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fix: potential fix for malloc deadlock in some corner cases (#30)
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@thefab
thefab authored Aug 16, 2021
1 parent fbc26e8 commit ae1c80f
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Showing 3 changed files with 68 additions and 40 deletions.
6 changes: 3 additions & 3 deletions src/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -32,11 +32,11 @@ else
DEBUG_CFLAGS=-O2 -Os
endif
ifeq ($(shell expr $(GCC_VERSION) \< "8.0.0" ), 1)
_CFLAGS=$(CFLAGS) -I. $(shell pkg-config --cflags $(_STATIC_EXTRA_OPT) glib-2.0) -fPIC -Wall -std=c99 -Wextra -pedantic -Wshadow -Wstrict-overflow -Wno-deprecated-declarations -fno-strict-aliasing -DG_LOG_DOMAIN=\"log_proxy\" $(DEBUG_CFLAGS) $(COVERAGE_CFLAGS)
_CFLAGS=$(CFLAGS) -I. $(shell pkg-config --cflags $(_STATIC_EXTRA_OPT) glib-2.0 gthread-2.0) -fPIC -Wall -std=c99 -Wextra -pedantic -Wshadow -Wstrict-overflow -Wno-deprecated-declarations -fno-strict-aliasing -DG_LOG_DOMAIN=\"log_proxy\" $(DEBUG_CFLAGS) $(COVERAGE_CFLAGS)
else
_CFLAGS=$(CFLAGS) -I. $(shell pkg-config --cflags $(_STATIC_EXTRA_OPT) glib-2.0) -fPIC -Wall -std=c99 -Wextra -pedantic -Wshadow -Wstrict-overflow -Wno-deprecated-declarations -Wno-cast-function-type -fno-strict-aliasing -DG_LOG_DOMAIN=\"log_proxy\" $(DEBUG_CFLAGS) $(COVERAGE_CFLAGS)
_CFLAGS=$(CFLAGS) -I. $(shell pkg-config --cflags $(_STATIC_EXTRA_OPT) glib-2.0 gthread-2.0) -fPIC -Wall -std=c99 -Wextra -pedantic -Wshadow -Wstrict-overflow -Wno-deprecated-declarations -Wno-cast-function-type -fno-strict-aliasing -DG_LOG_DOMAIN=\"log_proxy\" $(DEBUG_CFLAGS) $(COVERAGE_CFLAGS)
endif
_LDFLAGS=$(LDFLAGS) -L. $(shell pkg-config --libs $(_STATIC_EXTRA_OPT) glib-2.0) $(shell echo '$(FORCE_RPATH_STR)' |sed 's/@/$$/g' |sed s/~/"'"/g) -lrt
_LDFLAGS=$(LDFLAGS) -L. $(shell pkg-config --libs $(_STATIC_EXTRA_OPT) glib-2.0 gthread-2.0) $(shell echo '$(FORCE_RPATH_STR)' |sed 's/@/$$/g' |sed s/~/"'"/g) -lrt

OBJECTS=util.o control.o out.o
BINARIES=log_proxy log_proxy_wrapper
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101 changes: 65 additions & 36 deletions src/log_proxy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,13 +17,19 @@

struct sigaction sigact;
static gboolean first_iteration = TRUE;
static GMutex *mutex = NULL;
static GAsyncQueue *queue = NULL;
static volatile gboolean stop_signal = FALSE;
static GIOChannel *in = NULL;

gint _list_compare(gconstpointer a, gconstpointer b) {
gchar *ca = (gchar *) a;
gchar *cb = (gchar *) b;
return g_strcmp0(cb, ca);
}

#define UNUSED(x) (void)(x)

void clean_too_old_files() {
gchar *dirpath = g_path_get_dirname(log_file);
GDir *dir = g_dir_open(dirpath, 0, NULL);
Expand Down Expand Up @@ -92,12 +98,11 @@ gboolean rotate() {

void signal_handler(int signum) {
if ((signum == SIGTERM) || (signum == SIGTERM)) {
// nice exit to execute exit_handler
exit(0);
stop_signal = TRUE;
}
}

static void every_second(int sig) {
static void every_second() {
int fd = lock_control_file(log_file);
if (fd >= 0) {
if (first_iteration) {
Expand All @@ -111,19 +116,11 @@ static void every_second(int sig) {
destroy_output_channel();
init_output_channel(log_file, use_locks, TRUE, chmod_str, chown_str, chgrp_str);
unlock_control_file(fd);
if (sig > 0) {
// if sig<0, this is the final call before program end
alarm(1);
}
return;
}
glong size = get_file_size(log_file);
if (size < 0) {
unlock_control_file(fd);
if (sig > 0) {
// if sig<0, this is the final call before program end
alarm(1);
}
return;
}
gboolean must_rotate = FALSE;
Expand All @@ -149,18 +146,53 @@ static void every_second(int sig) {
}
unlock_control_file(fd);
}
if (sig > 0) {
// if sig<0, this is the final call before program end
alarm(1);
}

