1 files changed, 163 insertions, 0 deletions
diff --git a/libpod/logs/log.go b/libpod/logs/log.go
new file mode 100644
index 000000000..488291cfe
--- /dev/null
+++ b/libpod/logs/log.go
@@ -0,0 +1,163 @@
+package logs
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/hpcloud/tail"
+	"github.com/pkg/errors"
+)
+
+const (
+	// LogTimeFormat is the time format used in the log.
+	// It is a modified version of RFC3339Nano that guarantees trailing
+	// zeroes are not trimmed, taken from
+	// https://github.com/golang/go/issues/19635
+	LogTimeFormat = "2006-01-02T15:04:05.000000000Z07:00"
+
+	// PartialLogType signifies a log line that exceeded the buffer
+	// length and needed to spill into a new line
+	PartialLogType = "P"
+
+	// FullLogType signifies a log line is full
+	FullLogType = "F"
+)
+
+// LogOptions is the options you can use for logs
+type LogOptions struct {
+	Details    bool
+	Follow     bool
+	Since      time.Time
+	Tail       uint64
+	Timestamps bool
+	Multi      bool
+	WaitGroup  *sync.WaitGroup
+}
+
+// LogLine describes the information for each line of a log
+type LogLine struct {
+	Device       string
+	ParseLogType string
+	Time         time.Time
+	Msg          string
+	CID          string
+}
+
+// GetLogFile returns an hp tail for a container given options
+func GetLogFile(path string, options *LogOptions) (*tail.Tail, []*LogLine, error) {
+	var (
+		whence  int
+		err     error
+		logTail []*LogLine
+	)
+	// whence 0=origin, 2=end
+	if options.Tail > 0 {
+		whence = 2
+		logTail, err = getTailLog(path, int(options.Tail))
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+	seek := tail.SeekInfo{
+		Offset: 0,
+		Whence: whence,
+	}
+
+	t, err := tail.TailFile(path, tail.Config{MustExist: true, Poll: true, Follow: options.Follow, Location: &seek, Logger: tail.DiscardingLogger})
+	return t, logTail, err
+}
+
+func getTailLog(path string, tail int) ([]*LogLine, error) {
+	var (
+		tailLog     []*LogLine
+		nlls        []*LogLine
+		tailCounter int
+		partial     string
+	)
+	content, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	splitContent := strings.Split(string(content), "\n")
+	// We read the content in reverse and add each nll until we have the same
+	// number of F type messages as the desired tail
+	for i := len(splitContent) - 1; i >= 0; i-- {
+		if len(splitContent[i]) == 0 {
+			continue
+		}
+		nll, err := NewLogLine(splitContent[i])
+		if err != nil {
+			return nil, err
+		}
+		nlls = append(nlls, nll)
+		if !nll.Partial() {
+			tailCounter = tailCounter + 1
+		}
+		if tailCounter == tail {
+			break
+		}
+	}
+	// Now we iterate the results and assemble partial messages to become full messages
+	for _, nll := range nlls {
+		if nll.Partial() {
+			partial = partial + nll.Msg
+		} else {
+			nll.Msg = nll.Msg + partial
+			tailLog = append(tailLog, nll)
+			partial = ""
+		}
+	}
+	return tailLog, nil
+}
+
+// String converts a logline to a string for output given whether a detail
+// bool is specified.
+func (l *LogLine) String(options *LogOptions) string {
+	var out string
+	if options.Multi {
+		cid := l.CID
+		if len(cid) > 12 {
+			cid = cid[:12]
+		}
+		out = fmt.Sprintf("%s ", cid)
+	}
+	if options.Timestamps {
+		out = out + fmt.Sprintf("%s ", l.Time.Format(LogTimeFormat))
+	}
+	return out + l.Msg
+}
+
+// Since returns a bool as to whether a log line occurred after a given time
+func (l *LogLine) Since(since time.Time) bool {
+	return l.Time.After(since)
+}
+
+// NewLogLine creates a logLine struct from a container log string
+func NewLogLine(line string) (*LogLine, error) {
+	splitLine := strings.Split(line, " ")
+	if len(splitLine) < 4 {
+		return nil, errors.Errorf("'%s' is not a valid container log line", line)
+	}
+	logTime, err := time.Parse(LogTimeFormat, splitLine[0])
+	if err != nil {
+		return nil, errors.Wrapf(err, "unable to convert time %s from container log", splitLine[0])
+	}
+	l := LogLine{
+		Time:         logTime,
+		Device:       splitLine[1],
+		ParseLogType: splitLine[2],
+		Msg:          strings.Join(splitLine[3:], " "),
+	}
+	return &l, nil
+}
+
+// Partial returns a bool if the log line is a partial log type
+func (l *LogLine) Partial() bool {
+	if l.ParseLogType == PartialLogType {
+		return true
+	}
+	return false
+}