config, terminal, command: Add substitute-path parameter to configuration file. (#640)

Allows to rewrite a source path stored in program's debug information,
if the sources were moved to a different place between compilation and
debugging.

config/config.go

@@ -15,9 +15,23 @@ const (
 	configFile string = "config.yml"
 )
 
+// Describes a rule for substitution of path to source code file.
+type SubstitutePathRule struct {
+	// Directory path will be substituted if it matches `From`.
+	From string
+	// Path to which substitution is performed.
+	To   string
+}
+
+// Slice of source code path substitution rules.
+type SubstitutePathRules []SubstitutePathRule
+
 // Config defines all configuration options available to be set through the config file.
 type Config struct {
-	Aliases map[string][]string
+	// Commands aliases.
+	Aliases        map[string][]string
+	// Source code path substitution rules.
+	SubstitutePath SubstitutePathRules `yaml:"substitute-path"`
 }
 
 // LoadConfig attempts to populate a Config object from the config.yml file.
@@ -89,6 +103,14 @@ func writeDefaultConfig(f *os.File) error {
 # Provided aliases will be added to the default aliases for a given command.
 aliases:
   # command: ["alias1", "alias2"]
+
+# Define sources path substitution rules. Can be used to rewrite a source path stored
+# in program's debug information, if the sources were moved to a different place
+# between compilation and debugging.
+# Note that substitution rules will not be used for paths passed to "break" and "trace"
+# commands.
+substitute-path:
+  # - {from: path, to: path}
 `)
 	return err
 }

terminal/command.go

@@ -1252,7 +1252,7 @@ func printcontextThread(t *Term, th *api.Thread) {
 }
 
 func printfile(t *Term, filename string, line int, showArrow bool) error {
-	file, err := os.Open(filename)
+	file, err := os.Open(t.substitutePath(filename))
 	if err != nil {
 		return err
 	}

terminal/terminal.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"os"
 	"os/signal"
+	"runtime"
 	"strings"
 
 	"syscall"
@@ -24,6 +25,7 @@ const (
 // Term represents the terminal running dlv.
 type Term struct {
 	client   service.Client
+	conf     *config.Config
 	prompt   string
 	line     *liner.State
 	cmds     *Commands
@@ -49,9 +51,10 @@ func New(client service.Client, conf *config.Config) *Term {
 	}
 
 	return &Term{
+		client: client,
+		conf:   conf,
 		prompt: "(dlv) ",
 		line:   liner.NewLiner(),
-		client: client,
 		cmds:   cmds,
 		dumb:   dumb,
 		stdout: w,
@@ -150,6 +153,46 @@ func (t *Term) Println(prefix, str string) {
 	fmt.Fprintf(t.stdout, "%s%s\n", prefix, str)
 }
 
+// Substitues directory to source file.
+//
+// Ensures that only directory is substitued, for example:
+// substitute from `/dir/subdir`, substitute to `/new`
+// for file path `/dir/subdir/file` will return file path `/new/file`.
+// for file path `/dir/subdir-2/file` substitution will not be applied.
+//
+// If more than one substitution rule is defined, the rules are applied
+// in the order they are defined, first rule that matches is used for
+// substitution.
+func (t *Term) substitutePath(path string) string {
+	path = crossPlatformPath(path)
+	if t.conf == nil {
+		return path
+	}
+	separator := string(os.PathSeparator)
+	for _, r := range t.conf.SubstitutePath {
+		from := crossPlatformPath(r.From)
+		to := r.To
+
+		if !strings.HasSuffix(from, separator) {
+			from = from + separator
+		}
+		if !strings.HasSuffix(to, separator) {
+			to = to + separator
+		}
+		if strings.HasPrefix(path, from) {
+			return strings.Replace(path, from, to, 1)
+		}
+	}
+	return path
+}
+
+func crossPlatformPath(path string) string {
+	if runtime.GOOS == "darwin" || runtime.GOOS == "windows" {
+		return strings.ToLower(path)
+	}
+	return path
+}
+
 func (t *Term) promptForInput() (string, error) {
 	l, err := t.line.Prompt(t.prompt)
 	if err != nil {

