Make extraction buffer bigger

Tiny buffer for extracting led to worse performance, so increase the
size of it to where it should be able to accomodate SquashFS's max 1MiB
block size and now allocate libdeflate_decompressor on the stack. This
should make it thread-safe, but hasn't appeared to make much of a
performance impact and finally updated README.md, removing the reference
to `squashfuse_tool` and changing the time to the new improved
performance

README.md

@@ -12,11 +12,11 @@ My main goals for this project are as follows:
    but the vast majority is still just bindings
 
 With some very basic benchmarking, extracting a zlib-compressed AppImage
-(FreeCAD, the largest AppImage I've been able to find so far), takes 3.7
-seconds using squashfuse-zig's `squashfuse_tool`. Currently, `squashfs_tool`
-is single-thread only.
+(FreeCAD, the largest AppImage I've been able to find so far), takes 3.1
+seconds using the `--extract` flag with squashfuse-zig's CLI tool, which
+is currently single-thread only.
 
-For reference, `unsquashfs` with multi-threaded decompression takes 1.57 seconds
+For reference, `unsquashfs` with multi-threaded decompression takes 1.5 seconds
 and single-threaded takes 6.5 seconds.
 
 Surely almost all of the single-threaded performace gain can be chalked up to

lib/SquashFs.zig

@@ -650,15 +650,42 @@ usingnamespace if (build_options.enable_zlib)
             *usize,
         ) c_int;
 
-        var ldef_decompressor: ?*anyopaque = null;
+        // Deflate constants
+        const litlen_syms = 288;
+        const offset_syms = 32;
+        const max_lens_overrun = 137;
+        const max_num_syms = 288;
+        const precode_syms = 19;
+
+        // LibDeflate constants
+        const precode_enough = 128;
+        const litlen_enough = 2342;
+        const offset_enough = 402;
+
+        const Decompressor = extern struct {
+            _: extern union {
+                precode_lens: [precode_syms]u8,
+
+                _: extern struct {
+                    lens: [litlen_syms + offset_syms + max_lens_overrun]u8,
+                    precode_table: [precode_enough]u32,
+                },
+
+                litlen_decode_table: [litlen_enough]u32,
+            } = undefined,
+
+            offset_decode_table: [offset_enough]u32 = undefined,
+            sorted_syms: [max_num_syms]u16 = undefined,
+            static_codes_loaded: bool = false,
+            litlen_tablebits: u32 = undefined,
+            free_func: ?*anyopaque = undefined,
+        };
 
         export fn zig_zlib_decode(in: [*]u8, in_size: usize, out: [*]u8, out_size: *usize) callconv(.C) c.sqfs_err {
-            if (ldef_decompressor == null) {
-                ldef_decompressor = libdeflate_alloc_decompressor();
-            }
+            var decompressor = Decompressor{};
 
             const err = libdeflate_zlib_decompress(
-                ldef_decompressor.?,
+                &decompressor,
                 in,
                 in_size,
                 out,

lib/test.zig

@@ -17,6 +17,7 @@ test "open SquashFS image (zlib)" {
 }
 
 // TODO: more tests
+// TODO: test executable mounting, extracting, etc
 fn testWalk(allocator: std.mem.Allocator, sqfs: *SquashFs) !void {
     var root_inode = sqfs.getRootInode();
 

src/squashfuse.zig

@@ -29,18 +29,19 @@ pub fn main() !void {
     var stdout = std.io.getStdOut().writer();
 
     const params = comptime clap.parseParamsComptime(
-        \\-h, --help               display this help and exit
-        \\-f, --foreground         run in foreground
-        \\-d, --debug              enable debug output (runs in foreground)
-        \\-x, --extract            extract the SquashFS image
-        \\-l, --list               list file tree of SquashFS image
-        \\-o, --option <str>...    use a libFUSE mount option
+        \\-h, --help             display this help and exit
+        \\-f, --foreground       run in foreground
+        \\-d, --debug            enable debug output (runs in foreground)
+        \\-x, --extract          extract the SquashFS image
+        \\-l, --list             list file tree of SquashFS image
+        \\-o, --option <str>...  use a libFUSE mount option
+        \\
+        \\--offset <usize>      mount at an offset
+        \\--extract-src <str>   must be used with `--extract`; specify the source inode
+        \\--extract-dest <str>  must be used with `--extract`; specify the destination name
+        \\--version             print the current version
+        \\--verbose             enable verbose printing
         \\
-        \\    --offset <usize>  mount at an offset
-        \\    --extract-src <str>  must be used with `--extract`; specify the source inode
-        \\    --extract-dest <str> must be used with `--extract`; specify the destination name
-        \\    --version         print the current version
-        \\    --verbose         enable verbose printing
         \\<str>...
     );
 
@@ -467,6 +468,11 @@ fn extractArchive(
 
     var file_found = false;
 
+    // TODO: flag to change buf size
+    const buf_size = 1024 * 1024;
+    const buf = try allocator.alloc(u8, buf_size);
+    defer allocator.free(buf);
+
     // Iterate over the SquashFS image and extract each item
     while (try walker.next()) |entry| {
         // Skip if the path doesn't match our source
@@ -503,13 +509,11 @@ fn extractArchive(
             try stdout.print("{s}\n", .{prefixed_dest});
         }
 
-        // TODO: flag to change buf size
-        var buf: [4096]u8 = undefined;
-
         var inode = entry.inode();
-        try inode.extract(&buf, prefixed_dest);
+        try inode.extract(buf, prefixed_dest);
     }
 
+    // TODO: better error message
     if (!file_found) {
         std.debug.print("file ({s}) not found!\n", .{real_src});
     }