Add sys_exec () and libprocess wrapper, fix ramdisk tar parsing

kernel/syscall/syscall.c

@@ -1,7 +1,10 @@
 #include <aux/compiler.h>
 #include <device/device.h>
+#include <fs/path.h>
+#include <fs/vfs.h>
 #include <libk/assert.h>
 #include <libk/fieldlengthof.h>
+#include <libk/fieldsizeof.h>
 #include <libk/std.h>
 #include <limine/requests.h>
 #include <m/status.h>
@@ -181,7 +184,7 @@ DEFINE_SYSCALL (sys_device_do) {
   uintptr_t out_paddr;
 
   if (!(cmd >= 0 && cmd < (int)fieldlengthof (struct device, ops)))
-    return -ST_BAD_DEVICE_OP;
+    return SYSRESULT (-ST_BAD_DEVICE_OP);
 
   spin_lock (&proc->procgroup->lock);
 
@@ -206,7 +209,7 @@ DEFINE_SYSCALL (sys_device_do) {
   struct device* device = device_find (device_id);
 
   if (device == NULL)
-    return -ST_NOT_FOUND;
+    return SYSRESULT (-ST_NOT_FOUND);
 
   spin_lock (&device->lock);
 
@@ -214,7 +217,43 @@ DEFINE_SYSCALL (sys_device_do) {
 
   spin_unlock (&device->lock);
 
-  return ret;
+  return SYSRESULT (ret);
+}
+
+/* int exec (char* path) */
+DEFINE_SYSCALL (sys_exec) {
+  uintptr_t uvaddr_path = a1;
+
+  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
+
+  uintptr_t out_paddr;
+
+  spin_lock (&proc->procgroup->lock);
+  out_paddr = mm_v2p (&proc->procgroup->pd, uvaddr_path);
+  spin_unlock (&proc->procgroup->lock);
+
+  if (out_paddr == 0)
+    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);
+
+  const char* path = (const char*)((uintptr_t)hhdm->offset + out_paddr);
+
+  char mountpoint[fieldsizeof (struct vfs_mountpoint, key)];
+  const char* subpath = NULL;
+
+  if (!path_parse (path, mountpoint, &subpath))
+    return SYSRESULT (-ST_BAD_PATH);
+
+  struct proc* new = proc_from_file (mountpoint, subpath);
+
+  if (new == NULL)
+    return SYSRESULT (-ST_EXEC_ERROR);
+
+  int pid = new->pid;
+
+  if (proc_register (new, reschedule_cpu) == PROC_NEED_RESCHEDULE)
+    *reschedule = true;
+
+  return SYSRESULT (pid);
 }
 
 static syscall_handler_func_t handler_table[] = {
@@ -230,6 +269,7 @@ static syscall_handler_func_t handler_table[] = {
     [SYS_MUTEX_LOCK] = &sys_mutex_lock,
     [SYS_MUTEX_UNLOCK] = &sys_mutex_unlock,
     [SYS_DEVICE_DO] = &sys_device_do,
+    [SYS_EXEC] = &sys_exec,
 };
 
 syscall_handler_func_t syscall_find_handler (int syscall_num) {