first

.gitignore

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+/.zig-cache
+/zig-out
+

LICENSE

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+MIT License
+
+Copyright © 2004 Jeffrey C. Ollie
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# osc-fuzzer
+
+Simple OSC escape sequence fuzzer.
+
+This tries to break/crash terminal emulator by sending plausible, but random(ish) OSC
+sequences to the terminal. Hopefully your terminal doesn't crash.
+
+The last 1 MiB of data that was produced is saved to a file named `/tmp/osc-fuzzer-0x<timestamp>-0x<random seed>.txt`.
+
+A seed can be specified on the command line to replay a particular sequence of OSC sequences.

build.zig

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+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    const exe = b.addExecutable(.{
+        .name = "osc-fuzzer",
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    b.installArtifact(exe);
+    const run_cmd = b.addRunArtifact(exe);
+
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+
+    const exe_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
+
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&run_exe_unit_tests.step);
+}

build.zig.zon

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+.{
+    // This is the default name used by packages depending on this one. For
+    // example, when a user runs `zig fetch --save <url>`, this field is used
+    // as the key in the `dependencies` table. Although the user can choose a
+    // different name, most users will stick with this provided value.
+    //
+    // It is redundant to include "zig" in this name because it is already
+    // within the Zig package namespace.
+    .name = "osc-fuzzer",
+
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.0.0",
+
+    // This field is optional.
+    // This is currently advisory only; Zig does not yet do anything
+    // with this value.
+    //.minimum_zig_version = "0.11.0",
+
+    // This field is optional.
+    // Each dependency must either provide a `url` and `hash`, or a `path`.
+    // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+    // Once all dependencies are fetched, `zig build` no longer requires
+    // internet connectivity.
+    .dependencies = .{
+        // See `zig fetch --save <url>` for a command-line interface for adding dependencies.
+        //.example = .{
+        //    // When updating this field to a new URL, be sure to delete the corresponding
+        //    // `hash`, otherwise you are communicating that you expect to find the old hash at
+        //    // the new URL.
+        //    .url = "https://example.com/foo.tar.gz",
+        //
+        //    // This is computed from the file contents of the directory of files that is
+        //    // obtained after fetching `url` and applying the inclusion rules given by
+        //    // `paths`.
+        //    //
+        //    // This field is the source of truth; packages do not come from a `url`; they
+        //    // come from a `hash`. `url` is just one of many possible mirrors for how to
+        //    // obtain a package matching this `hash`.
+        //    //
+        //    // Uses the [multihash](https://multiformats.io/multihash/) format.
+        //    .hash = "...",
+        //
+        //    // When this is provided, the package is found in a directory relative to the
+        //    // build root. In this case the package's hash is irrelevant and therefore not
+        //    // computed. This field and `url` are mutually exclusive.
+        //    .path = "foo",
+
+        //    // When this is set to `true`, a package is declared to be lazily
+        //    // fetched. This makes the dependency only get fetched if it is
+        //    // actually used.
+        //    .lazy = false,
+        //},
+    },
+
+    // Specifies the set of files and directories that are included in this package.
+    // Only files and directories listed here are included in the `hash` that
+    // is computed for this package. Only files listed here will remain on disk
+    // when using the zig package manager. As a rule of thumb, one should list
+    // files required for compilation plus any license(s).
+    // Paths are relative to the build root. Use the empty string (`""`) to refer to
+    // the build root itself.
+    // A directory listed here means that all files within, recursively, are included.
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+        // For example...
+        //"LICENSE",
+        //"README.md",
+    },
+}

flake.lock

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+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1710146030,
+        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1725432240,
+        "narHash": "sha256-+yj+xgsfZaErbfYM3T+QvEE2hU7UuE+Jf0fJCJ8uPS0=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "ad416d066ca1222956472ab7d0555a6946746a80",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "ref": "nixos-unstable",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  inputs = {
+    nixpkgs = {
+      url = "nixpkgs/nixos-unstable";
+    };
+    flake-utils = {
+      url = "github:numtide/flake-utils";
+    };
+  };
+
+  outputs = {
+    nixpkgs,
+    flake-utils,
+    ...
+  }:
+    flake-utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+      in {
+        devShells.default = pkgs.mkShell {
+          nativeBuildInputs = [
+            pkgs.zig_0_13
+          ];
+          shellHook = ''
+            export name=osc-fuzzer
+          '';
+        };
+      }
+    );
+}

