From dff4234bf2d957a0328ff4f3dc4f9bba1fbeffd4 Mon Sep 17 00:00:00 2001
From: Martin Ashby <martin@ashbysoft.com>
Date: Sat, 11 Nov 2023 11:36:26 +0000
Subject: Extend meta info file parsing

---
 src/metainfo.zig | 54 +++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 47 insertions(+), 7 deletions(-)

(limited to 'src/metainfo.zig')

diff --git a/src/metainfo.zig b/src/metainfo.zig
index 9fa4788..a202b0e 100644
--- a/src/metainfo.zig
+++ b/src/metainfo.zig
@@ -2,6 +2,7 @@
 const std = @import("std");
 const bencode = @import("bencode.zig");
 const MetaInfo = @This();
+pub const Error = (error{Malformatted} || std.mem.Allocator.Error);
 
 pub const Info = struct {
     pub const File = struct {
@@ -12,36 +13,75 @@ pub const Info = struct {
     piece_length: u64,
     pieces: []const u8,
     files: []File,
-    pub fn parse(b: bencode.BValue) !Info {
+    pub fn parse(a: std.mem.Allocator, b: bencode.BValue) Error!Info {
         var d = b.asDict() catch return error.Malformatted;
         const pl = d.get("piece length") orelse return error.Malformatted;
         const pp = d.get("pieces") orelse return error.Malformatted;
+        var files = std.ArrayList(File).init(a);
+        defer files.deinit();
+        if (d.get("files")) |f| {
+            // multi-file mode
+            const l = f.asList() catch return error.Malformatted;
+            for (l.items) |fi| {
+                const fd = fi.asDict() catch return error.Malformatted;
+                const fin = fd.get("name") orelse return error.Malformatted;
+                const fl = fd.get("length") orelse return error.Malformatted;
+                const fp = fd.get("path") orelse return error.Malformatted;
+                try files.append(.{
+                    .name = fin.asString() catch return error.Malformatted,
+                    .length = fl.asInt(u64) catch return error.Malformatted,
+                    .path = fp.asString() catch return error.Malformatted,
+                });
+            }
+        } else {
+            // single-file mode
+            const fin = d.get("name") orelse return error.Malformatted;
+            const fl = d.get("length") orelse return error.Malformatted;
+            try files.append(.{
+                .name = fin.asString() catch return error.Malformatted,
+                .length = fl.asInt(u64) catch return error.Malformatted,
+                .path = fin.asString() catch return error.Malformatted, // just use the file name as path
+            });
+        }
+
         return .{
             .piece_length = pl.asInt(u64) catch return error.Malformatted,
             .pieces = pp.asString() catch return error.Malformatted,
-            .files = &[_]File{},
+            .files = try files.toOwnedSlice(),
         };
     }
+
+    pub fn deinit(self: *Info, a: std.mem.Allocator) void {
+        a.free(self.files);
+    }
 };
 
 info: Info,
 announce: []const u8,
 
-pub fn parse(b: bencode.BValue) !MetaInfo {
+pub fn parse(a: std.mem.Allocator, b: bencode.BValue) Error!MetaInfo {
+    // TODO diagnostics
     var d = b.asDict() catch return error.Malformatted;
     const i = d.get("info") orelse return error.Malformatted;
-    const a = d.get("announce") orelse return error.Malformatted;
+    const an = d.get("announce") orelse return error.Malformatted;
     return .{
-        .info = try Info.parse(i),
-        .announce = a.asString() catch return error.Malformatted,
+        .info = try Info.parse(a, i),
+        .announce = an.asString() catch return error.Malformatted,
     };
 }
 
+pub fn deinit(self: *MetaInfo, a: std.mem.Allocator) void {
+    self.info.deinit(a);
+}
+
 test "sample" {
     const a = std.testing.allocator;
     const sample_str = @embedFile("sample.torrent");
     var b = try bencode.bdecodeBuf(a, sample_str);
     defer b.deinit(a);
-    const mi = try MetaInfo.parse(b);
+    var mi = try MetaInfo.parse(a, b);
+    defer mi.deinit(a);
     try std.testing.expectEqualStrings("http://bittorrent-test-tracker.codecrafters.io/announce", mi.announce);
+    try std.testing.expectEqual(@as(usize, 1), mi.info.files.len);
+    try std.testing.expectEqualStrings("sample.txt", mi.info.files[0].name);
 }
-- 
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