replace ArrayLists with bounded storage

1 files changed, 82 insertions, 51 deletions

diff --git a/test/image_harness.zig b/test/image_harness.zig
index d4cb8955..601bce49 100644
--- a/test/image_harness.zig
+++ b/test/image_harness.zig
@@ -73,8 +73,27 @@ fn cleanupBase(arena: std.mem.Allocator, base: [:0]const u8) void {
     _ = libc.rmdir(base);
 }
 
-fn appendFmt(arena: std.mem.Allocator, out: *std.ArrayList(u8), comptime fmt: []const u8, args: anytype) !void {
-    try out.appendSlice(arena, try std.fmt.allocPrint(arena, fmt, args));
+const pdf_fixture_cap = 4096;
+
+const BoundedPdf = struct {
+    bytes: [pdf_fixture_cap]u8 = undefined,
+    len: usize = 0,
+
+    fn appendSlice(out: *BoundedPdf, bytes: []const u8) !void {
+        if (bytes.len > out.bytes.len - out.len) return error.FixturePdfTooLarge;
+        @memcpy(out.bytes[out.len..][0..bytes.len], bytes);
+        out.len += bytes.len;
+    }
+
+    fn written(out: *const BoundedPdf) []const u8 {
+        return out.bytes[0..out.len];
+    }
+};
+
+fn appendFmt(out: *BoundedPdf, comptime fmt: []const u8, args: anytype) !void {
+    const bytes = std.fmt.bufPrint(out.bytes[out.len..], fmt, args) catch
+        return error.FixturePdfTooLarge;
+    out.len += bytes.len;
 }
 
 /// A self-contained, valid PDF fixture. The first two pages retain the red /
@@ -83,6 +102,7 @@ fn appendFmt(arena: std.mem.Allocator, out: *std.ArrayList(u8), comptime fmt: []
 /// headers. Building it here keeps the backend test independent of mutool,
 /// fonts, and checked-in binary fixtures while the xref offsets remain exact.
 fn writePdf(arena: std.mem.Allocator, path: [:0]const u8) !void {
+    _ = arena;
     const first_stream =
         \\1 0 0 rg
         \\0 0 72 48 re
@@ -128,54 +148,63 @@ fn writePdf(arena: std.mem.Allocator, path: [:0]const u8) !void {
         \\ET
     ;
 
-    var out: std.ArrayList(u8) = .empty;
+    var out: BoundedPdf = .{};
     var offsets: [16]usize = @splat(0);
-    try out.appendSlice(arena, "%PDF-1.4\n%\xE2\xE3\xCF\xD3\n");
+    try out.appendSlice("%PDF-1.4\n%\xE2\xE3\xCF\xD3\n");
 
