Add a sighandler-safe logging mechanism

We had accidentially grown two fake ones: one for backtrace.c, and one
for sandbox.c.  Let's do this properly instead.

Now, when we configure logs, we keep track of fds that should get told
about bad stuff happening from signal handlers.  There's another entry
point for these that avoids using non-signal-handler-safe functions.

1 files changed, 12 insertions, 57 deletions

diff --git a/src/common/backtrace.c b/src/common/backtrace.c
index d3f59b2c70..2c49146a05 100644
--- a/src/common/backtrace.c
+++ b/src/common/backtrace.c
@@ -5,6 +5,7 @@
 #include "backtrace.h"
 #include "compat.h"
 #include "util.h"
+#include "torlog.h"
 
 #ifdef HAVE_EXECINFO_H
 #include <execinfo.h>
@@ -25,34 +26,8 @@
 #define NO_BACKTRACE_IMPL
 #endif
 
-static char *bt_filename = NULL;
 static char *bt_version = NULL;
 
-#ifndef NO_BACKTRACE_IMPL
-/**DOCDOC*/
-static int
-open_bt_target(void)
-{
-  int fd = -1;
-  if (bt_filename)
-    fd = open(bt_filename, O_WRONLY|O_CREAT|O_APPEND, 0700);
-  return fd;
-}
-#endif
-
-/**DOCDOC*/
-static void
-bt_write(int fd, const char *s, ssize_t n)
-{
-  int r;
-  if (n < 0) n = strlen(s);
-
-  r = write(STDERR_FILENO, s, n);
-  if (fd >= 0)
-    r = write(fd, s, n);
-  (void)r; 
-}
-
 #ifdef USE_BACKTRACE
 #define MAX_DEPTH 256
 static void *cb_buf[MAX_DEPTH];
@@ -61,33 +36,20 @@ static void *cb_buf[MAX_DEPTH];
 void
 dump_backtrace(const char *msg)
 {
-  char timebuf[32];
-  time_t t = time(NULL);
-  int timebuf_len;
   int depth;
-  int fd;
+  const int *fds;
+  int n_fds;
+  int i;
+
   if (!msg) msg = "unspecified crash";
 
   depth = backtrace(cb_buf, MAX_DEPTH);
 
-  t /= 900; t *= 900; /* Round to the previous 15 minutes */
-  timebuf[0] = '\0';
-  timebuf_len = format_dec_number_sigsafe(t, timebuf, sizeof(timebuf));
-
-  fd = open_bt_target();
-  bt_write(fd, "========================================"
-               "====================================\n", -1);
-  bt_write(fd, bt_version, -1);
-  bt_write(fd, " died around T=", -1);
-  bt_write(fd, timebuf, timebuf_len);
-  bt_write(fd, ": ", 2);
-  bt_write(fd, msg, -1);
-  bt_write(fd, "\n", 1);
-  backtrace_symbols_fd(cb_buf, depth, STDERR_FILENO);
-  if (fd >= 0)
-    backtrace_symbols_fd(cb_buf, depth, fd);
-
-  close(fd);
+  tor_log_err_sigsafe(bt_version, " died: ", msg, "\n",
+                      NULL);
+  n_fds = tor_log_get_sigsafe_err_fds(&fds);
+  for (i=0; i < n_fds; ++i)
+    backtrace_symbols_fd(cb_buf, depth, fds[i]);
 }
 
 /**DOCDOC*/
@@ -110,10 +72,7 @@ remove_bt_handler(void)
 void
 dump_backtrace(const char *msg)
 {
-  bt_write(-1, bt_version, -1);
-  bt_write(-1, " died: ", -1);
-  bt_write(-1, msg, -1);
-  bt_write(-1, "\n", -1);
+  tor_log_err_sigsafe(bt_version, " died: ", msg, "\n", NULL);
 }
 
 /**DOCDOC*/
@@ -132,11 +91,8 @@ remove_bt_handler(void)
 
 /**DOCDOC*/
 int
-configure_backtrace_handler(const char *filename, const char *tor_version)
+configure_backtrace_handler(const char *tor_version)
 {
-  tor_free(bt_filename);
-  if (filename)
-    bt_filename = tor_strdup(filename);
   tor_free(bt_version);
   if (!tor_version)
     tor_version = "Tor";
@@ -151,7 +107,6 @@ clean_up_backtrace_handler(void)
 {
   remove_bt_handler();
 
-  tor_free(bt_filename);
   tor_free(bt_version);
 }