Fixes and optimizations

Added FragManager so each frag block only gets decompressed once
Returned to C for decompression (only zstd stateless ATM)

build.zig

@@ -24,6 +24,16 @@ pub fn build(b: *std.Build) !void {
         .use_llvm = debug,
     });
 
+    const zstd = b.dependency("zstd", .{ .optimize = optimize, .target = target });
+    lib.root_module.linkLibrary(zstd.artifact("zstd"));
+
+    const c = b.addTranslateC(.{
+        .optimize = optimize,
+        .target = target,
+        .root_source_file = b.path("src/c.h"),
+    });
+    lib.root_module.addImport("c", c.createModule());
+
     var version = version_string_option orelse "0.0.0-testing";
     if (version[0] == 'v') version = version[1..];
     const unsquashfs_options = b.addOptions();

src/archive.zig

@@ -1,6 +1,7 @@
 const std = @import("std");
 const Io = std.Io;
 
+const Decomp = @import("decomp.zig");
 const ExtractionOptions = @import("options.zig");
 const File = @import("file.zig");
 const Inode = @import("inode.zig");
@@ -15,7 +16,7 @@ const Archive = @This();
 file: OffsetFile,
 super: Superblock,
 
-stateless_decomp: Decompressor,
+stateless_decomp: *const Decompressor,
 
 pub fn init(io: Io, file: std.Io.File, offset: u64) !Archive {
     var rdr = file.reader(io, &[0]u8{});
@@ -26,14 +27,7 @@ pub fn init(io: Io, file: std.Io.File, offset: u64) !Archive {
         .file = .init(file, offset),
         .super = super,
 
-        .stateless_decomp = switch (super.compression) {
-            .gzip => @import("decomp/zlib.zig").stateless_decompressor,
-            .lzma => @import("decomp/lzma.zig").stateless_decompressor,
-            .lzo => return error.LzoUnsupported,
-            .xz => @import("decomp/xz.zig").stateless_decompressor,
-            .lz4 => return error.Lz4Unsupported,
-            .zstd => @import("decomp/zstd.zig").stateless_decompressor,
-        },
+        .stateless_decomp = try Decomp.StatelessDecomp(super.compression),
     };
 }
 
@@ -43,7 +37,7 @@ pub fn root(self: Archive, alloc: std.mem.Allocator, io: Io) !File {
         alloc,
         io,
         self.file,
-        &self.stateless_decomp,
+        self.stateless_decomp,
         self.super.inode_start,
         self.super.block_size,
         self.super.root_ref,
@@ -65,7 +59,7 @@ pub fn extract(self: Archive, alloc: std.mem.Allocator, io: Io, extract_dir: []c
         alloc,
         io,
         self.file,
-        &self.stateless_decomp,
+        self.stateless_decomp,
         self.super.inode_start,
         self.super.block_size,
         self.super.root_ref,
@@ -128,14 +122,7 @@ pub const Superblock = extern struct {
     mod_time: u32,
     block_size: u32,
     frag_count: u32,
-    compression: enum(u16) {
-        gzip = 1,
-        lzma,
-        lzo,
-        xz,
-        lz4,
-        zstd,
-    },
+    compression: Decomp.Enum,
     block_log: u16,
     flags: packed struct(u16) {
         inode_uncompressed: bool,

src/bin/unsquashfs.zig

@@ -48,12 +48,14 @@ pub fn main(init: std.process.Init) !void {
     var out = stdout.writer(io, &[0]u8{});
     defer out.interface.flush() catch {};
 
-    try handleArgs(init.minimal.args, &out.interface);
-    if (archive.len == 0) {
-        try out.interface.print("You must provide a squashfs archive\n", .{});
-        try out.interface.print(help_mgs, .{});
-        return;
-    }
+    // try handleArgs(init.minimal.args, &out.interface);
+    // if (archive.len == 0) {
+    //     try out.interface.print("You must provide a squashfs archive\n", .{});
+    //     try out.interface.print(help_mgs, .{});
+    //     return;
+    // }
+    archive = "testing/LinuxPATest.sfs";
+    extLoc = "testing/LinuxPABinTest";
 
     var fil = try Io.Dir.cwd().openFile(io, archive, .{}); //TODO: Handle error gracefully.
     defer fil.close(io);

src/c.h

@@ -0,0 +1 @@
+#include <zstd.h>

src/decomp.zig

@@ -2,6 +2,26 @@ const std = @import("std");
 
 const Decompressor = @import("util/decompressor.zig");
 
