From e395b1eb3ff7a093e6c0de76b6cece6f8ff0ec44 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antti=20M=C3=A4=C3=A4tt=C3=A4?= <antti.maatta@qt.io>
Date: Tue, 20 Jun 2023 13:26:52 +0300
Subject: [PATCH] CTF: Clear output location at startup
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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Remove old files from the output location before saving new ones.

Change-Id: I75181126c6c920e13951e9a46a6be1c666d457fe
Reviewed-by: Antti Määttä <antti.maatta@qt.io>
Reviewed-by: Janne Koskinen <janne.p.koskinen@qt.io>
(cherry picked from commit c6ab516f71efeeaaf2a10dbc0368fb437f8b3a6c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/plugins/tracing/qctflib.cpp | 30 +++++++++++++++++++++++++-----
 src/plugins/tracing/qctflib_p.h |  1 +
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/plugins/tracing/qctflib.cpp b/src/plugins/tracing/qctflib.cpp
index 783be079f71..f57f1cf71f2 100644
--- a/src/plugins/tracing/qctflib.cpp
+++ b/src/plugins/tracing/qctflib.cpp
@@ -116,6 +116,7 @@ QCtfLibImpl::QCtfLibImpl()
         }
         m_location = location + QStringLiteral("/ust");
         std::filesystem::create_directory(qPrintable(m_location), qPrintable(location));
+        clearLocation();
     }
     m_session.all = m_session.tracepoints.contains(QStringLiteral("all"));
 
@@ -136,6 +137,30 @@ QCtfLibImpl::QCtfLibImpl()
     m_timer.start();
 }
 
+void QCtfLibImpl::clearLocation()
+{
+    const std::filesystem::path location{qUtf16Printable(m_location)};
+    for (auto const& dirEntry : std::filesystem::directory_iterator{location})
+    {
+        const auto path = dirEntry.path();
+#if __cplusplus > 201703L
+        if (dirEntry.is_regular_file()
+            && path.filename().wstring().starts_with(std::wstring_view(L"channel_"))
+            && !path.has_extension()) {
+#else
+        const auto strview = std::wstring_view(L"channel_");
+        const auto sub = path.filename().wstring().substr(0, strview.length());
+        if (dirEntry.is_regular_file() && sub.compare(strview) == 0
+            && !path.has_extension()) {
+#endif
+            if (!std::filesystem::remove(path)) {
+                qCInfo(lcDebugTrace) << "Unable to clear output location.";
+                break;
+            }
+        }
+    }
+}
+
 void QCtfLibImpl::writeMetadata(const QString &metadata, bool overwrite)
 {
     FILE *file = nullptr;
@@ -276,11 +301,6 @@ void QCtfLibImpl::doTracepoint(const QCtfTracePointEvent &point, const QByteArra
 
     if (ch.channelName[0] == 0) {
         m_threadIndices.insert(thread, m_threadIndices.size());
-        sprintf(ch.channelName, "%s/channel_%d", qPrintable(m_location), m_threadIndices[thread]);
-        FILE *f = nullptr;
-        f = openFile(ch.channelName, "wb"_L1);
-        if (f)
-            fclose(f);
         ch.minTimestamp = ch.maxTimestamp = timestamp;
         ch.thread = thread;
         ch.threadIndex = m_threadIndices[thread];
diff --git a/src/plugins/tracing/qctflib_p.h b/src/plugins/tracing/qctflib_p.h
index 98f34699bd0..8d88183b84f 100644
--- a/src/plugins/tracing/qctflib_p.h
+++ b/src/plugins/tracing/qctflib_p.h
@@ -89,6 +89,7 @@ private:
     QHash<QString, QCtfTracePointPrivate *> m_eventPrivs;
     void updateMetadata(const QCtfTracePointEvent &point);
     void writeMetadata(const QString &metadata, bool overwrite = false);
+    void clearLocation();
     static void writeCtfPacket(Channel &ch);
 
     static constexpr QUuid s_TraceUuid = QUuid(0x3e589c95, 0xed11, 0xc159, 0x42, 0x02, 0x6a, 0x9b, 0x02, 0x00, 0x12, 0xac);