lib9p: Allow specifying a maximum value for an atom in *.txt

3 files changed, 30 insertions, 21 deletions

diff --git a/lib9p/9P2000.txt b/lib9p/9P2000.txt
index fa04fe0..9cdb943 100644
--- a/lib9p/9P2000.txt
+++ b/lib9p/9P2000.txt
@@ -133,8 +133,8 @@ bitfield o 8
 107/Rerror   = "ename[s]"
 108/Tflush   = "oldtag[2]"
 109/Rflush   = ""
-110/Twalk    = "fid[4] newfid[4] nwname[2] nwname*(wname[s])" # nwname has a maximum of 16
-111/Rwalk    = "nwqid[2] nwqid*(wqid[qid])" # nwname has a maximum of 16
+110/Twalk    = "fid[4] newfid[4] nwname[2,max=16] nwname*(wname[s])"
+111/Rwalk    = "nwqid[2,max=16] nwqid*(wqid[qid])"
 112/Topen    = "fid[4] mode[o]"
 113/Ropen    = "qid[qid] iounit[4]"
 114/Tcreate  = "fid[4] name[s] perm[dm] mode[o]"
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
diff --git a/lib9p/9p.generated.c b/lib9p/9p.generated.c
index 387af79..0259e23 100644
--- a/lib9p/9p.generated.c
+++ b/lib9p/9p.generated.c
@@ -311,11 +311,8 @@ 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;
@@ -464,12 +461,20 @@ static FLATTEN bool validate_Twalk(struct _validate_ctx *ctx) {
 	return validate_4(ctx)
 	    || validate_4(ctx)
 	    || validate_2(ctx)
-	    || _validate_list(ctx, decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), 16, validate_s, sizeof(struct lib9p_s));
+	    || (decode_u16le(&ctx->net_bytes[ctx->net_offset-2]) > (uint16_t)(16)
+	       	? lib9p_errorf(ctx->ctx, LINUX_EBADMSG, "list size is too large (%"PRIu16" > %"PRIu16")",
+	       		decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), (uint16_t)(16))
+	       	: false)
+	    || _validate_list(ctx, decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), validate_s, sizeof(struct lib9p_s));
 }
 
 static FLATTEN bool validate_Rwalk(struct _validate_ctx *ctx) {
 	return validate_2(ctx)
-	    || _validate_list(ctx, decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), 16, validate_qid, sizeof(struct lib9p_qid));
+	    || (decode_u16le(&ctx->net_bytes[ctx->net_offset-2]) > (uint16_t)(16)
+	       	? lib9p_errorf(ctx->ctx, LINUX_EBADMSG, "list size is too large (%"PRIu16" > %"PRIu16")",
+	       		decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), (uint16_t)(16))
+	       	: false)
+	    || _validate_list(ctx, decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), validate_qid, sizeof(struct lib9p_qid));
 }
 
 static FLATTEN bool validate_Topen(struct _validate_ctx *ctx) {
@@ -558,7 +563,7 @@ static FLATTEN bool validate_Rsession(struct _validate_ctx *UNUSED(ctx)) {
 static FLATTEN bool validate_Tsread(struct _validate_ctx *ctx) {
 	return validate_4(ctx)
 	    || validate_2(ctx)
-	    || _validate_list(ctx, decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), 0, validate_s, sizeof(struct lib9p_s));
+	    || _validate_list(ctx, decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), validate_s, sizeof(struct lib9p_s));
 }
 
 static FLATTEN bool validate_Rsread(struct _validate_ctx *ctx) {
@@ -568,7 +573,7 @@ static FLATTEN bool validate_Rsread(struct _validate_ctx *ctx) {
 static FLATTEN bool validate_Tswrite(struct _validate_ctx *ctx) {
 	return validate_4(ctx)
 	    || validate_2(ctx)
-	    || _validate_list(ctx, decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), 0, validate_s, sizeof(struct lib9p_s))
+	    || _validate_list(ctx, decode_u16le(&ctx->net_bytes[ctx->net_offset-2]), validate_s, sizeof(struct lib9p_s))
 	    || validate_d(ctx);
 }