From bc045fc7b082b426d7fc165fd07f8184ba2c7ef2 Mon Sep 17 00:00:00 2001
From: "Luke T. Shumaker" <lukeshu@lukeshu.com>
Date: Thu, 3 Oct 2024 13:09:43 -0600
Subject: lib9p: Allow specifying a maximum value for an atom in *.txt

---
 lib9p/9p.gen | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

(limited to 'lib9p/9p.gen')

diff --git a/lib9p/9p.gen b/lib9p/9p.gen
index f974dd1..6e01b17 100755
--- a/lib9p/9p.gen
+++ b/lib9p/9p.gen
@@ -90,6 +90,7 @@ class Member:
     cnt: str | None = None
     name: str
     typ: Atom | Bitfield | Struct
+    max: int | None = None
     ver: set[str]
 
     @property
@@ -101,7 +102,7 @@ class Member:
 
 re_membername = "(?:[a-zA-Z_][a-zA-Z_0-9]*)"
 re_memberspec = (
-    f"(?:(?P<cnt>{re_membername})\\*\\()?(?P<name>{re_membername})\\[(?P<typ>.*)\\]\\)?"
+    f"(?:(?P<cnt>{re_membername})\\*\\()?(?P<name>{re_membername})\\[(?P<typ>[^,]*)(?:,max=(?P<max>[0-9]+))?\\]\\)?"
 )
 
 
@@ -135,6 +136,11 @@ def parse_members(
                 raise ValueError(f"list count must be an integer type: {repr(cnt)}")
             member.cnt = cnt
 
+        if maxstr := m.group("max"):
+            if (not isinstance(member.typ, Atom)) or member.cnt:
+                raise ValueError(f"',max=' may only be specified on a non-repeated atom")
+            member.max = int(maxstr)
+
         ret += [member]
     return ret
 
@@ -549,11 +555,8 @@ static ALWAYS_INLINE bool _validate_size_host(struct _validate_ctx *ctx, size_t
 }
 
 static ALWAYS_INLINE bool _validate_list(struct _validate_ctx *ctx,
-                                         size_t cnt, size_t max,
+                                         size_t cnt,
                                          _validate_fn_t item_fn, size_t item_host_size) {
-	if (max && cnt > max)
-		return lib9p_errorf(ctx->ctx, LINUX_EBADMSG, "list size is too large (%zu > %zu)",
-		                    cnt, max);
 	for (size_t i = 0; i < cnt; i++)
 		if (_validate_size_host(ctx, item_host_size) || item_fn(ctx))
 			return true;
@@ -654,6 +657,7 @@ static ALWAYS_INLINE bool _validate_list(struct _validate_ctx *ctx,
 
                 prefix0 = "\treturn "
                 prefix1 = "\t    || "
+                prefix2 = "\t       "
 
                 struct_versions = typ.members[0].ver
 
@@ -665,14 +669,14 @@ static ALWAYS_INLINE bool _validate_list(struct _validate_ctx *ctx,
                         ret += "( " + c_vercond(idprefix, member.ver) + " && "
                     if member.cnt is not None:
                         assert prev_size
-                        maxelem = 0
-                        if (
-                            typ.name in ["Twalk", "Rwalk"] and member.name[:1] == "w"
-                        ):  # SPECIAL
-                            maxelem = 16
-                        ret += f"_validate_list(ctx, decode_u{prev_size*8}le(&ctx->net_bytes[ctx->net_offset-{prev_size}]), {maxelem}, validate_{member.typ.name}, sizeof({c_typename(idprefix, member.typ)}))"
+                        ret += f"_validate_list(ctx, decode_u{prev_size*8}le(&ctx->net_bytes[ctx->net_offset-{prev_size}]), validate_{member.typ.name}, sizeof({c_typename(idprefix, member.typ)}))"
                     else:
                         ret += f"validate_{member.typ.name}(ctx)"
+                        if member.max:
+                            ret += f"\n{prefix1}(decode_u{member.static_size*8}le(&ctx->net_bytes[ctx->net_offset-{member.static_size}]) > ({c_typename(idprefix, member.typ)})({member.max})"
+                            ret += f'\n{prefix2}\t? lib9p_errorf(ctx->ctx, LINUX_EBADMSG, "list size is too large (%"PRIu{member.static_size*8}" > %"PRIu{member.static_size*8}")",'
+                            ret += f"\n{prefix2}\t\tdecode_u{member.static_size*8}le(&ctx->net_bytes[ctx->net_offset-{member.static_size}]), ({c_typename(idprefix, member.typ)})({member.max}))"
+                            ret += f"\n{prefix2}\t: false)"
                     if member.ver != struct_versions:
                         ret += " )"
                     prefix = prefix1
-- 
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