[NativeProcessLinux] Refactor PtraceWrapper

Summary:
This changes PtraceWrapper to return an Error, while the actual result is in an pointer parameter
(instead of the other way around). Also made a couple of PtraceWrapper arguments default to zero.
This arrangement makes a lot of the code much simpler.

Test Plan: Tests pass on linux. It compiles on android arm64/mips64.

Reviewers: chaoren, mohit.bhakkad

Subscribers: tberghammer, aemerson, lldb-commits

Differential Revision: http://reviews.llvm.org/D10808

llvm-svn: 241079

1 files changed, 23 insertions, 42 deletions

diff --git a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
index e47cb52e8cc..b956b88ce45 100644
--- a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
+++ b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
@@ -250,8 +250,7 @@ namespace
         assert(sizeof(data) >= word_size);
         for (bytes_read = 0; bytes_read < size; bytes_read += remainder)
         {
-            Error error;
-            data = NativeProcessLinux::PtraceWrapper(PTRACE_PEEKDATA, pid, (void*)vm_addr, nullptr, 0, error);
+            Error error = NativeProcessLinux::PtraceWrapper(PTRACE_PEEKDATA, pid, (void*)vm_addr, nullptr, 0, &data);
             if (error.Fail())
             {
                 if (log)
@@ -327,7 +326,8 @@ namespace
                     log->Printf ("NativeProcessLinux::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
                             (void*)vm_addr, *(const unsigned long*)src, data);
 
-                if (NativeProcessLinux::PtraceWrapper(PTRACE_POKEDATA, pid, (void*)vm_addr, (void*)data, 0, error))
+                error = NativeProcessLinux::PtraceWrapper(PTRACE_POKEDATA, pid, (void*)vm_addr, (void*)data);
+                if (error.Fail())
                 {
                     if (log)
                         ProcessPOSIXLog::DecNestLevel();
@@ -1115,7 +1115,7 @@ NativeProcessLinux::Launch(LaunchArgs *args, Error &error)
         // send log info to parent re: launch status, in place of the log lines removed here.
 
         // Start tracing this child that is about to exec.
-        NativeProcessLinux::PtraceWrapper(PTRACE_TRACEME, 0, nullptr, nullptr, 0, error);
+        error = PtraceWrapper(PTRACE_TRACEME, 0);
         if (error.Fail())
             exit(ePtraceFailed);
 
@@ -1351,7 +1351,7 @@ NativeProcessLinux::Attach(lldb::pid_t pid, Error &error)
 
                 // Attach to the requested process.
                 // An attach will cause the thread to stop with a SIGSTOP.
-                NativeProcessLinux::PtraceWrapper(PTRACE_ATTACH, tid, nullptr, nullptr, 0, error);
+                error = PtraceWrapper(PTRACE_ATTACH, tid);
                 if (error.Fail())
                 {
                     // No such thread. The thread may have exited.
@@ -1442,9 +1442,7 @@ NativeProcessLinux::SetDefaultPtraceOpts(lldb::pid_t pid)
     // (needed to disable legacy SIGTRAP generation)
     ptrace_opts |= PTRACE_O_TRACEEXEC;
 
-    Error error;
-    NativeProcessLinux::PtraceWrapper(PTRACE_SETOPTIONS, pid, nullptr, (void*)ptrace_opts, 0, error);
-    return error;
+    return PtraceWrapper(PTRACE_SETOPTIONS, pid, nullptr, (void*)ptrace_opts);
 }
 
 static ExitType convert_pid_status_to_exit_type (int status)
@@ -3173,11 +3171,7 @@ NativeProcessLinux::Resume (lldb::tid_t tid, uint32_t signo)
     if (signo != LLDB_INVALID_SIGNAL_NUMBER)
         data = signo;
 
-    Error error = DoOperation([&] {
-        Error error;
-        NativeProcessLinux::PtraceWrapper(PTRACE_CONT, tid, nullptr, (void*)data, 0, error);
-        return error;
-    });
+    Error error = DoOperation([&] { return PtraceWrapper(PTRACE_CONT, tid, nullptr, (void*)data); });
 
     if (log)
         log->Printf ("NativeProcessLinux::%s() resuming thread = %"  PRIu64 " result = %s", __FUNCTION__, tid, error.Success() ? "true" : "false");
@@ -3192,31 +3186,19 @@ NativeProcessLinux::SingleStep(lldb::tid_t tid, uint32_t signo)
     if (signo != LLDB_INVALID_SIGNAL_NUMBER)
         data = signo;
 