-    offsets[1] = out.items.len;
-    try out.appendSlice(arena, "1 0 obj\n<< /Type /Catalog /Pages 2 0 R /Outlines 12 0 R /PageMode /UseOutlines >>\nendobj\n");
-    offsets[2] = out.items.len;
-    try out.appendSlice(arena, "2 0 obj\n<< /Type /Pages /Count 4 /Kids [3 0 R 5 0 R 7 0 R 9 0 R] >>\nendobj\n");
-    offsets[3] = out.items.len;
-    try out.appendSlice(arena, "3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 72 48] /Resources << /Font << /F1 11 0 R >> >> /Contents 4 0 R >>\nendobj\n");
-    offsets[4] = out.items.len;
-    try appendFmt(arena, &out, "4 0 obj\n<< /Length {d} >>\nstream\n{s}endstream\nendobj\n", .{ first_stream.len, first_stream });
-    offsets[5] = out.items.len;
-    try out.appendSlice(arena, "5 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 72 48] /Resources << /Font << /F1 11 0 R >> >> /Contents 6 0 R >>\nendobj\n");
-    offsets[6] = out.items.len;
-    try appendFmt(arena, &out, "6 0 obj\n<< /Length {d} >>\nstream\n{s}endstream\nendobj\n", .{ second_stream.len, second_stream });
-    offsets[7] = out.items.len;
-    try out.appendSlice(arena, "7 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 72 50] /Resources << /Font << /F1 11 0 R >> >> /Contents 8 0 R >>\nendobj\n");
-    offsets[8] = out.items.len;
-    try appendFmt(arena, &out, "8 0 obj\n<< /Length {d} >>\nstream\n{s}endstream\nendobj\n", .{ third_stream.len, third_stream });
-    offsets[9] = out.items.len;
-    try out.appendSlice(arena, "9 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 72 52] /Resources << /Font << /F1 11 0 R >> >> /Contents 10 0 R >>\nendobj\n");
-    offsets[10] = out.items.len;
-    try appendFmt(arena, &out, "10 0 obj\n<< /Length {d} >>\nstream\n{s}endstream\nendobj\n", .{ fourth_stream.len, fourth_stream });
-    offsets[11] = out.items.len;
-    try out.appendSlice(arena, "11 0 obj\n<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>\nendobj\n");
-    offsets[12] = out.items.len;
-    try out.appendSlice(arena, "12 0 obj\n<< /Type /Outlines /First 13 0 R /Last 15 0 R /Count 3 >>\nendobj\n");
-    offsets[13] = out.items.len;
-    try out.appendSlice(arena, "13 0 obj\n<< /Title (Upper) /Parent 12 0 R /First 14 0 R /Last 14 0 R /Next 15 0 R /Count 1 /Dest [3 0 R /XYZ 4 8 null] >>\nendobj\n");
-    offsets[14] = out.items.len;
-    try out.appendSlice(arena, "14 0 obj\n<< /Title (Lower) /Parent 13 0 R /Dest [3 0 R /XYZ 4 28 null] >>\nendobj\n");
-    offsets[15] = out.items.len;
-    try out.appendSlice(arena, "15 0 obj\n<< /Title (Page two) /Parent 12 0 R /Prev 13 0 R /Dest [5 0 R /XYZ 4 38 null] >>\nendobj\n");
+    offsets[1] = out.len;
+    try out.appendSlice("1 0 obj\n<< /Type /Catalog /Pages 2 0 R /Outlines 12 0 R /PageMode /UseOutlines >>\nendobj\n");
+    offsets[2] = out.len;
+    try out.appendSlice("2 0 obj\n<< /Type /Pages /Count 4 /Kids [3 0 R 5 0 R 7 0 R 9 0 R] >>\nendobj\n");
+    offsets[3] = out.len;
+    try out.appendSlice("3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 72 48] /Resources << /Font << /F1 11 0 R >> >> /Contents 4 0 R >>\nendobj\n");
+    offsets[4] = out.len;
+    try appendFmt(&out, "4 0 obj\n<< /Length {d} >>\nstream\n{s}endstream\nendobj\n", .{ first_stream.len, first_stream });
+    offsets[5] = out.len;
+    try out.appendSlice("5 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 72 48] /Resources << /Font << /F1 11 0 R >> >> /Contents 6 0 R >>\nendobj\n");
+    offsets[6] = out.len;
+    try appendFmt(&out, "6 0 obj\n<< /Length {d} >>\nstream\n{s}endstream\nendobj\n", .{ second_stream.len, second_stream });
+    offsets[7] = out.len;
+    try out.appendSlice("7 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 72 50] /Resources << /Font << /F1 11 0 R >> >> /Contents 8 0 R >>\nendobj\n");
+    offsets[8] = out.len;
+    try appendFmt(&out, "8 0 obj\n<< /Length {d} >>\nstream\n{s}endstream\nendobj\n", .{ third_stream.len, third_stream });
+    offsets[9] = out.len;
+    try out.appendSlice("9 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 72 52] /Resources << /Font << /F1 11 0 R >> >> /Contents 10 0 R >>\nendobj\n");
+    offsets[10] = out.len;
+    try appendFmt(&out, "10 0 obj\n<< /Length {d} >>\nstream\n{s}endstream\nendobj\n", .{ fourth_stream.len, fourth_stream });
+    offsets[11] = out.len;
+    try out.appendSlice("11 0 obj\n<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>\nendobj\n");
+    offsets[12] = out.len;
+    try out.appendSlice("12 0 obj\n<< /Type /Outlines /First 13 0 R /Last 15 0 R /Count 3 >>\nendobj\n");
+    offsets[13] = out.len;
+    try out.appendSlice("13 0 obj\n<< /Title (Upper) /Parent 12 0 R /First 14 0 R /Last 14 0 R /Next 15 0 R /Count 1 /Dest [3 0 R /XYZ 4 8 null] >>\nendobj\n");
+    offsets[14] = out.len;
+    try out.appendSlice("14 0 obj\n<< /Title (Lower) /Parent 13 0 R /Dest [3 0 R /XYZ 4 28 null] >>\nendobj\n");
+    offsets[15] = out.len;
+    try out.appendSlice("15 0 obj\n<< /Title (Page two) /Parent 12 0 R /Prev 13 0 R /Dest [5 0 R /XYZ 4 38 null] >>\nendobj\n");
 
