Expose files' begin and end pieces via RPC (#5578)

* Expose files' begin and end pieces via RPC

This adds two arguments, `beginPiece` and `endPiece`, for each of the entries
in the `files` array of the RPC's `torrent-`get` method.

The point is to allow RPC clients to display a file's completion progress as
piece-based in addition to byte-based.

docs/rpc-spec.md

@@ -294,6 +294,8 @@ The 'source' column here corresponds to the data structure there.
 | `bytesCompleted` | number | tr_file_view
 | `length` | number | tr_file_view
 | `name` | string | tr_file_view
+| `beginPiece` | number | tr_file_view
+| `endPiece` | number | tr_file_view
 
 
 `fileStats`: a file's non-constant properties. An array of `tr_info.filecount` objects, each containing:
@@ -1009,3 +1011,5 @@ Transmission 4.1.0 (`rpc-version-semver` 5.4.0, `rpc-version`: 18)
 |:---|:---
 | `torrent-get` | new arg `sequentialDownload`
 | `torrent-set` | new arg `sequentialDownload`
+| `torrent-get` | new arg `files.beginPiece`
+| `torrent-get` | new arg `files.endPiece`

libtransmission/quark.cc

@@ -18,7 +18,7 @@ using namespace std::literals;
 namespace
 {
 
-auto constexpr MyStatic = std::array<std::string_view, 402>{ ""sv,
+auto constexpr MyStatic = std::array<std::string_view, 404>{ ""sv,
                                                              "activeTorrentCount"sv,
                                                              "activity-date"sv,
                                                              "activityDate"sv,
@@ -47,6 +47,7 @@ auto constexpr MyStatic = std::array<std::string_view, 402>{ ""sv,
                                                              "availability"sv,
                                                              "bandwidth-priority"sv,
                                                              "bandwidthPriority"sv,
+                                                             "beginPiece"sv,
                                                              "bind-address-ipv4"sv,
                                                              "bind-address-ipv6"sv,
                                                              "bitfield"sv,
@@ -108,6 +109,7 @@ auto constexpr MyStatic = std::array<std::string_view, 402>{ ""sv,
                                                              "editDate"sv,
                                                              "encoding"sv,
                                                              "encryption"sv,
+                                                             "endPiece"sv,
                                                              "error"sv,
                                                              "errorString"sv,
                                                              "eta"sv,

libtransmission/quark.h

@@ -50,6 +50,7 @@ enum
     TR_KEY_availability, // rpc
     TR_KEY_bandwidth_priority,
     TR_KEY_bandwidthPriority,
+    TR_KEY_beginPiece,
     TR_KEY_bind_address_ipv4,
     TR_KEY_bind_address_ipv6,
     TR_KEY_bitfield,
@@ -111,6 +112,7 @@ enum
     TR_KEY_editDate,
     TR_KEY_encoding,
     TR_KEY_encryption,
+    TR_KEY_endPiece,
     TR_KEY_error,
     TR_KEY_errorString,
     TR_KEY_eta,

libtransmission/rpcimpl.cc

@@ -326,8 +326,10 @@ void addFiles(tr_torrent const* tor, tr_variant* list)
     for (tr_file_index_t i = 0, n = tor->file_count(); i < n; ++i)
     {
         auto const file = tr_torrentFile(tor, i);
-        tr_variant* d = tr_variantListAddDict(list, 3);
+        tr_variant* d = tr_variantListAddDict(list, 5);
+        tr_variantDictAddInt(d, TR_KEY_beginPiece, file.beginPiece);
         tr_variantDictAddInt(d, TR_KEY_bytesCompleted, file.have);
+        tr_variantDictAddInt(d, TR_KEY_endPiece, file.endPiece);
         tr_variantDictAddInt(d, TR_KEY_length, file.length);
         tr_variantDictAddStr(d, TR_KEY_name, file.name);
     }

libtransmission/torrent.cc

@@ -1615,14 +1615,15 @@ tr_file_view tr_torrentFile(tr_torrent const* tor, tr_file_index_t file)
     auto const priority = tor->file_priorities_.file_priority(file);
     auto const wanted = tor->files_wanted_.file_wanted(file);
     auto const length = tor->file_size(file);
+    auto const [begin, end] = tor->pieces_in_file(file);
 
     if (tor->completeness == TR_SEED || length == 0)
     {
-        return { subpath.c_str(), length, length, 1.0, priority, wanted };
+        return { subpath.c_str(), length, length, 1.0, begin, end, priority, wanted };
     }
 
     auto const have = tor->completion.count_has_bytes_in_span(tor->fpm_.byte_span(file));
-    return { subpath.c_str(), have, length, have >= length ? 1.0 : have / double(length), priority, wanted };
+    return { subpath.c_str(), have, length, have >= length ? 1.0 : have / double(length), begin, end, priority, wanted };
 }
 
 size_t tr_torrentFileCount(tr_torrent const* torrent)

libtransmission/transmission.h

@@ -1334,6 +1334,8 @@ struct tr_file_view
     uint64_t have; // the current size of the file, i.e. how much we've downloaded
     uint64_t length; // the total size of the file
     double progress; // have / length
+    tr_piece_index_t beginPiece; // piece index where this file starts
+    tr_piece_index_t endPiece; // piece index where this file ends (exclusive)
     tr_priority_t priority; // the file's priority
     bool wanted; // do we want to download this file?
 };

tests/libtransmission/torrents-test.cc

@@ -14,6 +14,8 @@
 
 #include "gtest/gtest.h"
 
+#include "test-fixtures.h"
+
 using namespace std::literals;
 
 using TorrentsTest = ::testing::Test;
@@ -128,3 +130,13 @@ TEST_F(TorrentsTest, removedSince)
     remove = { torrents_v[0]->id(), torrents_v[1]->id(), torrents_v[2]->id(), torrents_v[3]->id() };
     EXPECT_EQ(remove, torrents.removedSince(50));
 }
+
+using TorrentsPieceSpanTest = libtransmission::test::SessionTest;
+
+TEST_F(TorrentsPieceSpanTest, exposesFilePieceSpan)
+{
+    auto tor = zeroTorrentInit(ZeroTorrentState::Complete);
+    auto file_view = tr_torrentFile(tor, 0);
+    EXPECT_EQ(file_view.beginPiece, 0);
+    EXPECT_EQ(file_view.endPiece, 32);
+}