Fix files past MAX_PATH not being claimed or decoded

.gitignore

@@ -27,8 +27,9 @@
 *.personalized_headphone
 rosella_kernels.npz
 
-# The component writes its own log next to the DLL
+# The component writes its own log next to the DLL, and rolls it to a .1 sibling
 joc_decoder.log
+joc_decoder.log.1
 
 # Measurement record: local working notes, kept on disk and never published.
 VERIFICATION.md

README.en.md

@@ -94,7 +94,11 @@ and test-bed scripts. Settings also read `JOC_*` environment overrides for one r
 only); the list and what each one does is in `src\settings.cpp`.
 
 To diagnose a problem, read `joc_decoder.log` beside the DLL: the component writes its own
-version, the core version and the log path there at start-up.
+version, the core version and the log path there at start-up. The log is capped by **bytes**: a
+file that reaches 16 MiB is rolled to `joc_decoder.log.1` beside it, replacing the previous roll
+rather than accumulating, so the two together never exceed 32 MiB and the newest lines are always
+in `joc_decoder.log`. The version banner is written again after a roll. A Media Library scan logs
+every container in the library, which is where the volume comes from.
 
 ## Known limitations
 

README.md

@@ -82,7 +82,9 @@ pwsh -File tools/package.ps1            # 两个架构，打包到 dist\*.fb2k-c
 另有 `JOC_*` 环境变量覆盖（仅用于开发运行），清单与含义在 `src\settings.cpp`。
 
 排查问题看 DLL 旁边的 `joc_decoder.log`；组件启动时会把自己的版本、核心版本、日志路径写在
-里面。
+里面。日志按**字节**封顶：单个文件写满 16 MiB 就滚到同目录的 `joc_decoder.log.1`（覆盖上一次
+滚动，不累积），所以两份加起来不超过 32 MiB，最新的内容始终在 `joc_decoder.log`。滚动之后版本
+信息会重写一遍。媒体库扫描会给库里每个容器写日志，体量主要来自这里。
 
 ## 已知限制
 

THIRD_PARTY_NOTICES.md

@@ -1,31 +1,9 @@
 # Third-party notices / 第三方通知
 
-本仓库包含 JustOneCacophony 原生库的逐字节副本（下称"复用文件"），以及遵循公开标准实现的
+本文件记录 64-QMF / 77-hybrid 滤波器组表（`kernel/src/hrtf/public_filterbank.h`、
-滤波器组表。本文件记录这些来源、公开标准依据与权利边界。
+`kernel/src/joc_core/qmf_tables.h`）与 JOC Huffman 表
-
+（`kernel/src/joc_bitstream/joc_huffman_tables.h`）的公开标准来源，以及 HRTF 数据与
-## 复用文件
+专利的边界说明。
-
-以下文件是本项目（JustOneCacophony，MIT）原生 C++ 库的逐字节副本，不修改、不追加注释：
-
-| 本仓库路径 | 上游路径 | SHA-256（前 16 位） |
-|---|---|---|
-| `src/joc_core/eac3joc_core.cpp` | `native/src/eac3joc_core.cpp` | `1978eea64a2616fa` |
-| `src/joc_core/qmf_tables.h` | `native/src/qmf_tables.h` | `c205ea187e956e87` |
-| `src/speaker/speaker_renderer.cpp` | `native/src/speaker_renderer.cpp` | `96f36f40daf86eec` |
-| `src/speaker/speaker_layouts.h` | `native/src/speaker_layouts.h` | `51e24c11be09787f` |
-| `src/binaural/binaural_renderer.cpp` | `native/src/binaural_renderer.cpp` | `d579803f0f5a6699` |
-| `src/joc_bitstream/joc_huffman_tables.h` | `native/src/joc_huffman_tables.h` | `698498b3778d88db` |
-| `include/eac3joc_core.h` | `native/include/eac3joc_core.h` | `7392f48dfd840656` |
-
-上游修订：`6bc2c2885666bb151bb66af93472199af9a99b81`。
-
-## 派生文件
-
-`src/binaural/sofa_binaural_renderer.cpp` 是上游 `native/src/sofa_binaural_renderer.cpp` 的派生
-实现：同一 `ejoc_sofa_binaural_*` C ABI，增加表提升、结果记忆化、输入校验与 SIMD 派发。它
-**不属于**逐字节副本，也不受"不得修改"约束，但来源固定为上述上游修订，对应上游源文件的
-SHA-256 为 `81b485e4c71907672ab308ddc382284acf29161cee93d7906785a4cce58941c7`，输出与原
-实现逐位相同（见该文件头部的验证记录）。
 
 ## 公开标准来源
 

foo_input_joc.vcxproj

@@ -114,6 +114,7 @@
     <ClInclude Include="src\prefs.h" />
     <ClInclude Include="src\resource.h" />
     <ClInclude Include="src\settings.h" />
+    <ClInclude Include="src\win_path.h" />
   </ItemGroup>
 
   <ItemGroup>

kernel/include/eac3joc_core.h

@@ -68,6 +68,15 @@ EJOC_API ejoc_renderer_handle EJOC_CALL ejoc_renderer_create(void);
 EJOC_API void EJOC_CALL ejoc_renderer_destroy(ejoc_renderer_handle handle);
 EJOC_API int EJOC_CALL ejoc_renderer_reset(ejoc_renderer_handle handle);
 EJOC_API int EJOC_CALL ejoc_renderer_set_threads(ejoc_renderer_handle handle, uint32_t total_threads);
+/*
+Enables or disables the Ls/Rs band-0 21-tap DC compensation. The caller derives
+it from the JOC downmix configuration: only configurations 3 and 4 enable the
+filter. When disabled, band 0 keeps the common per-band processing (surround
+delay plus -j rotation) instead of being overwritten by the FIR. The delay line
+and DC history advance either way, so the flag may change between frames.
+Defaults to enabled when never called.
+*/
+EJOC_API int EJOC_CALL ejoc_renderer_set_dc_filter(ejoc_renderer_handle handle, uint32_t enabled);
 EJOC_API uint32_t EJOC_CALL ejoc_renderer_thread_count(ejoc_renderer_handle handle);
 EJOC_API const char* EJOC_CALL ejoc_renderer_last_error(ejoc_renderer_handle handle);
 

kernel/src/joc_core/eac3joc_core.cpp

@@ -125,6 +125,10 @@ public:
         return error_[0] ? error_ : "";
     }
 
+    void set_dc_filter(const bool enabled) noexcept {
+        dc_filter_enabled_ = enabled;
+    }
+
     int process(
         const float* bed5,
         const float* lfe,
@@ -305,6 +309,7 @@ private:
                 for (int i = 0; i < 4; ++i) {
                     dc_buffer[20 + i] = current[i][0];
                 }
+                if (dc_filter_enabled_) {
                     for (int slot = 0; slot < 4; ++slot) {
                         Complex sum{0.0, 0.0};
                         for (int tap = 0; tap < 21; ++tap) {
@@ -316,6 +321,7 @@ private:
                         }
                         x_[channel][0][group + slot] = {2.0 * sum.re, 2.0 * sum.im};
                     }
+                }
                 for (int i = 0; i < 20; ++i) {
                     surround_history_[surround][i] = dc_buffer[i + 4];
                 }
@@ -641,6 +647,8 @@ private:
     float analysis_phase_;
     alignas(64) Complex surround_delay_[2][10][64];
     alignas(64) Complex surround_history_[2][20];
+    // band-0 的 21-tap DC 补偿开关；仅 downmix 配置 3/4 由调用方置位。
+    bool dc_filter_enabled_ = true;
     alignas(64) double lfe_delay_[kLfeDelay];
     alignas(64) double matrix_previous_[15][5][64];
     alignas(64) double synthesis_state_[15][640];
@@ -696,6 +704,14 @@ int EJOC_CALL ejoc_renderer_set_threads(ejoc_renderer_handle handle, uint32_t to
     return static_cast<ejoc::Renderer*>(handle)->set_threads(total_threads);
 }
 