+pub const Enum = enum(u16) {
+    gzip = 1,
+    lzma,
+    lzo,
+    xz,
+    lz4,
+    zstd,
+};
+
+pub fn StatelessDecomp(val: Enum) !*const Decompressor {
+    return switch (val) {
+        .gzip => &@import("decomp/zlib.zig").stateless_decompressor,
+        .lzma => &@import("decomp/lzma.zig").stateless_decompressor,
+        .lzo => error.LzoUnsupported,
+        .xz => &@import("decomp/xz.zig").stateless_decompressor,
+        .lz4 => error.Lz4Unsupported,
+        .zstd => &@import("decomp/zstd.zig").stateless_decompressor,
+    };
+}
+
 pub const Decomp = union(enum) {
     gzip: @import("decomp/zlib.zig"),
     lzma: @import("decomp/lzma.zig"),

src/decomp/zstd.zig

@@ -4,6 +4,8 @@ const Reader = std.Io.Reader;
 const zstd = std.compress.zstd;
 const Node = std.SinglyLinkedList.Node;
 
+const c = @import("c");
+
 const Decompressor = @import("../util/decompressor.zig");
 const Error = Decompressor.Error;
 
@@ -67,8 +69,14 @@ inline fn zstdDecomp(buffer: []u8, in: []u8, out: []u8) !usize {
 
 pub const stateless_decompressor: Decompressor = .{ .decomp_fn = statelessDecomp };
 
-fn statelessDecomp(_: ?*const Decompressor, alloc: std.mem.Allocator, in: []u8, out: []u8) Error!usize {
-    const buf = try alloc.alloc(u8, out.len + zstd.block_size_max);
-    defer alloc.free(buf);
-    return zstdDecomp(buf, in, out);
+fn statelessDecomp(d: ?*const Decompressor, alloc: std.mem.Allocator, in: []u8, out: []u8) Error!usize {
+    _ = d;
+    _ = alloc;
+    const res = c.ZSTD_decompress(out.ptr, out.len, in.ptr, in.len);
+    if (c.ZSTD_isError(res) == 1)
+        return Error.ReadFailed;
+    return res;
+    // const buf = try alloc.alloc(u8, out.len + zstd.block_size_max);
+    // defer alloc.free(buf);
+    // return zstdDecomp(buf, in, out);
 }

src/file.zig

@@ -37,7 +37,7 @@ pub fn init(alloc: std.mem.Allocator, archive: Archive, in: Inode, name: []const
 }
 pub fn fromDirEntry(alloc: std.mem.Allocator, io: Io, archive: Archive, ent: DirEntry) !File {
     var rdr = try archive.file.readerAt(io, archive.super.inode_start + ent.block_start, &[0]u8{});
-    var meta: MetadataReader = .init(alloc, &rdr.interface, &archive.stateless_decomp);
+    var meta: MetadataReader = .init(alloc, &rdr.interface, archive.stateless_decomp);
     try meta.interface.discardAll(ent.block_offset);
 
     var in: Inode = try .read(alloc, &meta.interface, archive.super.block_size);
@@ -54,7 +54,7 @@ pub fn open(self: File, alloc: std.mem.Allocator, io: Io, filepath: []const u8)
         alloc,
         io,
         self.archive.file,
-        &self.archive.stateless_decomp,
+        self.archive.stateless_decomp,
         self.archive.super.dir_start,
     );
     defer {

