From 5f24c4a2284a0af84fb9d116f7a39f6a58e42ae9 Mon Sep 17 00:00:00 2001
From: Gabriel Schneider <gbrls@0x4200.cafe>
Date: Mon, 14 Sep 2026 14:10:28 -0300
Subject: Implement base 9P2000 sessions, shared transports, and conformance
 probes

---
 test/fuzz.zig | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 test/fuzz.zig

(limited to 'test/fuzz.zig')

diff --git a/test/fuzz.zig b/test/fuzz.zig
new file mode 100644
index 0000000..b7d9f21
--- /dev/null
+++ b/test/fuzz.zig
@@ -0,0 +1,70 @@
+//! Deterministic local robustness probes; reference implementations see valid traffic only.
+const std = @import("std");
+const c9 = @import("cloud9");
+pub fn main(init: std.process.Init) !void {
+    const args = try init.minimal.args.toSlice(init.arena.allocator());
+    const seed = if (args.len > 1) try std.fmt.parseInt(u64, args[1], 10) else 4200;
+    const iterations = if (args.len > 2) try std.fmt.parseInt(u32, args[2], 10) else 100000;
+    if (args.len > 3 or iterations > 10000000) return error.Arguments;
+    var prng: std.Random.DefaultPrng = .init(seed);
+    const random = prng.random();
+    var accepted: usize = 0;
+    var rejected: usize = 0;
+    var buffer: [8192]u8 = undefined;
+    var encoded: [8192]u8 = undefined;
+    var payload: [4096]u8 = undefined;
+    var server_in: [8192]u8 = undefined;
+    var server_out: [8192]u8 = undefined;
+    for (0..iterations) |_| {
+        random.bytes(&payload);
+        const data = payload[0..random.uintLessThan(usize, payload.len)];
+        const qid: c9.Qid = .{ .type = random.int(u8), .version = random.int(u32), .path = random.int(u64) };
+        const stat: c9.Stat = .{
+            .type = 0,
+            .dev = 0,
+            .qid = qid,
+            .mode = random.int(u32),
+            .atime = 0,
+            .mtime = 0,
+            .length = random.int(u64),
+            .name = "file",
+            .uid = "user",
+            .gid = "group",
+            .muid = "",
+        };
+        const messages = [_]c9.Msg{
+            .{ .tversion = .{ .msize = 8192, .version = "9P2000" } },
+            .{ .twalk = .{ .fid = 0, .newfid = 1, .nwname = 16, .wname = @splat("dir") } },
+            .{ .rwalk = .{ .nwqid = 16, .wqid = @splat(qid) } },
+            .{ .twrite = .{ .fid = random.int(u32), .offset = random.int(u64), .data = data } },
+            .{ .rread = .{ .data = data } },
+            .{ .rstat = .{ .stat = stat } },
+            .{ .twstat = .{ .fid = 1, .stat = stat } },
+            .{ .tflush = .{ .oldtag = random.int(u16) } },
+            .{ .tread = .{ .fid = 1, .offset = random.int(u64), .count = random.int(u32) } },
+        };
+        const msg = messages[random.uintLessThan(usize, messages.len)];
+        var frame: []u8 = try c9.encode(msg, random.int(u16), &buffer);
+        // Leave some valid seeds unchanged; probe truncation and altered fields locally.
+        switch (random.uintLessThan(u8, 4)) {
+            0 => {},
+            1 => frame = frame[0..random.uintLessThan(usize, frame.len)],
+            2 => frame[random.uintLessThan(usize, frame.len)] ^= random.int(u8),
+            3 => std.mem.writeInt(u32, frame[0..4], random.int(u32), .little),
+            else => unreachable,
+        }
+        if (c9.decode(frame)) |decoded| {
+            const output = try c9.encode(decoded.msg, decoded.tag, &encoded);
+            if (!std.mem.eql(u8, frame, output)) return error.RoundTrip;
+            accepted += 1;
+        } else |_| rejected += 1;
+        var server: c9.Server = .init(.{ .in = &server_in, .out = &server_out });
+        _ = server.push(frame);
+        if (server.receive() catch null) |request| {
+            if (request.msg != .tversion) return error.BeforeVersion;
+            server.negotiate(request.msg.tversion.msize, request.msg.tversion.version) catch {};
+            server.release();
+        }
+    }
+    std.debug.print("seed={d} iterations={d} accepted={d} rejected={d}\n", .{ seed, iterations, accepted, rejected });
+}
-- 
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