terminal/terminal_test.go

@@ -0,0 +1,79 @@
+package terminal
+
+import (
+	"testing"
+	"runtime"
+
+	"github.com/derekparker/delve/config"
+)
+
+type tRule struct {
+	from string
+	to string
+}
+
+type tCase struct {
+	rules []tRule
+	path  string
+	res   string
+}
+
+func platformCases() []tCase {
+	casesUnix := []tCase{
+		// Should not depend on separator at the end of rule path
+		{[]tRule{{"/tmp/path", "/new/path2"}}, "/tmp/path/file.go", "/new/path2/file.go"},
+		{[]tRule{{"/tmp/path/", "/new/path2/"}}, "/tmp/path/file.go", "/new/path2/file.go"},
+		{[]tRule{{"/tmp/path/", "/new/path2"}}, "/tmp/path/file.go", "/new/path2/file.go"},
+		{[]tRule{{"/tmp/path", "/new/path2/"}}, "/tmp/path/file.go", "/new/path2/file.go"},
+		// Should apply only for directory names
+		{[]tRule{{"/tmp/path", "/new/path2"}}, "/tmp/path-2/file.go", "/tmp/path-2/file.go"},
+		// First matched rule should be used
+		{[]tRule{
+			{"/tmp/path1", "/new/path1"},
+			{"/tmp/path2", "/new/path2"},
+			{"/tmp/path2", "/new/path3"}}, "/tmp/path2/file.go", "/new/path2/file.go"},
+	}
+	casesLinux := []tCase{
+		// Should be case-sensitive
+		{[]tRule{{"/tmp/path", "/new/path2"}}, "/TmP/path/file.go", "/TmP/path/file.go"},
+	}
+	casesDarwin := []tCase{
+		// Should be case-insensitive
+		{[]tRule{{"/tmp/path", "/new/path2"}}, "/TmP/PaTh/file.go", "/new/path2/file.go"},
+	}
+	casesWindows := []tCase{
+		// Should not depend on separator at the end of rule path
+		{[]tRule{{`c:\tmp\path`, `d:\new\path2`}}, `c:\tmp\path\file.go`, `d:\new\path2\file.go`},
+		{[]tRule{{`c:\tmp\path\`, `d:\new\path2\`}}, `c:\tmp\path\file.go`, `d:\new\path2\file.go`},
+		{[]tRule{{`c:\tmp\path`, `d:\new\path2\`}}, `c:\tmp\path\file.go`, `d:\new\path2\file.go`},
+		{[]tRule{{`c:\tmp\path\`, `d:\new\path2`}}, `c:\tmp\path\file.go`, `d:\new\path2\file.go`},
+		// Should apply only for directory names
+		{[]tRule{{`c:\tmp\path`, `d:\new\path2`}}, `c:\tmp\path-2\file.go`, `c:\tmp\path-2\file.go`},
+		// Should be case-insensitive
+		{[]tRule{{`c:\tmp\path`, `d:\new\path2`}}, `C:\TmP\PaTh\file.go`, `d:\new\path2\file.go`},
+	}
+
+	if runtime.GOOS == "windows" {
+		return casesWindows
+	}
+	if runtime.GOOS == "darwin" {
+		return append(casesUnix, casesDarwin...)
+	}
+	if runtime.GOOS == "linux" {
+		return append(casesUnix, casesLinux...)
+	}
+	return casesUnix
+}
+
+func TestSubstitutePath(t *testing.T) {
+	for _, c := range(platformCases()) {
+		var subRules config.SubstitutePathRules
+		for _, r := range(c.rules) {
+			subRules = append(subRules, config.SubstitutePathRule{From: r.from, To: r.to})
+		}
+		res := New(nil, &config.Config{SubstitutePath: subRules}).substitutePath(c.path)
+		if c.res != res {
+			t.Errorf("terminal.SubstitutePath(%q) => %q, want %q", c.path, res, c.res)
+		}
+	}
+}