add docs for syscalls. make syscall code kind-of cleaner

1 files changed, 56 insertions, 49 deletions

diff --git a/sys/syscall.c b/sys/syscall.c
index 457b820..0da3475 100644
--- a/sys/syscall.c
+++ b/sys/syscall.c
@@ -24,28 +24,20 @@ int __syscall_generic_objpath(jove_owned_obj_t *objdir, size_t payload_bytes, vo
 }
 
 int
-_syscall_handle_generic(
-        jove_owned_obj_t *pcb_obj,
-        jove_owned_obj_t *objdir,
-        jove_owned_obj_t *message_obj,
-        jove_owned_obj_t *target_obj,
-        struct syscall_header *header,
-        size_t bytes_left,
-        void *payload)
+_syscall_handle_generic(syscall_context_t *ctx)
 {
-    pcb_t *pcb = obj_deref(pcb_obj);
-    klogf("Process %i encountered stub syscall on object %P\n", pcb_pid(pcb), header->path, header->pathlen);
-    return EBADOBJ;
+    pcb_t *pcb = obj_deref(ctx->pcb);
+    klogf("Process %i encountered stub syscall on object %P\n", pcb_pid(pcb), ctx->header->path, ctx->header->pathlen);
+    return -EBADOBJ;
 }
 
 static const syscall_handle_t s_syscall_handles[128] = {
-    [JOVE_OBJ_NONE] = NULL,
     [JOVE_OBJ_UNTYPED] = _syscall_handle_untyped,
     [JOVE_OBJ_OBJDIR] = _syscall_handle_objdir,
     [JOVE_OBJ_PAGEDIR] = _syscall_handle_pagedir,
     [JOVE_OBJ_PROCESSOR] = _syscall_handle_generic,
-    [JOVE_OBJ_HWMEMORY] = _syscall_handle_generic,
-    [JOVE_OBJ_PROCESS] = _syscall_handle_generic,
+    [JOVE_OBJ_SHMEMORY] = _syscall_handle_generic,
+    [JOVE_OBJ_PCB] = _syscall_handle_generic,
     [JOVE_OBJ_INT_HANDLE] = _syscall_handle_generic,
     [JOVE_OBJ_INITRD_FILE] = _syscall_handle_generic,
     [JOVE_OBJ_FRAMEBUFFER] = _syscall_handle_generic,
@@ -55,36 +47,63 @@ static const syscall_handle_t s_syscall_handles[128] = {
 };
 
 int
+_syscall_handle_switch(syscall_context_t *ctx)
+{
+    uint8_t target_type = obj_gettype(ctx->target.obj);
+    if(target_type > 0x7F) {
+        return _syscall_handle_arch(ctx);
+    }
+    else {
+        syscall_handle_t call_handle = s_syscall_handles[target_type];
+        if(call_handle == NULL) {
+            klogf("Tried to call syscall on object %P which doesn't support syscalls!\n",
+                    ctx->header->path, ctx->header->pathlen);
+            return -EBADOBJ;
+        }
+        else {
+            return call_handle(ctx);
+        }
+    }
+}
+
+int
 syscall_handler(uintmax_t message_path_raw, uint16_t message_pathlen)
 {
     uint16_t *message_path = (uint16_t*)&message_path_raw;
     if(message_pathlen > sizeof(uintmax_t) >> 1) {
-        return EBADPATH;
+        return -EBADPATH;
     }
 
-    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_trygetobj(objdir, message_path, message_pathlen);
+    syscall_context_t ctx;
+    ctx.lockstack.depth = 0;
 
     int sysret = 0;
 
-    if(message_obj == NULL) {
-        klogf("Process %i tried to call syscall with bad message %P : %s\n",
+    ctx.pcb = lockstack_push(&ctx.lockstack, process_current());
+    pcb_t *pcb = obj_deref(ctx.pcb);
+    ctx.objdir = lockstack_push(&ctx.lockstack, obj_take(pcb_rootdir(pcb)));
+
+    ctx.message = link_try_traverse(
+            lockstack_push(&ctx.lockstack, objdir_trygetobj(
+                    ctx.objdir, message_path, message_pathlen)), 
+            &ctx.lockstack);
+
+    if(ctx.message.obj == NULL) {
+        klogf("Process %i failed to get message %P : %s\n",
                 pcb_pid(pcb), message_path, message_pathlen, errstr(errno));
         sysret = -errno;
-        goto release_premsg;
+        goto release_return;
     }
 
-    if(obj_gettype_linked(message_obj) != JOVE_OBJ_MESSAGE) {
+    if(obj_gettype(ctx.message.obj) != JOVE_OBJ_MESSAGE) {
         klogf("Process %i tried to call syscall with invalid object %P\n", 
                 pcb_pid(pcb), message_path, message_pathlen);
         sysret = -EBADOBJ;
         goto release_return;
     }
 
-    size_t messagelen = message_len(message_obj);
-    void *messagedata = message_data(message_obj);
+    size_t messagelen = message_len(ctx.message.obj);
+    void *messagedata = message_data(ctx.message.obj);
     struct syscall_header *header = messagedata;
 
     size_t bytes_needed = sizeof(struct syscall_header) + header->pathlen * 2;
@@ -94,8 +113,14 @@ syscall_handler(uintmax_t message_path_raw, uint16_t message_pathlen)
         sysret = -ETOOSMALL;
         goto release_return;
     }
-    jove_owned_obj_t *target = objdir_trygetobj(objdir, header->path, header->pathlen);
-    if(target == 0) {
+
+    ctx.header = header;
+    ctx.bytes_left = messagelen - bytes_needed;
+    ctx.payload = (void*)((uintptr_t)header + bytes_needed);
+
+    ctx.target.obj = lockstack_push(&ctx.lockstack,
+            objdir_trygetobj(ctx.objdir, header->path, header->pathlen));
+    if(ctx.target.obj == 0) {
         //Could not find payload target in pcb rootdir.
         klogf("Process %i tried to call syscall with bad target path %P : %s\n", 
                 pcb_pid(pcb), header->path, header->pathlen, errstr(errno));
@@ -103,28 +128,10 @@ syscall_handler(uintmax_t message_path_raw, uint16_t message_pathlen)
         goto release_return;
     }
 
-    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 + bytes_needed);
-    }else{
-        syscall_handle_t call_handle = s_syscall_handles[obj_gettype(target)];
-        if(call_handle == NULL) {
-            klogf("Process %i tried to call syscall on object %P which doesn't support syscalls!\n",
-                    pcb_pid(pcb), header->path, header->pathlen);
-            sysret = -EBADOBJ;
-        }else 
-            sysret = call_handle(
-                    pcb_obj, objdir, message_obj, target, 
-                    header, bytes_left, messagedata + bytes_needed);
-    }
-    obj_release(target);
+    ctx.target.permissions = JOVE_PERM_ALL;
+    sysret = _syscall_handle_switch(&ctx);
+
 release_return:
-    obj_release(message_obj);
-release_premsg:
-    obj_release(objdir);
-    obj_release(pcb_obj);
+    lockstack_popall(&ctx.lockstack);
     return sysret;
 }