src/frag.zig

@@ -1,7 +1,84 @@
+const std = @import("std");
+const Io = std.Io;
+
 const BlockSize = @import("inode_data/file.zig").BlockSize;
+const LookupTable = @import("lookup_table.zig");
+const Decompressor = @import("util/decompressor.zig");
+const MetadataReader = @import("util/metadata.zig");
+const OffsetFile = @import("util/offset_file.zig");
+
+const FragManager = @This();
 
 pub const FragEntry = extern struct {
     start: u64,
     size: BlockSize,
     _: u32,
 };
+
+alloc: std.mem.Allocator,
+fil: OffsetFile,
+decomp: *const Decompressor,
+block_size: u32,
+
+entries: []FragEntry,
+
+frag_cache: std.array_hash_map.Auto(u32, []u8),
+cache_mut: std.Io.Mutex = .init,
+
+pub fn init(alloc: std.mem.Allocator, io: Io, fil: OffsetFile, decomp: *const Decompressor, frag_start: u64, frag_num: u32, block_size: u32) !FragManager {
+    var buf: [8 * 1024]u8 = undefined;
+    var rdr = try fil.readerAt(io, frag_start, &buf);
+    var first_offset: u64 = undefined;
+    try rdr.interface.readSliceEndian(u64, @ptrCast(&first_offset), .little);
+
+    rdr = try fil.readerAt(io, first_offset, &buf);
+    var meta: MetadataReader = .init(alloc, &rdr.interface, decomp);
+
+    const entries = try alloc.alloc(FragEntry, frag_num);
+    errdefer alloc.free(entries);
+
+    try meta.interface.readSliceEndian(FragEntry, entries, .little);
+
+    return .{
+        .alloc = alloc,
+        .fil = fil,
+        .decomp = decomp,
+        .block_size = block_size,
+
+        .entries = entries,
+
+        .frag_cache = .empty,
+    };
+}
+pub fn deinit(self: *FragManager, io: Io) void {
+    self.cache_mut.lockUncancelable(io);
+    self.alloc.free(self.entries);
+    for (self.frag_cache.values()) |v|
+        self.alloc.free(v);
+    self.frag_cache.deinit(self.alloc);
+}
+
+pub fn get(self: *FragManager, io: Io, idx: u32) ![]u8 {
+    if (self.frag_cache.contains(idx))
+        return self.frag_cache.get(idx).?;
+
+    try self.cache_mut.lock(io);
+    defer self.cache_mut.unlock(io);
+
+    const entry = self.entries[idx];
+
+    const out = try self.alloc.alloc(u8, if (entry.size.uncompressed) entry.size.size else self.block_size);
+
+    var buf: [1024 * 1024]u8 = undefined;
+    var rdr = try self.fil.readerAt(io, entry.start, &buf);
+    if (entry.size.uncompressed) {
+        try rdr.interface.readSliceAll(out);
+    } else {
+        @branchHint(.likely);
+        try rdr.interface.fill(entry.size.size);
+        _ = try self.decomp.Decompress(self.alloc, buf[0..entry.size.size], out);
+    }
+
+    try self.frag_cache.put(self.alloc, idx, out);
+    return out;
+}

src/util/data_extractor.zig

@@ -10,7 +10,7 @@ const OffsetFile = @import("offset_file.zig");
 
 // const SharedCache = @import("shared_cache.zig");
 
-pub const Error = error{OutOfMemory} || Io.File.Reader.SeekError || Io.Writer.Error;
+pub const Error = error{OutOfMemory} || Io.File.Reader.SeekError || Io.Writer.Error || Io.File.Writer.Error;
 
 const DataExtractor = @This();
 
@@ -23,7 +23,7 @@ start: u64,
 blocks: []BlockSize,
 
 frag_offset: u32 = 0,
-frag_entry: ?FragEntry = null,
+frag_block: ?[]u8 = null,
 
 err: ?Error = null,
 
@@ -38,14 +38,14 @@ pub fn init(fil: OffsetFile, decomp: *const Decompressor, block_size: u32, file_
         .blocks = blocks,
     };
 }
-pub fn addFrag(self: *DataExtractor, frag_offset: u32, entry: FragEntry) void {
+pub fn addFrag(self: *DataExtractor, frag_offset: u32, block: []u8) void {
     self.frag_offset = frag_offset;
-    self.frag_entry = entry;
+    self.frag_block = block;
 }
 
 fn numBlocks(self: DataExtractor) usize {
     var num = self.blocks.len;
-    if (self.frag_entry != null) num += 1;
+    if (self.frag_block != null) num += 1;
     return num;
 }
 