gpointer stop_thread(gpointer data) {
// we do this here and not in signal_handler to avoid malloc in signal
// handlers
UNUSED(data);
while (stop_signal == FALSE) {
sleep(1);
}
g_async_queue_push(queue, GINT_TO_POINTER(2));
return NULL;
}

void init_every_second_signal() {
sigact.sa_handler = every_second;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = 0;
sigaction(SIGALRM, &sigact, (struct sigaction *)NULL);
alarm(1);
gpointer management_thread(gpointer data) {
gpointer qdata;
GTimeVal tval;
gint stop_flag = 0;
UNUSED(data);
while (TRUE) {
g_get_current_time(&tval);
g_time_val_add(&tval, 1000000);
qdata = g_async_queue_timed_pop(queue, &tval);
if (qdata != NULL) {
stop_flag = GPOINTER_TO_INT(qdata);
}
g_mutex_lock(mutex);
every_second();
g_mutex_unlock(mutex);
if (qdata != NULL) {
break;
}
}
if (stop_flag == 2) {
// in this case (sigterm), we prefer to keep the mutex
g_mutex_lock(mutex);
}
destroy_output_channel();
if (rm_fifo_at_exit == TRUE) {
if (fifo != NULL) {
g_unlink(fifo);
}
}
if (stop_flag == 2) {
// we exit here for sigterm as main thread is blocked in reading
exit(0);
}
return NULL;
}

void init_or_reinit_output_channel(const gchar *lg_file, gboolean us_locks) {
Expand All @@ -174,14 +206,6 @@ void init_or_reinit_output_channel(const gchar *lg_file, gboolean us_locks) {
unlock_control_file(lock_fd);
}

void exit_handler() {
if (rm_fifo_at_exit == TRUE) {
if (fifo != NULL) {
g_unlink(fifo);
}
}
}

int main(int argc, char *argv[])
{
GOptionContext *context;
Expand All @@ -198,7 +222,9 @@ int main(int argc, char *argv[])
g_print("%s", g_option_context_get_help(context, TRUE, NULL));
exit(1);
}
atexit(exit_handler);
g_thread_init(NULL);
mutex = g_mutex_new();
queue = g_async_queue_new();
signal(SIGTERM, signal_handler);
signal(SIGINT, signal_handler);
set_default_values_from_env();
Expand All @@ -212,7 +238,6 @@ int main(int argc, char *argv[])
}
}
g_free(log_dir);
GIOChannel *in = NULL;
if (fifo == NULL) {
// We read from stdin
in = g_io_channel_unix_new(fileno(stdin));
Expand All @@ -228,30 +253,34 @@ int main(int argc, char *argv[])
GIOStatus in_status = G_IO_STATUS_NORMAL;
GString *in_buffer = g_string_new(NULL);
init_or_reinit_output_channel(log_file, use_locks);
init_every_second_signal();
g_thread_create(stop_thread, NULL, FALSE, NULL);
GThread* management = g_thread_create(management_thread, NULL, TRUE, NULL);
while ((in_status != G_IO_STATUS_EOF) && (in_status != G_IO_STATUS_ERROR)) {
in_status = g_io_channel_read_line_string(in, in_buffer, NULL, NULL);
if (in_status == G_IO_STATUS_NORMAL) {
g_mutex_lock(mutex);
while (TRUE) {
gboolean write_status = write_output_channel(in_buffer);
if (write_status == FALSE) {
g_warning("error during write on: %s", log_file);
alarm(0); // to avoid a potential deadlock with SIGALARM every_second() calls
init_or_reinit_output_channel(log_file, use_locks);
alarm(1);
continue;
}
break;
}
g_mutex_unlock(mutex);
}
}
alarm(0); // to avoid a potential deadlock with SIGALARM every_second() calls
every_second(-1);
destroy_output_channel();
// if we are here, the "in" input channel is closed
signal(SIGINT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
g_async_queue_push(queue, GINT_TO_POINTER(1));
g_thread_join(management);
g_io_channel_shutdown(in, FALSE, NULL);
g_io_channel_unref(in);
g_string_free(in_buffer, TRUE);
g_option_context_free(context);
g_free(log_file);
g_mutex_free(mutex);
return 0;
}
1 change: 0 additions & 1 deletion src/out.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include "util.h"
#include "control.h"
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