-    return DoOperation([&] {
-        Error error;
-        NativeProcessLinux::PtraceWrapper(PTRACE_SINGLESTEP, tid, nullptr, (void*)data, 0, error);
-        return error;
-    });
+    return DoOperation([&] { return PtraceWrapper(PTRACE_SINGLESTEP, tid, nullptr, (void*)data); });
 }
 
 Error
 NativeProcessLinux::GetSignalInfo(lldb::tid_t tid, void *siginfo)
 {
-    return DoOperation([&] {
-        Error error;
-        NativeProcessLinux::PtraceWrapper(PTRACE_GETSIGINFO, tid, nullptr, siginfo, 0, error);
-        return error;
-    });
+    return DoOperation([&] { return PtraceWrapper(PTRACE_GETSIGINFO, tid, nullptr, siginfo); });
 }
 
 Error
 NativeProcessLinux::GetEventMessage(lldb::tid_t tid, unsigned long *message)
 {
-    return DoOperation([&] {
-        Error error;
-        NativeProcessLinux::PtraceWrapper(PTRACE_GETEVENTMSG, tid, nullptr, message, 0, error);
-        return error;
-    });
+    return DoOperation([&] { return PtraceWrapper(PTRACE_GETEVENTMSG, tid, nullptr, message); });
 }
 
 Error
@@ -3225,11 +3207,7 @@ NativeProcessLinux::Detach(lldb::tid_t tid)
     if (tid == LLDB_INVALID_THREAD_ID)
         return Error();
 
-    return DoOperation([&] {
-        Error error;
-        NativeProcessLinux::PtraceWrapper(PTRACE_DETACH, tid, nullptr, 0, 0, error);
-        return error;
-    });
+    return DoOperation([&] { return PtraceWrapper(PTRACE_DETACH, tid); });
 }
 
 bool
@@ -3732,27 +3710,30 @@ NativeProcessLinux::DoOperation(const Operation &op)
 
 // Wrapper for ptrace to catch errors and log calls.
 // Note that ptrace sets errno on error because -1 can be a valid result (i.e. for PTRACE_PEEK*)
-long
-NativeProcessLinux::PtraceWrapper(int req, lldb::pid_t pid, void *addr, void *data, size_t data_size, Error& error)
+Error
+NativeProcessLinux::PtraceWrapper(int req, lldb::pid_t pid, void *addr, void *data, size_t data_size, long *result)
 {
-    long int result;
+    Error error;
+    long int ret;
 
     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PTRACE));
 
     PtraceDisplayBytes(req, data, data_size);
 
-    error.Clear();
     errno = 0;
     if (req == PTRACE_GETREGSET || req == PTRACE_SETREGSET)
-        result = ptrace(static_cast<__ptrace_request>(req), static_cast< ::pid_t>(pid), *(unsigned int *)addr, data);
+        ret = ptrace(static_cast<__ptrace_request>(req), static_cast< ::pid_t>(pid), *(unsigned int *)addr, data);
     else
-        result = ptrace(static_cast<__ptrace_request>(req), static_cast< ::pid_t>(pid), addr, data);
+        ret = ptrace(static_cast<__ptrace_request>(req), static_cast< ::pid_t>(pid), addr, data);
 
-    if (result == -1)
+    if (ret == -1)
         error.SetErrorToErrno();
 
+    if (result)
+        *result = ret;
+
     if (log)
-        log->Printf("ptrace(%d, %" PRIu64 ", %p, %p, %zu)=%lX", req, pid, addr, data, data_size, result);
+        log->Printf("ptrace(%d, %" PRIu64 ", %p, %p, %zu)=%lX", req, pid, addr, data, data_size, ret);
 
     PtraceDisplayBytes(req, data, data_size);
 
@@ -3770,5 +3751,5 @@ NativeProcessLinux::PtraceWrapper(int req, lldb::pid_t pid, void *addr, void *da
         log->Printf("ptrace() failed; errno=%d (%s)", error.GetError(), str);
     }
 
-    return result;
+    return error;
 }