feat: DTail fork — server/client feature development

Squashed development of the snonux/dtail fork's product code (internal/, cmd/)
since diverging from mimecast/dtail. Major areas:

- Read/output path: the former "turbo" channel-less path is now the single,
  default server-side read/output path for cat/grep/tail and MapReduce; the old
  channel-based path and its config/env toggles were removed.
- MapReduce: single aggregate implementation (server + serverless) fed directly
  by a processor pipeline, with input-exhausted finalization via the shutdown
  coordinator; high-concurrency and data-race fixes.
- Journal source reads (journal:unit.service) via journalctl, Linux-gated behind
  a journal-v1 capability.
- Auth-key fast reconnect: in-memory per-user public-key cache with TTL/max-keys,
  registered over an authenticated session (AUTHKEY), checked before
  authorized_keys.
- Interactive query reload (--interactive-query) with SESSION START/UPDATE
  generation boundaries and capability negotiation.
- Client-side deadlines: --timeout / --shutdownAfter as context deadlines;
  follow shutdown handling.
- Client logging: diagnostics-only daily log by default, opt-in payload tee via
  --log-payload.
- Numerous correctness fixes (buffer-pool double-recycle races, EOF-sentinel
  leaks, glob-expansion cap, TOCTOU in CSV parsing) with accompanying unit tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 15 insertions, 21 deletions

diff --git a/internal/mapr/logformat/generickv.go b/internal/mapr/logformat/generickv.go
index 9c3de92..5a0595d 100644
--- a/internal/mapr/logformat/generickv.go
+++ b/internal/mapr/logformat/generickv.go
@@ -1,15 +1,13 @@
 package logformat
 
-import (
-	"strings"
-
-	"github.com/mimecast/dtail/internal/protocol"
-)
+import "github.com/mimecast/dtail/internal/protocol"
 
 type genericKVParser struct {
 	defaultParser
 }
 
+var _ Parser = (*genericKVParser)(nil)
+
 func newGenericKVParser(hostname, timeZoneName string, timeZoneOffset int) (*genericKVParser, error) {
 	defaultParser, err := newDefaultParser(hostname, timeZoneName, timeZoneOffset)
 	if err != nil {
@@ -18,25 +16,21 @@ func newGenericKVParser(hostname, timeZoneName string, timeZoneOffset int) (*gen
 	return &genericKVParser{defaultParser: *defaultParser}, nil
 }
 
-func (p *genericKVParser) MakeFields(maprLine string) (map[string]string, error) {
-	splitted := strings.Split(maprLine, protocol.FieldDelimiter)
-	fields := make(map[string]string, len(splitted))
+func (p *genericKVParser) MakeFields(maprLine, _ string) (map[string]string, error) {
+	fields := make(map[string]string, p.fieldsCapacity)
+	p.addDefaultFields(fields, maprLine)
+	start := 0
+	delimiter := protocol.FieldDelimiter[0]
 
-	fields["*"] = "*"
-	fields["$line"] = maprLine
-	fields["$empty"] = ""
-	fields["$hostname"] = p.hostname
-	fields["$server"] = p.hostname
-	fields["$timezone"] = p.timeZoneName
-	fields["$timeoffset"] = p.timeZoneOffset
-
-	for _, kv := range splitted[0:] {
-		keyAndValue := strings.SplitN(kv, "=", 2)
-		if len(keyAndValue) != 2 {
-			//dlog.Common.Debug("Unable to parse key-value token, ignoring it", kv)
+	for {
+		token, next, done := scanDelimitedField(maprLine, start, delimiter)
+		if err := p.addKeyValueField(fields, token); err != nil {
 			continue
 		}
-		fields[keyAndValue[0]] = keyAndValue[1]
+		if done {
+			break
+		}
+		start = next
 	}
 
 	return fields, nil