feat: implement utime libc function, SYS_UTIME syscall, filesystem support (ext2 only)

kernel/src/Api/BuildNo.hpp

@@ -12,4 +12,4 @@
 
 #pragma once
 
-#define MONTAUK_BUILD_NUMBER 94
+#define MONTAUK_BUILD_NUMBER 95

kernel/src/Api/Filesystem.hpp

@@ -15,6 +15,7 @@
 #include <Memory/Paging.hpp>
 #include <Libraries/Memory.hpp>
 #include <Ipc/Ipc.hpp>
+#include <Timekeeping/Time.hpp>
 #include "Path.hpp"
 
 namespace montauk::abi {
@@ -133,6 +134,18 @@ namespace montauk::abi {
         return 0;
     }
 
+    static int Sys_Utime(const char* path, int64_t atime, int64_t mtime,
+                         bool useCurrent) {
+        char resolved[256];
+        if (!ResolveProcessPath(path, resolved, sizeof(resolved))) return -1;
+        if (useCurrent) {
+            int64_t now = Timekeeping::GetUnixTimestamp();
+            atime = now;
+            mtime = now;
+        }
+        return Fs::Vfs::VfsSetTimes(resolved, atime, mtime);
+    }
+
     static int Sys_FMkdir(const char* path) {
         char resolved[256];
         if (!ResolveProcessPath(path, resolved, sizeof(resolved))) return -1;

kernel/src/Api/Syscall.cpp

@@ -174,6 +174,12 @@ namespace montauk::abi {
                 if (!UserMemory::String(frame->arg1, kMaxPathBytes)) return -1;
                 if (!UserMemory::Writable<FileStat>(frame->arg2)) return -1;
                 return (int64_t)Sys_Stat((const char*)frame->arg1, (FileStat*)frame->arg2);
+            case SYS_UTIME:
+                if (!UserMemory::String(frame->arg1, kMaxPathBytes)) return -1;
+                return (int64_t)Sys_Utime((const char*)frame->arg1,
+                                          (int64_t)frame->arg2,
+                                          (int64_t)frame->arg3,
+                                          frame->arg4 != 0);
             case SYS_TERMSIZE:
                 return (int64_t)Sys_TermSize();
             case SYS_GETARGS:

kernel/src/Api/Syscall.hpp

@@ -310,6 +310,9 @@ namespace montauk::abi {
     /* Keyboard.hpp */
     static constexpr uint64_t SYS_GETCHAR_NB          = 166;  // () -> ascii, 0 if nothing pending; never blocks
 
+    // Set path access/modification times. (path, atime, mtime, useCurrent)
+    static constexpr uint64_t SYS_UTIME               = 167;
+
     // Tunable parameters (for SYS_SDR_SETPARAM / SYS_SDR_GETPARAM).
     static constexpr int SDR_PARAM_FREQ        = 0;  // center frequency, Hz
     static constexpr int SDR_PARAM_SAMPLE_RATE = 1;  // sample rate, Hz