Update protoc build scripts.

1. Changed maven script to only do artifact uploading and removed build
script invocation from it. We didn't use maven to invoke the build
script before (we built protoc manually and editted pom.xml to only do
uploading for previous releases), and will not use it in the future (we
will use kokoro to build artifacts).
2. Cleaned up build-protoc.sh and README.md: removed the part about
using maven to build and listed supported platforms explicitly.

1 files changed, 34 insertions, 21 deletions

diff --git a/protoc-artifacts/build-protoc.sh b/protoc-artifacts/build-protoc.sh
index c50a1207..076e6b48 100755
--- a/protoc-artifacts/build-protoc.sh
+++ b/protoc-artifacts/build-protoc.sh
@@ -1,24 +1,34 @@
 #!/bin/bash
 
-# Builds protoc executable into target/protoc.exe; optionally build protoc
-# plugins into target/protoc-gen-*.exe
-# To be run from Maven.
-# Usage: build-protoc.sh <OS> <ARCH> <TARGET>
-# <OS> and <ARCH> are ${os.detected.name} and ${os.detected.arch} from os-maven-plugin
-# <TARGET> can be "protoc" or "protoc-gen-javalite"
+# Builds protoc executable into target/<OS>/<ARCH>/protoc.exe; optionally builds
+# protoc plugins into target/<OS>/<ARCH>/protoc-gen-*.exe
 #
-# The script now supports cross-compiling windows, linux-arm64, and linux-ppc64le in linux-x86
-# environment. Required packages:
-# - Windows: i686-w64-mingw32-gcc (32bit) and x86_64-w64-mingw32-gcc (64bit)
-# - Arm64: g++-aarch64-linux-gnu
-# - Ppc64le: g++-powerpc64le-linux-gcc
+# Usage: ./build-protoc.sh <OS> <ARCH> <TARGET>
+#
+# <TARGET> can be "protoc" or "protoc-gen-javalite". Supported <OS> <ARCH>
+# combinations:
+#   HOST   <OS>    <ARCH>   <COMMENT>
+#   cygwin windows x86_32   Requires: i686-w64-mingw32-gcc
+#   cygwin windows x86_64   Requires: x86_64-w64-mingw32-gcc
+#   linux  linux   aarch_64 Requires: g++-aarch64-linux-gnu
+#   linux  linux   x86_32
+#   linux  linux   x86_64
+#   linux  windows x86_32   Requires: i686-w64-mingw32-gcc
+#   linux  windows x86_64   Requires: x86_64-w64-mingw32-gcc
+#   macos  osx     x86_32
+#   macos  osx     x86_64
+#   mingw  windows x86_32
+#   mingw  windows x86_64
+#
+# Before running this script, make sure you have generated the configure script
+# in the parent directory (i.e., run ./autogen.sh there).
 
 OS=$1
 ARCH=$2
 MAKE_TARGET=$3
 
 if [[ $# < 3 ]]; then
-  echo "No arguments provided. This script is intended to be run from Maven."
+  echo "Not enough arguments provided."
   exit 1
 fi
 
@@ -166,13 +176,8 @@ checkDependencies ()
 
 echo "Building protoc, OS=$OS ARCH=$ARCH TARGET=$TARGET"
 
-# Nested double quotes are unintuitive, but it works.
-cd "$(dirname "$0")"
-
-WORKING_DIR=$(pwd)
 CONFIGURE_ARGS="--disable-shared"
 
-TARGET_FILE=target/$MAKE_TARGET.exe
 if [[ "$OS" == windows ]]; then
   MAKE_TARGET="${MAKE_TARGET}.exe"
 fi
@@ -253,10 +258,18 @@ fi
 
 export CXXFLAGS LDFLAGS
 
-cd "$WORKING_DIR"/.. && ./configure $CONFIGURE_ARGS &&
-  cd src && make clean && make $MAKE_TARGET &&
-  cd "$WORKING_DIR" && mkdir -p target &&
-  cp ../src/$MAKE_TARGET $TARGET_FILE ||
+# Nested double quotes are unintuitive, but it works.
+cd "$(dirname "$0")"
+
+WORKING_DIR="$(pwd)"
+BUILD_DIR="build/$OS/$ARCH"
+TARGET_FILE="target/$OS/$ARCH/$MAKE_TARGET.exe"
+
+mkdir -p "$BUILD_DIR" && cd "$BUILD_DIR" &&
+  ../../../../configure $CONFIGURE_ARGS &&
+  cd src && make $MAKE_TARGET -j8 &&
+  cd "$WORKING_DIR" && mkdir -p $(dirname $TARGET_FILE) &&
+  cp $BUILD_DIR/src/$MAKE_TARGET $TARGET_FILE ||
   exit 1
 
 if [[ "$OS" == osx ]]; then