Fix building RN Android from source on Windows. (#30535)

Summary:
Running `.\gradlew installArchives` is currently broken on Windows. This is because .sh scripts were added in the codegen module, which cannot be run by the Command Prompt on Windows. It can be worked around by installing eg. Git Bash., which can be then leveraged using the code modifications in this PR, which include sanitizing mixed Linux-Windows relative paths, and other minor Windows-specific adjustments.

It's required that the user adds a Windows Environment variable storing the path to their bash binary named `REACT_WINDOWS_BASH`.

Pair-programmed with davinci26
## Changelog

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[Android] [Fix] - Fix building React Android on Windows.

Fixes #30271

Pull Request resolved: #30535

Reviewed By: ShikaSD

Differential Revision: D25909760

Pulled By: appden

fbshipit-source-id: ea0e6e7c161a5e4a937d46e8e6972ce142fead4e

packages/react-native-codegen/android/build.gradle

@@ -5,6 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import org.apache.tools.ant.taskdefs.condition.Os
+
 buildscript {
     repositories {
         mavenLocal()
@@ -42,5 +44,23 @@ task('buildCodegenCLI', type: Exec) {
     nodeModulesDir.mkdirs();
     outputs.dirs(libDir, nodeModulesDir)
 
-    commandLine("$codegenRoot/scripts/oss/build.sh")
+    if (Os.isFamily(Os.FAMILY_WINDOWS)) {
+      // Convert path to Linux format: use canonical path to strip it off relative elements in the middle of the string.
+      // Then replace baskslashes with slashes, remove leading colon, add leading slash.
+      // Eg. D:\path1\sub2/.. -> /D/path1/path2
+      String canonicalPath = new File(codegenRoot).getCanonicalPath()
+      String linuxPath = canonicalPath.replace('\\', '/');
+      linuxPath = linuxPath.replace(':', '')
+      linuxPath = '/' + linuxPath
+
+      // Get the location of bash in the system; assume environment variable created to store it.
+      String bashHome = "$System.env.REACT_WINDOWS_BASH"
+      if (bashHome == null) {
+        throw new GradleException("REACT_WINDOWS_BASH is not defined.")
+      }
+      commandLine(bashHome, "-c", "$linuxPath/scripts/oss/build.sh")
+    }
+    else {
+        commandLine("$codegenRoot/scripts/oss/build.sh")
+    }
 }

packages/react-native-codegen/android/gradlePlugin-build/gradlePlugin/src/main/java/com/facebook/react/codegen/plugin/CodegenPlugin.java

@@ -33,6 +33,8 @@ public void apply(final Project project) {
     final File generatedSchemaFile = new File(generatedSrcDir, "schema.json");
 
     // 2. Task: produce schema from JS files.
+    String os = System.getProperty("os.name").toLowerCase();
+
     project
         .getTasks()
         .register(
@@ -62,7 +64,7 @@ public void apply(final Project project) {
 
               ImmutableList<String> execCommands =
                   new ImmutableList.Builder<String>()
-                      .add("yarn")
+                      .add(os.contains("windows") ? "yarn.cmd" : "yarn")
                       .addAll(ImmutableList.copyOf(extension.nodeExecutableAndArgs))
                       .add(extension.codegenGenerateSchemaCLI().getAbsolutePath())
                       .add(generatedSchemaFile.getAbsolutePath())
@@ -96,7 +98,7 @@ public void apply(final Project project) {
 
               ImmutableList<String> execCommands =
                   new ImmutableList.Builder<String>()
-                      .add("yarn")
+                      .add(os.contains("windows") ? "yarn.cmd" : "yarn")
                       .addAll(ImmutableList.copyOf(extension.nodeExecutableAndArgs))
                       .add(extension.codegenGenerateNativeModuleSpecsCLI().getAbsolutePath())
                       .add("android")

packages/react-native-codegen/scripts/oss/build.sh

@@ -32,12 +32,22 @@ if [[ ${FBSOURCE_ENV:-0} -eq 1 ]]; then
   "$YARN_BINARY" run build
 
   popd >/dev/null
+
 else
   # Run yarn install in a separate tmp dir to avoid conflict with the rest of the repo.
   # Note: OSS-only.
   TMP_DIR=$(mktemp -d)
 
-  cp -R "$CODEGEN_DIR/." "$TMP_DIR"
+  # On Windows this script gets run by a seprate Git Bash instance, which cannot perform the copy
+  # due to file locks created by the host process. Need to exclude .lock files while copying.
+  # Using in-memory tar operation because piping `find` and `grep` doesn't preserve folder structure
+  # during recursive copying, and `rsync` is not installed by default in Git Bash.
+  # As an added benefit, blob copy is faster.
+  if [ "$OSTYPE" = "msys" ] || [ "$OSTYPE" = "cygwin" ]; then
+    tar cf - --exclude='*.lock' "$CODEGEN_DIR" | (cd "$TMP_DIR" && tar xvf - );
+  else
+    cp -R "$CODEGEN_DIR/." "$TMP_DIR";
+  fi
 
   pushd "$TMP_DIR" >/dev/null