3 files changed, 41 insertions, 10 deletions

diff --git a/src/kernel/arch/generic.h b/src/kernel/arch/generic.h
index 3e98001..a9e1ac9 100644
--- a/src/kernel/arch/generic.h
+++ b/src/kernel/arch/generic.h
@@ -35,6 +35,8 @@ void pagedir_map(struct pagedir *dir, void __user *virt, void *phys,
                  bool user, bool writeable);
 bool pagedir_iskern(struct pagedir *, const void __user *virt);
 
+void __user *pagedir_findfree(struct pagedir *dir, char __user *start, size_t len);
+
 void pagedir_switch(struct pagedir *);
 
 // return 0 on failure
diff --git a/src/kernel/arch/i386/pagedir.c b/src/kernel/arch/i386/pagedir.c
index 28608dc..e607cc7 100644
--- a/src/kernel/arch/i386/pagedir.c
+++ b/src/kernel/arch/i386/pagedir.c
@@ -184,3 +184,23 @@ void *pagedir_virt2phys(struct pagedir *dir, const void __user *virt,
 	phys |= ((uintptr_t)virt) & 0xFFF;
 	return (void*)phys;
 }
+
+void __user *pagedir_findfree(struct pagedir *dir, char __user *start, size_t len) {
+	struct pagetable_entry *page;
+	char __user *iter;
+	start = (userptr_t)(((uintptr_t __force)start + PAGE_MASK) & ~PAGE_MASK); // round up to next page
+	iter = start;
+
+	while (iter < (char __user *)0xFFF00000) { // TODO better boundary
+		page = get_entry(dir, iter);
+		if (page && page->present) {
+			start = iter + PAGE_SIZE;
+		} else {
+			if ((size_t)(iter + PAGE_SIZE - start) >= len)
+				return start;
+		}
+		iter += PAGE_SIZE;
+	}
+
+	return NULL;
+}
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 4d64d32..540611e 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -250,34 +250,42 @@ int _syscall_fs_respond(char __user *buf, int ret) {
 	SYSCALL_RETURN(0);
 }
 
-int _syscall_memflag(void __user *addr, size_t len, int flags) {
-	userptr_t goal = addr + len;
+void __user *_syscall_memflag(void __user *addr, size_t len, int flags) {
 	struct pagedir *pages = process_current->pages;
 	void *phys;
-
 	addr = (userptr_t)((int __force)addr & ~PAGE_MASK); // align to page boundary
-	for (; addr < goal; addr += PAGE_SIZE) {
-		if (pagedir_iskern(pages, addr)) {
+
+	if (flags & MEMFLAG_FINDFREE) {
+		addr = pagedir_findfree(pages, addr, len);
+		if (!(flags & MEMFLAG_PRESENT)) goto ret;
+	}
+
+
+	for (userptr_t iter = addr; iter < addr + len; iter += PAGE_SIZE) {
+		if (pagedir_iskern(pages, iter)) {
 			// TODO reflect failure in return value
 			continue;
 		}
 
-		phys = pagedir_virt2phys(pages, addr, false, false); 
+		phys = pagedir_virt2phys(pages, iter, false, false); 
 
 		if (!(flags & MEMFLAG_PRESENT)) {
 			if (phys)
-				page_free(pagedir_unmap(pages, addr), 1);
+				page_free(pagedir_unmap(pages, iter), 1);
 			continue;
 		}
 
 		if (!phys) {
 			phys = page_alloc(1);
 			memset(phys, 0, PAGE_SIZE); // TODO somehow test this
-			pagedir_map(pages, addr, phys, true, true);
+			pagedir_map(pages, iter, phys, true, true);
 		}
 	}
 
-	SYSCALL_RETURN(-1);
+ret: // the macro is too stupid to handle returning pointers
+	assert(process_current->state == PS_RUNNING); // TODO move to regs_savereturn
+	regs_savereturn(&process_current->regs, (uintptr_t)addr);
+	return addr;
 }
 
 int _syscall(int num, int a, int b, int c, int d) {
@@ -303,7 +311,8 @@ int _syscall(int num, int a, int b, int c, int d) {
 		case _SYSCALL_FS_RESPOND:
 			return _syscall_fs_respond((userptr_t)a, b);
 		case _SYSCALL_MEMFLAG:
-			return _syscall_memflag((userptr_t)a, b, c);
+			_syscall_memflag((userptr_t)a, b, c);
+			return -1; // unused anyways
 		default:
 			kprintf("unknown syscall ");
 			panic_unimplemented(); // TODO fail gracefully