From 311da7c314e27cf27cd003a848b468a0964be71a Mon Sep 17 00:00:00 2001
From: aarzilli <alessandro.arzilli@gmail.com>
Date: Tue, 28 Jul 2015 21:54:40 +0200
Subject: [PATCH] bugfix: version string parsing support for beta versions and
 tolerance for devel versions

fixes issue #179
---
 proc/arch.go       |  2 +-
 proc/go_version.go | 64 ++++++++++++++++++++++++++++++++++++----------
 proc/proc_test.go  | 24 +++++++++++++++++
 3 files changed, 75 insertions(+), 15 deletions(-)

diff --git a/proc/arch.go b/proc/arch.go
index 48f15531..81a62fd2 100644
--- a/proc/arch.go
+++ b/proc/arch.go
@@ -39,7 +39,7 @@ func (a *AMD64) SetGStructOffset(ver GoVersion, isextld bool) {
 		a.gStructOffset = 0xfffffffffffffff0
 	}
 
-	if isextld || ver.After(GoVersion{1, 5, 0}) {
+	if isextld || ver.After(GoVersion{1, 5, -1, 2}) || ver.IsDevel() {
 		a.gStructOffset += 8
 	}
 }
diff --git a/proc/go_version.go b/proc/go_version.go
index f373f7f9..6aaa3ebd 100644
--- a/proc/go_version.go
+++ b/proc/go_version.go
@@ -9,28 +9,54 @@ type GoVersion struct {
 	Major int
 	Minor int
 	Rev   int
+	Beta  int
 }
 
 func parseVersionString(ver string) (GoVersion, bool) {
-	if ver[:2] != "go" {
-		return GoVersion{}, false
-	}
-	v := strings.SplitN(ver[2:], ".", 3)
-	if len(v) != 3 {
-		return GoVersion{}, false
-	}
-
 	var r GoVersion
 	var err1, err2, err3 error
 
-	r.Major, err1 = strconv.Atoi(v[0])
-	r.Minor, err2 = strconv.Atoi(v[1])
-	r.Rev, err3 = strconv.Atoi(v[2])
-	if err1 != nil || err2 != nil || err3 != nil {
-		return GoVersion{}, false
+	if strings.HasPrefix(ver, "devel") {
+		return GoVersion{-1, 0, 0, 0}, true
 	}
 
-	return r, true
+	if strings.HasPrefix(ver, "go") {
+		v := strings.SplitN(ver[2:], ".", 3)
+		switch len(v) {
+		case 2:
+			r.Major, err1 = strconv.Atoi(v[0])
+			v = strings.SplitN(v[1], "beta", 2)
+			if len(v) != 2 {
+				return GoVersion{}, false
+			}
+
+			r.Minor, err2 = strconv.Atoi(v[0])
+			r.Rev = -1
+			r.Beta, err3 = strconv.Atoi(v[1])
+
+			if err1 != nil || err2 != nil || err3 != nil {
+				return GoVersion{}, false
+			}
+
+			return r, true
+
+		case 3:
+
+			r.Major, err1 = strconv.Atoi(v[0])
+			r.Minor, err2 = strconv.Atoi(v[1])
+			r.Rev, err3 = strconv.Atoi(v[2])
+			if err1 != nil || err2 != nil || err3 != nil {
+				return GoVersion{}, false
+			}
+
+			return r, true
+
+		default:
+			return GoVersion{}, false
+		}
+	}
+
+	return GoVersion{}, false
 }
 
 func (a *GoVersion) After(b GoVersion) bool {
@@ -48,7 +74,17 @@ func (a *GoVersion) After(b GoVersion) bool {
 
 	if a.Rev < b.Rev {
 		return false
+	} else if a.Rev > b.Rev {
+		return true
+	}
+
+	if a.Beta < b.Beta {
+		return false
 	}
 
 	return true
 }
+
+func (v *GoVersion) IsDevel() bool {
+	return v.Major < 0
+}
diff --git a/proc/proc_test.go b/proc/proc_test.go
index 220822f0..840c67a7 100644
--- a/proc/proc_test.go
+++ b/proc/proc_test.go
@@ -659,3 +659,27 @@ func TestContinueMulti(t *testing.T) {
 		}
 	})
 }
+
+func versionAfter(t *testing.T, verStr string, ver GoVersion) {
+	pver, ok := parseVersionString(verStr)
+	if !ok {
+		t.Fatalf("Could not parse version string <%s>", verStr)
+	}
+	if !pver.After(ver) {
+		t.Fatalf("Version <%s> parsed as %v not after %v", verStr, pver, ver)
+	}
+	t.Logf("version string <%s> → %v", verStr, ver)
+}
+
+func TestParseVersionString(t *testing.T) {
+	versionAfter(t, "go1.5.0", GoVersion{1, 5, 0, 0})
+	versionAfter(t, "go1.4.2", GoVersion{1, 4, 2, 0})
+	versionAfter(t, "go1.5beta2", GoVersion{1, 5, -1, 2})
+	ver, ok := parseVersionString("devel +17efbfc Tue Jul 28 17:39:19 2015 +0000 linux/amd64")
+	if !ok {
+		t.Fatalf("Could not parse devel version string")
+	}
+	if !ver.IsDevel() {
+		t.Fatalf("Devel version string not correctly recognized")
+	}
+}