[gjs/wip/package: 56/57] system: add a wrapper around exec()

[Giovanni Campagna <gcampagna src gnome org>]

commit b29591f9a9ffef90ddab16e701164762c742a4a3
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Tue May 7 23:29:32 2013 +0200

    system: add a wrapper around exec()
    
    The main use case for this is replacing the current program with
    a debugger, so that you can run "my-js-app --debug --arg" which
    becomes the equivalent of
    /usr/bin/gdb --args /usr/bin/gjs /usr/bin/my-js-app --arg
    
    In the future we might have a JS debugger too, but for now having
    a C debugger is an improvement.

 modules/system.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 48 insertions(+), 0 deletions(-)
---
diff --git a/modules/system.c b/modules/system.c
index 8ae4e62..bea7e5a 100644
--- a/modules/system.c
+++ b/modules/system.c
@@ -26,6 +26,7 @@
 
 #include <sys/types.h>
 #include <unistd.h>
+#include <glib-unix.h>
 
 #include <gjs/gjs-module.h>
 #include <gi/object.h>
@@ -119,6 +120,47 @@ gjs_exit(JSContext *context,
     return JS_TRUE;
 }
 
+static JSBool
+gjs_exec(JSContext *context,
+         unsigned   argc,
+         jsval     *vp)
+{
+    jsval *argv = JS_ARGV(cx, vp);
+    jsval v;
+    JSObject *arg_array;
+    char **c_argv;
+    unsigned i;
+    GError *error;
+
+    if (!gjs_parse_args(context, "exec", "o", argc, argv,
+                        "argv", &arg_array))
+        return JS_FALSE;
+
+    if (!JS_GetArrayLength(context, arg_array, &argc))
+        return JS_FALSE;
+
+    c_argv = g_new0(char *, argc + 1);
+
+    for (i = 0; i < argc; i++) {
+        if (!JS_GetElement(context, arg_array, i, &v))
+            goto out;
+
+        if (!gjs_string_to_utf8(context, v, &c_argv[i]))
+            goto out;
+    }
+
+    execvp(c_argv[0], c_argv);
+
+    error = g_error_new(G_UNIX_ERROR, errno,
+                        "Failed to execute new program: %s", strerror(errno));
+    gjs_throw_g_error(context, error);
+    g_error_free(error);
+
+ out:
+    g_strfreev(c_argv);
+    return JS_FALSE;
+}
+
 JSBool
 gjs_js_define_system_stuff(JSContext *context,
                            JSObject  *module)
@@ -158,6 +200,12 @@ gjs_js_define_system_stuff(JSContext *context,
                            1, GJS_MODULE_PROP_FLAGS))
         return JS_FALSE;
 
+    if (!JS_DefineFunction(context, module,
+                           "exec",
+                           (JSNative) gjs_exec,
+                           0, GJS_MODULE_PROP_FLAGS))
+        return JS_FALSE;
+
     retval = JS_FALSE;
 
     gjs_context = JS_GetContextPrivate(context);