+int EJOC_CALL ejoc_renderer_set_dc_filter(ejoc_renderer_handle handle, uint32_t enabled) {
+    if (!handle) {
+        return -1;
+    }
+    static_cast<ejoc::Renderer*>(handle)->set_dc_filter(enabled != 0);
+    return 0;
+}
+
 uint32_t EJOC_CALL ejoc_renderer_thread_count(ejoc_renderer_handle handle) {
     if (!handle) {
         return 0;

kernel/src/joc_core/objects16.cpp

@@ -52,6 +52,15 @@ Status rebuild_objects16(ejoc_renderer_handle handle, const joc_frame_params& pa
     }
 
     out16->assign(static_cast<std::size_t>(JOC_OUTPUT_CHANNELS) * JOC_FRAME_SAMPLES, 0.0f);
+    // band-0 的 21-tap DC 补偿只在 downmix 配置 3/4 下启用，其余配置 band 0
+    // 走与其他 band 相同的处理。
+    const bool dc_filter = params.dmx_config_idx == 3 || params.dmx_config_idx == 4;
+    if (ejoc_renderer_set_dc_filter(handle, dc_filter ? 1u : 0u) != 0) {
+        if (error != nullptr) {
+            *error = "ejoc_renderer_set_dc_filter failed";
+        }
+        return Status::fail(JOC_ERR_RENDER_FAILED, stage::kDsp, "ejoc_renderer_set_dc_filter failed");
+    }
     const int result = ejoc_renderer_process(
         handle, bed5_planar, lfe, params.present_mask, n_bands, n_dpoints, slope_idx, offset_ts,
         dq.data(), params.clipgain, 0.0625f, gain, out16->data());

kernel/src/stream/stream.cpp

@@ -118,7 +118,6 @@ Status Stream::create(const Config& config) {
             }
             render_options.object_delay_samples = config_.object_delay_samples;
             render_options.tail_seconds = config_.tail_seconds;
-            render_options.output_gain = 1.0;
             if (status.ok()) {
                 status = rosella_.open(model, render_options);
             }

kernel/src/task/task.cpp

@@ -1209,7 +1209,6 @@ Status run(const joc_task_config& raw, const joc_event_sink* sink, joc_task_resu
             }
             render_options.object_delay_samples = cfg.object_delay_samples;
             render_options.tail_seconds = cfg.tail_seconds;
-            render_options.output_gain = std::pow(10.0, cfg.gain_db / 20.0);
             if (status.ok()) {
                 status = rosella.open(model, render_options);
             }

src/container_scan.cpp

@@ -8,18 +8,19 @@
 #include <vector>
 
 #include "log.h"
+#include "win_path.h"
 
 namespace joc_container {
 namespace {
 
-std::wstring utf8_to_wide(const std::string& text) {
+// A library scan probes every container in the library, and most of them are
-    if (text.empty()) return {};
+// declined; they also mostly share a directory, so the path would spend the log's
-    const int needed = MultiByteToWideChar(CP_UTF8, 0, text.c_str(),
+// byte budget repeating the same prefix once per file.  The file name is what
-                                           static_cast<int>(text.size()), nullptr, 0);
+// identifies the line.  Files this component claims are logged with their full
-    std::wstring out(static_cast<std::size_t>(needed), L'\0');
+// path by the caller.
-    MultiByteToWideChar(CP_UTF8, 0, text.c_str(), static_cast<int>(text.size()), out.data(),
+std::string file_name_of(const std::string& path) {
-                        needed);
+    const std::string::size_type slash = path.find_last_of("\\/");
-    return out;
+    return (slash == std::string::npos) ? path : path.substr(slash + 1);
 }
 
 // A bounded, read-only view of the file.  Every accessor returns false instead of
@@ -27,7 +28,7 @@ std::wstring utf8_to_wide(const std::string& text) {
 class Window {
 public:
     bool open(const std::string& path) {
-        const std::wstring wide = utf8_to_wide(path);
+        const std::wstring wide = joc_path::to_wide_extended(path);
         handle_ = CreateFileW(wide.c_str(), GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE,
                               nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
         if (handle_ == INVALID_HANDLE_VALUE) {
@@ -200,15 +201,24 @@ Result scan_mp4(const Window& file, std::size_t max_bytes) {
     Result result;
     result.kind = Kind::kMp4;
 
-    // moov is usually at the start for streamed files and at the end otherwise.
+    // moov is usually at the start for streamed files and at the end otherwise.  The
+    // walk reads box headers where they lie and steps over mdat in one go, so the
+    // whole file is walked from the top: a fixed prefix window cannot reach a moov
+    // that is larger than the window, which is what an MP4 with its cover art stored
+    // as a video track produces (a 4.9 MB moov against a 4 MiB window).  The tail
+    // range stays as a fallback for a file whose leading boxes do not parse.
     struct Range {
         std::uint64_t begin;
         std::uint64_t end;
     };
-    std::vector<Range> ranges{{0, (std::min<std::uint64_t>)(file.size(), max_bytes)}};
+    std::vector<Range> ranges{{0, file.size()}};
     if (file.size() > max_bytes) {
         ranges.push_back({file.size() - max_bytes, file.size()});
     }
+    // An oversized moov is a file this probe cannot describe, and walking it would be
+    // unbounded work; it is reported instead of entered.
+    constexpr std::uint64_t kMaxMoovBytes = 64ull * 1024ull * 1024ull;
+    bool oversized_moov = false;
 
     unsigned audio_seen = 0;
     bool found_any_audio = false;
@@ -218,6 +228,10 @@ Result scan_mp4(const Window& file, std::size_t max_bytes) {
                    [&](const std::string& type, std::uint64_t payload, std::uint64_t box_end,
                        std::size_t) {
                        if (type != "moov") return true;
+                       if (box_end - payload > kMaxMoovBytes) {
+                           oversized_moov = true;
+                           return true;
+                       }
                        walk_boxes(file, payload, box_end, 1,
                                   [&](const std::string& inner, std::uint64_t inner_payload,
                                       std::uint64_t inner_end, std::size_t) {
@@ -273,6 +287,8 @@ Result scan_mp4(const Window& file, std::size_t max_bytes) {
         result.detail = "mp4: first audio track is " +
                         (first_audio_format.empty() ? std::string("unknown")
                                                     : first_audio_format);
+    } else if (oversized_moov) {
+        result.detail = "mp4: moov is larger than the scan limit";
     } else {
         result.detail = "mp4: no audio track found in the scanned window";
     }
@@ -519,7 +535,7 @@ Result scan(const std::string& path, std::size_t max_bytes) {
     } else {
         result = scan_mp4(file, max_bytes);
     }
-    joc_log::line("container: %s -> %s (eac3=%d audio#%u codec=%s)", path.c_str(),
+    joc_log::line("container: %s -> %s (eac3=%d audio#%u codec=%s)", file_name_of(path).c_str(),
                   result.detail.c_str(), result.eac3 ? 1 : 0, result.audio_index,
                   result.codec.empty() ? "-" : result.codec.c_str());
     return result;

src/input_joc.cpp

@@ -17,6 +17,8 @@
 #include <SDK/input_impl.h>
 #include <SDK/tag_processor.h>
 
+#include <atomic>
+#include <cstdarg>
 #include <cstring>
 #include <string>
 
@@ -66,6 +68,31 @@ std::string file_name_of(const std::string& path) {
     return slash == std::string::npos ? path : path.substr(slash + 1);
 }
 
