[#251] Change p4 -d default directory from p4 rootDir to TCR base dir…

… for p4 diff and reconcile

src/vcs/p4/p4_impl.go

@@ -151,7 +151,7 @@ func (p *p4Impl) Add(paths ...string) error {
 	} else {
 		p4Args = append(p4Args, paths...)
 	}
-	return p.traceP4(p4Args...)
+	return p.traceP4FromBaseDir(p4Args...)
 }
 
 type changeList struct {
@@ -213,7 +213,7 @@ func (*p4Impl) UnStash(_ bool) error {
 // Diff returns the list of files modified since last commit with diff info for each file
 func (p *p4Impl) Diff() (diffs vcs.FileDiffs, err error) {
 	var p4Output []byte
-	p4Output, err = p.runP4("diff", "-f", "-Od", "-dw", "-ds")
+	p4Output, err = p.runP4FromBaseDir("diff", "-f", "-Od", "-dw", "-ds")
 	if err != nil {
 		return nil, err
 	}
@@ -275,12 +275,24 @@ func (p *p4Impl) traceP4(args ...string) error {
 	return p.traceP4Function(p.buildP4Args(args...)...)
 }
 
+// traceP4 runs a p4 command and traces its output.
+// The command is launched from the p4 root directory
+func (p *p4Impl) traceP4FromBaseDir(args ...string) error {
+	return p.traceP4Function(p.buildP4ArgsWithBaseDir(args...)...)
+}
+
 // runP4 calls p4 command in a separate process and returns its output traces
 // The command is launched from the p4 root directory
 func (p *p4Impl) runP4(args ...string) (output []byte, err error) {
 	return p.runP4Function(p.buildP4Args(args...)...)
 }
 
+// runP4 calls p4 command in a separate process and returns its output traces
+// The command is launched from the p4 root directory
+func (p *p4Impl) runP4FromBaseDir(args ...string) (output []byte, err error) {
+	return p.runP4Function(p.buildP4ArgsWithBaseDir(args...)...)
+}
+
 func (p *p4Impl) runPipedP4(toCmd shell.Command, args ...string) (output []byte, err error) {
 	return p.runPipedP4Function(toCmd, p.buildP4Args(args...)...)
 }
@@ -289,6 +301,10 @@ func (p *p4Impl) buildP4Args(args ...string) []string {
 	return append([]string{"-d", p.GetRootDir(), "-c", p.clientName}, args...)
 }
 
+func (p *p4Impl) buildP4ArgsWithBaseDir(args ...string) []string {
+	return append([]string{"-d", p.baseDir, "-c", p.clientName}, args...)
+}
+
 func (p *p4Impl) createChangeList(messages ...string) (*changeList, error) {
 	// Command: p4 --field "Description=<message>" change -o | p4 change -i
 	out, err := p.runPipedP4(newP4Command(p.buildP4Args("change", "-i")...),