lib9p_srv: Cap Tread->count

6 files changed, 33 insertions, 25 deletions

diff --git a/lib9p/core.c b/lib9p/core.c
index adf7ecf..03cdea5 100644
--- a/lib9p/core.c
+++ b/lib9p/core.c
@@ -125,9 +125,14 @@ const char *lib9p_version_str(enum lib9p_version ver) {
 	return _lib9p_table_ver[ver].name;
 }
 
-uint32_t lib9p_version_min_msg_size(enum lib9p_version ver) {
+uint32_t lib9p_version_min_Rerror_size(enum lib9p_version ver) {
 	assert_ver(ver);
-	return _lib9p_table_ver[ver].min_msg_size;
+	return _lib9p_table_ver[ver].min_Rerror_size;
+}
+
+uint32_t lib9p_version_min_Rread_size(enum lib9p_version ver) {
+	assert_ver(ver);
+	return _lib9p_table_ver[ver].min_Rread_size;
 }
 
 const char *lib9p_msgtype_str(enum lib9p_version ver, enum lib9p_msg_type typ) {
diff --git a/lib9p/core_gen/c.py b/lib9p/core_gen/c.py
index 998031b..b0ff871 100644
--- a/lib9p/core_gen/c.py
+++ b/lib9p/core_gen/c.py
@@ -123,18 +123,15 @@ def gen_c(versions: set[str], typs: list[idl.UserType]) -> str:
     ret += "\n"
     ret += f"const struct {c9util.ident('_ver_tentry')} {c9util.ident('_table_ver')}[{c9util.ver_enum('NUM')}] = {{\n"
     rerror = next(typ for typ in typs if typ.typname == "Rerror")
+    rlerror = next(typ for typ in typs if typ.typname == "Rlerror")
+    rread = next(typ for typ in typs if typ.typname == "Rread")
     for ver in sorted(versions):
-        # XXX: There are good arguments that min_msg_size should be
-        # something larger than rerror.min_size().
-        # srv.c:respond_error() assumes that min_msg_size is
-        # rerror.min_size(); if you do change min_msg_size to
-        # something larger, then be sure to update respond_error().
         ret += cutil.ifdef_push(1, c9util.ver_ifdef({ver}))
-        min_msg_size = rerror.min_size(ver)
+        min_rerror_size = rerror.min_size(ver)
         if ver == "9P2000.L":  # SPECIAL (9P2000.L)
-            rlerror = next(typ for typ in typs if typ.typname == "Rlerror")
-            min_msg_size = rlerror.min_size(ver)
-        ret += f'\t[{c9util.ver_enum(ver)}] = {{.name="{ver}", .min_msg_size={min_msg_size}}},\n'
+            min_rerror_size = rlerror.min_size(ver)
+        min_rread_size = rread.min_size(ver)
+        ret += f'\t[{c9util.ver_enum(ver)}] = {{.name="{ver}", .min_Rerror_size={min_rerror_size}, .min_Rread_size={min_rread_size}}},\n'
     ret += cutil.ifdef_pop(0)
     ret += "};\n"
 
diff --git a/lib9p/core_generated.c b/lib9p/core_generated.c
index 4d9ba6a..1de7c67 100644
--- a/lib9p/core_generated.c
+++ b/lib9p/core_generated.c
@@ -7851,22 +7851,22 @@ static void lib9p_msg_Rswrite_format(struct lib9p_msg_Rswrite *self, struct fmt_
 
 const struct _lib9p_ver_tentry _lib9p_table_ver[LIB9P_VER_NUM] = {
 #if CONFIG_9P_ENABLE_9P2000
-	[LIB9P_VER_9P2000] = {.name="9P2000", .min_msg_size=9},
+	[LIB9P_VER_9P2000] = {.name="9P2000", .min_Rerror_size=9, .min_Rread_size=11},
 #endif /* CONFIG_9P_ENABLE_9P2000 */
 #if CONFIG_9P_ENABLE_9P2000_L
-	[LIB9P_VER_9P2000_L] = {.name="9P2000.L", .min_msg_size=11},
+	[LIB9P_VER_9P2000_L] = {.name="9P2000.L", .min_Rerror_size=11, .min_Rread_size=11},
 #endif /* CONFIG_9P_ENABLE_9P2000_L */
 #if CONFIG_9P_ENABLE_9P2000_e
-	[LIB9P_VER_9P2000_e] = {.name="9P2000.e", .min_msg_size=9},
+	[LIB9P_VER_9P2000_e] = {.name="9P2000.e", .min_Rerror_size=9, .min_Rread_size=11},
 #endif /* CONFIG_9P_ENABLE_9P2000_e */
 #if CONFIG_9P_ENABLE_9P2000_p9p
-	[LIB9P_VER_9P2000_p9p] = {.name="9P2000.p9p", .min_msg_size=9},
+	[LIB9P_VER_9P2000_p9p] = {.name="9P2000.p9p", .min_Rerror_size=9, .min_Rread_size=11},
 #endif /* CONFIG_9P_ENABLE_9P2000_p9p */
 #if CONFIG_9P_ENABLE_9P2000_u
-	[LIB9P_VER_9P2000_u] = {.name="9P2000.u", .min_msg_size=13},
+	[LIB9P_VER_9P2000_u] = {.name="9P2000.u", .min_Rerror_size=13, .min_Rread_size=11},
 #endif /* CONFIG_9P_ENABLE_9P2000_u */
 #if CONFIG_9P_ENABLE_uninitialized
-	[LIB9P_VER_uninitialized] = {.name="uninitialized", .min_msg_size=9},
+	[LIB9P_VER_uninitialized] = {.name="uninitialized", .min_Rerror_size=9, .min_Rread_size=0},
 #endif /* CONFIG_9P_ENABLE_uninitialized */
 };
 
