From 53fa3cd2bfdb122d773024612d8c1d71f0dd8188 Mon Sep 17 00:00:00 2001
From: Jon Santmyer <jon@jonsantmyer.com>
Date: Sat, 12 Sep 2026 22:00:09 -0400
Subject: add paging support

---
 sys/syscall.c | 41 ++++++++++++++++++++++++++++-------------
 1 file changed, 28 insertions(+), 13 deletions(-)

(limited to 'sys/syscall.c')

diff --git a/sys/syscall.c b/sys/syscall.c
index 9a98030..eb2874d 100644
--- a/sys/syscall.c
+++ b/sys/syscall.c
@@ -7,6 +7,22 @@
 #include "sys/link.h"
 #include "sys/message.h"
 
+int __syscall_generic_objpath(jove_owned_obj_t *objdir, size_t payload_bytes, void *payload_data, jove_owned_obj_t **retobj)
+{
+    size_t bytes_needed = sizeof(struct syscall_generic_objpath);
+    CHECK_TOOSMALL(bytes_needed, payload_bytes,
+            "Message too small for payload.");
+    struct syscall_generic_objpath *payload = payload_data;
+ 
+    bytes_needed += payload->pathlen << 1;
+    CHECK_TOOSMALL(bytes_needed, payload_bytes,
+            "Message too small for object path.");
+        
+    errno = 0;
+    *retobj = objdir_getobj(objdir, payload->path, payload->pathlen);
+    return errno;
+}
+
 int
 _syscall_handle_generic(
         jove_owned_obj_t *pcb_obj,
@@ -47,17 +63,15 @@ syscall_handler(uintmax_t message_path_raw, uint16_t message_pathlen)
 
     jove_owned_obj_t *pcb_obj = process_current();
     pcb_t *pcb = obj_deref(pcb_obj);
-
     jove_owned_obj_t *objdir = pcb_rootdir(pcb);
-
     jove_owned_obj_t *message_obj = objdir_getobj(objdir, message_path, message_pathlen);
+
+    int sysret = 0;
     if(message_obj == 0) {
-        obj_release(objdir);
-        obj_release(pcb_obj);
-        return errno;
+        sysret = errno;
+        goto release_premsg;
     }
 
-    int sysret = 0;
     if(obj_gettype_linked(message_obj) != JOVE_OBJ_MESSAGE) {
         kprintf("syscall: Process %i tried to call syscall with invalid object: %P\n", pcb_pid(pcb), message_path, message_pathlen);
         sysret = EBADOBJ;
@@ -68,12 +82,11 @@ syscall_handler(uintmax_t message_path_raw, uint16_t message_pathlen)
     void *messagedata = message_data(message_obj);
     struct syscall_header *header = messagedata;
 
-    size_t header_bytes = sizeof(struct syscall_header) + header->pathlen * 2;
-    int bytes_left = messagelen - header_bytes;
-    if(bytes_left < 0) {
+    size_t bytes_needed = sizeof(struct syscall_header) + header->pathlen * 2;
+    if(bytes_needed > messagelen) {
         //Target path exceeds message length.
-        kprintf("syscall: Process %i tried to call syscall with OOB target path.\n", pcb_pid(pcb));
-        sysret = EBADPATH;
+        kprintf("syscall: Process %i tried to call syscall with target path too big for message.\n", pcb_pid(pcb));
+        sysret = ETOOSMALL;
         goto release_return;
     }
     jove_owned_obj_t *target = objdir_getobj(objdir, header->path, header->pathlen);
@@ -86,10 +99,11 @@ syscall_handler(uintmax_t message_path_raw, uint16_t message_pathlen)
     }
 
     uint8_t target_type = obj_gettype(target);
+    size_t bytes_left = messagelen - bytes_needed;
     if(target_type > 0x7F) {
         sysret = _syscall_handle_arch(
                 pcb_obj, objdir, message_obj, target,
-                header, bytes_left, messagedata + header_bytes);
+                header, bytes_left, messagedata + bytes_needed);
     }else{
         syscall_handle_t call_handle = s_syscall_handles[obj_gettype(target)];
         if(call_handle == NULL) {
@@ -99,11 +113,12 @@ syscall_handler(uintmax_t message_path_raw, uint16_t message_pathlen)
         }else 
             sysret = call_handle(
                     pcb_obj, objdir, message_obj, target, 
-                    header, bytes_left, messagedata + header_bytes);
+                    header, bytes_left, messagedata + bytes_needed);
     }
     obj_release(target);
 release_return:
     obj_release(message_obj);
+release_premsg:
     obj_release(objdir);
     obj_release(pcb_obj);
     return sysret;
-- 
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