Add toolchain'd protoc compiler to the engine/client target (pantsb…

…uild#19853)

This change just adds a toolchained `protoc` to the compilation of the
engine/client, ever strengthening our march towards hermetiocity,
isolation, and reproducibility.

Future changes will continue porting more from `tools` to being
vendored, but still done so piecemeal so we can tease them apart if
needed.

---------

Co-authored-by: Huon Wilson <[email protected]>

3rdparty/tools/protoc/BUILD

@@ -0,0 +1,40 @@
+# Copyright 2023 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+file(
+    name="compressed-protoc",
+    source=per_platform(
+        linux_arm64=http_source(
+            url="https://github.com/protocolbuffers/protobuf/releases/download/v24.3/protoc-24.3-linux-aarch_64.zip",
+            len=2971115,
+            sha256="77a5a41f3e9712af6a35de13143b9b2b77f075aa1ab18a63cca4483b30f6e3cd",
+            filename="protoc.zip",
+        ),
+        linux_x86_64=http_source(
+            url="https://github.com/protocolbuffers/protobuf/releases/download/v24.3/protoc-24.3-linux-x86_64.zip",
+            len=3005508,
+            sha256="fc793561283d9ea6813fb757ae54f1afea6770afcd930904bdf3e590910420aa",
+            filename="protoc.zip",
+        ),
+        macos_arm64=http_source(
+            url="https://github.com/protocolbuffers/protobuf/releases/download/v24.3/protoc-24.3-osx-aarch_64.zip",
+            len=2089053,
+            sha256="cca53adb73a6686dd60bb3b0da33961e6b9dab1f833c851b5e1bb7b5df02b36f",
+            filename="protoc.zip",
+        ),
+        macos_x86_64=http_source(
+            url="https://github.com/protocolbuffers/protobuf/releases/download/v24.3/protoc-24.3-osx-x86_64.zip",
+            len=2121387,
+            sha256="13b45cdcde9b2101e982de897d5490cfd81dfa181605749c23982379ba0e3288",
+            filename="protoc.zip",
+        ),
+    ),
+)
+
+shell_command(
+    name="protoc",
+    command="unzip protoc.zip -d protoc",
+    tools=["unzip"],
+    execution_dependencies=[":compressed-protoc"],
+    output_directories=["protoc"],
+)

src/rust/engine/BUILD

@@ -23,10 +23,11 @@ shell_command(
     execution_dependencies=[
         ":rust_sources",
         "./cargo_build_shim.sh:shell",
+        "3rdparty/tools/protoc:protoc",
         "3rdparty/tools/python3:python3",
     ],
     extra_env_vars=["CHROOT={chroot}", "MODE"],
-    tools=["bash", "cc", "ld", "as", "ar", "cargo", "protoc", "python3.9"],
+    tools=["bash", "cc", "ld", "as", "ar", "cargo", "python3.9"],
     output_files=[
         f"target/debug/libengine.so",
         f"target/debug/libengine.dylib",

src/rust/engine/cargo_build_shim.sh

@@ -6,7 +6,8 @@
 # from the rule's env and the `extra_env_vars`.
 
 PYTHON_PATH="${CHROOT}/3rdparty/tools/python3/python/bin"
-export PATH="$PATH:$PYTHON_PATH"
+PROTOC_PATH="${CHROOT}/3rdparty/tools/protoc/protoc/bin"
+export PATH="$PATH:$PYTHON_PATH:$PROTOC_PATH"
 
 RELTYPE_FLAG=""
 [ "$MODE" == "debug" ] || RELTYPE_FLAG="--release"