Fix another race in log initializations.

[simgrid.git] / src / xbt / backtrace_linux.c

diff --git a/src/xbt/backtrace_linux.c b/src/xbt/backtrace_linux.c
index 9cfea87..4fc1ebc 100644 (file)
--- a/src/xbt/backtrace_linux.c
+++ b/src/xbt/backtrace_linux.c
@@ -25,13 +25,64 @@ void xbt_backtrace_postexit(void)
 {
 }
 
+#include <unwind.h>
+struct trace_arg {
+  void **array;
+  int cnt, size;
+};
+
+static _Unwind_Reason_Code
+backtrace_helper (struct _Unwind_Context *ctx, void *a)
+{
+  struct trace_arg *arg = a;
+
+  /* We are first called with address in the __backtrace function.
+     Skip it.  */
+  if (arg->cnt != -1)
+    {
+      arg->array[arg->cnt] = (void *) _Unwind_GetIP(ctx);
+
+      /* Check whether we make any progress.  */
+      if (arg->cnt > 0 && arg->array[arg->cnt - 1] == arg->array[arg->cnt])
+        return _URC_END_OF_STACK;
+    }
+  if (++arg->cnt == arg->size)
+    return _URC_END_OF_STACK;
+  return _URC_NO_REASON;
+}
+
+/** @brief reimplementation of glibc backtrace based directly on gcc library, without implicit malloc
+ *
+ * See http://webloria.loria.fr/~quinson/blog/2012/0208/system_programming_fun_in_SimGrid/
+ * for the motivation behind this function
+ * */
+
+int xbt_backtrace_no_malloc(void **array, int size) {
+  struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+
+  if (size >= 1)
+    _Unwind_Backtrace(backtrace_helper, &arg);
+
+  /* _Unwind_Backtrace on IA-64 seems to put NULL address above
+     _start.  Fix it up here.  */
+  if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
+    --arg.cnt;
+  return arg.cnt != -1 ? arg.cnt : 0;
+}
+
 void xbt_backtrace_current(xbt_ex_t * e)
 {
   e->used = backtrace((void **) e->bt, XBT_BACKTRACE_SIZE);
+  if (e->used == 0) {
+    fprintf(stderr, "The backtrace() function failed, which probably means that the memory is exhausted. Here is a crude dump of the exception that I was trying to build:");
+    fprintf(stderr, "%s:%s(%d) [%s:%d] %s", e->host,e->procname,e->pid, e->file,e->line,e->msg);
+    fprintf(stderr, "Bailing out now since there is nothing I can do without a decent amount of memory. Please go fix the memleaks\n");
+    exit(1);
+  }
 }
 
 
-void xbt_ex_setup_backtrace(xbt_ex_t * e)
+void xbt_ex_setup_backtrace(xbt_ex_t * e) //FIXME: This code could be greatly improved/simplifyied with http://cairo.sourcearchive.com/documentation/1.9.4/backtrace-symbols_8c-source.html
 {
   int i;
 
@@ -56,23 +107,21 @@ void xbt_ex_setup_backtrace(xbt_ex_t * e)
   struct stat stat_buf;
   char *binary_name = NULL;
 
-  xbt_assert0(e
-              && e->used,
-              "Backtrace not setup yet, cannot set it up for display");
+  xbt_assert(e, "Backtrace not setup yet, cannot set it up for display");
+
+  e->bt_strings = NULL;
 
   if (!xbt_binary_name) /* no binary name, nothing to do */
     return;
 
-  backtrace_syms = backtrace_symbols(e->bt, e->used);
-  /* ignore first one, which is this xbt_backtrace_current() */
-  e->used--;
-  memmove(backtrace_syms, backtrace_syms + 1, sizeof(char *) * e->used);
+  if (e->used <= 1)
+    return;
 
-  e->bt_strings = NULL;
+  /* ignore first one, which is xbt_backtrace_current() */
+  e->used--;
+  memmove(e->bt, e->bt + 1, (sizeof *e->bt) * e->used);
 
-  /* Some arches only have stubs of backtrace, no implementation (hppa comes to mind) */
-  if (!e->used)
-    return;
+  backtrace_syms = backtrace_symbols(e->bt, e->used);
 
   /* build the commandline */
   if (stat(xbt_binary_name, &stat_buf)) {
@@ -86,8 +135,7 @@ void xbt_ex_setup_backtrace(xbt_ex_t * e)
         char *data;
 
         xbt_dynar_foreach(path, cpt, data) {
-          if (binary_name)
-            free(binary_name);
+          free(binary_name);
           binary_name = bprintf("%s/%s", data, xbt_binary_name);
           if (!stat(binary_name, &stat_buf)) {
             /* Found. */
@@ -185,10 +233,8 @@ void xbt_ex_setup_backtrace(xbt_ex_t * e)
       maps_name = bprintf("/proc/%d/maps", (int) getpid());
       maps = fopen(maps_name, "r");
 
-      sscanf(addrs[i], "%lx", &addr);
-      sprintf(maps_buff, "%#lx", addr);
-
-      if (strcmp(addrs[i], maps_buff)) {
+      addr = strtol(addrs[i], &p, 16);
+      if (*p != '\0') {
         XBT_CRITICAL("Cannot parse backtrace address '%s' (addr=%#lx)",
                   addrs[i], addr);
       }