Kernel+LibC+LibCore+UE: Implement `fchmodat(2)`

This function is an extended version of `chmod(2)` that lets one control
whether to dereference symlinks, and specify a file descriptor to a
directory that will be used as the base for relative paths.

2 files changed, 10 insertions, 5 deletions

diff --git a/Userland/DevTools/UserspaceEmulator/Emulator.h b/Userland/DevTools/UserspaceEmulator/Emulator.h
index 90c4d8644f..b62f66fdd3 100644
--- a/Userland/DevTools/UserspaceEmulator/Emulator.h
+++ b/Userland/DevTools/UserspaceEmulator/Emulator.h
@@ -136,7 +136,7 @@ private:
     int virt$beep();
     int virt$bind(int sockfd, FlatPtr address, socklen_t address_length);
     int virt$chdir(FlatPtr, size_t);
-    int virt$chmod(FlatPtr, size_t, mode_t);
+    int virt$chmod(FlatPtr);
     int virt$chown(FlatPtr);
     int virt$clock_gettime(int, FlatPtr);
     int virt$clock_nanosleep(FlatPtr);
diff --git a/Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp b/Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp
index adba1a8faf..ed29cbd10d 100644
--- a/Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp
+++ b/Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp
@@ -52,7 +52,7 @@ u32 Emulator::virt_syscall(u32 function, u32 arg1, u32 arg2, u32 arg3)
     case SC_chdir:
         return virt$chdir(arg1, arg2);
     case SC_chmod:
-        return virt$chmod(arg1, arg2, arg3);
+        return virt$chmod(arg1);
     case SC_chown:
         return virt$chown(arg1);
     case SC_clock_gettime:
@@ -418,10 +418,15 @@ int Emulator::virt$dbgputstr(FlatPtr characters, int length)
     return 0;
 }
 
-int Emulator::virt$chmod(FlatPtr path_addr, size_t path_length, mode_t mode)
+int Emulator::virt$chmod(FlatPtr params_addr)
 {
-    auto path = mmu().copy_buffer_from_vm(path_addr, path_length);
-    return syscall(SC_chmod, path.data(), path.size(), mode);
+    Syscall::SC_chmod_params params;
+    mmu().copy_from_vm(&params, params_addr, sizeof(params));
+
+    auto path = mmu().copy_buffer_from_vm((FlatPtr)params.path.characters, params.path.length);
+    params.path.characters = (char const*)path.data();
+    params.path.length = path.size();
+    return syscall(SC_chmod, &params);
 }
 
 int Emulator::virt$chown(FlatPtr params_addr)