+// A library scan opens every container in the library through open(), and all but
+// a few of them are declined because their audio is not E-AC-3 JOC.  The per-file
+// lines are what makes a scan diagnosable -- "the file that should have been
+// claimed was not, and here is why" -- but a large library is hundreds of
+// thousands of them, so a running summary is logged as well.  It is short enough
+// to survive the log rolling over, which is what a scan of that size makes it do.
+constexpr unsigned kDeclineSummaryEvery = 1000;
+std::atomic<unsigned> g_declined{0};
+std::atomic<unsigned> g_claimed{0};
+
+// One place for "this file is not ours".  The message stays the caller's, so a
+// decline that failed rather than decided still reads as one.
+void decline(const char* fmt, ...) {
+    va_list args;
+    va_start(args, fmt);
+    joc_log::line_v(fmt, args);
+    va_end(args);
+
+    const unsigned count = g_declined.fetch_add(1, std::memory_order_relaxed) + 1;
+    if ((count % kDeclineSummaryEvery) == 0u) {
+        joc_log::line("scan: %u file(s) declined, %u claimed so far", count,
+                      g_claimed.load(std::memory_order_relaxed));
+    }
+}
+
 // ---------------------------------------------------------------------------
 // Tags of a file this component has taken over.
 //
@@ -200,8 +227,7 @@ public:
         try {
             m_native_path = filesystem::g_get_native_path(m_path.c_str());
         } catch (const pfc::exception& error) {
-            joc_log::line("decoder: not a native file path (%s): %s", m_path.c_str(),
+            decline("decoder: not a native file path (%s): %s", m_path.c_str(), error.what());
-                          error.what());
             throw exception_io_unsupported_format();
         }
 
@@ -249,10 +275,11 @@ public:
 
         if (scan.joc != joc_eac3::JocState::kYes) {
             // Hand the file to the next entry in the priority table.
-            joc_log::line("decoder: yielding to the built-in decoder (%s)", scan.detail);
+            decline("decoder: yielding to the built-in decoder (%s)", scan.detail);
             throw exception_io_unsupported_format();
         }
         joc_log::line("decoder: claiming this file as E-AC-3 JOC (bare stream)");
+        g_claimed.fetch_add(1, std::memory_order_relaxed);
         m_input_kind = joc_decode::InputKind::kBare;
     }
 
@@ -263,7 +290,7 @@ public:
     void open_container(const char* extension) {
         m_container = joc_container::scan(m_native_path.get_ptr());
         if (!m_container.eac3) {
-            joc_log::line("decoder: yielding to the built-in decoder (%s)",
+            decline("decoder: yielding to the built-in decoder (%s)",
                     m_container.detail.c_str());
             throw exception_io_unsupported_format();
         }
@@ -273,12 +300,11 @@ public:
         std::string detail;
         if (!joc_decode::probe_container_joc(settings.ffmpeg_path, m_native_path.get_ptr(),
                                             m_container.audio_index, &joc, &detail)) {
-            joc_log::line("decoder: cannot examine the E-AC-3 track (%s); yielding",
+            decline("decoder: cannot examine the E-AC-3 track (%s); yielding", detail.c_str());
-                          detail.c_str());
             throw exception_io_unsupported_format();
         }
         if (!joc) {
-            joc_log::line("decoder: yielding to the built-in decoder (E-AC-3 track %u carries "
+            decline("decoder: yielding to the built-in decoder (E-AC-3 track %u carries "
                     "no JOC: %s)",
                     m_container.audio_index, detail.c_str());
             throw exception_io_unsupported_format();
@@ -287,6 +313,7 @@ public:
         joc_log::line("decoder: claiming this file as E-AC-3 JOC (%s, audio track %u, .%s)",
                       joc_container::kind_name(m_container.kind), m_container.audio_index,
                       extension);
+        g_claimed.fetch_add(1, std::memory_order_relaxed);
         m_input_kind = joc_decode::InputKind::kContainer;
         m_audio_index = m_container.audio_index;
     }

src/joc_decode.cpp

@@ -14,6 +14,7 @@
 
 #include "eac3_scan.h"
 #include "log.h"
+#include "win_path.h"
 
 namespace joc_decode {
 namespace {
@@ -30,6 +31,32 @@ constexpr std::size_t kBedReadBytes = 48u * 1024u;
 constexpr std::size_t kBedPipeBytes = 1u << 20;
 constexpr std::size_t kFrameSamples = JOC_FRAME_SAMPLES;
 
+// The decoded bed has to stay on the E-AC-3 frame grid that the JOC matrix and the
+// OAMD are indexed by.  An mp4/mov edit list trims the decoded audio instead, which
+// takes the bed off that grid by however much the list removes -- a Dolby Atmos
+// download loses 2432 samples (1.58 frames) -- and every frame's matrix would then be
+// applied to audio tens of milliseconds away from it, so a subset of the objects comes
+// out attenuated.  The demuxer's own option drops the trim; the option exists only on
+// the mov/mp4 demuxer, so it is passed for that family alone.
+bool has_mov_timeline(const std::string& path) {
+    static const char* const kExtensions[] = {".mp4", ".m4a", ".m4b", ".m4v",
+                                              ".mov", ".3gp", ".3g2", ".mj2"};
+    std::string lowered = path;
+    for (char& character : lowered) {
+        if (character >= 'A' && character <= 'Z') {
+            character = static_cast<char>(character - 'A' + 'a');
+        }
+    }
+    for (const char* extension : kExtensions) {
+        const std::size_t length = std::strlen(extension);
+        if (lowered.size() >= length &&
+            lowered.compare(lowered.size() - length, length, extension) == 0) {
+            return true;
+        }
+    }
+    return false;
+}
+
 // ---------------------------------------------------------------------------
 // Kernel entry points.
 //
@@ -52,18 +79,8 @@ struct CoreApi {
     const char*(JOC_CALL* error_name)(joc_error) = joc_error_name;
 };
 
-std::wstring utf8_to_wide(const std::string& text) {
-    if (text.empty()) return {};
-    const int needed = MultiByteToWideChar(CP_UTF8, 0, text.c_str(),
-                                           static_cast<int>(text.size()), nullptr, 0);
-    std::wstring out(static_cast<std::size_t>(needed), L'\0');
-    MultiByteToWideChar(CP_UTF8, 0, text.c_str(), static_cast<int>(text.size()), out.data(),
-                        needed);
-    return out;
-}
-
 bool file_exists(const std::string& path) {
-    const std::wstring wide = utf8_to_wide(path);
+    const std::wstring wide = joc_path::to_wide_extended(path);
     if (wide.empty()) return false;
     const DWORD attributes = GetFileAttributesW(wide.c_str());
     return attributes != INVALID_FILE_ATTRIBUTES &&
@@ -121,11 +138,11 @@ public:
                                         FILE_SHARE_READ | FILE_SHARE_WRITE, &attributes,
                                         CREATE_ALWAYS, 0, nullptr);
 
-        std::wstring command = L"\"" + utf8_to_wide(ffmpeg_path) + L"\"";
+        std::wstring command = L"\"" + joc_path::to_wide_extended(ffmpeg_path) + L"\"";
         command += L" -hide_banner -loglevel error -nostdin -y ";
         command += input_arguments;  // input options must precede -i
         command += L" -i \"";
-        command += utf8_to_wide(input_path);
+        command += joc_path::to_wide_extended(input_path);
         command += L"\" ";
         command += output_arguments;
 
@@ -197,7 +214,7 @@ class InputFile {
 public:
     ~InputFile() { close(); }
     bool open(const std::string& path) {
-        handle_ = CreateFileW(utf8_to_wide(path).c_str(), GENERIC_READ,
+        handle_ = CreateFileW(joc_path::to_wide_extended(path).c_str(), GENERIC_READ,
                               FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr, OPEN_EXISTING,
                               FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, nullptr);
         return handle_ != INVALID_HANDLE_VALUE;
@@ -422,8 +439,8 @@ bool probe_container_joc(const std::string& ffmpeg_path, const std::string& path
     std::uint64_t modified = 0;
     {
         WIN32_FILE_ATTRIBUTE_DATA data{};
-        if (GetFileAttributesExW(utf8_to_wide(path).c_str(), GetFileExInfoStandard, &data) !=
+        if (GetFileAttributesExW(joc_path::to_wide_extended(path).c_str(), GetFileExInfoStandard,
-            FALSE) {
+                                 &data) != FALSE) {
             size = (static_cast<std::uint64_t>(data.nFileSizeHigh) << 32) | data.nFileSizeLow;
             modified = (static_cast<std::uint64_t>(data.ftLastWriteTime.dwHighDateTime) << 32) |
                        data.ftLastWriteTime.dwLowDateTime;
@@ -685,6 +702,7 @@ bool Engine::Impl::start_bed(std::uint64_t source_sample, std::string* error) {
     // at the start of the file, which is a low-level, noise-like difference from a
     // play-through rather than a misalignment: the position stays exact.
     std::wstring input_arguments = L"-drc_scale 0 -target_level 0";
+    if (has_mov_timeline(input_path)) input_arguments += L" -ignore_editlist 1";
     const std::wstring offset = seek_time(source_sample);
     if (!offset.empty()) input_arguments += L" -ss " + offset;
     std::wstring bed_arguments = L"-map 0:a:";

src/log.cpp

@@ -8,6 +8,8 @@
 #include <mutex>
 #include <string>
 
+#include "win_path.h"
+
 namespace joc_log {
 namespace {
 
@@ -16,12 +18,20 @@ FILE* g_file = nullptr;
 bool g_opened = false;
 std::string g_path;          // UTF-8, for reporting
 std::wstring g_wide_path;    // for _wfopen
-unsigned long long g_lines = 0;
+std::wstring g_wide_rolled;  // g_wide_path with the .1 suffix
-bool g_capped = false;
+unsigned long long g_bytes = 0;
 
