vfs: VOP_RESIZE

kernel-src/fs/devfs.c

@@ -322,7 +322,8 @@ static vops_t vnops = {
 	.munmap = devfs_munmap,
 	.getdents = devfs_getdents,
 	.isatty = devfs_isatty,
-	.ioctl = devfs_ioctl
+	.ioctl = devfs_ioctl,
+	.resize = devfs_enodev
 };
 
 static void ctor(scache_t *cache, void *obj) {

kernel-src/fs/pipefs.c

@@ -227,7 +227,8 @@ static vops_t vnops = {
 	.inactive = pipefs_inactive,
 	.mmap = pipefs_enodev,
 	.munmap = pipefs_enodev,
-	.getdents = pipefs_enodev
+	.getdents = pipefs_enodev,
+	.resize = pipefs_enodev
 };
 
 static void ctor(scache_t *cache, void *obj) {

kernel-src/fs/tmpfs.c

@@ -32,7 +32,7 @@ static int tmpfs_mount(vfs_t **vfs, vnode_t *mountpoint, vnode_t *backing, void
 #define DATAMMUFLAGS (ARCH_MMU_FLAGS_WRITE | ARCH_MMU_FLAGS_READ | ARCH_MMU_FLAGS_NOEXEC)
 
 // expects to be called with node locked
-static int tmpfs_resize(tmpfsnode_t *node, size_t size) {
+static int resize(tmpfsnode_t *node, size_t size) {
 	if (size == node->attr.size || node->vnode.type != V_TYPE_REGULAR)
 		return 0;
 
@@ -264,7 +264,7 @@ static int tmpfs_write(vnode_t *node, void *buffer, size_t size, uintmax_t offse
 
 	VOP_LOCK(node);
 	if (top > tmpnode->attr.size) {
-		int err = tmpfs_resize(tmpnode, top);
+		int err = resize(tmpnode, top);
 		if (err) {
 			VOP_UNLOCK(node);
 			return err;
@@ -468,6 +468,15 @@ static int tmpfs_inactive(vnode_t *node) {
 	return 0;
 }
 
+static int tmpfs_resize(vnode_t *node, size_t size, cred_t *) {
+	VOP_LOCK(node);
+
+	int err = resize((tmpfsnode_t *)node, size);
+
+	VOP_UNLOCK(node);
+	return err;
+}
+
 static vfsops_t vfsops = {
 	.mount = tmpfs_mount,
 	.root = tmpfs_root
@@ -491,7 +500,8 @@ static vops_t vnops = {
 	.inactive = tmpfs_inactive,
 	.mmap = tmpfs_mmap,
 	.munmap = tmpfs_munmap,
-	.getdents = tmpfs_getdents
+	.getdents = tmpfs_getdents,
+	.resize = tmpfs_resize
 };
 
 static tmpfsnode_t *newnode(vfs_t *vfs, int type) {

kernel-src/include/kernel/vfs.h

@@ -95,6 +95,7 @@ typedef struct vops_t {
 	int (*getdents)(vnode_t *node, dent_t *buffer, size_t count, uintmax_t offset, size_t *readcount);
 	int (*isatty)(vnode_t *node);
 	int (*ioctl)(vnode_t *node, unsigned long request, void *arg, int *result);
+	int (*resize)(vnode_t *node, size_t newsize, cred_t *cred);
 } vops_t;
 
 #define VFS_MOUNT(vfs, mp, b, d) (vfs)->ops->mount(vfs, mp, b, d)
@@ -124,6 +125,7 @@ typedef struct vops_t {
 #define VOP_POLL(v, d, p) (v)->ops->poll(v, d, p)
 #define VOP_ISATTY(v) ((v)->ops->isatty ? (v)->ops->isatty(v) : ENOTTY)
 #define VOP_IOCTL(v, r, a, rp) ((v)->ops->ioctl ? (v)->ops->ioctl(v, r, a, rp) : ENOTTY)
+#define VOP_RESIZE(v, s, c) (v)->ops->resize(v, s, c)
 #define VOP_HOLD(v) __atomic_add_fetch(&(v)->refcount, 1, __ATOMIC_SEQ_CST)
 #define VOP_RELEASE(v) {\
 		if (__atomic_sub_fetch(&(v)->refcount, 1, __ATOMIC_SEQ_CST) == 0) {\

kernel-src/sys/syscalls/open.c

@@ -56,6 +56,12 @@ syscallret_t syscall_openat(context_t *context, int dirfd, const char *path, int
 	if (ret.errno)
 		goto cleanup;
 
+	if (vnode->type == V_TYPE_REGULAR && (flags & O_TRUNC)) {
+		ret.errno = VOP_RESIZE(vnode, 0, &_cpu()->thread->proc->cred);
+		if (ret.errno)
+			goto cleanup;
+	}
+
 	// node refcount is already increased by open
 	newfile->vnode = vnode;
 	newfile->flags = flags;