Caleb Gardner
62 lines
2.4 KiB
Zig
62 lines
2.4 KiB
Zig
const std = @import("std");
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const Reader = @import("reader.zig").Reader;
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const DecompressType = @import("decompress.zig").DecompressType;
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const FileHolder = @import("readers/file_holder.zig").FileHolder;
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const FileOffsetReader = @import("readers/file_holder.zig").FileOffsetReader;
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const MetadataReader = @import("readers/metadata.zig").MetadataReader;
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const TableError = error{InvalidIndex};
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/// A lazily read squashfs table.
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pub fn Table(
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comptime T: type,
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) type {
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return struct {
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alloc: std.mem.Allocator,
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decomp: DecompressType,
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table: []T = &[0]T{},
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offset: u64,
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item_count: u32,
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pub fn init(read: *Reader, offset: u64, item_count: u32) Self {
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return .{
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.alloc = read.alloc,
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.decomp = read.super.decomp,
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.offset = offset,
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.item_count = item_count,
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};
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}
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pub fn deinit(self: *Self, alloc: std.mem.Allocator) void {
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alloc.free(self.table);
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}
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pub fn getValue(self: *Self, read: *Reader, i: u64) !T {
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if (i >= self.item_count) return TableError.InvalidIndex;
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if (self.table.len > i) return self.table[i];
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var meta_rdr: MetadataReader = undefined;
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var offset_rdr: FileOffsetReader = undefined;
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var meta_offset: u64 = 0;
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var to_read: u32 = 0;
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while (self.table.len <= i) {
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_ = try read.holder.file.preadAll(std.mem.sliceAsBytes(&meta_offset), self.offset);
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self.offset += 8;
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offset_rdr = read.holder.readerAt(meta_offset);
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meta_rdr = .init(self.alloc, self.decomp, offset_rdr.any());
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defer meta_rdr.deinit();
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to_read = @min(self.item_count - self.table.len, comptime blk: {
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break :blk 8192 / @sizeOf(T);
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});
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if (!self.alloc.resize(self.table, self.table.len + to_read)) {
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const alloc_size = self.table.len + to_read;
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self.alloc.free(self.table);
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self.table = try self.alloc.alloc(T, alloc_size);
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}
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_ = try meta_rdr.any().readAll(std.mem.asBytes(self.table[self.table.len - to_read ..]));
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}
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return self.table[i];
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}
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const Self: type = @This();
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};
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}
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