From 8d41fd0d7f211309fc5a231e06b8d6c627608c59 Mon Sep 17 00:00:00 2001
From: Kir Kolyshkin <kolyshkin@gmail.com>
Date: Thu, 14 Apr 2022 12:19:39 -0700
Subject: [PATCH] libct/cg/sd: stop using regex, fix systemdVersionAtoi

Rewrite systemdVersionAtoi to not use regexp, and fix two issues:

1. It was returning 0 (rather than -1) for some errors.

2. The comment was saying that the input string is without quotes,
   while in fact it is.

Note the new function, similar to the old one, works on input either
with or without quotes. Amend the test to add test cases without quotes.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
---
 libcontainer/cgroups/systemd/common.go       | 22 +++++++++++---------
 libcontainer/cgroups/systemd/systemd_test.go |  7 +++++--
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/libcontainer/cgroups/systemd/common.go b/libcontainer/cgroups/systemd/common.go
index 0c3562e6bfe..65d28cb85a3 100644
--- a/libcontainer/cgroups/systemd/common.go
+++ b/libcontainer/cgroups/systemd/common.go
@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"math"
 	"os"
-	"regexp"
 	"strconv"
 	"strings"
 	"sync"
@@ -231,18 +230,21 @@ func systemdVersion(cm *dbusConnManager) int {
 	return version
 }
 
-func systemdVersionAtoi(verStr string) (int, error) {
-	// verStr should be of the form:
-	// "v245.4-1.fc32", "245", "v245-1.fc32", "245-1.fc32" (without quotes).
+func systemdVersionAtoi(str string) (int, error) {
+	// str should be of the form:
+	// "v245.4-1.fc32", "245", "v245-1.fc32", "245-1.fc32" (with quotes).
 	// The result for all of the above should be 245.
-	// Thus, we unconditionally remove the "v" prefix
+	// Thus, we unconditionally remove the "v prefix
 	// and then match on the first integer we can grab.
-	re := regexp.MustCompile(`v?([0-9]+)`)
-	matches := re.FindStringSubmatch(verStr)
-	if len(matches) < 2 {
-		return 0, fmt.Errorf("can't parse version %s: incorrect number of matches %v", verStr, matches)
+	str = strings.TrimLeft(str, `"v`)
+	for i := 0; i < len(str); i++ {
+		if str[i] < '0' || str[i] > '9' {
+			// First non-digit.
+			str = str[:i]
+			break
+		}
 	}
-	ver, err := strconv.Atoi(matches[1])
+	ver, err := strconv.Atoi(str)
 	if err != nil {
 		return -1, fmt.Errorf("can't parse version: %w", err)
 	}
diff --git a/libcontainer/cgroups/systemd/systemd_test.go b/libcontainer/cgroups/systemd/systemd_test.go
index d280a3090aa..40584f78eba 100644
--- a/libcontainer/cgroups/systemd/systemd_test.go
+++ b/libcontainer/cgroups/systemd/systemd_test.go
@@ -35,8 +35,11 @@ func TestSystemdVersion(t *testing.T) {
 		{`"v245.4-1.fc32"`, 245, false},
 		{`"241-1"`, 241, false},
 		{`"v241-1"`, 241, false},
-		{"NaN", 0, true},
-		{"", 0, true},
+		{`333.45"`, 333, false},
+		{`v321-0`, 321, false},
+		{"NaN", -1, true},
+		{"", -1, true},
+		{"v", -1, true},
 	}
 	for _, sdTest := range systemdVersionTests {
 		ver, err := systemdVersionAtoi(sdTest.verStr)