common/Log.cpp | 3 ++-
common/SigUtil.cpp | 41 +++++++++--------------------------------
2 files changed, 11 insertions(+), 33 deletions(-)
New commits:
commit 3ebbc6213b6e398bfc4a71b3eb5f03f421d0ffe6
Author: Ashod Nakashian <ashod.nakash...@collabora.co.uk>
AuthorDate: Mon Nov 18 22:13:00 2019 -0500
Commit: Ashod Nakashian <ashnak...@gmail.com>
CommitDate: Tue Nov 19 16:13:33 2019 +0100
wsd: avoid malloc in signal handler
malloc is not signal safe, and must not be called
from signal-safe functions. If malloc itself signals,
calling it in the signal handler can deadlock.
Luckily, we only needed malloc for getting the
backtrace strings. Now we just write directly to
stderr, which is faster, cleaner, and safer.
Change-Id: I54093f45e05f2a0fd3c5cde0cc2104ffe6d81d2a
Reviewed-on: https://gerrit.libreoffice.org/83151
Reviewed-by: Ashod Nakashian <ashnak...@gmail.com>
Tested-by: Ashod Nakashian <ashnak...@gmail.com>
diff --git a/common/Log.cpp b/common/Log.cpp
index e08287bb9..ef2b03038 100644
--- a/common/Log.cpp
+++ b/common/Log.cpp
@@ -83,7 +83,7 @@ namespace Log
while (true)
{
const int length = std::strlen(message);
- const int written = write (STDERR_FILENO, message, length);
+ const int written = write(STDERR_FILENO, message, length);
if (written < 0)
{
if (errno == EINTR)
@@ -119,6 +119,7 @@ namespace Log
Poco::DateTime time;
#ifdef __linux
const long osTid = Util::getThreadId();
+ // Note that snprintf is deemed signal-safe in most common
implementations.
snprintf(buffer, len, "%s-%.05lu %.4u-%.2u-%.2u %.2u:%.2u:%.2u.%.6u [
%s ] %s ",
(Source.getInited() ? Source.getId().c_str() :
"<shutdown>"),
osTid,
diff --git a/common/SigUtil.cpp b/common/SigUtil.cpp
index e5dabcb6f..c24ffb9d5 100644
--- a/common/SigUtil.cpp
+++ b/common/SigUtil.cpp
@@ -251,13 +251,6 @@ namespace SigUtil
Log::signalLog(signalName(signal));
Log::signalLog("\n");
- if (std::getenv("LOOL_DEBUG"))
- {
- Log::signalLog(FatalGdbString);
- LOG_ERR("Sleeping 30s to allow debugging.");
- sleep(30);
- }
-
struct sigaction action;
sigemptyset(&action.sa_mask);
@@ -274,34 +267,17 @@ namespace SigUtil
void dumpBacktrace()
{
- char header[32];
- sprintf(header, "Backtrace %d:\n", getpid());
-
#if !defined(__ANDROID__)
+ Log::signalLog("\nBacktrace ");
+ Log::signalLogNumber(getpid());
+ Log::signalLog(":\n");
+
const int maxSlots = 50;
void *backtraceBuffer[maxSlots];
- int numSlots = backtrace(backtraceBuffer, maxSlots);
+ const int numSlots = backtrace(backtraceBuffer, maxSlots);
if (numSlots > 0)
{
- char **symbols = backtrace_symbols(backtraceBuffer, numSlots);
- if (symbols != nullptr)
- {
- struct iovec ioVector[maxSlots*2+1];
- ioVector[0].iov_base = static_cast<void*>(header);
- ioVector[0].iov_len = std::strlen(static_cast<const
char*>(ioVector[0].iov_base));
- for (int i = 0; i < numSlots; i++)
- {
- ioVector[1+i*2+0].iov_base = symbols[i];
- ioVector[1+i*2+0].iov_len = std::strlen(static_cast<const
char *>(ioVector[1+i*2+0].iov_base));
- ioVector[1+i*2+1].iov_base =
const_cast<void*>(static_cast<const void*>("\n"));
- ioVector[1+i*2+1].iov_len = 1;
- }
-
- if (writev(STDERR_FILENO, ioVector, numSlots*2+1) == -1)
- {
- LOG_SYS("Failed to dump backtrace to stderr.");
- }
- }
+ backtrace_symbols_fd(backtraceBuffer, numSlots, STDERR_FILENO);
}
#else
LOG_SYS("Backtrace not available on Android.");
@@ -309,6 +285,7 @@ namespace SigUtil
if (std::getenv("LOOL_DEBUG"))
{
+ Log::signalLog(FatalGdbString);
LOG_ERR("Sleeping 30s to allow debugging.");
sleep(30);
}
@@ -328,9 +305,9 @@ namespace SigUtil
sigaction(SIGILL, &action, nullptr);
sigaction(SIGFPE, &action, nullptr);
- // prepare this in advance just in case.
+ // Prepare this in advance just in case.
std::ostringstream stream;
- stream << "\nFatal signal! Attach debugger with:\n"
+ stream << "\nERROR: Fatal signal! Attach debugger with:\n"
<< "sudo gdb --pid=" << getpid() << "\n or \n"
<< "sudo gdb --q --n --ex 'thread apply all backtrace full'
--batch --pid="
<< getpid() << "\n";
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