syscall: openat

kernel-src/sys/syscalls/open.c

@@ -0,0 +1,98 @@
+#include <kernel/syscalls.h>
+#include <kernel/file.h>
+#include <kernel/abi.h>
+#include <kernel/alloc.h>
+#include <errno.h>
+#include <logging.h>
+
+syscallret_t syscall_openat(context_t *context, int dirfd, const char *path, int flags, mode_t mode) {
+	syscallret_t ret = {
+		.ret = -1,
+		.errno = 0
+	};
+
+	// transform O_RDONLY, O_WRONLY, O_RDWR into FILE_READ and FILE_WRITE
+	++flags;
+
+	__assert((~FILE_KNOWN_FLAGS & flags) == 0);
+
+	vnode_t *dirnode = NULL;
+	file_t *dirfile;
+
+	size_t pathsize = strlen(path); // TODO u_strlen
+	char *pathbuf = alloc(pathsize + 1);
+	strcpy(pathbuf, path); // TODO u_strcpy
+
+	if (*pathbuf == '/') {
+		dirnode = sched_getroot();
+		dirfile = NULL;
+	} else if (dirfd == AT_FDCWD) {
+		dirnode = sched_getcwd();
+		dirfile = NULL;
+	} else {
+		dirfile = fd_get(dirfd);
+		if (dirfile == NULL) {
+			ret.errno = EBADF;
+			goto cleanup;
+		}
+
+		dirnode = dirfile->vnode;
+		if (dirnode->type != V_TYPE_DIR) {
+			ret.errno = ENOTDIR;
+			goto cleanup;
+		}
+	}
+
+	// TODO pass CLOEXEC to fd
+	file_t *newfile = NULL;
+	int newfd;
+	ret.errno = fd_new(0, &newfile, &newfd);
+	if (ret.errno)
+		goto cleanup;
+
+	vnode_t *vnode = NULL;
+	ret.errno = vfs_open(dirnode, pathbuf, fileflagstovnodeflags(flags), &vnode);
+	if (ret.errno)
+		goto cleanup;
+
+	vattr_t attr;
+	VOP_LOCK(vnode);
+	ret.errno = VOP_GETATTR(vnode, &attr, &_cpu()->thread->proc->cred);
+	VOP_UNLOCK(vnode);
+	if (ret.errno)
+		goto cleanup;
+
+	// node refcount is already increased by open
+	newfile->vnode = vnode;
+	newfile->flags = flags;
+	newfile->offset = 0;
+	newfile->mode = attr.mode;
+
+	ret.errno = 0;
+	ret.ret = newfd;
+
+	cleanup:
+	if (vnode && ret.errno) {
+		vfs_close(vnode, fileflagstovnodeflags(flags));
+		VOP_RELEASE(vnode);
+	}
+
+	if (newfile) {
+		if (ret.errno) {
+			__assert(fd_close(newfd) == 0);
+		} else {
+			fd_release(newfile);
+		}
+	}
+
+	if (pathbuf)
+		free(pathbuf);
+
+	if (dirfile) {
+		fd_release(dirfile);
+	} else if (dirnode){
+		VOP_RELEASE(dirnode);
+	}
+
+	return ret;
+}