diff --git a/lib9p/core_include/lib9p/core.h b/lib9p/core_include/lib9p/core.h
index b6d149b..549411f 100644
--- a/lib9p/core_include/lib9p/core.h
+++ b/lib9p/core_include/lib9p/core.h
@@ -77,7 +77,8 @@ bool lib9p_ctx_has_error(struct lib9p_ctx *ctx);
 
 /* misc utilities *************************************************************/
 
-uint32_t lib9p_version_min_msg_size(enum lib9p_version);
+uint32_t lib9p_version_min_Rerror_size(enum lib9p_version);
+uint32_t lib9p_version_min_Rread_size(enum lib9p_version);
 
 lo_interface fmt_formatter lo_box_lib9p_msg_as_fmt_formatter(struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body);
 
diff --git a/lib9p/core_tables.h b/lib9p/core_tables.h
index 17e9398..da2027a 100644
--- a/lib9p/core_tables.h
+++ b/lib9p/core_tables.h
@@ -13,7 +13,8 @@
 
 struct _lib9p_ver_tentry {
 	const char      *name;
-	uint32_t         min_msg_size;
+	uint32_t         min_Rerror_size;
+	uint32_t         min_Rread_size;
 };
 
 extern const struct _lib9p_ver_tentry _lib9p_table_ver[LIB9P_VER_NUM];
diff --git a/lib9p/srv.c b/lib9p/srv.c
index befeb6a..6d9d992 100644
--- a/lib9p/srv.c
+++ b/lib9p/srv.c
@@ -393,10 +393,7 @@ static void srv_respond_error(struct srv_req *req) {
 
 	struct srv_sess *sess = req->parent_sess;
 
-	/* XXX: This assumes that a version's min_msg_size is the
-	 * Rerror overhead.  That's true for the current
-	 * implementation of core_gen, but is a sneaky assumption.  */
-	uint32_t overhead = lib9p_version_min_msg_size(sess->version);
+	uint32_t overhead = lib9p_version_min_Rerror_size(sess->version);
 
 	/* Truncate the error-string if necessary to avoid needing to
 	 * return LIB9P_ERRNO_L_ERANGE.  */
@@ -748,7 +745,11 @@ static void handle_Tversion(struct srv_req *ctx,
 #endif
 	}
 
-	uint32_t min_msg_size = lib9p_version_min_msg_size(version);
+	/* XXX: There are good arguments that min_msg_size should be
+	 * something larger than max(rerror.min_size(),
+	 * rread.min_size()+1).  */
+	uint32_t min_msg_size = _LIB9P_MAX(lib9p_version_min_Rerror_size(ctx->basectx.version),
+	                                   lib9p_version_min_Rread_size(ctx->basectx.version)+1);
 	if (req->max_msg_size < min_msg_size) {
 		lib9p_errorf(&ctx->basectx,
 		             LIB9P_ERRNO_L_EDOM, "requested max_msg_size is less than minimum for %s (%"PRIu32" < %"PRIu32")",
@@ -1175,6 +1176,9 @@ static void handle_Tread(struct srv_req *ctx,
 
 	/* TODO: serialize simultaneous reads to the same FID */
 
+	if (req->count > ctx->basectx.max_msg_size - lib9p_version_min_Rread_size(ctx->basectx.version))
+		req->count = ctx->basectx.max_msg_size - lib9p_version_min_Rread_size(ctx->basectx.version);
+
 	/* Check that the FID is valid for this.  */
 	struct srv_fidinfo *fidinfo = map_load(&ctx->parent_sess->fids, req->fid);
 	if (!fidinfo) {
@@ -1205,7 +1209,7 @@ static void handle_Tread(struct srv_req *ctx,
 			goto tread_return;
 		}
 		/* Read.  */
-		resp.data = heap = malloc(req->count); /* TODO: cap req->count */
+		resp.data = heap = malloc(req->count);
 		resp.count = 0;
 		struct srv_pathinfo *dir_pathinfo = NULL;
 		for (;;) {