run-rust

#!/bin/sh

# ———  Config  ———

# If it exists, this script is executed first. Config variables can be set there.
if [ -f "$HOME/.config/run-rust" ]
then
    source "$HOME/.config/run-rust"
fi

# Directory where Rust should be installed; this should be user-writable if you
# want to install/update rust easily, e.g. "$HOME/.local/share/rust".
if [ -z "$RUST_INST" ]; then
    RUST_INST="$HOME/.local/share/rust"
fi

# Platform thing
if [ -z "$PLATFORM" ]; then
    PLATFORM="x86_64-unknown-linux-gnu"
fi

# ———  Instructions  ———

# 1. Put this script somewhere in your PATH, e.g. ~/.bin or ~/.local/bin
# (Note: it must be called run-rust, because a switch below checks if this is the name.)
# 
# 2. In the same directory, create sym-links to it for each rust binary you want:
#   for name in rustc rustdoc rust-gdb rust-lldb cargo; do ln -s run-rust $name; done
#   
# 3. Check usage and install rust:
#   run-rust
#   run-rust install nightly
# 
# 4. Run cargo/rustc/...
#   rustc --version
#   cargo new my_project
#   
# 5. Temporarily use a different installed rust version via environment variable:
#   export RUST_VER=1.14.0
#   rustc --version
# or:
#   RUST_VER=nightly rustc --version


# ———  Script functions  ———

usage() {
    echo "run-rust 2.0-rc1

To manage installs:

    run-rust install VER [DATE]
VER should look like 1.14.0 or beta or nightly (you may have to look up the
latest stable version).
If a DATE (e.g. 2017-01-16) is given, download from the archives for this date
(e.g. run-rust install nightly 2017-01-16).

    run-rust list
Shows installed versions.

    run-rust set VER [NICK]
Set a rust version VER to be the default, or give it nickname NICK.
Rust rust-VER should be installed.

To delete installed versions, manually delete from $RUST_INST .

To select a (non-default) rust version, set the environment variable RUST_VER:
    export RUST_VER=nightly
    rustc --version
or:
    RUST_VER=nightly rustc --version
    
    run-rust run CMD ARGS
To run the rust binary CMD.

    CMD ARGS
To run CMD (assuming a symlink exists in your path with the name CMD but
pointing to this script)."
}

list() {
    if [ ! -e "$RUST_INST" ]; then
        echo "No installation directory. Maybe run install first?" >&2
        exit 1
    fi
    
    echo "Rust installations found in $RUST_INST :"
    cd "$RUST_INST" && ls rust-*
    echo "(You can omit rust- prefix when setting RUST_VER.)"
}

install() {
    mkdir -p "$RUST_INST" || exit 1
    if [ $# -eq 0 ]; then
        echo "Which version? E.g. 1.14.0 or nightly" >&2
        exit 1
    elif [ $# -eq 1 ]; then
        VER="$1"
        DATE=""
        DEST="$RUST_INST/rust-$VER"
    elif [ $# -eq 2 ]; then
        VER="$1"
        DATE="$2"
        DEST="$RUST_INST/rust-$DATE-$VER"
    else
        echo "Too many args: $@" >&2
    fi
    
    NAME="rust-$VER-$PLATFORM"
    # Both .tar.gz and .tar.xz are supported:
    FILENAME="$NAME.tar.xz"
    if [ -z "$DATE" ]; then
        SOURCE="https://static.rust-lang.org/dist/$FILENAME"
    else
        SOURCE="https://static.rust-lang.org/dist/$DATE/$FILENAME"
    fi
    
