Add os.chdir and os.setenv to d8. Move system() to os.system().

Protect os.chdir, os.setenv, os.system against string conversion
failures.  Add comment about the issue to include/v8.h.
Review URL: http://codereview.chromium.org/57005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1644 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -883,7 +883,10 @@ class V8EXPORT String : public Primitive {
 
   /**
    * Converts an object to a utf8-encoded character array.  Useful if
-   * you want to print the object.
+   * you want to print the object.  If conversion to a string fails
+   * (eg. due to an exception in the toString() method of the object)
+   * then the length() method returns 0 and the * operator returns
+   * NULL.
    */
   class V8EXPORT Utf8Value {
    public:
@@ -903,6 +906,9 @@ class V8EXPORT String : public Primitive {
   /**
    * Converts an object to an ascii string.
    * Useful if you want to print the object.
+   * If conversion to a string fails (eg. due to an exception in the toString()
+   * method of the object) then the length() method returns 0 and the * operator
+   * returns NULL.
    */
   class V8EXPORT AsciiValue {
    public:
@@ -921,6 +927,9 @@ class V8EXPORT String : public Primitive {
 
   /**
    * Converts an object to a two-byte string.
+   * If conversion to a string fails (eg. due to an exception in the toString()
+   * method of the object) then the length() method returns 0 and the * operator
+   * returns NULL.
    */
   class V8EXPORT Value {
    public:

src/d8-posix.cc

@@ -184,9 +184,18 @@ class OpenFDCloser {
 // scope.
 class ExecArgs {
  public:
-  ExecArgs(Handle<Value> arg0, Handle<Array> command_args) {
+  ExecArgs() {
+    exec_args_[0] = NULL;
+  }
+  bool Init(Handle<Value> arg0, Handle<Array> command_args) {
     String::Utf8Value prog(arg0);
-    int len = prog.length() + 1;
+    if (*prog == NULL) {
+      const char* message =
+          "os.system(): String conversion of program name failed";
+      ThrowException(String::New(message));
+      return false;
+    }
+    int len = prog.length() + 3;
     char* c_arg = new char[len];
     snprintf(c_arg, len, "%s", *prog);
     exec_args_[0] = c_arg;
@@ -194,12 +203,20 @@ class ExecArgs {
     for (unsigned j = 0; j < command_args->Length(); i++, j++) {
       Handle<Value> arg(command_args->Get(Integer::New(j)));
       String::Utf8Value utf8_arg(arg);
+      if (*utf8_arg == NULL) {
+        exec_args_[i] = NULL;  // Consistent state for destructor.
+        const char* message =
+            "os.system(): String conversion of argument failed.";
+        ThrowException(String::New(message));
+        return false;
+      }
       int len = utf8_arg.length() + 1;
       char* c_arg = new char[len];
       snprintf(c_arg, len, "%s", *utf8_arg);
       exec_args_[i] = c_arg;
     }
     exec_args_[i] = NULL;
+    return true;
   }
   ~ExecArgs() {
     for (unsigned i = 0; i < kMaxArgs; i++) {
@@ -454,7 +471,10 @@ Handle<Value> Shell::System(const Arguments& args) {
   struct timeval start_time;
   gettimeofday(&start_time, NULL);
 
-  ExecArgs exec_args(args[0], command_args);
+  ExecArgs exec_args;
+  if (!exec_args.Init(args[0], command_args)) {
+    return v8::Undefined();
+  }
   int exec_error_fds[2];
   int stdout_fds[2];
 
@@ -501,4 +521,21 @@ Handle<Value> Shell::System(const Arguments& args) {
 }
 
 
+Handle<Value> Shell::ChangeDirectory(const Arguments& args) {
+  if (args.Length() != 1) {
+    const char* message = "chdir() takes one argument";
+    return ThrowException(String::New(message));
+  }
+  String::Utf8Value directory(args[0]);
+  if (*directory == NULL) {
+    const char* message = "os.chdir(): String conversion of argument failed.";
+    return ThrowException(String::New(message));
+  }
+  if (chdir(*directory) != 0) {
+    return ThrowException(String::New(strerror(errno)));
+  }
+  return v8::Undefined();
+}
+
+
 }  // namespace v8