src/main.zig

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+const std = @import("std");
+
+pub fn CircularBuffer(comptime T: type) type {
+    const info = @typeInfo(T);
+    std.debug.assert(info == .Int);
+    std.debug.assert(info.Int.signedness == .unsigned);
+
+    return struct {
+        data: [std.math.maxInt(T) + 1]u8 = undefined,
+        head: T = 0,
+        tail: T = 0,
+        full: bool = false,
+
+        pub fn isEmpty(self: *CircularBuffer(T)) bool {
+            return self.head == self.tail and !self.full;
+        }
+
+        pub fn isFull(self: *CircularBuffer(T)) bool {
+            return self.full;
+        }
+
+        pub fn reset(self: *CircularBuffer(T)) void {
+            self.head = 0;
+            self.tail = 0;
+            self.full = false;
+        }
+
+        pub fn size(self: *CircularBuffer(size)) T {
+            if (self.full) return std.math.maxInt(T);
+            if (self.head >= self.tail) return @intCast(self.head - self.tail);
+            return @intCast(std.math.maxInt(T) + self.head - self.tail);
+        }
+
+        fn advance(self: *CircularBuffer(T)) void {
+            self.head +%= 1;
+            if (self.full) self.tail +%= 1;
+            self.full = self.head == self.tail;
+        }
+
+        fn retreat(self: *CircularBuffer(T)) void {
+            self.full = false;
+            self.tail -%= 1;
+        }
+
+        pub fn pushByte(self: *CircularBuffer(T), byte: u8) void {
+            self.data[self.head] = byte;
+            self.advance();
+        }
+
+        pub fn popByte(self: *CircularBuffer(T)) !u8 {
+            if (self.isEmpty()) return error.BufferEmpty;
+            defer self.retreat();
+            return self.data[self.tail];
+        }
+
+        pub fn pushAll(self: *CircularBuffer(T), data: []const u8) void {
+            if (data.len >= self.data.len) {
+                @memcpy(&self.data, data[(data.len - self.data.len)..]);
+                self.tail = 0;
+                self.head = 0;
+                self.full = true;
+                return;
+            }
+
+            for (data) |c| self.pushByte(c);
+        }
+
+        pub fn write(self: *CircularBuffer(T), writer: anytype) !void {
+            if (self.head <= self.tail) {
+                try writer.writeAll(self.data[self.tail..]);
+                try writer.writeAll(self.data[0..self.head]);
+            } else {
+                try writer.writeAll(self.data[self.tail..self.head]);
+            }
+        }
+    };
+}
+
+test "circular buffer 1" {
+    var cb = CircularBuffer(u2){};
+    cb.pushByte('a');
+    try std.testing.expect(!cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(1, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("a", result);
+}
+
+test "circular buffer 2" {
+    var cb = CircularBuffer(u2){};
+    cb.pushByte('a');
+    cb.pushByte('b');
+    cb.pushByte('c');
+    try std.testing.expect(!cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(3, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+    try std.testing.expectEqual('b', cb.data[1]);
+    try std.testing.expectEqual('c', cb.data[2]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("abc", result);
+}
+
+test "circular buffer 3" {
+    var cb = CircularBuffer(u2){};
+    cb.pushByte('a');
+    cb.pushByte('b');
+    cb.pushByte('c');
+    cb.pushByte('d');
+    cb.pushByte('e');
+    try std.testing.expect(cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(1, cb.tail);
+    try std.testing.expectEqual(1, cb.head);
+    try std.testing.expectEqual('e', cb.data[0]);
+    try std.testing.expectEqual('b', cb.data[1]);
+    try std.testing.expectEqual('c', cb.data[2]);
+    try std.testing.expectEqual('d', cb.data[3]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("bcde", result);
+}
+
+test "circular buffer 4" {
+    var cb = CircularBuffer(u2){};
+    cb.pushAll("a");
+    try std.testing.expect(!cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(1, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("a", result);