    TMP=$(mktemp -d)
    cd "$TMP" || exit 1
    echo "Downloading: $SOURCE.sha256"
    curl -O "$SOURCE.sha256" || exit 1
    SHA="$FILENAME.sha256"
    
    if [ -e "$DEST" ]; then
        if [ -f "$DEST/$SHA" ]
        then
            if diff -q "$DEST/$SHA" "$SHA"
            then
                echo "Already up to date"
                exit 0
            else
                echo "Removing outdated installation"
                rm -rf "$DEST"
            fi
        else
            echo "Error: directory used; not upgradeable: $DEST" >&2
            exit 1
        fi
    fi
    
    echo "Downloading: $SOURCE"
    curl -O "$SOURCE" || exit 1
    shasum -a 256 -c "$SHA" || exit 1
    tar xaf "$FILENAME" || exit 1
    "$NAME/install.sh" "--prefix=$DEST" || exit 1
    mv "$SHA" "$DEST/$SHA"
    cd -
    rm -rf "$TMP"
    echo "Installed: $DEST"
    
    if [ ! -e "$RUST_INST/rust-default" ]; then
        setlink "$VER"
        echo "Set as default"
    fi
}

setlink() {
    if [ ! -e "$RUST_INST" ]; then
        echo "No installation directory. Maybe run install first?" >&2
        exit 1
    fi
    
    if [ $# -eq 0 ]; then
        echo "Set what version as default (or give what version a nickname)?" >&2
        exit 1
    elif [ $# -eq 1 ]; then
        VER="$1"
        NICK="default"
    elif [ $# -eq 2 ]; then
        VER="$1"
        NICK="$2"
    else
        echo "Too many args: $@" >&2
    fi
    
    TARG="rust-$VER"
    LINK="$RUST_INST/rust-$NICK"
    if [ -e "$LINK" ]; then
        if [ -h "$LINK" ]; then
            # consider links safe to delete
            rm "$LINK"
        else
            echo "Already exists: $LINK" >&2
            exit 1
        fi
    fi
    ln -s "$TARG" "$LINK"
}

run() {
    if [ -z "$RUST_VER" ]
    then
        # there should be a symlink with this name:
        RUST_VER=default
    fi
    RUST_HOME="$RUST_INST/rust-$RUST_VER"
    
    # Sanity check
    if [ ! -e "$RUST_INST" ]; then
        echo "No installation directory. Maybe run install first?" >&2
        exit 1
    elif [ ! -e "$RUST_HOME" ]
    then
        echo "run-rust: not found: $RUST_HOME" >&2
        echo "run-rust: did you install?" >&2
        if [ "$RUST_VER" != "default" ]
        then
            echo "run-rust: did you set the wrong RUST_VER?" >&2
        fi
        exit 1
    elif [ ! -x "$RUST_HOME/bin/rustc" ]
    then
        echo "run-rust: not found: $RUST_HOME/bin/rustc" >&2
        echo "run-rust: bad installation?" >&2
        exit 1
    elif [ ! -x "$RUST_HOME/bin/$BIN" ]; then
        echo "run-rust: could not find binary: $RUST_HOME/bin/$BIN" >&2
        echo "run-rust: binaries available:" >&2
        ls "$RUST_HOME/bin" >&2
        exit 1
    fi

    export PATH="$PATH:$RUST_HOME/bin"
    export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$RUST_HOME/lib"

    "$RUST_HOME/bin/$BIN" "$@"
}


# ———  script entrypoint  ———

BIN=$(basename $0)

if [ "$BIN" == "run-rust" ]
then
    # management / general help
    if [ $# -eq 0 ]; then
        usage
    fi
    CMD="$1"
    shift
    case "$CMD" in
        list)
        list
        ;;
        install)
        install "$@"
        ;;
        run)
        if [ $# -eq 0 ]; then
            echo "Run what?" >&2
            exit 1
        fi
        BIN="$1"
        shift
        run "$@"
        ;;
        set)
        setlink "$@"
        ;;
        help)
        usage
        ;;
        *)
        echo "run-rust: unknown command $CMD" >&2
        usage
        exit 1
        ;;
    esac
else
    # assume user wanted to run a rust binary
    run "$@"
fi