@@ -60,8 +60,8 @@ pub fn extractAsync(self: DataExtractor, alloc: std.mem.Allocator, io: Io, fil:
         group.async(io, blockThread, .{ self, alloc, io, fil, read_offset, idx, &err });
         read_offset += self.blocks[idx].size;
     }
-    if (self.frag_entry != null)
-        group.async(io, fragThread, .{ self, alloc, io, fil, &err });
+    if (self.frag_block != null)
+        group.async(io, fragThread, .{ self, io, fil, &err });
 
     group.await(io) catch |cancel| return err orelse cancel;
 }
@@ -126,55 +126,26 @@ fn blockThread(self: DataExtractor, alloc: std.mem.Allocator, io: Io, fil: Io.Fi
         };
     }
 }
-fn fragThread(self: DataExtractor, alloc: std.mem.Allocator, io: Io, fil: Io.File, ret_err: *?Error) Io.Cancelable!void {
-    const frag = self.frag_entry.?;
+fn fragThread(self: DataExtractor, io: Io, fil: Io.File, ret_err: *?Error) Io.Cancelable!void {
     const cur_block_size = self.file_size % self.block_size;
 
-    var wrt = fil.writer(io, &[0]u8{});
+    var write_buf: [10 * 1024]u8 = undefined;
+    var wrt = fil.writer(io, &write_buf);
     wrt.seekTo(self.blocks.len * self.block_size) catch |err| {
         ret_err.* = err;
         if (err == error.Canceled) io.recancel();
         return Io.Cancelable.Canceled;
     };
-    defer wrt.flush() catch {};
 
-    var rdr = self.fil.readerAt(io, frag.start, &[0]u8{}) catch |err| {
+    wrt.interface.writeAll(self.frag_block.?[self.frag_offset .. self.frag_offset + cur_block_size]) catch |err| {
         ret_err.* = err;
         if (err == error.Canceled) io.recancel();
         return Io.Cancelable.Canceled;
     };
-    if (frag.size.uncompressed) {
-        rdr.interface.discardAll(self.frag_offset) catch |err| {
-            ret_err.* = err;
-            if (err == error.Canceled) io.recancel();
-            return Io.Cancelable.Canceled;
-        };
-        rdr.interface.streamExact(&wrt.interface, cur_block_size) catch |err| {
-            ret_err.* = err;
-            if (err == error.Canceled) io.recancel();
-            return Io.Cancelable.Canceled;
-        };
-        return;
-    } else {
-        @branchHint(.likely);
 
-        var cache: [1024 * 1024]u8 = undefined;
-        var tmp: [1024 * 1024]u8 = undefined;
-
-        rdr.interface.readSliceAll(cache[0..frag.size.size]) catch |err| {
-            ret_err.* = err;
-            if (err == error.Canceled) io.recancel();
-            return Io.Cancelable.Canceled;
-        };
-        _ = self.decomp.Decompress(alloc, cache[0..frag.size.size], tmp[0..self.block_size]) catch |err| {
-            ret_err.* = err;
-            if (err == error.Canceled) io.recancel();
-            return Io.Cancelable.Canceled;
-        };
-        wrt.interface.writeAll(tmp[self.frag_offset .. self.frag_offset + cur_block_size]) catch |err| {
+    wrt.flush() catch |err| {
         ret_err.* = err;
         if (err == error.Canceled) io.recancel();
         return Io.Cancelable.Canceled;
     };
 }
-}

src/util/data_reader.zig

@@ -6,7 +6,6 @@ const Reader = Io.Reader;
 const Writer = Io.Writer;
 const Limit = Io.Limit;
 
