Please don't use those functions (like syslog etc.) that are not
/Async/-/signal/-/safe /functions in signal handler function.
Thanks,
Ramesh.
On 4/8/2015 6:03 PM, Anders Widell wrote:
> Ack with comments.
>
> * Make sure to have a properly formatted commit message ("base:" was
> duplicated, square brackets missing around ticket number).
> * It could be useful to see the identity of one who sent the signal
> (PID, maybe also UID).
> * See below for inline comments.
>
> / Anders Widell
>
> On 04/01/2015 10:32 AM, Hans Nordeback wrote:
>> osaf/libs/core/common/daemon.c | 117
>> +++++++++++++++++++++++++++++++++++++++++
>> 1 files changed, 117 insertions(+), 0 deletions(-)
>>
>>
>> Use dlsym on bactrace symbols to circumvent lsb compliance problems.
>>
>> diff --git a/osaf/libs/core/common/daemon.c
>> b/osaf/libs/core/common/daemon.c
>> --- a/osaf/libs/core/common/daemon.c
>> +++ b/osaf/libs/core/common/daemon.c
>> @@ -34,6 +34,8 @@
>> #include <sys/stat.h>
>> #include <sys/file.h>
>> +#include <dlfcn.h>
>> +
>> #include <configmake.h>
>> #include "daemon.h"
>> @@ -43,6 +45,8 @@
>> #include <os_defs.h>
>> #include <osaf_secutil.h>
>> +#include <sys/types.h>
>> +#include <time.h>
>> #define DEFAULT_RUNAS_USERNAME "opensaf"
>> @@ -57,6 +61,8 @@ static unsigned int __tracemask;
>> static unsigned int __nofork = 0;
>> static int __logmask;
>> +static void install_fatal_signal_handlers();
> C functions taking no parameters should be declared as (void) instead
> of ().
>> +
>> static void __print_usage(const char* progname, FILE* stream, int
>> exit_code)
>> {
>> fprintf(stream, "Usage: %s [OPTIONS]...\n", progname);
>> @@ -350,6 +356,9 @@ void daemonize(int argc, char *argv[])
>> }
>> #endif
>> + /* install fatal signal handlers for writing backtrace to
>> file */
>> + install_fatal_signal_handlers();
>> +
> Whitespace problems on the three lines above (space instead of tab,
> whitespace at end of line).
>> /* Initialize the log/trace interface */
>> if (logtrace_init_daemon(basename(argv[0]), __tracefile,
>> __tracemask, __logmask) != 0)
>> exit(EXIT_FAILURE);
>> @@ -414,3 +423,111 @@ void daemon_sigterm_install(int *term_fd
>> *term_fd = term_sel_obj.rmv_obj;
>> }
>> +
>> +static char bt_filename[80];
> This variable shall hold the result of sprintf(..., PKGLOGDIR
> "/bt_%s_%d", ...). PKLOGDIR is a path that can be configured by the
> user. Therefore, this buffer ought to be either PATH_MAX bytes large,
> or dynamically allocated.
>> +
>> +static int (*plibc_backtrace) (void **buffer, int size) = NULL;
>> +static int (*plibc_backtrace_symbols_fd) (void *const *buffer, int
>> size, int fd) = NULL;
>> +
>> +static int init_backtrace_fptrs()
> C functions taking no parameters should be declared as (void) instead
> of ().
>> +{
>> + plibc_backtrace = dlsym(RTLD_NEXT, "backtrace");
> Should use RTLD_DEFAULT instead of RTLD_NEXT.
>> + if (plibc_backtrace == NULL) {
>> + syslog(LOG_ERR, "unable to find \"backrace\" symbol");
>> + return -1;
>> + }
>> + plibc_backtrace_symbols_fd = dlsym(RTLD_NEXT,
>> "backtrace_symbols_fd");
> Should use RTLD_DEFAULT instead of RTLD_NEXT.
>> + if (plibc_backtrace_symbols_fd == NULL) {
>> + syslog(LOG_ERR, "unable to find \"backrace_symbols_fd\"
>> symbol");
>> + return -1;
>> + }
>> + return 0;
>> +}
>> +
>> +/**
>> + * Signal handler for fatal errors. Writes a backtrace and
>> "re-throws" the signal.
>> + */
>> +static void fatal_signal_handler(int sig, siginfo_t* siginfo, void*
>> ctx)
>> +{
>> + const int BT_ARRAY_SIZE = 20;
>> + void *bt_array[BT_ARRAY_SIZE];
>> + size_t bt_size;
>> + int fd;
>> + char bt_header[30];
>> +
>> + if ((fd = open(bt_filename, O_RDWR|O_CREAT, 0644)) < 0) {
>> + goto done;
>> + }
>> +
>> + snprintf(bt_header, sizeof(bt_header), "signal: %d\n", sig);
>> +
>> + if (write(fd, bt_header, strlen(bt_header)) < 0) {
>> + close(fd);
>> + goto done;
>> + }
>> +
>> + bt_size = plibc_backtrace(bt_array, BT_ARRAY_SIZE);
>> + plibc_backtrace_symbols_fd(bt_array, bt_size, fd);
>> +
>> + close(fd);
>> +done:
>> + // re-throw the signal
>> + raise(sig);
>> +}
>> +
>> +/**
>> + * Install signal handlers for fatal errors to be able to print a
>> backtrace.
>> + */
>> +static void install_fatal_signal_handlers()
> C functions taking no parameters should be declared as (void) instead
> of ().
>> +{
>> +
>> + time_t current_time;
>> + char time_string[20];
>> +
>> + struct sigaction action;
>> + int i = 0;
>> + const int HANDLED_SIGNALS_MAX = 7;
>> + static const int handled_signals[] = {
>> + SIGHUP,
>> + SIGILL,
>> + SIGABRT,
>> + SIGFPE,
>> + SIGSEGV,
>> + SIGPIPE,
>> + SIGBUS
>> + };
>> +
>> + // to circumvent lsb use dlsym to retrieve backtrace in runtime
>> + if (init_backtrace_fptrs() < 0) {
>> + syslog(LOG_WARNING, "backtrace symbols not found, no fatal
>> signal handlers will be installed");
>> + }
>> + else {
> No new line before the "else" keyword.
>> +
>> + // prepare a filename for backtrace
>> + time_string[0] = '\0';
>> +
>> + if (time(¤t_time) < 0) {
>> + syslog(LOG_WARNING, "time failed: %s", strerror(errno));
>> + }
>> + else {
> No new line before the "else" keyword.
>> + if (strftime(time_string, sizeof(time_string),
>> "%Y%m%d_%T", localtime(¤t_time)) == 0) {
>> + syslog(LOG_WARNING, "strftime failed");
>> + }
>> + }
>> +
>> + snprintf(bt_filename, sizeof(bt_filename), PKGLOGDIR
>> "/bt_%s_%d", time_string, getpid());
>> +
>> + memset(&action, 0, sizeof(action));
>> + action.sa_sigaction = fatal_signal_handler;
>> + sigfillset(&action.sa_mask);
>> + action.sa_flags = SA_RESETHAND | SA_SIGINFO;
>> +
>> + for (i = 0; i < HANDLED_SIGNALS_MAX; ++i)
>> + {
> No new line before opening brace.
>> + if (sigaction(handled_signals[i], &action, NULL) < 0)
>> + {
> No new line before opening brace.
>> + syslog(LOG_WARNING, "sigaction %d failed: %s",
>> handled_signals[i], strerror(errno));
>> + }
>> + }
>> + }
>> +}
>
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