+
+/** \brief show the backtrace of the current point (lovely while debuging) */
+void xbt_backtrace_display(void) {
+#if defined(HAVE_EXECINFO_H) && defined(HAVE_POPEN) && defined(ADDR2LINE)
+ xbt_ex_t e;
+ int i;
+
+ e.used = backtrace((void**)e.bt,XBT_BACKTRACE_SIZE);
+ e.bt_strings = NULL;
+ xbt_ex_setup_backtrace(&e);
+ for (i=1; i<e.used; i++) /* no need to display "xbt_display_backtrace" */
+ fprintf(stderr,"%s\n",e.bt_strings[i]);
+
+ e.msg=NULL;
+ e.remote=0;
+ xbt_ex_free(e);
+#else
+ ERROR0("No backtrace on this arch");
+#endif
+}
+
+
+void xbt_ex_setup_backtrace(xbt_ex_t *e) {
+#if defined(HAVE_EXECINFO_H) && defined(HAVE_POPEN) && defined(ADDR2LINE)
+ int i;
+ /* to get the backtrace from the libc */
+ char **backtrace = backtrace_symbols (e->bt, e->used);
+
+ /* To build the commandline of addr2line */
+ char *cmd = xbt_new(char,strlen(ADDR2LINE)+25+strlen(xbt_binary_name)+32*e->used);
+ char *curr=cmd;
+
+ /* to extract the addresses from the backtrace */
+ char **addrs=xbt_new(char*,e->used);
+ char buff[256],*p;
+
+ /* To read the output of addr2line */
+ FILE *pipe;
+ char line_func[1024],line_pos[1024];
+
+ /* size (in char) of pointers on this arch */
+ int addr_len=0;
+
+ /* Some arches only have stubs of backtrace, no implementation (hppa comes to mind) */
+ if (!e->used)
+ return;
+
+ /* build the commandline */
+ curr += sprintf(curr,"%s -f -e %s ",ADDR2LINE,xbt_binary_name);
+ for (i=0; i<e->used;i++) {
+ /* retrieve this address */
+ DEBUG2("Retrieving address number %d from '%s'", i, backtrace[i]);
+ snprintf(buff,256,"%s",strchr(backtrace[i],'[')+1);
+ p=strchr(buff,']');
+ *p='\0';
+ addrs[i]=bprintf("%s", buff);
+ DEBUG3("Set up a new address: %d, '%s'(%p)", i, addrs[i], addrs[i]);
+
+ /* Add it to the command line args */
+ curr+=sprintf(curr,"%s ",addrs[i]);
+ }
+ addr_len = strlen(addrs[0]);
+
+ /* parse the output and build a new backtrace */
+ e->bt_strings = xbt_new(char*,e->used);
+
+ VERB1("Fire a first command: '%s'", cmd);
+ pipe = popen(cmd, "r");
+ if (!pipe) {
+ CRITICAL0("Cannot fork addr2line to display the backtrace");
+ abort();
+ }
+
+ for (i=0; i<e->used; i++) {
+ DEBUG2("Looking for symbol %d, addr = '%s'", i, addrs[i]);
+ fgets(line_func,1024,pipe);
+ line_func[strlen(line_func)-1]='\0';
+ fgets(line_pos,1024,pipe);
+ line_pos[strlen(line_pos)-1]='\0';
+
+ if (strcmp("??",line_func)) {
+ DEBUG2("Found static symbol %s() at %s", line_func, line_pos);
+ e->bt_strings[i] = bprintf("** In %s() at %s (static symbol)", line_func,line_pos);
+ } else {
+ /* Damn. The symbol is in a dynamic library. Let's get wild */
+ char *maps_name;
+ FILE *maps;
+ char maps_buff[512];
+
+ long int addr,offset=0;
+ char *p,*p2;
+
+ char *subcmd;
+ FILE *subpipe;
+ int found=0;
+
+ /* let's look for the offset of this library in our addressing space */
+ 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)) {
+ CRITICAL2("Cannot parse backtrace address '%s' (addr=%#lx)",
+ addrs[i], addr);
+ }
+ DEBUG2("addr=%s (as string) =%#lx (as number)",addrs[i],addr);
+
+ while (!found) {
+ long int first, last;
+ if (fgets(maps_buff,512,maps) == NULL)
+ break;
+ if (i==0) {
+ maps_buff[strlen(maps_buff) -1]='\0';
+ DEBUG1("map line: %s", maps_buff);
+ }
+ sscanf(maps_buff,"%lx",&first);
+ p=strchr(maps_buff,'-')+1;
+ sscanf(p,"%lx",&last);
+ if (first < addr && addr < last) {
+ offset = first;
+ found=1;
+ }
+ DEBUG4("%#lx %s [%#lx-%#lx]",
+ addr, found? "in":"out of",first,last);
+ }
+ fclose(maps);
+ free(maps_name);
+
+ if (!found) {
+ VERB0("Problem while reading the maps file. Following backtrace will be mangled.");
+ DEBUG1("No dynamic. Static symbol: %s", backtrace[i]);
+ e->bt_strings[i] = bprintf("** In ?? (%s)", backtrace[i]);
+ continue;
+ }
+
+ /* Ok, Found the offset of the maps line containing the searched symbol.
+ We now need to substract this from the address we got from backtrace.
+ */
+
+ free(addrs[i]);
+ addrs[i] = bprintf("0x%0*lx",addr_len-2,addr-offset);
+ DEBUG2("offset=%#lx new addr=%s",offset,addrs[i]);
+
+ /* Got it. We have our new address. Let's get the library path and we
+ are set */
+ p = xbt_strdup(backtrace[i]);
+ p2 = strrchr(p,'(');
+ if (p2) *p2= '\0';
+ p2 = strrchr(p,' ');
+ if(p2) *p2= '\0';
+
+ /* Here we go, fire an addr2line up */
+ subcmd = bprintf("%s -f -e %s %s",ADDR2LINE,p, addrs[i]);
+ free(p);
+ VERB1("Fire a new command: '%s'",subcmd);
+ subpipe = popen(subcmd,"r");
+ if (!subpipe) {
+ CRITICAL0("Cannot fork addr2line to display the backtrace");
+ abort();
+ }
+ fgets(line_func,1024,subpipe);
+ line_func[strlen(line_func)-1]='\0';
+ fgets(line_pos,1024,subpipe);
+ line_pos[strlen(line_pos)-1]='\0';
+ pclose(subpipe);
+ free(subcmd);
+
+ /* check whether the trick worked */
+ if (strcmp("??",line_func)) {
+ DEBUG2("Found dynamic symbol %s() at %s", line_func, line_pos);
+ e->bt_strings[i] = bprintf("** In %s() at %s (dynamic symbol)", line_func,line_pos);
+ } else {
+ /* damn, nothing to do here. Let's print the raw address */
+ DEBUG1("Dynamic symbol not found. Raw address = %s", backtrace[i]);
+ e->bt_strings[i] = bprintf("** In ?? (%s)", backtrace[i]);
+ }
+ }
+ free(addrs[i]);
+ }
+ pclose(pipe);
+ free(addrs);
+ free(backtrace);
+ free(cmd);
+#endif
+}
+