syscalls: fchmod and fchmodat

kernel-src/sys/syscalls/chmod.c

@@ -0,0 +1,74 @@
+#include <kernel/syscalls.h>
+#include <kernel/alloc.h>
+#include <kernel/file.h>
+#include <kernel/vfs.h>
+#include <arch/cpu.h>
+
+static int dochmod(vnode_t *node, mode_t mode) {
+	vattr_t attr;
+	cred_t *cred = &_cpu()->thread->proc->cred;
+	int e = VOP_GETATTR(node, &attr, cred);
+	if (e)
+		return e;
+
+	attr.mode = mode;
+
+	return VOP_SETATTR(node, &attr, cred);
+}
+
+syscallret_t syscall_fchmodat(context_t *, int dirfd, const char *upath, mode_t mode, int flags) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	char *path = alloc(strlen(upath) + 1);
+	if (path == NULL) {
+		ret.errno = ENOMEM;
+		return ret;
+	}
+
+	strcpy(path, upath);
+
+	file_t *file = NULL;
+	vnode_t *dirnode = NULL;
+	vnode_t *node = NULL;
+	ret.errno = dirfd_enter(path, dirfd, &file, &dirnode);
+	if (ret.errno)
+		goto cleanup;
+
+	ret.errno = vfs_lookup(&node, dirnode, path, NULL, (flags & AT_SYMLINK_NOFOLLOW) ? VFS_LOOKUP_NOLINK : 0);
+	if (ret.errno)
+		goto cleanup;
+
+	ret.errno = dochmod(node, mode);
+	ret.ret = ret.errno ? -1 : 0;
+
+	cleanup:
+
+	if (node)
+		VOP_RELEASE(node);
+
+	if (dirnode)
+		dirfd_leave(dirnode, file);
+
+	free(path);
+
+	return ret;
+}
+
+syscallret_t syscall_fchmod(context_t *, int fd, mode_t mode) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	file_t *file = fd_get(fd);
+	if (file == NULL) {
+		ret.errno = EBADF;
+		return ret;
+	}
+
+	ret.errno = dochmod(file->vnode, mode);
+	ret.ret = ret.errno ? -1 : 0;
+
+	return ret;
+}