SUSE/saptune

package note

import (
    "fmt"
    "github.com/SUSE/saptune/system"
    "io/ioutil"
    "os"
    "path"
    "regexp"
    "strings"
)

// section [login]

// GetLoginVal initialise the systemd login structure with the current
// system settings
func GetLoginVal(key string) (string, error) {
    var val string
    var utmPat = regexp.MustCompile(`UserTasksMax=(.*)`)
    switch key {
    case "UserTasksMax":
        logindContent, err := ioutil.ReadFile(path.Join(LogindConfDir, LogindSAPConfFile))
        if err != nil && !os.IsNotExist(err) {
            return "", err
        }
        system.DebugLog("GetLoginVal - UserTasksMax: content of file '%s' is '%s' - error is '%v'", LogindSAPConfFile, string(logindContent), err)
        matches := utmPat.FindStringSubmatch(string(logindContent))
        if len(matches) != 0 {
            val = matches[1]
        } else {
            val = "NA"
        }
    }
    return val, nil
}

// OptLoginVal returns the value from the configuration file
func OptLoginVal(cfgval string) string {
    return strings.ToLower(cfgval)
}

// SetLoginVal applies the settings to the system
func SetLoginVal(key, value string, revert bool) error {
    switch key {
    case "UserTasksMax":
        system.DebugLog("SetLoginVal - key is '%s', value is '%s', revert is '%v'\n", key, value, revert)
        // because of systemd problems during shutting down a node,
        // I need to change the code blocks to get UserTasksMax working
        // properly after a Reboot. To prevent left-over drop-in file
        // which will cause a wrong 'saved_state' value for UserTasksMax
        // which will result in a wrong system value after a revert of
        // a Note containing UserTasksMax setting
        //
        // So first handle drop-in file during revert
        // then set limit per active user
        //
        // Because of the changed order we need 'exitEarly', because
        // in case of removing the drop-in file we do not need to
        // execute the rest of the code

        exitEarly := false
        // handle drop-in file during revert
        if revert && IsLastNoteOfParameter(key) {
            system.DebugLog("SetLoginVal - UserTasksMax: remove drop-in file")
            exitEarly = true
            // revert - remove logind drop-in file
            os.Remove(path.Join(LogindConfDir, LogindSAPConfFile))
            // reload-or-try-restart systemd-logind.service
            if err := system.SystemctlReloadTryRestart("systemd-logind.service"); err != nil {
                return err
            }
        }
        // set limit per active user (for both - revert and apply)
        if value != "" && value != "NA" {
            for _, userID := range system.GetCurrentLogins() {
                system.DebugLog("userID is '%v'\n", userID)
                if err := system.SetTasksMax(userID, value); err != nil {
                    system.DebugLog("error is '%v'\n", err)
                    return err
                }
            }
        }
        if exitEarly {
            // we are in 'revert' and it's the last Note handling
            // UserTasksMax setting
            // so exit now
            return nil
        }

        if value != "" && value != "NA" {
            // revert with value from another former applied note
            // or
            // apply - Prepare logind drop-in file
            // LogindSAPConfContent is the verbatim content of
            // SAP-specific logind settings file.
            LogindSAPConfContent := fmt.Sprintf("[Login]\nUserTasksMax=%s\n", value)
            if err := os.MkdirAll(LogindConfDir, 0755); err != nil {
                return err
            }
            if err := ioutil.WriteFile(path.Join(LogindConfDir, LogindSAPConfFile), []byte(LogindSAPConfContent), 0644); err != nil {
                return err
            }
            // reload-or-try-restart systemd-logind.service
            if err := system.SystemctlReloadTryRestart("systemd-logind.service"); err != nil {
                return err
            }
            if value == "infinity" {
                system.InfoLog("Be aware: system-wide UserTasksMax is now set to infinity according to SAP recommendations.\n" +
                    "This opens up entire system to fork-bomb style attacks.")
            }
        }
    }
    return nil
}