1 files changed, 125 insertions, 0 deletions
diff --git a/src/cmd/internal/objabi/line.go b/src/cmd/internal/objabi/line.go
new file mode 100644
index 0000000..0733b65
--- /dev/null
+++ b/src/cmd/internal/objabi/line.go
@@ -0,0 +1,125 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package objabi
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// WorkingDir returns the current working directory
+// (or "/???" if the directory cannot be identified),
+// with "/" as separator.
+func WorkingDir() string {
+	var path string
+	path, _ = os.Getwd()
+	if path == "" {
+		path = "/???"
+	}
+	return filepath.ToSlash(path)
+}
+
+// AbsFile returns the absolute filename for file in the given directory,
+// as rewritten by the rewrites argument.
+// For unrewritten paths, AbsFile rewrites a leading $GOROOT prefix to the literal "$GOROOT".
+// If the resulting path is the empty string, the result is "??".
+//
+// The rewrites argument is a ;-separated list of rewrites.
+// Each rewrite is of the form "prefix" or "prefix=>replace",
+// where prefix must match a leading sequence of path elements
+// and is either removed entirely or replaced by the replacement.
+func AbsFile(dir, file, rewrites string) string {
+	abs := file
+	if dir != "" && !filepath.IsAbs(file) {
+		abs = filepath.Join(dir, file)
+	}
+
+	abs, rewritten := ApplyRewrites(abs, rewrites)
+	if !rewritten && hasPathPrefix(abs, GOROOT) {
+		abs = "$GOROOT" + abs[len(GOROOT):]
+	}
+
+	if abs == "" {
+		abs = "??"
+	}
+	return abs
+}
+
+// ApplyRewrites returns the filename for file in the given directory,
+// as rewritten by the rewrites argument.
+//
+// The rewrites argument is a ;-separated list of rewrites.
+// Each rewrite is of the form "prefix" or "prefix=>replace",
+// where prefix must match a leading sequence of path elements
+// and is either removed entirely or replaced by the replacement.
+func ApplyRewrites(file, rewrites string) (string, bool) {
+	start := 0
+	for i := 0; i <= len(rewrites); i++ {
+		if i == len(rewrites) || rewrites[i] == ';' {
+			if new, ok := applyRewrite(file, rewrites[start:i]); ok {
+				return new, true
+			}
+			start = i + 1
+		}
+	}
+
+	return file, false
+}
+
+// applyRewrite applies the rewrite to the path,
+// returning the rewritten path and a boolean
+// indicating whether the rewrite applied at all.
+func applyRewrite(path, rewrite string) (string, bool) {
+	prefix, replace := rewrite, ""
+	if j := strings.LastIndex(rewrite, "=>"); j >= 0 {
+		prefix, replace = rewrite[:j], rewrite[j+len("=>"):]
+	}
+
+	if prefix == "" || !hasPathPrefix(path, prefix) {
+		return path, false
+	}
+	if len(path) == len(prefix) {
+		return replace, true
+	}
+	if replace == "" {
+		return path[len(prefix)+1:], true
+	}
+	return replace + path[len(prefix):], true
+}
+
+// Does s have t as a path prefix?
+// That is, does s == t or does s begin with t followed by a slash?
+// For portability, we allow ASCII case folding, so that hasPathPrefix("a/b/c", "A/B") is true.
+// Similarly, we allow slash folding, so that hasPathPrefix("a/b/c", "a\\b") is true.
+// We do not allow full Unicode case folding, for fear of causing more confusion
+// or harm than good. (For an example of the kinds of things that can go wrong,
+// see http://article.gmane.org/gmane.linux.kernel/1853266.)
+func hasPathPrefix(s string, t string) bool {
+	if len(t) > len(s) {
+		return false
+	}
+	var i int
+	for i = 0; i < len(t); i++ {
+		cs := int(s[i])
+		ct := int(t[i])
+		if 'A' <= cs && cs <= 'Z' {
+			cs += 'a' - 'A'
+		}
+		if 'A' <= ct && ct <= 'Z' {
+			ct += 'a' - 'A'
+		}
+		if cs == '\\' {
+			cs = '/'
+		}
+		if ct == '\\' {
+			ct = '/'
+		}
+		if cs != ct {
+			return false
+		}
+	}
+	return i >= len(s) || s[i] == '/' || s[i] == '\\'
+}