-// A Media Library scan calls into us for every file; the cap keeps a long
+// A Media Library scan calls into us for every file it walks, so the cap has to
-// session from filling the disk, and says so once when it is reached.
+// be on bytes: the lines a scan produces run from 40 to 2048 bytes each, and a
-constexpr unsigned long long kMaxLines = 500000;
+// cap on their number leaves the file they build unpredictable by a factor of
+// fifty.  Sixteen mebibytes per file, one previous file kept, so the component
+// never holds more than 32 MiB of log.
+constexpr unsigned long long kMaxBytes = 16ull << 20;
+
+// The lines recorded between header_begin() and header_end(): the version
+// banner, a handful of lines written once per process.
+bool g_recording = false;
+std::string g_header;
 
 std::wstring module_directory() {
     HMODULE module = nullptr;
@@ -39,32 +49,26 @@ std::wstring module_directory() {
     return dir;
 }
 
-std::string to_utf8(const std::wstring& text) {
-    if (text.empty()) return {};
-    const int needed = WideCharToMultiByte(CP_UTF8, 0, text.c_str(),
-                                           static_cast<int>(text.size()), nullptr, 0,
-                                           nullptr, nullptr);
-    std::string out(static_cast<std::string::size_type>(needed), '\0');
-    WideCharToMultiByte(CP_UTF8, 0, text.c_str(), static_cast<int>(text.size()),
-                        out.data(), needed, nullptr, nullptr);
-    return out;
-}
-
 void open_locked() {
     g_opened = true;
 
     wchar_t from_env[4096] = {};
     const DWORD env_length = GetEnvironmentVariableW(L"JOC_LOG", from_env,
                                                      static_cast<DWORD>(4096));
+    std::wstring plain;
     if (env_length > 0 && env_length < 4096) {
-        g_wide_path.assign(from_env, env_length);
+        plain.assign(from_env, env_length);
     } else {
         const std::wstring dir = module_directory();
         if (dir.empty()) return;
-        g_wide_path = dir + L"\\joc_decoder.log";
+        plain = dir + L"\\joc_decoder.log";
     }
 
-    g_path = to_utf8(g_wide_path);
+    // g_path is the one the component reports and a user reads; the handles work on
+    // the extended form, because a portable install can sit deeper than MAX_PATH.
+    g_path = joc_path::to_utf8(plain);
+    g_wide_path = joc_path::to_wide_extended(plain);
+    g_wide_rolled = g_wide_path + L".1";
     g_file = _wfopen(g_wide_path.c_str(), L"wb");
     if (g_file == nullptr) {
         g_path.clear();
@@ -74,6 +78,52 @@ void open_locked() {
     std::setvbuf(g_file, nullptr, _IONBF, 0);
 }
 
+// Composes one line with its timestamp, writes it, and accounts for it.  Returns
+// the bytes written, 0 when there was nowhere to write them.
+unsigned long long write_locked(const char* text) {
+    if (g_file == nullptr) return 0;
+
+    SYSTEMTIME now;
+    GetLocalTime(&now);
+    char composed[2100];
+    const int length =
+        std::snprintf(composed, sizeof(composed), "%02u:%02u:%02u.%03u [t%05lu] %s\n", now.wHour,
+                      now.wMinute, now.wSecond, now.wMilliseconds,
+                      static_cast<unsigned long>(GetCurrentThreadId()), text);
+    if (length <= 0) return 0;
+    // snprintf reports the length it would have needed, which for a truncated
+    // line is past the end of the buffer.
+    const std::size_t size = (static_cast<std::size_t>(length) < sizeof(composed))
+                                 ? static_cast<std::size_t>(length)
+                                 : sizeof(composed) - 1;
+    std::fwrite(composed, 1, size, g_file);
+    g_bytes += size;
+    if (g_recording) g_header.append(composed, size);
+    return size;
+}
+
+// Moves the full file aside and starts an empty one.  Called with the mutex held,
+// once the budget is spent.  The banner is written again afterwards, so a log
+// that has rolled still opens with the versions it was produced by.
+void roll_locked() {
+    std::fclose(g_file);
+    g_file = nullptr;
+    // One previous window, replaced rather than chained: a chain of rolls would
+    // be the same unbounded log under another name.  A move that fails -- the .1
+    // file held open by a reader -- leaves the truncation below to bound the file
+    // anyway, at the cost of the window that would have been kept.
+    MoveFileExW(g_wide_path.c_str(), g_wide_rolled.c_str(), MOVEFILE_REPLACE_EXISTING);
+    g_file = _wfopen(g_wide_path.c_str(), L"wb");
+    if (g_file == nullptr) return;
+    std::setvbuf(g_file, nullptr, _IONBF, 0);
+    g_bytes = 0;
+    write_locked("[log rolled: the previous window is in the .1 file beside this one]");
+    if (!g_header.empty()) {
+        std::fwrite(g_header.c_str(), 1, g_header.size(), g_file);
+        g_bytes += g_header.size();
+    }
+}
+
 }  // namespace
 
 void open() {
@@ -86,30 +136,34 @@ const char* path() {
     return g_path.c_str();
 }
 
-void line(const char* fmt, ...) {
+unsigned long long budget_bytes() { return kMaxBytes; }
-    va_list args;
+
-    va_start(args, fmt);
+void line_v(const char* fmt, va_list args) {
     char text[2048];
     std::vsnprintf(text, sizeof(text), fmt, args);
-    va_end(args);
 
     std::lock_guard<std::mutex> guard(g_mutex);
     if (!g_opened) open_locked();
     if (g_file == nullptr) return;
-    if (g_lines >= kMaxLines) {
+    if (write_locked(text) != 0 && g_bytes >= kMaxBytes) roll_locked();
-        if (!g_capped) {
+}
-            g_capped = true;
-            std::fputs("[log capped]\n", g_file);
-        }
-        return;
-    }
-    ++g_lines;
 
-    SYSTEMTIME now;
+void line(const char* fmt, ...) {
-    GetLocalTime(&now);
+    va_list args;
-    std::fprintf(g_file, "%02u:%02u:%02u.%03u [t%05lu] %s\n", now.wHour, now.wMinute,
+    va_start(args, fmt);
-                 now.wSecond, now.wMilliseconds,
+    line_v(fmt, args);
-                 static_cast<unsigned long>(GetCurrentThreadId()), text);
+    va_end(args);
+}
+
+void header_begin() {
+    std::lock_guard<std::mutex> guard(g_mutex);
+    g_header.clear();
+    g_recording = true;
+}
+
+void header_end() {
+    std::lock_guard<std::mutex> guard(g_mutex);
+    g_recording = false;
 }
 
