Kernel, libc: Add F_GETFD, F_SETFD and FD_CLOEXEC

kernel/include/fs/FileDescriptor.h

@@ -55,6 +55,11 @@ struct Descriptor
         return m_close_on_exec;
     }
 
+    void set_close_on_exec(bool value)
+    {
+        m_close_on_exec = value;
+    }
+
     Descriptor(const Descriptor& other);
     Descriptor();
 

kernel/src/sys/stdio.cpp

@@ -29,6 +29,10 @@
 
 #define FCNTL_DUPFD 0
 #define FCNTL_ISTTY 1
+#define FCNTL_GETFD 2
+#define FCNTL_SETFD 3
+
+#define FD_CLOEXEC 1
 
 void sys_fcntl(Context* context, int fd, int command, uintptr_t arg)
 {
@@ -42,12 +46,13 @@ void sys_fcntl(Context* context, int fd, int command, uintptr_t arg)
     }
     if (command == FCNTL_DUPFD)
     {
-        if ((int)arg < 0 || (int)arg >= TASK_MAX_FDS)
+        int minfd = (int)arg;
+        if (minfd < 0 || minfd >= TASK_MAX_FDS)
         {
             context->rax = -EINVAL;
             return;
         }
-        int dupfd = current_task->alloc_fd_greater_than_or_equal((int)arg);
+        int dupfd = current_task->alloc_fd_greater_than_or_equal(minfd);
         if (dupfd < 0)
         {
             context->rax = -EMFILE;
@@ -66,6 +71,22 @@ void sys_fcntl(Context* context, int fd, int command, uintptr_t arg)
             context->rax = -ENOTTY;
         return;
     }
+    else if (command == FCNTL_GETFD)
+    {
+        int flags = 0;
+        if (file->close_on_exec()) context->rax |= FD_CLOEXEC;
+        context->rax = flags;
+        return;
+    }
+    else if (command == FCNTL_SETFD)
+    {
+        int flags = (int)arg;
+        if (flags & FD_CLOEXEC) file->set_close_on_exec(true);
+        else
+            file->set_close_on_exec(false);
+        context->rax = 0;
+        return;
+    }
     else
     {
         context->rax = -EINVAL;

libs/libc/include/fcntl.h

@@ -26,6 +26,13 @@
 #define F_DUPFD 0
 /* Is a file descriptor a TTY? */
 #define F_ISTTY 1
+/* Get the file descriptor flags. */
+#define F_GETFD 2
+/* Set the file descriptor flags. */
+#define F_SETFD 3
+
+/* Close the file descriptor on a call to execve(). */
+#define FD_CLOEXEC 1
 
 #ifdef __cplusplus
 extern "C"