build: pin the build host and the shipped ABIs

The native scripts picked an NDK host tag for macOS as well, but
ci/setup-toolchain.sh provisions nothing outside Linux x86_64 and no
pipeline exercises the other branch. Fail with the message setup already
gives instead of naming a toolchain nobody can obtain here.

The armeabi-v7a and x86 cases were never reachable either: ABIS ships
arm64-v8a and x86_64, and ci/verify-apk.sh has no machine check for the
other two, so adding one to ABIS failed the build it was meant to
enable. Record what a new ABI actually costs instead of inviting a
one-line edit that cannot work.

3 files changed, 24 insertions, 29 deletions

diff --git a/rsh/build.sh b/rsh/build.sh
index f91343a..0363553 100755
--- a/rsh/build.sh
+++ b/rsh/build.sh
@@ -27,15 +27,14 @@ if [ -z "$ndk" ] || [ ! -d "$ndk" ]; then
 	echo "rsh: Android NDK not found; set ANDROID_NDK_HOME" >&2
 	exit 1
 fi
-# NDK prebuilt toolchains are named by build host, not target. Pick the tag
-# matching this machine (macOS ships an x86_64 clang that runs under Rosetta on
-# Apple Silicon); the target ABI is selected separately below.
-case "$(uname -s)" in
-Linux)  host_tag=linux-x86_64 ;;
-Darwin) host_tag=darwin-x86_64 ;;
-*)      echo "rsh: unsupported build host $(uname -s)" >&2; exit 1 ;;
-esac
-tc="$ndk/toolchains/llvm/prebuilt/$host_tag/bin"
+# NDK prebuilt toolchains are named by build host, not target; the target ABI is
+# selected separately below. ci/setup-toolchain.sh provisions Linux x86_64 only,
+# so that is the only host tag worth naming here.
+if [ "$(uname -s)" != Linux ] || [ "$(uname -m)" != x86_64 ]; then
+	echo "rsh: only Linux x86_64 build hosts are supported" >&2
+	exit 1
+fi
+tc="$ndk/toolchains/llvm/prebuilt/linux-x86_64/bin"
 if [ ! -d "$tc" ]; then
 	echo "rsh: NDK toolchain not found at $tc" >&2
 	exit 1
@@ -56,17 +55,15 @@ cd "$root/rsh"
 
 for abi in $ABIS; do
 	case "$abi" in
-	arm64-v8a)   goarch=arm64 goarm='' cc="aarch64-linux-android${ANDROID_MIN_SDK}-clang" ;;
-	armeabi-v7a) goarch=arm   goarm=7 cc="armv7a-linux-androideabi${ANDROID_MIN_SDK}-clang" ;;
-	x86_64)      goarch=amd64 goarm='' cc="x86_64-linux-android${ANDROID_MIN_SDK}-clang" ;;
-	x86)         goarch=386   goarm='' cc="i686-linux-android${ANDROID_MIN_SDK}-clang" ;;
+	arm64-v8a) goarch=arm64 cc="aarch64-linux-android${ANDROID_MIN_SDK}-clang" ;;
+	x86_64)    goarch=amd64 cc="x86_64-linux-android${ANDROID_MIN_SDK}-clang" ;;
 	*) echo "rsh: unknown ABI $abi" >&2; exit 1 ;;
 	esac
 	dest="$root/app/src/main/jniLibs/$abi"
 	mkdir -p "$dest"
 	echo "rsh: building $abi (android/$goarch)"
 	output="$dest/libxrsh.so.part.$$"
-	CGO_ENABLED=1 GOOS=android GOARCH="$goarch" GOARM="$goarm" \
+	CGO_ENABLED=1 GOOS=android GOARCH="$goarch" \
 		CC="$tc/$cc" GOFLAGS=-trimpath \
 		CGO_CFLAGS="-fstack-protector-strong -D_FORTIFY_SOURCE=2 -ffile-prefix-map=$root=." \
 		go build -buildvcs=false -buildmode=pie -ldflags "$android_ldflags" -o "$output" .
diff --git a/rsync/build.sh b/rsync/build.sh
index 1af7fbb..ae4026a 100755
--- a/rsync/build.sh
+++ b/rsync/build.sh
@@ -23,15 +23,14 @@ if [ -z "$ndk" ] || [ ! -d "$ndk" ]; then
 	echo "rsync: Android NDK not found; set ANDROID_NDK_HOME" >&2
 	exit 1
 fi
-# NDK prebuilt toolchains are named by build host, not target. Pick the tag
-# matching this machine (macOS ships an x86_64 clang that runs under Rosetta on
-# Apple Silicon); the target ABI is selected separately below.
-case "$(uname -s)" in
-Linux)  host_tag=linux-x86_64 ;;
-Darwin) host_tag=darwin-x86_64 ;;
-*)      echo "rsync: unsupported build host $(uname -s)" >&2; exit 1 ;;
-esac
-tc="$ndk/toolchains/llvm/prebuilt/$host_tag/bin"
+# NDK prebuilt toolchains are named by build host, not target; the target ABI is
+# selected separately below. ci/setup-toolchain.sh provisions Linux x86_64 only,
+# so that is the only host tag worth naming here.
+if [ "$(uname -s)" != Linux ] || [ "$(uname -m)" != x86_64 ]; then
+	echo "rsync: only Linux x86_64 build hosts are supported" >&2
+	exit 1
+fi
+tc="$ndk/toolchains/llvm/prebuilt/linux-x86_64/bin"
 if [ ! -d "$tc" ]; then
 	echo "rsync: NDK toolchain not found at $tc" >&2
 	exit 1
@@ -71,10 +70,8 @@ echo "rsync: verifying sha256"
 
 for abi in $ABIS; do
 	case "$abi" in
-	arm64-v8a)   host=aarch64-linux-android  cc="aarch64-linux-android${ANDROID_MIN_SDK}-clang" ;;
-	armeabi-v7a) host=arm-linux-androideabi  cc="armv7a-linux-androideabi${ANDROID_MIN_SDK}-clang" ;;
-	x86_64)      host=x86_64-linux-android   cc="x86_64-linux-android${ANDROID_MIN_SDK}-clang" ;;
-	x86)         host=i686-linux-android     cc="i686-linux-android${ANDROID_MIN_SDK}-clang" ;;
+	arm64-v8a) host=aarch64-linux-android cc="aarch64-linux-android${ANDROID_MIN_SDK}-clang" ;;
+	x86_64)    host=x86_64-linux-android  cc="x86_64-linux-android${ANDROID_MIN_SDK}-clang" ;;
 	*) echo "rsync: unknown ABI $abi" >&2; exit 1 ;;
 	esac
 
diff --git a/versions b/versions
index d52e433..a2faa47 100644
--- a/versions
+++ b/versions
@@ -47,6 +47,7 @@ ANDROID_CMDLINE_TOOLS_SHA256=7ec965280a073311c339e571cd5de778b9975026cfcbe79f2b1
 GRADLE_SHA256=d725d707bfabd4dfdc958c624003b3c80accc03f7037b5122c4b1d0ef15cecab
 
 # Native ABIs to build, and to ship in the APK. arm64-v8a is every current
-# phone; x86_64 covers x86 Android devices and the emulator. Add armeabi-v7a to
-# support 32-bit phones. Keep this in step with abiFilters in app/build.gradle.
+# phone; x86_64 covers x86 Android devices and the emulator. Another ABI needs a
+# case in rsync/build.sh, rsh/build.sh, and ci/verify-apk.sh, and abiFilters in
+# app/build.gradle kept in step with this line.
 ABIS="arm64-v8a x86_64"