 }  // namespace joc_log

src/log.h

@@ -4,10 +4,22 @@
 // harness and so that it is safe to call from any thread the core queries us on.
 //
 // Path: %JOC_LOG% if set, otherwise <directory of this DLL>\joc_decoder.log.
-// The file is truncated once per process, line-buffered, and every line is
+// The file is truncated once per process, unbuffered, and every line is written
-// flushed so the log can be read while foobar2000 is still running.
+// straight out so the log can be read while foobar2000 is still running.
+//
+// Size: what is bounded is bytes, not lines.  A line is anywhere between 40 and
+// 2048 bytes, so a cap on the number of lines leaves the size of the file
+// unpredictable by a factor of fifty.  A file that reaches budget_bytes() is
+// moved to <path>.1 -- replacing any previous roll, so there is never a chain of
+// them -- and a fresh one is started.  Two files of the budget is therefore the
+// most the component ever holds, and the newest lines are always the ones in
+// <path>.  Lines written between header_begin() and header_end() are written
+// again at the top of every window, so a rolled log still says which build
+// produced it.
 #pragma once
 
+#include <cstdarg>
+
 namespace joc_log {
 
 // Opens (truncating) the log.  Called lazily by line(); call it explicitly to
@@ -17,7 +29,18 @@ void open();
 // Absolute path of the log file, or "" when it could not be opened.
 const char* path();
 
+// Bytes one file holds before it is rolled to <path>.1.
+unsigned long long budget_bytes();
+
 // printf-style, thread safe, appends one line.
 void line(const char* fmt, ...);
 
+// The va_list form, for a wrapper that forwards its own arguments.
+void line_v(const char* fmt, va_list args);
+
+// Remembers the lines written in between and writes them again after every roll.
+// Meant for the version banner: a handful of lines, written once.
+void header_begin();
+void header_end();
+
 }  // namespace joc_log

src/main.cpp

@@ -12,7 +12,7 @@
 
 // Kept in one place: the string reported to foobar2000 and written to the log
 // must not drift apart.
-#define JOC_VERSION "0.2.0"
+#define JOC_VERSION "0.2.2"
 
 DECLARE_COMPONENT_VERSION("JOC decoder (E-AC-3 JOC)", JOC_VERSION,
                           "Plays E-AC-3 JOC (Dolby Atmos) files: the JOC objects are "
@@ -30,6 +30,9 @@ class joc_initquit : public initquit {
 public:
     void on_init() override {
         joc_log::open();
+        // Recorded, so that a log which has rolled still opens with the versions
+        // it was produced by.
+        joc_log::header_begin();
         joc_log::line("=== foo_input_joc %s ===", JOC_VERSION);
         joc_log::line("foobar2000 core : %s", core_version_info::g_get_version_string());
         joc_log::line("component file  : %s", core_api::get_my_file_name());
@@ -37,6 +40,8 @@ public:
         joc_log::line("portable mode   : %s",
                       core_api::is_portable_mode_enabled() ? "yes" : "no");
         joc_log::line("log file        : %s", joc_log::path());
+        joc_log::line("log limit       : %llu byte(s) per file, then rolled to the .1 suffix",
+                      joc_log::budget_bytes());
         joc_log::line("compiled as     : %s",
 #if defined(_M_IX86)
                       "x86 (32-bit)"
@@ -46,6 +51,7 @@ public:
                       "other"
 #endif
         );
+        joc_log::header_end();
     }
 
     void on_quit() override { joc_log::line("=== foo_input_joc shutdown ==="); }

src/prefs.cpp

@@ -189,6 +189,7 @@ private:
                     }
                     if (pick_file(m_hwnd, path, title, filter)) {
                         set_text(GetDlgItem(m_hwnd, IDC_EDIT_HRTF), path);
+                        update_status();
                         notify();
                     }
                     return TRUE;
@@ -219,6 +220,10 @@ private:
                     return TRUE;
                 }
                 if (code == EN_CHANGE || code == CBN_SELCHANGE) {
+                    if (id == IDC_EDIT_HRTF || id == IDC_COMBO_LAYOUT ||
+                        id == IDC_EDIT_GAIN) {
+                        update_status();
+                    }
                     notify();
                     return TRUE;
                 }
@@ -338,35 +343,36 @@ private:
     void update_enabled_state() { update_status(); }
 
     void update_status() {
-        const joc_settings::Values values = joc_settings::read();
+        const joc_settings::Values values = read_controls();
-        std::string status;
+        std::string output_status;
         if (values.output != 0) {
             char text[96] = {};
             const unsigned channels = joc_decode::speaker_channels(values.speaker_layout);
             std::snprintf(text, sizeof(text), "扬声器布局 %s（%u 声道）",
                           values.speaker_layout.c_str(), channels);
-            status = text;
+            output_status = text;
-        } else {
+        }
-            // Show what will actually be read, so an empty box is not a mystery.
+        set_text(GetDlgItem(m_hwnd, IDC_LABEL_OUTPUT_STATUS), output_status);
+
         joc_decode::Settings effective = joc_settings::current();
         effective.hrtf_source =
             static_cast<joc_decode::HrtfSource>(values.hrtf_source);
         effective.hrtf_file = values.hrtf_file;
         const std::string file = joc_decode::resolve_hrtf_file(effective);
-            status = std::string(joc_settings::hrtf_source_name(values.hrtf_source)) + "：" +
+        std::string hrtf_status =
-                     (file.empty() ? std::string("无法确定默认路径")
+            std::string(joc_settings::hrtf_source_name(values.hrtf_source)) + "：";
-                                   : (values.hrtf_file.empty() ? "默认 " + file : file));
+        if (values.hrtf_file.empty()) hrtf_status += "默认";
-        }
+        hrtf_status += "\n" +
-        // Say what is actually in effect, including the parts that do not apply
+                       (file.empty() ? std::string("无法确定默认路径") : file);
-        // to the selected output mode, so nothing has to be greyed out.
+        set_text(GetDlgItem(m_hwnd, IDC_LABEL_STATUS), hrtf_status);
+
         char gain[96] = {};
         if (values.gain_enabled) {
-            std::snprintf(gain, sizeof(gain), "\n增益开 %.2f dB", values.gain_db);
+            std::snprintf(gain, sizeof(gain), "增益开 %.2f dB", values.gain_db);
         } else {
-            std::snprintf(gain, sizeof(gain), "\n增益关（输出不衰减）");
+            std::snprintf(gain, sizeof(gain), "增益关（输出不衰减）");
         }
-        status += gain;
+        set_text(GetDlgItem(m_hwnd, IDC_LABEL_GAIN_STATUS), gain);
-        set_text(GetDlgItem(m_hwnd, IDC_LABEL_STATUS), status);
     }
 
     bool changed() const {

src/prefs.rc

@@ -7,11 +7,11 @@
 // sample page uses (SDK\foobar2000\foo_sample\foo_sample.rc).  A CAPTION statement
 // implies WS_CAPTION, which would draw a second frame inside the host's and shift
 // every control down by the caption height -- visible but not clickable.
-IDD_JOC_PREFS DIALOGEX 0, 0, 330, 226
+IDD_JOC_PREFS DIALOGEX 0, 0, 330, 273
 STYLE DS_SETFONT | WS_CHILD
 FONT 8, "Microsoft Sans Serif", 400, 0, 0x0
 BEGIN
-    GROUPBOX        "输出", IDC_GROUP_OUTPUT, 7, 5, 316, 64
+    GROUPBOX        "输出", IDC_GROUP_OUTPUT, 7, 5, 316, 61
     CONTROL         "双耳（HRTF）", IDC_RADIO_BINAURAL, "Button",
                     BS_AUTORADIOBUTTON | WS_GROUP | WS_TABSTOP, 16, 20, 72, 10
     CONTROL         "扬声器布局", IDC_RADIO_SPEAKER, "Button",
@@ -22,31 +22,33 @@ BEGIN
     LTEXT           "双耳模式", IDC_LABEL_MODE, 172, 22, 42, 10
     COMBOBOX        IDC_COMBO_MODE, 216, 19, 96, 90,
                     CBS_DROPDOWNLIST | WS_VSCROLL | WS_TABSTOP
-    LTEXT           "房间尾音（秒）", IDC_LABEL_TAIL, 172, 41, 46, 10
+    LTEXT           "房间尾音（秒）", IDC_LABEL_TAIL, 172, 41, 62, 10
-    EDITTEXT        IDC_EDIT_TAIL, 220, 38, 40, 13, ES_AUTOHSCROLL
+    EDITTEXT        IDC_EDIT_TAIL, 238, 38, 40, 13, ES_AUTOHSCROLL
+    LTEXT           "", IDC_LABEL_OUTPUT_STATUS, 16, 52, 300, 10
 
