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crash_signal_handler: avoid backtrace interleaving

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Previously, if eg. multiple worker crashed, backtraces were interleaved
- use temporary file to print it. It seems that the new implementation
prints backtrace just from one thread, which shouldn't matter, anyways,
because it is improbable that there are two different crashes at the
same time.
This commit is contained in:
Martin Pulec
2023-11-13 12:51:52 +01:00
parent 6b12ca5231
commit db8a6cd2dc
1 changed files with 47 additions and 7 deletions
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54
src/host.cpp
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@@ -46,6 +46,7 @@
#ifndef _WIN32
#include <execinfo.h>
#include <fcntl.h>
#endif // defined WIN32
#include "host.h"
@@ -64,6 +65,7 @@
#include "messaging.h"
#include "module.h"
#include "utils/color_out.h"
#include "utils/fs.h"
#include "utils/misc.h" // unit_evaluate
#include "utils/random.h"
#include "utils/string.h"
@@ -1051,19 +1053,57 @@ bool running_in_debugger(){
return false;
}
static void
print_backtrace()
{
#ifndef _WIN32
// print to a temporary file to avoid interleaving from multiple
// threads
#ifdef __APPLE__
char path[MAX_PATH_SIZE];
snprintf(path, sizeof path, "%s/ug-%u", get_temp_dir(),
pthread_mach_thread_np(pthread_self()));
int fd = open(path, O_CLOEXEC | O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
unlink(path);
#else
int fd = memfd_create("ultragrid_backtrace", MFD_CLOEXEC);
#endif
if (fd == -1) {
fd = STDERR_FILENO;
}
char backtrace_msg[] = "Backtrace:\n";
write_all(fd, sizeof backtrace_msg, backtrace_msg);
array<void *, 256> addresses{};
const int num_symbols = backtrace(addresses.data(), addresses.size());
backtrace_symbols_fd(addresses.data(), num_symbols, fd);
if (fd == STDERR_FILENO) {
return;
}
lseek(fd, 0, SEEK_SET);
char buf[STR_LEN];
ssize_t rbytes = 0;
while ((rbytes = read(fd, buf, sizeof buf)) > 0) {
ssize_t written = 0;
ssize_t wbytes = 0;
while (written < rbytes &&
(wbytes = write(STDERR_FILENO, buf + written,
rbytes - written)) > 0) {
written += wbytes;
}
}
close(fd);
#endif // defined WIN32
}
void crash_signal_handler(int sig)
{
print_backtrace();
char buf[1024];
char *ptr = buf;
char *ptr_end = buf + sizeof buf;
strappend(&ptr, ptr_end, "\n" PACKAGE_NAME " has crashed");
#ifndef WIN32
char backtrace_msg[] = "Backtrace:\n";
write_all(STDERR_FILENO, sizeof backtrace_msg, backtrace_msg);
array<void *, 256> addresses{};
int num_symbols = backtrace(addresses.data(), addresses.size());
backtrace_symbols_fd(addresses.data(), num_symbols, 2);
#endif // defined WIN32
append_sig_desc(&ptr, ptr_end, sig);