configuration.go

// Copyright 2018-2022 VirtualTam.
// Use of this source code is governed by a MIT license
// that can be found in the LICENSE file.

package ccache

import (
	"bufio"
	"path/filepath"
	"strings"
	"unicode"

	"github.com/alecthomas/units"
)

// Configuration represents information about ccache configuration.
type Configuration struct {
	CacheDirectory    string            `json:"cache_directory"`
	PrimaryConfig     string            `json:"primary_config"`
	MaxCacheSize      string            `json:"max_cache_size"`
	MaxCacheSizeBytes units.MetricBytes `json:"max_cache_size_bytes"`
}

func splitConfigurationField(c rune) bool {
	return unicode.IsSpace(c) || c == '=' || c == '(' || c == ')'
}

// ParseConfiguration parses ccache configuration returned by the
// `--show-config` (ccache >= 3.7) or the `--print-config` (ccache < 3.7)
// command.
//
// See https://ccache.dev/releasenotes.html#_ccache_3_7
func ParseConfiguration(text string) (*Configuration, error) {
	reader := strings.NewReader(text)
	scanner := bufio.NewScanner(reader)

	configuration := &Configuration{}
	var err error

	for scanner.Scan() {
		// split each configuration line into 3 fields:
		//
		// (<configuration source>) <key> = <value>
		fields := strings.FieldsFunc(scanner.Text(), splitConfigurationField)
		if len(fields) < 3 {
			continue
		}

		switch fields[1] {
		case "cache_dir":
			configuration.CacheDirectory = fields[2]
			configuration.PrimaryConfig = filepath.Join(fields[2], "ccache.conf")

		case "max_size":
			var sanitizedMaxCacheSize string
			if len(fields) == 4 {
				sanitizedMaxCacheSize = fields[2] + fields[3]
			} else {
				sanitizedMaxCacheSize = fields[2]
			}

			sanitizedMaxCacheSize = strings.Replace(strings.ToUpper(sanitizedMaxCacheSize), " ", "", -1)

			if !strings.HasSuffix(sanitizedMaxCacheSize, "B") {
				sanitizedMaxCacheSize += "B"
			}

			configuration.MaxCacheSize = sanitizedMaxCacheSize
			configuration.MaxCacheSizeBytes, err = units.ParseMetricBytes(sanitizedMaxCacheSize)
			if err != nil {
				return &Configuration{}, err
			}
		}
	}

	return configuration, nil
}