-    GROUPBOX        "HRTF", IDC_GROUP_HRTF, 7, 74, 316, 84
+    GROUPBOX        "HRTF", IDC_GROUP_HRTF, 7, 71, 316, 100
     CONTROL         "SOFA 文件", IDC_RADIO_HRTF_SOFA, "Button",
-                    BS_AUTORADIOBUTTON | WS_GROUP | WS_TABSTOP, 16, 89, 56, 10
+                    BS_AUTORADIOBUTTON | WS_GROUP | WS_TABSTOP, 16, 86, 56, 10
     CONTROL         "Rosella 个性化模型", IDC_RADIO_HRTF_ROSELLA, "Button",
-                    BS_AUTORADIOBUTTON | WS_TABSTOP, 78, 89, 78, 10
+                    BS_AUTORADIOBUTTON | WS_TABSTOP, 78, 86, 78, 10
-    LTEXT           "HRTF 文件（留空＝默认位置）", IDC_LABEL_HRTF, 16, 106, 92, 10
+    LTEXT           "HRTF 文件（留空＝默认位置）", IDC_LABEL_HRTF, 16, 105, 106, 10
-    EDITTEXT        IDC_EDIT_HRTF, 110, 103, 164, 13, ES_AUTOHSCROLL
+    EDITTEXT        IDC_EDIT_HRTF, 126, 102, 148, 13, ES_AUTOHSCROLL
-    PUSHBUTTON      "浏览…", IDC_BROWSE_HRTF, 279, 103, 38, 13
+    PUSHBUTTON      "浏览…", IDC_BROWSE_HRTF, 279, 102, 38, 13
     LTEXT           "留空时读组件目录下 HRTF\\binaural.sofa 或 binaural.personalized_headphone；SOFA 由渲染器内部编译，滤波组表已编入库中。",
-                    IDC_LABEL_HRTF_HINT, 16, 122, 300, 30
+                    IDC_LABEL_HRTF_HINT, 16, 121, 300, 20
+    LTEXT           "", IDC_LABEL_STATUS, 16, 145, 300, 20
 
-    GROUPBOX        "增益", IDC_GROUP_GAIN, 7, 162, 152, 56
+    GROUPBOX        "增益", IDC_GROUP_GAIN, 7, 176, 316, 48
     CONTROL         "应用增益", IDC_CHECK_GAIN, "Button",
-                    BS_AUTOCHECKBOX | WS_TABSTOP, 16, 178, 58, 10
+                    BS_AUTOCHECKBOX | WS_TABSTOP, 16, 192, 58, 10
-    LTEXT           "dB", IDC_LABEL_GAIN, 80, 178, 12, 10
+    LTEXT           "dB", IDC_LABEL_GAIN, 80, 192, 12, 10
-    EDITTEXT        IDC_EDIT_GAIN, 96, 175, 40, 13, ES_AUTOHSCROLL
+    EDITTEXT        IDC_EDIT_GAIN, 96, 189, 40, 13, ES_AUTOHSCROLL
+    LTEXT           "", IDC_LABEL_GAIN_STATUS, 145, 192, 171, 10
     LTEXT           "双耳渲染后可能超过 0 dBFS，可用负值衰减。",
-                    IDC_LABEL_GAIN_HINT, 16, 194, 134, 20
+                    IDC_LABEL_GAIN_HINT, 16, 208, 300, 10
 
-    GROUPBOX        "其它", IDC_GROUP_MISC, 165, 162, 158, 56
+    GROUPBOX        "其它", IDC_GROUP_MISC, 7, 229, 316, 38
-    LTEXT           "ffmpeg.exe", IDC_LABEL_FFMPEG, 173, 178, 44, 10
+    LTEXT           "ffmpeg.exe", IDC_LABEL_FFMPEG, 16, 245, 44, 10
-    EDITTEXT        IDC_EDIT_FFMPEG, 216, 175, 62, 13, ES_AUTOHSCROLL
+    EDITTEXT        IDC_EDIT_FFMPEG, 64, 242, 210, 13, ES_AUTOHSCROLL
-    PUSHBUTTON      "浏览…", IDC_BROWSE_FFMPEG, 282, 175, 35, 13
+    PUSHBUTTON      "浏览…", IDC_BROWSE_FFMPEG, 279, 242, 38, 13
-    LTEXT           "", IDC_LABEL_STATUS, 173, 194, 144, 20
 END

src/resource.h

@@ -12,6 +12,7 @@
 #define IDC_COMBO_MODE 2016
 #define IDC_LABEL_TAIL 2017
 #define IDC_EDIT_TAIL 2018
+#define IDC_LABEL_OUTPUT_STATUS 2019
 
 #define IDC_GROUP_HRTF 2020
 #define IDC_RADIO_HRTF_SOFA 2021
@@ -26,6 +27,7 @@
 #define IDC_LABEL_GAIN 2032
 #define IDC_EDIT_GAIN 2033
 #define IDC_LABEL_GAIN_HINT 2034
+#define IDC_LABEL_GAIN_STATUS 2035
 
 #define IDC_GROUP_MISC 2040
 #define IDC_LABEL_FFMPEG 2041

src/win_path.h

@@ -0,0 +1,90 @@
+// Paths handed to the Win32 file APIs.
+//
+// Windows refuses a path of MAX_PATH characters or more to any call that does not
+// carry the \\?\ prefix.  The prefix is a property of the path, not of the process:
+// a component cannot inherit it from the host's manifest, so whoever calls the API
+// has to add it.  A file that plays from the desktop therefore stops being found
+// once its folder tree is deep enough, which is what this header exists to prevent.
+//
+// Everything in this component that hands a path to Win32 -- or puts one on an
+// ffmpeg command line, which is the same call made by the child process -- goes
+// through to_wide_extended().  What is deliberately not routed through it is the
+// path the component keeps for itself: the one it logs, and the one it uses as the
+// container-probe cache key.  Those stay in their plain form, so a log line reads
+// like a path a user can paste into Explorer.
+#pragma once
+
+#include <windows.h>
+
+#include <string>
+
+namespace joc_path {
+
+// UTF-8 -> UTF-16, for the W APIs.  Every path crosses into the OS through here:
+// the narrow CRT would convert it through the ANSI code page, which is what breaks
+// names like "Les Fêtes d'Hébé".
+inline std::wstring to_wide(const std::string& utf8) {
+    if (utf8.empty()) return {};
+    const int needed = MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(),
+                                           static_cast<int>(utf8.size()), nullptr, 0);
+    if (needed <= 0) return {};
+    std::wstring out(static_cast<std::size_t>(needed), L'\0');
+    MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(), static_cast<int>(utf8.size()), out.data(),
+                        needed);
+    return out;
+}
+
+// The same path in the form the Win32 file APIs need.  Three kinds of path are left
+// exactly as they came in, and each of them would be broken by a prefix:
+//
+//   * one that already carries \\?\, which makes this idempotent;
+//   * one that is not fully qualified -- a relative path, or the ffmpeg setting
+//     when it is a bare executable name that PATH resolves.  \\?\ is undefined for
+//     those;
+//   * one with a "." or ".." segment, because \\?\ switches off the normalization
+//     that would resolve it.
+//
+// The separators are settled first for the same reason: once the prefix is on,
+// nothing turns a forward slash into a backslash any more, and both of the checks
+// above have to see the path the way the file system will.
+inline std::wstring to_wide_extended(const std::wstring& path) {
+    if (path.empty()) return path;
+    if (path.compare(0, 4, L"\\\\?\\") == 0) return path;
+
+    std::wstring plain = path;
+    for (wchar_t& character : plain) {
+        if (character == L'/') character = L'\\';
+    }
+
+    const bool unc = plain.size() >= 2 && plain[0] == L'\\' && plain[1] == L'\\';
+    const bool drive = plain.size() >= 3 && plain[1] == L':' && plain[2] == L'\\';
+    if (!unc && !drive) return path;
+    if (plain.find(L"\\.\\") != std::wstring::npos ||
+        plain.find(L"\\..\\") != std::wstring::npos) {
+        return path;
+    }
+
+    // A UNC path drops its two leading separators; everything else is copied whole.
+    std::wstring out = unc ? L"\\\\?\\UNC\\" : L"\\\\?\\";
+    out.append(plain, unc ? 2 : 0, std::wstring::npos);
+    return out;
+}
+
+inline std::wstring to_wide_extended(const std::string& utf8) {
+    return to_wide_extended(to_wide(utf8));
+}
+
+// UTF-16 -> UTF-8, the direction the component reports paths in.
+inline std::string to_utf8(const std::wstring& wide) {
+    if (wide.empty()) return {};
+    const int needed = WideCharToMultiByte(CP_UTF8, 0, wide.c_str(),
+                                           static_cast<int>(wide.size()), nullptr, 0, nullptr,
+                                           nullptr);
+    if (needed <= 0) return {};
+    std::string out(static_cast<std::string::size_type>(needed), '\0');
+    WideCharToMultiByte(CP_UTF8, 0, wide.c_str(), static_cast<int>(wide.size()), out.data(),
+                        needed, nullptr, nullptr);
+    return out;
+}
+
+}  // namespace joc_path