+}
+
+test "circular buffer 5" {
+    var cb = CircularBuffer(u2){};
+    cb.pushAll("ab");
+    try std.testing.expect(!cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(2, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+    try std.testing.expectEqual('b', cb.data[1]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("ab", result);
+}
+
+test "circular buffer 6" {
+    var cb = CircularBuffer(u2){};
+    cb.pushAll("abcd");
+    try std.testing.expect(cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(0, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+    try std.testing.expectEqual('b', cb.data[1]);
+    try std.testing.expectEqual('c', cb.data[2]);
+    try std.testing.expectEqual('d', cb.data[3]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("abcd", result);
+}
+
+test "circular buffer 7" {
+    var cb = CircularBuffer(u2){};
+    cb.pushAll("abcde");
+    try std.testing.expect(cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(0, cb.head);
+    try std.testing.expectEqual('b', cb.data[0]);
+    try std.testing.expectEqual('c', cb.data[1]);
+    try std.testing.expectEqual('d', cb.data[2]);
+    try std.testing.expectEqual('e', cb.data[3]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("bcde", result);
+}
+
+pub fn main() !void {
+    var cb = CircularBuffer(u20){};
+
+    const seed = seed: {
+        var buf: [4096]u8 = undefined;
+        var fba = std.heap.FixedBufferAllocator.init(&buf);
+
+        var args = try std.process.argsWithAllocator(fba.allocator());
+        defer args.deinit();
+
+        _ = args.next();
+
+        while (args.next()) |arg| {
+            break :seed try std.fmt.parseUnsigned(u64, arg, 0);
+        }
+
+        var seed: u64 = undefined;
+        try std.posix.getrandom(std.mem.asBytes(&seed));
+        break :seed seed;
+    };
+
+    var buffer = std.io.bufferedWriter(std.io.getStdOut().writer());
+    const stdout = buffer.writer();
+
+    var tmp = try std.fs.openDirAbsolute("/tmp", .{});
+    defer tmp.close();
+
+    var prng = std.rand.DefaultPrng.init(seed);
+    var random = prng.random();
+
+    var fn_buf: [std.fs.max_path_bytes]u8 = undefined;
+    const filename = try std.fmt.bufPrint(&fn_buf, "osc-fuzzer-0x{x:0>16}-0x{x:0>16}.txt", .{ @abs(std.time.timestamp()), seed });
+
+    var iteration: usize = 0;
+    while (true) : (iteration += 1) {
+        if (iteration & 0x3ff == 0) {
+            try stdout.writeByte('.');
+            try buffer.flush();
+        }
+
+        var osc_buf: [256]u8 = undefined;
+        var osc_fbs = std.io.fixedBufferStream(&osc_buf);
+        var osc_writer = osc_fbs.writer();
+        try osc_writer.print("\x1b]{d};", .{random.int(u12)});
+        for (0..random.int(u2)) |_| {
+            for (0..random.int(u4)) |_| {
+                try osc_writer.writeByte(byte: {
+                    while (true) {
+                        const b = random.int(u8);
+                        if (b != '\x1b' and b != '=' and b != ';') break :byte b;
+                    }
+                });
+            }
+            if (random.bool()) {
+                for (0..random.int(u5)) |_| {
+                    try osc_writer.writeByte(byte: {
+                        while (true) {
+                            const b = random.int(u8);
+                            if (b != '\x1b' and b != ';') break :byte b;
+                        }
+                    });
+                }
+            }
+        }
+        if (random.bool()) try osc_writer.writeByte(';');
+        try osc_writer.writeAll("\x1b\\");
+
+        const osc = osc_fbs.getWritten();
+
+        for (osc) |c| cb.pushByte(c);
+
+        var file = try tmp.atomicFile(filename, .{});
+        defer file.deinit();
+
+        try cb.write(file.file.writer());
+
+        // try file.file.writeAll(osc);
+        try file.finish();
+
+        try stdout.writeAll(osc);
+        try buffer.flush();
+    }
+}