#!/bin/sh
set -e
USAGE=$(cat <<"EOF"
  COMMANDS

./miri install <flags>:
Installs the miri driver and cargo-miri. <flags> are passed to `cargo
install`.  Sets up the rpath such that the installed binary should work in any
working directory.

./miri build <flags>:
Just build miri.  <flags> are passed to `cargo build`.

./miri test <flags>:
Build miri, set up a sysroot and then run the test suite. <flags> are passed
to the final `cargo test` invocation.

./miri run <flags>:
Build miri, set up a sysroot and then run the driver with the given <flags>.

All commands also exist in a "-debug" variant (e.g. "./miri run-debug
<flags>") which uses debug builds instead of release builds, for faster build
times and slower execution times.

  ENVIRONMENT VARIABLES

MIRI_SYSROOT:
If already set, the "sysroot setup" step is skipped.

CARGO_EXTRA_FLAGS:
Pass extra flags to all cargo invocations.
EOF
)

## Preparation
TARGET=$(rustc --version --verbose | grep "^host:" | cut -d ' ' -f 2)
SYSROOT=$(rustc --print sysroot)
LIBDIR=$SYSROOT/lib/rustlib/$TARGET/lib
if ! test -d "$LIBDIR"; then
    echo "Something went wrong determining the library dir."
    echo "I got $LIBDIR but that does not exist."
    echo "Please report a bug at https://github.com/rust-lang/miri/issues."
    exit 2
fi
# We set the rpath so that Miri finds the private rustc libraries it needs.
# We enable debug-assertions to get tracing.
# We enable line-only debuginfo for backtraces.
export RUSTFLAGS="-C link-args=-Wl,-rpath,$LIBDIR -C debug-assertions -C debuginfo=1"

## Helper functions

# Build a sysroot and set MIRI_SYSROOT to use it.  Arguments are passed to `cargo miri setup`.
build_sysroot() {
    # Build once, for the user to see.
    cargo run $CARGO_BUILD_FLAGS --bin cargo-miri -- miri setup "$@"
    # Call again, to just set env var.
    eval $(cargo run $CARGO_BUILD_FLAGS -q --bin cargo-miri -- miri setup --env "$@")
}

# Prepare and set MIRI_SYSROOT.  Respects `MIRI_TEST_TARGET` and takes into account
# locally built vs. distributed rustc.
find_sysroot() {
    # Get ourselves a sysroot
    if [ -n "$MIRI_SYSROOT" ]; then
        # Sysroot already set, use that.
        true
    elif echo "$SYSROOT" | egrep -q 'build/[^/]+/stage'; then
        # A local rustc build.
        if [ -n "$MIRI_TEST_TARGET" ]; then
            # Foreign targets still need a build.  Use the rustc sources.
            export XARGO_RUST_SRC="$SYSROOT/../../../src"
            build_sysroot --target "$MIRI_TEST_TARGET"
        else
            # Assume we have a proper host libstd in $SYSROOT.
            MIRI_SYSROOT="$SYSROOT"
        fi
    else
        # A normal toolchain.  We have to build a sysroot either way.
        if [ -n "$MIRI_TEST_TARGET" ]; then
            build_sysroot --target "$MIRI_TEST_TARGET"
        else
            build_sysroot
        fi
    fi
    export MIRI_SYSROOT
}

## Main

# Determine command.
COMMAND="$1"
shift

# Determine flags passed to all cargo invocations.
# This is a bit more annoying that one would hope due to
# <https://github.com/rust-lang/cargo/issues/6992>.
case "$COMMAND" in
*-debug)
    CARGO_INSTALL_FLAGS="--debug $CARGO_EXTRA_FLAGS"
    CARGO_BUILD_FLAGS="$CARGO_EXTRA_FLAGS"
    ;;
*)
    CARGO_INSTALL_FLAGS="$CARGO_EXTRA_FLAGS"
    CARGO_BUILD_FLAGS="--release $CARGO_EXTRA_FLAGS"
    ;;
esac

# Run command.
case "$COMMAND" in
install|install-debug)
    # "--locked" to respect the Cargo.lock file if it exists,
    # "--offline" to avoid querying the registry (for yanked packages).
    exec cargo install $CARGO_INSTALL_FLAGS --path "$(dirname "$0")" --force --locked --offline "$@"
    ;;
build|build-debug)
    # Build, and let caller control flags.
    exec cargo build $CARGO_BUILD_FLAGS "$@"
    ;;
test|test-debug)
    # First build and get a sysroot.
    cargo build $CARGO_BUILD_FLAGS
    find_sysroot
    # Then test, and let caller control flags.
    exec cargo test $CARGO_BUILD_FLAGS "$@"
    ;;
run|run-debug)
    # Scan for "--target" to set the "MIRI_TEST_TARGET" env var so
    # that we set the MIRI_SYSROOT up the right way.
    if [ -z "$MIRI_TEST_TARGET" ]; then
        for ARG in "$@"; do
            if [ "$LAST_ARG" = "--target" ]; then
                # Found it!
                export MIRI_TEST_TARGET="$ARG"
                break
            fi
            LAST_ARG="$ARG"
        done
    fi
    # First build and get a sysroot.
    cargo build $CARGO_BUILD_FLAGS
    find_sysroot
    # Then run the actual command.
    exec cargo run $CARGO_BUILD_FLAGS -- --sysroot "$MIRI_SYSROOT" "$@"
    ;;
*)
    echo "Unknown command: $COMMAND"
    echo
    echo "$USAGE"
    exit 1
esac