tests/log_rotation_test.cpp

@@ -0,0 +1,111 @@
+// Drives the diagnostic log past its byte budget, without foobar2000.
+//
+//   log_rotation_test
+//
+// The component's log is bounded by rolling: a file that reaches the budget is
+// moved to a .1 sibling and a fresh one is started.  What pushes it there is a
+// Media Library scan, which a test cannot arrange, so the budget is spent here
+// with lines of a known size instead.  What is checked is what the bound
+// promises: neither file passes the budget, there is no chain of rolls, the
+// newest lines are the ones in the live file, and the session banner is written
+// again after a roll -- which is the only reason a rolled log still says which
+// build produced it.
+
+#include <windows.h>
+
+#include <cstdio>
+#include <string>
+
+#include "../src/log.h"
+
+namespace {
+
+std::wstring temp_directory() {
+    wchar_t buffer[MAX_PATH + 1] = {};
+    const DWORD length = GetTempPathW(MAX_PATH, buffer);
+    return std::wstring(buffer, length) + L"joc_log_rotation_test";
+}
+
+bool read_file(const std::wstring& path, std::string* out) {
+    std::FILE* file = _wfopen(path.c_str(), L"rb");
+    if (file == nullptr) return false;
+    char buffer[64 * 1024];
+    std::size_t got = 0;
+    while ((got = std::fread(buffer, 1, sizeof(buffer), file)) != 0) out->append(buffer, got);
+    std::fclose(file);
+    return true;
+}
+
+unsigned long long file_size(const std::wstring& path) {
+    WIN32_FILE_ATTRIBUTE_DATA data{};
+    if (GetFileAttributesExW(path.c_str(), GetFileExInfoStandard, &data) == FALSE) return 0;
+    return (static_cast<unsigned long long>(data.nFileSizeHigh) << 32) | data.nFileSizeLow;
+}
+
+bool contains(const std::string& haystack, const std::string& needle) {
+    return haystack.find(needle) != std::string::npos;
+}
+
+int failures = 0;
+
+void check(bool ok, const char* what) {
+    std::printf("%-4s %s\n", ok ? "ok" : "FAIL", what);
+    if (!ok) ++failures;
+}
+
+}  // namespace
+
+int main() {
+    const std::wstring dir = temp_directory();
+    CreateDirectoryW(dir.c_str(), nullptr);
+    const std::wstring live = dir + L"\\rotation.log";
+    const std::wstring rolled = live + L".1";
+    const std::wstring chained = live + L".2";
+    DeleteFileW(live.c_str());
+    DeleteFileW(rolled.c_str());
+    DeleteFileW(chained.c_str());
+    SetEnvironmentVariableW(L"JOC_LOG", live.c_str());
+
+    const unsigned long long budget = joc_log::budget_bytes();
+    std::printf("budget %llu byte(s) per file\n", budget);
+
+    joc_log::open();
+    joc_log::header_begin();
+    joc_log::line("=== header marker ===");
+    joc_log::header_end();
+
+    // Enough lines to spend the budget twice over, so the roll has to happen and
+    // the file it produces has to be replaced rather than added to.
+    const std::string filler(160, 'x');
+    const unsigned lines = static_cast<unsigned>(budget / 190ull * 3ull);
+    for (unsigned i = 1; i <= lines; ++i) joc_log::line("filler %u %s", i, filler.c_str());
+
+    const unsigned long long live_size = file_size(live);
+    const unsigned long long rolled_size = file_size(rolled);
+    std::printf("wrote %u line(s): live %llu byte(s), rolled %llu byte(s)\n", lines, live_size,
+                rolled_size);
+
+    check(live_size > 0 && live_size <= budget + 4096, "live file is inside the budget");
+    check(rolled_size > 0 && rolled_size <= budget + 4096, "rolled file is inside the budget");
+    check(live_size + rolled_size <= 2 * budget + 8192, "the two together are inside twice it");
+    check(file_size(chained) == 0, "no second roll is kept");
+
+    std::string live_text;
+    std::string rolled_text;
+    check(read_file(live, &live_text), "live file reads back");
+    check(read_file(rolled, &rolled_text), "rolled file reads back");
+    check(contains(live_text, "[log rolled"), "the live file says it rolled");
+    check(contains(live_text, "=== header marker ==="), "the banner was written again");
+
+    char newest[64] = {};
+    std::snprintf(newest, sizeof(newest), "filler %u ", lines);
+    check(contains(live_text, newest), "the newest line is in the live file");
+    check(!contains(rolled_text, newest), "and not in the rolled one");
+
+    if (failures == 0) {
+        std::printf("log rotation holds\n");
+        return 0;
+    }
+    std::printf("%d check(s) failed\n", failures);
+    return 1;
+}

