replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

[LLGS] Log more precise errors during inferior launch 

Summary:
We are seeing infrequent failures to launch the inferior process on android. The failing call
seems to be execve(). This adds more logging to see the actual error reported by the call.

Reviewers: tberghammer

Subscribers: tberghammer, lldb-commits, danalbert

Differential Revision: http://reviews.llvm.org/D22039

llvm-svn: 274624
This commit is contained in:
Pavel Labath 2016-07-06 13:18:50 +00:00
parent 3c21a69077
commit 0c4f01d44b
2 changed files with 129 additions and 113 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

191
lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
View File

@ -130,6 +130,37 @@ ResolveProcessArchitecture(lldb::pid_t pid, ArchSpec &arch)
return Error("failed to retrieve a valid architecture from the exe module");
}
// Used to notify the parent about which part of the launch sequence failed.
enum LaunchCallSpecifier
{
ePtraceFailed,
eDupStdinFailed,
eDupStdoutFailed,
eDupStderrFailed,
eChdirFailed,
eExecFailed,
eSetGidFailed,
eSetSigMaskFailed,
eLaunchCallMax = eSetSigMaskFailed
};
static uint8_t LLVM_ATTRIBUTE_NORETURN
ExitChildAbnormally(LaunchCallSpecifier spec)
{
static_assert(eLaunchCallMax < 0x8, "Have more launch calls than we are able to represent");
// This may truncate the topmost bits of the errno because the exit code is only 8 bits wide.
// However, it should still give us a pretty good indication of what went wrong. (And the
// most common errors have small numbers anyway).
_exit(unsigned(spec) | (errno << 3));
}
// The second member is the errno (or its 5 lowermost bits anyway).
inline std::pair<LaunchCallSpecifier, uint8_t>
DecodeChildExitCode(int exit_code)
{
return std::make_pair(LaunchCallSpecifier(exit_code & 0x7), exit_code >> 3);
}
void
DisplayBytes (StreamString &s, void *bytes, uint32_t count)
{
@ -453,65 +484,16 @@ NativeProcessLinux::AttachToInferior (MainLoop &mainloop, lldb::pid_t pid, Error
Attach(pid, error);
}
::pid_t
NativeProcessLinux::Launch(LaunchArgs *args, Error &error)
void
NativeProcessLinux::ChildFunc(const LaunchArgs &args)
{
assert (args && "null args");
const char **argv = args->m_argv;
const char **envp = args->m_envp;
const FileSpec working_dir = args->m_working_dir;
lldb_utility::PseudoTerminal terminal;
const size_t err_len = 1024;
char err_str[err_len];
lldb::pid_t pid;
// Propagate the environment if one is not supplied.
if (envp == NULL || envp[0] == NULL)
envp = const_cast<const char **>(environ);
if ((pid = terminal.Fork(err_str, err_len)) == static_cast<lldb::pid_t> (-1))
{
error.SetErrorToGenericError();
error.SetErrorStringWithFormat("Process fork failed: %s", err_str);
return -1;
}
// Recognized child exit status codes.
enum {
ePtraceFailed = 1,
eDupStdinFailed,
eDupStdoutFailed,
eDupStderrFailed,
eChdirFailed,
eExecFailed,
eSetGidFailed,
eSetSigMaskFailed
};
// Child process.
if (pid == 0)
{
// First, make sure we disable all logging. If we are logging to stdout, our logs can be
// mistaken for inferior output.
Log::DisableAllLogChannels(nullptr);
// FIXME consider opening a pipe between parent/child and have this forked child
// send log info to parent re: launch status.
// Start tracing this child that is about to exec.
error = PtraceWrapper(PTRACE_TRACEME, 0);
if (error.Fail())
exit(ePtraceFailed);
// terminal has already dupped the tty descriptors to stdin/out/err.
// This closes original fd from which they were copied (and avoids
// leaking descriptors to the debugged process.
terminal.CloseSlaveFileDescriptor();
if (ptrace(PTRACE_TRACEME, 0, nullptr, nullptr) == -1)
ExitChildAbnormally(ePtraceFailed);
// Do not inherit setgid powers.
if (setgid(getgid()) != 0)
exit(eSetGidFailed);
ExitChildAbnormally(eSetGidFailed);
// Attempt to have our own process group.
if (setpgid(0, 0) != 0)
@ -521,30 +503,30 @@ NativeProcessLinux::Launch(LaunchArgs *args, Error &error)
}
// Dup file descriptors if needed.
if (args->m_stdin_file_spec)
if (!DupDescriptor(args->m_stdin_file_spec, STDIN_FILENO, O_RDONLY))
exit(eDupStdinFailed);
if (args.m_stdin_file_spec)
if (!DupDescriptor(args.m_stdin_file_spec, STDIN_FILENO, O_RDONLY))
ExitChildAbnormally(eDupStdinFailed);
if (args->m_stdout_file_spec)
if (!DupDescriptor(args->m_stdout_file_spec, STDOUT_FILENO, O_WRONLY | O_CREAT | O_TRUNC))
exit(eDupStdoutFailed);
if (args.m_stdout_file_spec)
if (!DupDescriptor(args.m_stdout_file_spec, STDOUT_FILENO, O_WRONLY | O_CREAT | O_TRUNC))
ExitChildAbnormally(eDupStdoutFailed);
if (args->m_stderr_file_spec)
if (!DupDescriptor(args->m_stderr_file_spec, STDERR_FILENO, O_WRONLY | O_CREAT | O_TRUNC))
