runtime: add a simple version number parser

This will be used to parse the Linux kernel versions, but this code is
generic and can be tested on its own.

For #35777.

Change-Id: If1df48d07250e5855dde45bc9d57c66f777b9fb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/209597
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/src/runtime/string_test.go b/src/runtime/string_test.go
index a1716fa32f..80c5fa6406 100644
--- a/src/runtime/string_test.go
+++ b/src/runtime/string_test.go
@@ -454,3 +454,34 @@ func TestAtoi32(t *testing.T) {
 		}
 	}
 }
+
+type parseReleaseTest struct {
+	in                  string
+	major, minor, patch int
+}
+
+var parseReleaseTests = []parseReleaseTest{
+	{"", -1, -1, -1},
+	{"x", -1, -1, -1},
+	{"5", 5, 0, 0},
+	{"5.12", 5, 12, 0},
+	{"5.12-x", 5, 12, 0},
+	{"5.12.1", 5, 12, 1},
+	{"5.12.1-x", 5, 12, 1},
+	{"5.12.1.0", 5, 12, 1},
+	{"5.20496382327982653440", -1, -1, -1},
+}
+
+func TestParseRelease(t *testing.T) {
+	for _, test := range parseReleaseTests {
+		major, minor, patch, ok := runtime.ParseRelease(test.in)
+		if !ok {
+			major, minor, patch = -1, -1, -1
+		}
+		if test.major != major || test.minor != minor || test.patch != patch {
+			t.Errorf("parseRelease(%q) = (%v, %v, %v) want (%v, %v, %v)",
+				test.in, major, minor, patch,
+				test.major, test.minor, test.patch)
+		}
+	}
+}