tests/long_path_test.cpp

@@ -0,0 +1,172 @@
+// Checks that the component works with a path past MAX_PATH.
+//
+//   long_path_test
+//
+// Windows refuses a path of MAX_PATH characters or more to any Win32 call that does
+// not carry the \\?\ prefix.  The prefix is a property of the path rather than of the
+// process, so it has to be added by whoever calls the API -- which is why a file that
+// plays from the desktop stops being found once its folder tree is deep enough, the
+// shape an Atmos download under a long album title has.
+//
+// The path is built here rather than taken from the command line, so the test needs
+// no fixture and cannot be defeated by the ANSI argv a console tool is handed.
+
+#include <windows.h>
+
+#include <cstdio>
+#include <string>
+
+#include "../src/container_scan.h"
+#include "../src/joc_decode.h"
+#include "../src/win_path.h"
+
+namespace {
+
+int failures = 0;
+
+void check(bool ok, const char* what) {
+    std::printf("%-4s %s\n", ok ? "ok" : "FAIL", what);
+    if (!ok) ++failures;
+}
+
+// %TEMP%\joc_long_path
+std::string temp_root() {
+    wchar_t buffer[MAX_PATH + 1] = {};
+    const DWORD length = GetTempPathW(MAX_PATH, buffer);
+    if (length == 0) return {};
+    return joc_path::to_utf8(std::wstring(buffer, length) + L"joc_long_path");
+}
+
+// One 45-character directory name.  Five of them put the file comfortably past the
+// limit whatever %TEMP% is.
+std::string level_name(int index) {
+    return "level-" + std::string(39, static_cast<char>('a' + index));
+}
+
+bool make_directory(const std::string& path) {
+    if (CreateDirectoryW(joc_path::to_wide_extended(path).c_str(), nullptr)) return true;
+    return GetLastError() == ERROR_ALREADY_EXISTS;
+}
+
+// Builds the deep tree one level at a time, so every parent already exists by the
+// time its child is asked for.
+std::string build_tree() {
+    std::string path = temp_root();
+    if (path.empty() || !make_directory(path)) return {};
+    for (int i = 0; i < 5; ++i) {
+        path += "\\" + level_name(i);
+        if (!make_directory(path)) return {};
+    }
+    return path;
+}
+
+// A file that is a container but holds no audio track: enough for the probe to walk
+// its boxes and report something of its own, rather than "cannot open the file".
+bool write_container(const std::string& path) {
+    unsigned char bytes[32] = {};
+    bytes[3] = sizeof(bytes);  // box size, big-endian
+    const char type[] = "ftypisom";
+    for (int i = 0; i < 8; ++i) bytes[4 + i] = static_cast<unsigned char>(type[i]);
+    std::FILE* file = _wfopen(joc_path::to_wide_extended(path).c_str(), L"wb");
+    if (file == nullptr) return false;
+    const std::size_t written = std::fwrite(bytes, 1, sizeof(bytes), file);
+    std::fclose(file);
+    return written == sizeof(bytes);
+}
+
+void remove_tree(const std::string& root, const std::string& leaf) {
+    // Files before the directories that hold them, deepest directory first, and
+    // never above root.  Worth doing at all because a tree past MAX_PATH is one
+    // Explorer cannot delete: leaving it behind would be worse than the disk it
+    // occupies.
+    DeleteFileW(joc_path::to_wide_extended(leaf + "\\probe.m4a").c_str());
+    DeleteFileW(joc_path::to_wide_extended(root + "\\short.m4a").c_str());
+    std::string current = leaf;
+    while (current.size() > root.size()) {
+        RemoveDirectoryW(joc_path::to_wide_extended(current).c_str());
+        const std::string::size_type slash = current.find_last_of('\\');
+        if (slash == std::string::npos) break;
+        current.resize(slash);
+    }
+    RemoveDirectoryW(joc_path::to_wide_extended(root).c_str());
+}
+
+// The rules that keep the prefix from being applied where it would break a path.
+void check_helper_rules() {
+    check(joc_path::to_wide_extended(std::string("ffmpeg")) == L"ffmpeg",
+          "a bare executable name is left for PATH to resolve");
+    check(joc_path::to_wide_extended(std::string("sub\\file.m4a")) == L"sub\\file.m4a",
+          "a relative path is left alone");
+    check(joc_path::to_wide_extended(std::string("C:\\a\\b.m4a")) == L"\\\\?\\C:\\a\\b.m4a",
+          "an absolute path gains the prefix");
+    check(joc_path::to_wide_extended(std::string("\\\\?\\C:\\a\\b.m4a")) ==
+              L"\\\\?\\C:\\a\\b.m4a",
+          "an already-prefixed path is not prefixed twice");
+    check(joc_path::to_wide_extended(std::string("\\\\server\\share\\b.m4a")) ==
+              L"\\\\?\\UNC\\server\\share\\b.m4a",
+          "a UNC path takes the UNC form");
+    check(joc_path::to_wide_extended(std::string("//server/share/b.m4a")) ==
+              L"\\\\?\\UNC\\server\\share\\b.m4a",
+          "and the same one in forward slashes, without doubling a separator");
+    check(joc_path::to_wide_extended(std::string("C:/a/b.m4a")) == L"\\\\?\\C:\\a\\b.m4a",
+          "forward slashes become backslashes, which the prefix stops normalizing");
+    check(joc_path::to_wide_extended(std::string("C:\\a\\..\\b.m4a")) == L"C:\\a\\..\\b.m4a",
+          "a .. segment is left alone, since the prefix would stop resolving it");
+    check(joc_path::to_wide_extended(std::string("C:/a/../b.m4a")) == L"C:/a/../b.m4a",
+          "and one in forward slashes is recognized as well");
+}
+
+}  // namespace
+
+int main() {
+    check_helper_rules();
+
+    const std::string tree = build_tree();
+    if (tree.empty()) {
+        std::printf("FAIL cannot build the tree under %s\n", temp_root().c_str());
+        return 1;
+    }
+    const std::string long_file = tree + "\\probe.m4a";
+    const std::string short_file = temp_root() + "\\short.m4a";
+    std::printf("long path  : %zu chars\n", long_file.size());
+    std::printf("short path : %zu chars\n", short_file.size());
+
+    check(long_file.size() > MAX_PATH, "the path is past MAX_PATH, so the test is on it");
+    check(write_container(long_file), "the file was written at the long path");
+    check(write_container(short_file), "the control file was written at the short path");
+
+    // The premise: without the prefix the very same path is refused.  If this ever
+    // starts passing, the machine lifts MAX_PATH for ordinary processes and the rest
+    // of the test no longer proves anything.
+    const HANDLE raw = CreateFileW(joc_path::to_wide(long_file).c_str(), GENERIC_READ,
+                                   FILE_SHARE_READ, nullptr, OPEN_EXISTING,
+                                   FILE_ATTRIBUTE_NORMAL, nullptr);
+    check(raw == INVALID_HANDLE_VALUE, "the raw path is still refused without the prefix");
+    if (raw != INVALID_HANDLE_VALUE) CloseHandle(raw);
+
+    const joc_container::Result long_result = joc_container::scan(long_file);
+    std::printf("container probe: kind=%s detail=%s\n",
+                joc_container::kind_name(long_result.kind), long_result.detail.c_str());
+    check(long_result.kind == joc_container::Kind::kMp4,
+          "the container probe reads the long path");
+    check(long_result.detail != "cannot open the file",
+          "and did not fall back to the unreadable-file answer");
+
+    const joc_decode::FileProbe probe = joc_decode::probe_file(long_file);
+    std::printf("decode reader  : readable=%d detail=%s\n", probe.readable ? 1 : 0,
+                probe.detail.c_str());
+    check(probe.readable, "the decode-side reader opens the long path too");
+
+    const joc_container::Result short_result = joc_container::scan(short_file);
+    check(short_result.kind == joc_container::Kind::kMp4 && short_result.detail != "cannot open the file",
+          "a short path in the same tree still probes, prefix and all");
+
+    remove_tree(temp_root(), tree);
+
+    if (failures == 0) {
+        std::printf("long paths are handled\n");
+        return 0;
+    }
+    std::printf("%d check(s) failed\n", failures);
+    return 1;
+}

tools/build_tests.ps1

@@ -40,6 +40,8 @@ $lines = @(
     "cd /d `"$projectRoot`"",
     # log.cpp comes along because the engine writes its diagnostics through it.
     "cl $common /Fe:`"$outDir\container_scan_test.exe`" /Fo:`"$outDir\\`" tests\container_scan_test.cpp src\container_scan.cpp src\log.cpp",
+    "cl $common /Fe:`"$outDir\log_rotation_test.exe`" /Fo:`"$outDir\\`" tests\log_rotation_test.cpp src\log.cpp",
+    "cl $common /Fe:`"$outDir\long_path_test.exe`" /Fo:`"$outDir\\`" tests\long_path_test.cpp src\container_scan.cpp src\joc_decode.cpp src\eac3_scan.cpp src\log.cpp `"$coreLib`" shell32.lib",
     "cl $common /Fe:`"$outDir\scan_selftest.exe`" /Fo:`"$outDir\\`" tests\scan_selftest.cpp src\eac3_scan.cpp",
     "cl $common /Fe:`"$outDir\prefs_layout_check.exe`" /Fo:`"$outDir\\`" tests\prefs_layout_check.cpp user32.lib gdi32.lib",
     "cl $common /Fe:`"$outDir\scan_crosscheck.exe`" /Fo:`"$outDir\\`" tests\scan_crosscheck.cpp src\eac3_scan.cpp `"$coreLib`" shell32.lib",

tools/run.ps1

@@ -39,7 +39,10 @@ if (Test-Path -LiteralPath $running) {
 }
 
 $arguments = @()
-if ($Play) { $arguments += $Play }
+# Start-Process joins the array with spaces and quotes nothing itself, so a path with
+# a space in it would reach foobar2000 as several arguments and nothing would play --
+# silently, which is the worst way for a test bed to fail.
+if ($Play) { $arguments += ($Play | ForEach-Object { '"' + $_ + '"' }) }
 $process = Start-Process -FilePath $exe -ArgumentList $arguments -PassThru
 Write-Host "started pid=$($process.Id) $($Play -join ', ')"
 Start-Sleep -Seconds $WaitSeconds