6 files changed, 100 insertions, 0 deletions

diff --git a/src/lib/exec.go b/src/lib/exec.go
index c832c17ff..effb46fa4 100644
--- a/src/lib/exec.go
+++ b/src/lib/exec.go
@@ -7,6 +7,7 @@ package exec
 
 import (
 	"os";
+	"strings";
 )
 
 // Arguments to Run.
@@ -183,3 +184,45 @@ func (p *Cmd) Close() *os.Error {
 	return err;
 }
 
+func canexec(file string) bool{
+	d, err := os.Stat(file);
+	if err != nil {
+		return false;
+	}
+	return d.IsRegular() && d.Permission() & 0111 != 0;
+}
+
+// LookPath searches for an executable binary named file
+// in the directories named by the PATH environment variable.
+// If file contains a slash, it is tried directly and the PATH is not consulted.
+//
+// TODO(rsc): Does LookPath belong in os instead?
+func LookPath(file string) (string, *os.Error) {
+	// NOTE(rsc): I wish we could use the Plan 9 behavior here
+	// (only bypass the path if file begins with / or ./ or ../)
+	// but that would not match all the Unix shells.
+
+	if strings.Index(file, "/") >= 0 {
+		if canexec(file) {
+			return file, nil;
+		}
+		return "", os.ENOENT;
+	}
+	pathenv, err := os.Getenv("PATH");
+	if err != nil {
+		// Unix shell semantics: no $PATH means assume PATH=""
+		// (equivalent to PATH=".").
+		pathenv = "";
+	}
+	for i, dir := range strings.Split(pathenv, ":") {
+		if dir == "" {
+			// Unix shell semantics: path element "" means "."
+			dir = ".";
+		}
+		if canexec(dir+"/"+file) {
+			return dir+"/"+file, nil;
+		}
+	}
+	return "", os.ENOENT;
+}
+
diff --git a/src/lib/flag.go b/src/lib/flag.go
index f8e31ca68..d8830c9dc 100644
--- a/src/lib/flag.go
+++ b/src/lib/flag.go
@@ -290,6 +290,11 @@ func NArg() int {
 	return len(sys.Args) - flags.first_arg
 }
 
+// Args returns the non-flag command-line arguments.
+func Args() []string {
+	return sys.Args[flags.first_arg:len(sys.Args)];
+}
+
 func add(name string, value FlagValue, usage string) {
 	// Remember the default value as a string; it won't change.
 	f := &Flag{name, usage, value, value.String()};
diff --git a/src/lib/os/file.go b/src/lib/os/file.go
index 48daf0bce..80f43bb59 100644
--- a/src/lib/os/file.go
+++ b/src/lib/os/file.go
@@ -267,3 +267,33 @@ func Chdir(dir string) *os.Error {
 	return ErrnoToError(e);
 }
 
+// Remove removes the named file or directory.
+func Remove(name string) *os.Error {
+	// System call interface forces us to know
+	// whether name is a file or directory.
+	// Try both: it is cheaper on average than
+	// doing a Stat plus the right one.
+	r, e := syscall.Unlink(name);
+	if e == 0 {
+		return nil;
+	}
+	r1, e1 := syscall.Rmdir(name);
+	if e1 == 0 {
+		return nil;
+	}
+
+	// Both failed: figure out which error to return.
+	// OS X and Linux differ on whether unlink(dir)
+	// returns EISDIR, so can't use that.  However,
+	// both agree that rmdir(file) returns ENOTDIR,
+	// so we can use that to decide which error is real.
+	// Rmdir might return ENOTDIR if given a bad
+	// file path, like /etc/passwd/foo, but in that case,
+	// both errors will be ENOTDIR, so it's okay to
+	// use the error from unlink.
+	if e1 != syscall.ENOTDIR {
+		e = e1;
+	}
+	return ErrnoToError(e1);
+}
+
diff --git a/src/lib/strings.go b/src/lib/strings.go
index 06a923427..5ce4a8dae 100644
--- a/src/lib/strings.go
+++ b/src/lib/strings.go
@@ -107,3 +107,13 @@ func Join(a []string, sep string) string {
 	}
 	return string(b)
 }
+
+// HasPrefix tests whether the string s begins with prefix.
+func HasPrefix(s, prefix string) bool {
+	return len(s) >= len(prefix) && s[0:len(prefix)] == prefix
+}
+
+// HasSuffix tests whether the string s ends with suffix.
+func HasSuffix(s, suffix string) bool {
+	return len(s) >= len(suffix) && s[len(s)-len(suffix):len(s)] == suffix
+}
diff --git a/src/lib/syscall/file_darwin.go b/src/lib/syscall/file_darwin.go
index b0777b5df..01005d207 100644
--- a/src/lib/syscall/file_darwin.go
+++ b/src/lib/syscall/file_darwin.go
@@ -78,6 +78,12 @@ func Unlink(name string) (ret int64, errno int64) {
 	return r1, err;
 }
 
+func Rmdir(name string) (ret int64, errno int64) {
+	namebuf := StringBytePtr(name);
+	r1, r2, err := Syscall(SYS_RMDIR, int64(uintptr(unsafe.Pointer(namebuf))), 0, 0);
+	return r1, err;
+}
+
 func Fcntl(fd, cmd, arg int64) (ret int64, errno int64) {
 	r1, r2, err := Syscall(SYS_FCNTL, fd, cmd, arg);
 	return r1, err
diff --git a/src/lib/syscall/file_linux.go b/src/lib/syscall/file_linux.go
index 9bf440884..80800b615 100644
--- a/src/lib/syscall/file_linux.go
+++ b/src/lib/syscall/file_linux.go
@@ -79,6 +79,12 @@ func Unlink(name string) (ret int64, errno int64) {
 	return r1, err;
 }
 
+func Rmdir(name string) (ret int64, errno int64) {
+	namebuf := StringBytePtr(name);
+	r1, r2, err := Syscall(SYS_RMDIR, int64(uintptr(unsafe.Pointer(namebuf))), 0, 0);
+	return r1, err;
+}
+
 func Fcntl(fd, cmd, arg int64) (ret int64, errno int64) {
 	r1, r2, err := Syscall(SYS_FCNTL, fd, cmd, arg);
 	return r1, err