bin: add check_go_version

License: MIT
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>

bin/check_go_version

@@ -0,0 +1,86 @@
+#!/bin/sh
+#
+# Check that the go version is at least equal to a minimum version
+# number.
+#
+# Call it for example like this:
+#
+#   $ check_go_version "1.5.2"
+#
+
+USAGE="$0 GO_MIN_VERSION"
+
+die() {
+    printf >&2 "fatal: %s\n" "$@"
+    exit 1
+}
+
+# Get arguments
+
+test "$#" -eq "1" || die "This program must be passed exactly 1 arguments" "Usage: $USAGE"
+
+GO_MIN_VERSION="$1"
+
+UPGRADE_MSG="Please take a look at https://golang.org/doc/install to install or upgrade go."
+
+die_upgrade() {
+    printf >&2 "fatal: %s\n" "$@"
+    printf >&2 "=> %s\n" "$UPGRADE_MSG"
+    exit 1
+}
+
+major_number() {
+    vers="$1"
+
+    # Hack around 'expr' exiting with code 1 when it outputs 0
+    case "$vers" in
+        0) echo "0" ;;
+        0.*) echo "0" ;;
+        *) expr "$vers" : "\([^.]*\).*" || return 1
+    esac
+}
+
+check_at_least_version() {
+    MIN_VERS="$1"
+    CUR_VERS="$2"
+    PROG_NAME="$3"
+
+    # Get major, minor and fix numbers for each version
+    MIN_MAJ=$(major_number "$MIN_VERS") || die "No major version number in '$MIN_VERS' for '$PROG_NAME'"
+    CUR_MAJ=$(major_number "$CUR_VERS") || die "No major version number in '$CUR_VERS' for '$PROG_NAME'"
+
+    if MIN_MIN=$(expr "$MIN_VERS" : "[^.]*\.\([^.]*\).*"); then
+        MIN_FIX=$(expr "$MIN_VERS" : "[^.]*\.[^.]*\.\([^.]*\).*") || MIN_FIX="0"
+    else
+        MIN_MIN="0"
+        MIN_FIX="0"
+    fi
+    if CUR_MIN=$(expr "$CUR_VERS" : "[^.]*\.\([^.]*\).*"); then
+        CUR_FIX=$(expr "$CUR_VERS" : "[^.]*\.[^.]*\.\([^.]*\).*") || CUR_FIX="0"
+    else
+        CUR_MIN="0"
+        CUR_FIX="0"
+    fi
+
+    # Compare versions
+    VERS_LEAST="$PROG_NAME version '$CUR_VERS' should be at least '$MIN_VERS'"
+    test "$CUR_MAJ" -gt $(expr "$MIN_MAJ" - 1) || die_upgrade "$VERS_LEAST"
+    test "$CUR_MAJ" -gt "$MIN_MAJ" || {
+        test "$CUR_MIN" -gt $(expr "$MIN_MIN" - 1) || die_upgrade "$VERS_LEAST"
+        test "$CUR_MIN" -gt "$MIN_MIN" || {
+            test "$CUR_FIX" -ge "$MIN_FIX" || die_upgrade "$VERS_LEAST"
+        }
+    }
+}
+
+# Check that the go binary exist and is in the path
+
+type go >/dev/null 2>&1 || die_upgrade "go is not installed or not in the PATH!"
+
+# Check the go binary version
+
+VERS_STR=$(go version 2>&1) || die "'go version' failed with output: $VERS_STR"
+
+GO_CUR_VERSION=$(expr "$VERS_STR" : ".*go version go\([^ ]*\) .*") || die "Invalid 'go version' output: $VERS_STR"
+
+check_at_least_version "$GO_MIN_VERSION" "$GO_CUR_VERSION" "go"