile to copy the files which is as efficient as
+      # hardlink but ensure the file have distinct metadata (thus avoid the
+      # error with ditto, see https://crbug.com/1042182).
+      command =
+          "rm -rf {{output}} && cp -fRc {{source}} {{output}} 2>/dev/null " +
+          "|| (rm -rf {{output}} && cp -fR {{source}} {{output}})"
 
       description = "COPY_BUNDLE_DATA {{source}} {{output}}"
       pool = ":bundle_pool($default_toolchain)"