Add simple shared memory facility to IPC (no syscall yet)

4 files changed, 86 insertions, 4 deletions

diff --git a/src/kernel/user/ipc.c b/src/kernel/user/ipc.c
index a8362ea..e565082 100644
--- a/src/kernel/user/ipc.c
+++ b/src/kernel/user/ipc.c
@@ -227,6 +227,84 @@ void channel_dispose(fs_node_t *n) {
 	free(c);
 }
 
+//  ---- ------ ------
+//  ---- Shared memory
+//  ---- ------ ------
+
+bool shm_open(fs_node_ptr n, int mode);
+void shm_close(fs_handle_t *h);
+bool shm_stat(fs_node_ptr n, stat_t *st);
+void shm_dispose(fs_node_t *n);
+
+fs_node_ops_t shm_ops = {
+	.open = shm_open,
+	.read = fs_read_from_pager,
+	.write = fs_write_to_pager,
+	.readdir = 0,
+	.poll = 0,
+	.close = shm_close,
+	.stat = shm_stat,
+	.ioctl = 0,
+	.walk = 0,
+	.delete = 0,
+	.move = 0,
+	.create = 0,
+	.dispose = shm_dispose,
+};
+
+fs_handle_t* make_shm(size_t size) {
+	fs_node_t *n = 0;
+	fs_handle_t *h = 0;
+
+	n = (fs_node_t*)malloc(sizeof(fs_node_t));
+	if (n == 0) goto error;
+	memset(n, 0, sizeof(fs_node_t));
+
+	h = (fs_handle_t*)malloc(sizeof(fs_handle_t));
+	if (h == 0) goto error;
+
+	n->pager = new_swap_pager(size, false);
+	if (n->pager == 0) goto error;
+
+	n->refs = 1;
+	n->lock = MUTEX_UNLOCKED;
+	n->ops = &shm_ops;
+	n->data = 0;
+
+	h->fs = 0;
+	h->node = n;
+	h->refs = 1;
+	h->mode = FM_READ | FM_WRITE | FM_MMAP;
+
+	return h;
+
+error:
+	if (n && n->pager) delete_pager(n->pager);
+	if (n) free(n);
+	if (h) free(h);
+	return 0;
+}
+
+bool shm_open(fs_node_ptr n, int mode) {
+	int ok_modes = FM_READ | FM_WRITE | FM_MMAP;
+	if (mode & ~ok_modes) return false;
+
+	return true;
+}
+
+void shm_close(fs_handle_t *h) {
+	// nothing to do
+}
+
+bool shm_stat(fs_node_ptr n, stat_t *st) {
+	// TODO
+	return false;
+}
+
+void shm_dispose(fs_node_t *n) {
+	delete_pager(n->pager);
+}
+
 //  ---- ------
 //  ---- Tokens
 //  ---- ------
diff --git a/src/kernel/user/nullfs.c b/src/kernel/user/nullfs.c
index d4f345f..636d7fa 100644
--- a/src/kernel/user/nullfs.c
+++ b/src/kernel/user/nullfs.c
@@ -204,7 +204,7 @@ bool nullfs_add_ram_file(fs_t *fs, const char* name, const char* data, size_t in
 	nullfs_file_t *f = (nullfs_file_t*)malloc(sizeof(nullfs_file_t));
 	if (f == 0) return false;
 	
-	p = new_swap_pager(init_sz);
+	p = new_swap_pager(init_sz, true);
 	if (p == 0) goto error;
 
 	f->ok_modes = ok_modes & (FM_MMAP | FM_TRUNC | FM_READ | FM_WRITE);
@@ -339,7 +339,7 @@ bool nullfs_d_create(fs_node_ptr n, const char* file, int type) {
 		nullfs_file_t *f = (nullfs_file_t*)malloc(sizeof(nullfs_file_t));
 		if (f == 0) goto f_error;
 
-		p = new_swap_pager(0);
+		p = new_swap_pager(0, true);
 		if (p == 0) goto f_error;
 
 		f->ok_modes = FM_READ | FM_WRITE | FM_TRUNC | FM_APPEND;
diff --git a/src/kernel/user/pager.c b/src/kernel/user/pager.c
index 79f293b..b9233b0 100644
--- a/src/kernel/user/pager.c
+++ b/src/kernel/user/pager.c
@@ -26,7 +26,7 @@ pager_ops_t swap_pager_ops = {
 	.resize = swap_pager_resize,
 };
 
-pager_t *new_swap_pager(size_t size) {
+pager_t *new_swap_pager(size_t size, bool allow_resize) {
 	pager_t *p = (pager_t*)malloc(sizeof(pager_t));
 	if (p == 0) return 0;
 
@@ -38,6 +38,8 @@ pager_t *new_swap_pager(size_t size) {
 	p->lock = MUTEX_UNLOCKED;
 	p->maps = 0;
 
+	p->swap_pager.allow_resize = allow_resize;
+
 	return p;
 
 error:
@@ -86,6 +88,8 @@ void swap_page_release(pager_t *p, size_t offset, size_t len) {
 }
 
 bool swap_pager_resize(pager_t *p, size_t new_size) {
+	if (!p->swap_pager.allow_resize) return false;
+
 	// later : remove unused pages in swap file
 
 	return true;
diff --git a/src/kernel/user/process.c b/src/kernel/user/process.c
index 4d79327..85530ca 100644
--- a/src/kernel/user/process.c
+++ b/src/kernel/user/process.c
@@ -500,7 +500,7 @@ bool mmap(process_t *proc, void* addr, size_t size, int mode) {
 	r->size = size;
 
 	r->own_pager = true;
-	r->pager = new_swap_pager(size);
+	r->pager = new_swap_pager(size, false);
 	if (r->pager == 0) goto error;
 	r->offset = 0;