syscalls: chdir

kernel-src/arch/x86-64/syscall.asm

@@ -20,6 +20,7 @@ extern syscall_dup
 extern syscall_dup2
 extern syscall_dup3
 extern syscall_fcntl
+extern syscall_chdir
 syscalltab:
 dq syscall_print
 dq syscall_mmap
@@ -42,7 +43,8 @@ dq syscall_dup
 dq syscall_dup2
 dq syscall_dup3
 dq syscall_fcntl
-syscallcount equ 21
+dq syscall_chdir
+syscallcount equ 22
 section .text
 global arch_syscall_entry
 ; on entry:

kernel-src/sys/syscalls/chdir.c

@@ -0,0 +1,43 @@
+#include <kernel/syscalls.h>
+#include <kernel/scheduler.h>
+#include <kernel/vfs.h>
+#include <kernel/alloc.h>
+#include <errno.h>
+
+syscallret_t syscall_chdir(context_t *, const char *upath) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	if (upath > (char *)USERSPACE_END) {
+		ret.errno = EFAULT;
+		return ret;
+	}
+
+	// TODO safe string ops
+	char *path = alloc(strlen(upath) + 1);
+	strcpy(path, upath);
+
+	vnode_t *ref = path[0] == '/' ? sched_getroot() : sched_getcwd();
+	vnode_t *new = NULL;
+
+	ret.errno = vfs_lookup(&new, ref, path, NULL, 0);
+	if (ret.errno)
+		goto cleanup;
+
+	if (new->type != V_TYPE_DIR) {
+		ret.errno = ENOTDIR;
+		goto cleanup;
+	}
+
+	sched_setcwd(new);
+
+	cleanup:
+	if (new)
+		VOP_RELEASE(new);
+
+	free(path);
+	VOP_RELEASE(ref);
+
+	return ret;
+}