pkg/email: move patch parsing from pkg/kernel

ParsePatch is used by appengine app.
Appengine apps can't depend on syscall/unsafe,
but pkg/kernel currently does.
Move patch parsing to pkg/email which does not
depend on syscall/unsafe.

1 files changed, 69 insertions, 0 deletions

diff --git a/pkg/email/patch.go b/pkg/email/patch.go
new file mode 100644
index 000000000..46a31a05d
--- /dev/null
+++ b/pkg/email/patch.go
@@ -0,0 +1,69 @@
+// Copyright 2017 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package email
+
+import (
+	"bufio"
+	"fmt"
+	"strings"
+)
+
+func ParsePatch(text string) (title string, diff string, err error) {
+	s := bufio.NewScanner(strings.NewReader(text))
+	parsingDiff := false
+	diffStarted := false
+	lastLine := ""
+	for s.Scan() {
+		ln := s.Text()
+		if strings.HasPrefix(ln, "--- a/") || strings.HasPrefix(ln, "--- /dev/null") {
+			parsingDiff = true
+			if title == "" {
+				title = lastLine
+			}
+		}
+		if parsingDiff {
+			if ln == "--" || ln == "-- " {
+				break
+			}
+			diff += ln + "\n"
+			continue
+		}
+		if strings.HasPrefix(ln, "diff --git") {
+			diffStarted = true
+			continue
+		}
+		if strings.HasPrefix(ln, "Subject: ") {
+			title = ln[len("Subject: "):]
+			continue
+		}
+		if ln == "" || title != "" || diffStarted {
+			continue
+		}
+		lastLine = ln
+		if strings.HasPrefix(ln, "    ") {
+			title = ln[4:]
+		}
+	}
+	if err = s.Err(); err != nil {
+		return
+	}
+	if strings.Contains(strings.ToLower(title), "[patch") {
+		pos := strings.IndexByte(title, ']')
+		if pos == -1 {
+			err = fmt.Errorf("title contains '[patch' but not ']'")
+			return
+		}
+		title = title[pos+1:]
+	}
+	title = strings.TrimSpace(title)
+	if title == "" {
+		err = fmt.Errorf("failed to extract title")
+		return
+	}
+	if diff == "" {
+		err = fmt.Errorf("failed to extract diff")
+		return
+	}
+	return
+}