*: getxattr

1 files changed, 43 insertions, 4 deletions

diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 0730620..436000c 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -302,11 +302,13 @@ long _sys_fs_respond(hid_t hid, const void __user *buf, long ret, int flags) {
 	if (!h || h->type != HANDLE_FS_REQ) SYSCALL_RETURN(-EBADF);
 	VfsReq *req = h->req;
 	if (req) {
+		// TODO this shouldn't be limited to 32 bits
+		long len = min(ret, capped_cast32(req->outlen));
 		if (ret > 0 && req->type == VFSOP_READ) {
-			/* vfsreq_finish can't copy this data, as it doesn't know where the
-			 * buf argument came from */
-			ret = min(ret, capped_cast32(req->outlen));
-			ret = pcpy_bi(req->caller, req->out, proc_cur, buf, ret);
+			ret = pcpy_bi(req->caller, req->out, proc_cur, buf, len);
+		} else if (ret > 0 && req->type == VFSOP_GETXATTR) {
+			/* intentionally ignoring the return value */
+			pcpy_bi(req->caller, req->out, proc_cur, buf, len);
 		}
 		vfsreq_finish(req, (void __user *)buf, ret, flags, proc_cur);
 	}
@@ -510,6 +512,42 @@ void _sys_intr_return(struct intr_data __user *intr, int flags) {
 	regs_safecopy(&proc_cur->regs, &d.reg);
 }
 
+ssize_t _sys_getxattr(hid_t hid, const char __user *name, void __user *buf, size_t len, int flags) {
+	Handle *h = hs_get(proc_cur->hs, hid);
+	if (!h) {
+		SYSCALL_RETURN(-EBADF);
+	}
+	if (h->type != HANDLE_FILE || flags != 0) {
+		SYSCALL_RETURN(-ENOSYS);
+	}
+	if (!h->readable) {
+		SYSCALL_RETURN(-EACCES);
+	}
+	char tmpbuf[XATTRNAME_MAX];
+	// TODO test pcpy_from_str edge cases
+	size_t namelen = pcpy_from_str(proc_cur, tmpbuf, name, XATTRNAME_MAX);
+	if (namelen == 0) {
+		SYSCALL_RETURN(-EFAULT);
+	}
+	assert(namelen <= XATTRNAME_MAX);
+	assert(tmpbuf[namelen-1] == '\0');
+
+	char *namebuf = kmalloc(namelen, TagXattrName);
+	memcpy(namebuf, tmpbuf, namelen);
+
+	vfsreq_dispatchcopy((VfsReq) {
+		.type = VFSOP_GETXATTR,
+		.backend = h->backend,
+		.id = h->file_id,
+		.caller = proc_cur,
+		.kin = namebuf,
+		.kinlen = namelen-1,
+		.out = buf,
+		.outlen = len,
+	});
+	return 0;
+}
+
 long _sys_execbuf(void __user *ubuf, size_t len) {
 	if (len == 0) SYSCALL_RETURN(0);
 	static_assert(EXECBUF_MAX_LEN <= KMALLOC_MAX);
@@ -568,6 +606,7 @@ long _syscall(long num, long a, long b, long c, long d, long e) {
 		break; case _SYS_GETNULL:	_sys_getnull(a);
 		break; case _SYS_DUPLEX:	_sys_duplex(a, b, c);
 		break; case _SYS_INTR_RETURN:	_sys_intr_return((userptr_t)a, b);
+		break; case _SYS_GETXATTR:	_sys_getxattr(a, (userptr_t)b, (userptr_t)c, d, e);
 		break; case _SYS_EXECBUF:	_sys_execbuf((userptr_t)a, b);
 		break; case _SYS_DEBUG_KLOG:	_sys_debug_klog((userptr_t)a, b);
 		break;