-const FragEntry = @import("../frag.zig").FragEntry;
 const BlockSize = @import("../inode_data/file.zig").BlockSize;
 const Decompressor = @import("decompressor.zig");
 const OffsetFile = @import("offset_file.zig");
@@ -28,7 +27,7 @@ cur_offset: u64,
 blocks: []BlockSize,
 
 frag_offset: u32 = 0,
-frag_entry: ?FragEntry = null,
+frag_block: ?[]u8 = null,
 
 block_idx: usize = 0,
 sparse_block: bool = false,
@@ -64,14 +63,14 @@ pub fn init(alloc: std.mem.Allocator, io: Io, fil: OffsetFile, decomp: *const De
 pub fn deinit(self: *DataReader) void {
     self.alloc.free(self.interface.buffer);
 }
-pub fn addFrag(self: *DataReader, frag_offset: u32, entry: FragEntry) void {
+pub fn addFrag(self: *DataReader, frag_offset: u32, block: []u8) void {
     self.frag_offset = frag_offset;
-    self.frag_entry = entry;
+    self.frag_block = block;
 }
 
 fn numBlocks(self: DataReader) usize {
     var num = self.blocks.len;
-    if (self.frag_entry != null) num += 1;
+    if (self.frag_block != null) num += 1;
     return num;
 }
 fn advanceBuffer(self: *DataReader) !void {
@@ -81,26 +80,13 @@ fn advanceBuffer(self: *DataReader) !void {
     defer self.block_idx += 1;
 
     self.interface.end = if (self.block_idx == self.numBlocks() - 1)
-        self.size % self.block_size
+        self.file_size % self.block_size
     else
         self.block_size;
 
     // Fragment
     if (self.block_idx == self.blocks.len) {
-        const entry = self.frag_entry.?;
-        if (entry.size.uncompressed) {
-            var rdr = try self.fil.readerAt(self.io, entry.start + self.frag_offset, &[0]u8{});
-            try rdr.interface.readSliceAll(self.interface.buffer[0..self.interface.end]);
-        } else {
-            @branchHint(.likely);
-            const tmp = try self.cache.getOne(self.io);
-            defer self.cache.putOne(tmp) catch {};
-
-            var rdr = try self.fil.readerAt(self.io, entry.start, &[0]u8{});
-            try rdr.interface.readSliceAll(tmp.cache[0..entry.size.size]);
-            _ = try self.decomp.Decompress(self.alloc, tmp.cache[0..entry.size.size], self.interface.buffer[0..self.block_size]);
-            @memmove(self.interface.buffer[0..self.interface.end], self.interface.buffer[self.frag_offset .. self.frag_offset + self.interface.end]);
-        }
+        @memcpy(self.interface.buffer[0..self.interface.end], self.frag_block.?[self.frag_offset .. self.frag_offset + self.interface.end]);
         self.interface.seek = 0;
         return;
     }
@@ -120,12 +106,13 @@ fn advanceBuffer(self: *DataReader) !void {
     } else {
         @branchHint(.likely);
         const tmp = try self.cache.getOne(self.io);
-        defer self.cache.putOne(tmp) catch {};
+        defer self.cache.putOne(self.io, tmp) catch {};
 
-        var rdr = try self.fil.readerAt(self.io, self.cur_offset, &[0]u8{});
-        try rdr.interface.readSliceAll(tmp.cache[0..block.size]);
+        var rdr_buf: [50 * 1024]u8 = undefined;
+        var rdr = try self.fil.readerAt(self.io, self.cur_offset, &rdr_buf);
+        try rdr.interface.readSliceAll(tmp[0..block.size]);
         self.cur_offset += block.size;
-        _ = try self.decomp.Decompress(self.alloc, tmp.cache[0..block.size], self.interface.buffer[0..self.interface.end]);
+        _ = try self.decomp.Decompress(self.alloc, tmp[0..block.size], self.interface.buffer[0..self.interface.end]);
     }
     self.interface.seek = 0;
 }