exit(eDupStderrFailed);
if (args.m_stderr_file_spec)
if (!DupDescriptor(args.m_stderr_file_spec, STDERR_FILENO, O_WRONLY | O_CREAT | O_TRUNC))
ExitChildAbnormally(eDupStderrFailed);
// Close everything besides stdin, stdout, and stderr that has no file
// action to avoid leaking
for (int fd = 3; fd < sysconf(_SC_OPEN_MAX); ++fd)
if (!args->m_launch_info.GetFileActionForFD(fd))
if (!args.m_launch_info.GetFileActionForFD(fd))
close(fd);
// Change working directory
if (working_dir && 0 != ::chdir(working_dir.GetCString()))
exit(eChdirFailed);
if (args.m_working_dir && 0 != ::chdir(args.m_working_dir.GetCString()))
ExitChildAbnormally(eChdirFailed);
// Disable ASLR if requested.
if (args->m_launch_info.GetFlags ().Test (lldb::eLaunchFlagDisableASLR))
if (args.m_launch_info.GetFlags().Test(lldb::eLaunchFlagDisableASLR))
{
const int old_personality = personality(LLDB_PERSONALITY_GET_CURRENT_SETTINGS);
if (old_personality == -1)
@ -569,20 +551,52 @@ NativeProcessLinux::Launch(LaunchArgs *args, Error &error)
// any masking done by the parent.
sigset_t set;
if (sigemptyset(&set) != 0 || pthread_sigmask(SIG_SETMASK, &set, nullptr) != 0)
exit(eSetSigMaskFailed);
ExitChildAbnormally(eSetSigMaskFailed);
// Propagate the environment if one is not supplied.
const char **envp = args.m_envp;
if (envp == NULL || envp[0] == NULL)
envp = const_cast<const char **>(environ);
// Execute. We should never return...
execve(argv[0],
const_cast<char *const *>(argv),
const_cast<char *const *>(envp));
execve(args.m_argv[0], const_cast<char *const *>(args.m_argv), const_cast<char *const *>(envp));
// ...unless exec fails. In which case we definitely need to end the child here.
exit(eExecFailed);
ExitChildAbnormally(eExecFailed);
}
::pid_t
NativeProcessLinux::Launch(LaunchArgs *args, Error &error)
{
assert (args && "null args");
lldb_utility::PseudoTerminal terminal;
const size_t err_len = 1024;
char err_str[err_len];
lldb::pid_t pid;
if ((pid = terminal.Fork(err_str, err_len)) == static_cast<lldb::pid_t> (-1))
{
error.SetErrorToGenericError();
error.SetErrorStringWithFormat("Process fork failed: %s", err_str);
return -1;
}
// Child process.
if (pid == 0)
{
// First, make sure we disable all logging. If we are logging to stdout, our logs can be
// mistaken for inferior output.
Log::DisableAllLogChannels(nullptr);
// terminal has already dupped the tty descriptors to stdin/out/err.
// This closes original fd from which they were copied (and avoids
// leaking descriptors to the debugged process.
terminal.CloseSlaveFileDescriptor();
ChildFunc(*args);
}
//
// This is the parent code here.
//
Log *log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS));
// Wait for the child process to trap on its call to execve.
@ -603,38 +617,37 @@ NativeProcessLinux::Launch(LaunchArgs *args, Error &error)
}
else if (WIFEXITED(status))
{
// open, dup or execve likely failed for some reason.
error.SetErrorToGenericError();
switch (WEXITSTATUS(status))
auto p = DecodeChildExitCode(WEXITSTATUS(status));
Error child_error(p.second, eErrorTypePOSIX);
const char *failure_reason;
switch (p.first)
{
case ePtraceFailed:
error.SetErrorString("Child ptrace failed.");
failure_reason = "Child ptrace failed";
break;
case eDupStdinFailed:
error.SetErrorString("Child open stdin failed.");
failure_reason = "Child open stdin failed";
break;
case eDupStdoutFailed:
error.SetErrorString("Child open stdout failed.");
failure_reason = "Child open stdout failed";
break;
case eDupStderrFailed:
error.SetErrorString("Child open stderr failed.");
failure_reason = "Child open stderr failed";
break;
case eChdirFailed:
error.SetErrorString("Child failed to set working directory.");
failure_reason = "Child failed to set working directory";
break;
case eExecFailed:
error.SetErrorString("Child exec failed.");
failure_reason = "Child exec failed";
break;
case eSetGidFailed:
error.SetErrorString("Child setgid failed.");
failure_reason = "Child setgid failed";
break;
case eSetSigMaskFailed:
error.SetErrorString("Child failed to set signal mask.");
break;
default:
error.SetErrorString("Child returned unknown exit status.");
failure_reason = "Child failed to set signal mask";
break;
}
error.SetErrorStringWithFormat("%s: %d - %s (error code truncated)", failure_reason, child_error.GetError(), child_error.AsCString());
if (log)
{

3
lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
View File

@ -202,6 +202,9 @@ namespace process_linux {
::pid_t
Attach(lldb::pid_t pid, Error &error);
static void
ChildFunc(const LaunchArgs &args) LLVM_ATTRIBUTE_NORETURN;
static Error
SetDefaultPtraceOpts(const lldb::pid_t);