From 93027f442fa660b51233076697fc71aa3c2a2f7a Mon Sep 17 00:00:00 2001
From: Ingo Weinhold <ingo_weinhold@gmx.de>
Date: Tue, 22 Apr 2008 14:57:50 +0000
Subject: [PATCH] Added "straced" debugger command which basically works like
 "traced", but also prints post syscall entries not matching the filter, if
 the respective pre syscall entry matched. This way one also sees the syscall
 return values. Works only in forward direction ATM.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25095 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 src/system/kernel/syscalls.cpp | 154 ++++++++++++++++++++++++++++++++-
 1 file changed, 153 insertions(+), 1 deletion(-)

diff --git a/src/system/kernel/syscalls.cpp b/src/system/kernel/syscalls.cpp
index 86d92299f5..d1d5a1251b 100644
--- a/src/system/kernel/syscalls.cpp
+++ b/src/system/kernel/syscalls.cpp
@@ -58,6 +58,9 @@ static struct mutex sGenericSyscallLock;
 static struct list sGenericSyscalls;
 
 
+static int dump_syscall_tracing(int argc, char** argv);
+
+
 static generic_syscall *
 find_generic_syscall(const char *subsystem)
 {
@@ -206,7 +209,23 @@ status_t
 generic_syscall_init(void)
 {
 	list_init(&sGenericSyscalls);
-	return mutex_init(&sGenericSyscallLock, "generic syscall");
+	if (mutex_init(&sGenericSyscallLock, "generic syscall") != B_OK) {
+		panic("generic_syscall_init(): mutex init failed");
+		return B_ERROR;
+	}
+
+#if	ENABLE_TRACING && defined(SYSCALL_TRACING)
+	add_debugger_command_etc("straced", &dump_syscall_tracing,
+		"Dump recorded syscall trace entries",
+		"Prints recorded trace entries. It is wrapper for the \"traced\"\n"
+		"command and supports all of its command line options (though\n"
+		"backward tracing doesn't really work). The difference is that if a\n"
+		"pre syscall trace entry is encountered, the corresponding post\n"
+		"syscall traced entry is also printed, even if it doesn't match the\n"
+		"given filter.\n", 0);
+#endif	// ENABLE_TRACING
+
+	return B_OK;
 }
 
 
@@ -463,6 +482,139 @@ trace_post_syscall(int syscallNumber, uint64 returnValue)
 }
 
 
+using namespace SyscallTracing;
+
+class SyscallWrapperTraceFilter : public WrapperTraceFilter {
+public:
+	virtual void Init(TraceFilter* filter, int direction, bool continued)
+	{
+		fFilter = filter;
+		fHitThreadLimit = false;
+		fDirection = direction;
+
+		if (!continued)
+			fPendingThreadCount = 0;
+	}
+
+	virtual bool Filter(const TraceEntry* _entry, LazyTraceOutput& out)
+	{
+		if (fFilter == NULL)
+			return true;
+
+		if (fDirection < 0)
+			return fFilter->Filter(_entry, out);
+
+		if (const PreSyscall* entry = dynamic_cast<const PreSyscall*>(_entry)) {
+			_RemovePendingThread(entry->Thread());
+
+			bool accepted = fFilter->Filter(entry, out);
+			if (accepted)
+				_AddPendingThread(entry->Thread());
+			return accepted;
+
+		} else if (const PostSyscall* entry
+				= dynamic_cast<const PostSyscall*>(_entry)) {
+			bool wasPending = _RemovePendingThread(entry->Thread());
+
+			return wasPending || fFilter->Filter(entry, out);
+
+		} else if (const AbstractTraceEntry* entry
+				= dynamic_cast<const AbstractTraceEntry*>(_entry)) {
+			bool isPending = _IsPendingThread(entry->Thread());
+
+			return isPending || fFilter->Filter(entry, out);
+
+		} else {
+			return fFilter->Filter(_entry, out);
+		}
+	}
+
+	bool HitThreadLimit() const
+	{
+		return fHitThreadLimit;
+	}
+
+	int Direction() const
+	{
+		return fDirection;
+	}
+
+private:
+	enum {
+		MAX_PENDING_THREADS = 32
+	};
+
+	bool _AddPendingThread(thread_id thread)
+	{
+		int32 index = _PendingThreadIndex(thread);
+		if (index >= 0)
+			return true;
+
+		if (fPendingThreadCount == MAX_PENDING_THREADS) {
+			fHitThreadLimit = true;
+			return false;
+		}
+
+		fPendingThreads[fPendingThreadCount++] = thread;
+		return true;
+	}
+
+	bool _RemovePendingThread(thread_id thread)
+	{
+		int32 index = _PendingThreadIndex(thread);
+		if (index < 0)
+			return false;
+
+		if (index + 1 < fPendingThreadCount) {
+			memmove(fPendingThreads + index, fPendingThreads + index + 1,
+				fPendingThreadCount - index - 1);
+		}
+
+		fPendingThreadCount--;
+		return true;
+	}
+
+	bool _IsPendingThread(thread_id thread)
+	{
+		return _PendingThreadIndex(thread) >= 0;
+	}
+
+	int32 _PendingThreadIndex(thread_id thread)
+	{
+		for (int32 i = 0; i < fPendingThreadCount; i++) {
+			if (fPendingThreads[i] == thread)
+				return i;
+		}
+		return -1;
+	}
+
+	TraceFilter*	fFilter;
+	thread_id		fPendingThreads[MAX_PENDING_THREADS];
+	int32			fPendingThreadCount;
+	int				fDirection;
+	bool			fHitThreadLimit;
+};
+
+
+static SyscallWrapperTraceFilter sFilter;
+
+static int
+dump_syscall_tracing(int argc, char** argv)
+{
+	new(&sFilter) SyscallWrapperTraceFilter;
+	int result = dump_tracing(argc, argv, &sFilter);
+
+	if (sFilter.HitThreadLimit()) {
+		kprintf("Warning: The thread buffer was too small to track all "
+			"threads!\n");
+	} else if (sFilter.HitThreadLimit()) {
+		kprintf("Warning: Can't track syscalls backwards!\n");
+	}
+
+	return result;
+}
+
+
 #endif	// SYSCALL_TRACING