src/d8-windows.cc

@@ -42,4 +42,11 @@ Handle<Value> Shell::System(const Arguments& args) {
 }
 
 
+Handle<Value> Shell::ChangeDirectory(const Arguments& args) {
+  Handle<String> error_message =
+      String::New("chdir() is not yet supported on your OS");
+  return ThrowException(error_message);
+}
+
+
 }  // namespace v8

src/d8.cc

@@ -163,6 +163,28 @@ Handle<Value> Shell::Print(const Arguments& args) {
 }
 
 
+Handle<Value> Shell::SetEnvironment(const Arguments& args) {
+  if (args.Length() != 2) {
+    const char* message = "setenv() takes two arguments";
+    return ThrowException(String::New(message));
+  }
+  String::Utf8Value var(args[0]);
+  String::Utf8Value value(args[1]);
+  if (*var == NULL) {
+    const char* message =
+        "os.setenv(): String conversion of variable name failed.";
+    return ThrowException(String::New(message));
+  }
+  if (*value == NULL) {
+    const char* message =
+        "os.setenv(): String conversion of variable contents failed.";
+    return ThrowException(String::New(message));
+  }
+  setenv(*var, *value, 1);
+  return v8::Undefined();
+}
+
+
 Handle<Value> Shell::Load(const Arguments& args) {
   for (int i = 0; i < args.Length(); i++) {
     HandleScope handle_scope;
@@ -342,7 +364,12 @@ void Shell::Initialize() {
   global_template->Set(String::New("load"), FunctionTemplate::New(Load));
   global_template->Set(String::New("quit"), FunctionTemplate::New(Quit));
   global_template->Set(String::New("version"), FunctionTemplate::New(Version));
-  global_template->Set(String::New("system"), FunctionTemplate::New(System));
+
+  Handle<ObjectTemplate> os_templ = ObjectTemplate::New();
+  os_templ->Set(String::New("system"), FunctionTemplate::New(System));
+  os_templ->Set(String::New("chdir"), FunctionTemplate::New(ChangeDirectory));
+  os_templ->Set(String::New("setenv"), FunctionTemplate::New(SetEnvironment));
+  global_template->Set(String::New("os"), os_templ);
 
   utility_context_ = Context::New(NULL, global_template);
   utility_context_->SetSecurityToken(Undefined());

src/d8.h

@@ -130,9 +130,12 @@ class Shell: public i::AllStatic {
   static Handle<Value> Quit(const Arguments& args);
   static Handle<Value> Version(const Arguments& args);
   static Handle<Value> Load(const Arguments& args);
-  // system("program_name", ["arg1", "arg2", ...], timeout1, timeout2) will run
-  // the command, passing the arguments to the program.  The standard output of
-  // the program will be picked up and returned as a multiline string.  If
+  // The OS object on the global object contains methods for performing
+  // operating system calls:
+  //
+  // os.system("program_name", ["arg1", "arg2", ...], timeout1, timeout2) will
+  // run the command, passing the arguments to the program.  The standard output
+  // of the program will be picked up and returned as a multiline string.  If
   // timeout1 is present then it should be a number.  -1 indicates no timeout
   // and a positive number is used as a timeout in milliseconds that limits the
   // time spent waiting between receiving output characters from the program.
@@ -140,7 +143,16 @@ class Shell: public i::AllStatic {
   // milliseconds on the total running time of the program.  Exceptions are
   // thrown on timeouts or other errors or if the exit status of the program
   // indicates an error.
+  //
+  // os.chdir(dir) changes directory to the given directory.  Throws an
+  // exception/ on error.
+  //
+  // os.setenv(variable, value) sets an environment variable.  Repeated calls to
+  // this method leak memory due to the API of setenv in the standard C library.
+  static Handle<Value> OSObject(const Arguments& args);
   static Handle<Value> System(const Arguments& args);
+  static Handle<Value> ChangeDirectory(const Arguments& args);
+  static Handle<Value> SetEnvironment(const Arguments& args);
 
   static Handle<Context> utility_context() { return utility_context_; }