-    const xref = out.items.len;
-    try out.appendSlice(arena, "xref\n0 16\n0000000000 65535 f \n");
+    const xref = out.len;
+    try out.appendSlice("xref\n0 16\n0000000000 65535 f \n");
     for (offsets[1..]) |offset|
-        try appendFmt(arena, &out, "{d:0>10} 00000 n \n", .{offset});
-    try appendFmt(arena, &out, "trailer\n<< /Size 16 /Root 1 0 R >>\nstartxref\n{d}\n%%EOF\n", .{xref});
-    try eh.writeFile(path, out.items);
+        try appendFmt(&out, "{d:0>10} 00000 n \n", .{offset});
+    try appendFmt(&out, "trailer\n<< /Size 16 /Root 1 0 R >>\nstartxref\n{d}\n%%EOF\n", .{xref});
+    try eh.writeFile(path, out.written());
 }
 
 fn writePpm(arena: std.mem.Allocator, path: [:0]const u8, width: usize, height: usize) !void {
-    var out: std.ArrayList(u8) = .empty;
-    try out.appendSlice(arena, try std.fmt.allocPrint(arena, "P6\n{d} {d}\n255\n", .{ width, height }));
-    for (0..width * height) |_| try out.appendSlice(arena, &fixture_rgb);
-    try eh.writeFile(path, out.items);
+    var header_buf: [64]u8 = undefined;
+    const header = std.fmt.bufPrint(&header_buf, "P6\n{d} {d}\n255\n", .{ width, height }) catch
+        return error.FixturePpmHeaderTooLarge;
+    const pixel_count = try std.math.mul(usize, width, height);
+    const pixel_bytes = try std.math.mul(usize, pixel_count, fixture_rgb.len);
+    const out = try arena.alloc(u8, try std.math.add(usize, header.len, pixel_bytes));
+    @memcpy(out[0..header.len], header);
+    var offset = header.len;
+    for (0..pixel_count) |_| {
+        @memcpy(out[offset..][0..fixture_rgb.len], &fixture_rgb);
+        offset += fixture_rgb.len;
+    }
+    try eh.writeFile(path, out);
 }
 
 fn runKitty(arena: std.mem.Allocator, exe: [:0]const u8, base: [:0]const u8) !void {
@@ -656,16 +685,18 @@ fn readFile(allocator: std.mem.Allocator, path: [:0]const u8) ![]u8 {
     const fd = libc.open(path, .{ .ACCMODE = .RDONLY }, @as(libc.mode_t, 0));
     if (fd < 0) return error.OpenFailed;
     defer _ = libc.close(fd);
-    var out: std.ArrayList(u8) = .empty;
-    errdefer out.deinit(allocator);
-    var buf: [8192]u8 = undefined;
-    while (true) {
-        const n = libc.read(fd, &buf, buf.len);
+    const end = libc.lseek(fd, 0, libc.SEEK.END);
+    if (end < 0 or libc.lseek(fd, 0, libc.SEEK.SET) < 0) return error.ReadFailed;
+    const out = try allocator.alloc(u8, @intCast(end));
+    errdefer allocator.free(out);
+    var filled: usize = 0;
+    while (filled < out.len) {
+        const n = libc.read(fd, out[filled..].ptr, out.len - filled);
         if (n < 0) return error.ReadFailed;
-        if (n == 0) break;
-        try out.appendSlice(allocator, buf[0..@intCast(n)]);
+        if (n == 0) return error.UnexpectedEof;
+        filled += @intCast(n);
     }
-    return out.toOwnedSlice(allocator);
+    return out;
 }
 
 fn ppmPixels(bytes: []const u8) ?[]const u8 {