Merge pull request #6076 from evsh/warn-if-no-function-names

Warn if no function names are present in the stacktrace

src/app/stacktrace.h

@@ -15,78 +15,86 @@ static inline void print_stacktrace(FILE *out = stderr, unsigned int max_frames
     fprintf(out, "stack trace:\n");
 
     // storage array for stack trace address data
-    void* addrlist[max_frames+1];
+    void *addrlist[max_frames + 1];
 
     // retrieve current stack addresses
-    int addrlen = backtrace(addrlist, sizeof(addrlist) / sizeof(void*));
+    int addrlen = backtrace(addrlist, sizeof(addrlist) / sizeof(void *));
 
     if (addrlen == 0) {
-	fprintf(out, "  <empty, possibly corrupt>\n");
-	return;
+        fprintf(out, "  <empty, possibly corrupt>\n");
+        return;
     }
 
     // resolve addresses into strings containing "filename(function+address)",
     // this array must be free()-ed
-    char** symbollist = backtrace_symbols(addrlist, addrlen);
+    char * *symbollist = backtrace_symbols(addrlist, addrlen);
 
     // allocate string which will be filled with the demangled function name
     size_t funcnamesize = 256;
-    char* funcname = (char*)malloc(funcnamesize);
+    char *funcname = (char *)malloc(funcnamesize);
 
+    int functionNamesFound = 0;
     // iterate over the returned symbol lines. skip the first, it is the
     // address of this function.
-    for (int i = 2; i < addrlen; i++)
-    {
-	char *begin_name = 0, *begin_offset = 0, *end_offset = 0;
+    for (int i = 2; i < addrlen; i++) {
+        char *begin_name = 0, *begin_offset = 0, *end_offset = 0;
 
-	// find parentheses and +address offset surrounding the mangled name:
-	// ./module(function+0x15c) [0x8048a6d]
-	//fprintf(out, "%s TT\n", symbollist[i]);
-	for (char *p = symbollist[i]; *p; ++p)
-	{
-	    if (*p == '(')
-		begin_name = p;
-	    else if (*p == '+')
-		begin_offset = p;
-	    else if (*p == ')' && begin_offset) {
-		end_offset = p;
-		break;
-	    }
-	}
+        // find parentheses and +address offset surrounding the mangled name:
+        // ./module(function+0x15c) [0x8048a6d]
+        // fprintf(out, "%s TT\n", symbollist[i]);
+        for (char *p = symbollist[i]; *p; ++p) {
+            if (*p == '(') {
+                begin_name = p;
+            }
+            else if (*p == '+') {
+                begin_offset = p;
+            }
+            else if ((*p == ')') && begin_offset) {
+                end_offset = p;
+                break;
+            }
+        }
 
-	if (begin_name && begin_offset && end_offset
-	    && begin_name < begin_offset)
-	{
-	    *begin_name++ = '\0';
-	    *begin_offset++ = '\0';
-	    *end_offset = '\0';
+        if (begin_name && begin_offset && end_offset
+            && (begin_name < begin_offset)) {
+            *begin_name++ = '\0';
+            *begin_offset++ = '\0';
+            *end_offset = '\0';
 
-	    // mangled name is now in [begin_name, begin_offset) and caller
-	    // offset in [begin_offset, end_offset). now apply
-	    // __cxa_demangle():
+            // mangled name is now in [begin_name, begin_offset) and caller
+            // offset in [begin_offset, end_offset). now apply
+            // __cxa_demangle():
 
-	    int status;
-	    char* ret = abi::__cxa_demangle(begin_name,
-					    funcname, &funcnamesize, &status);
-	    if (status == 0) {
-		funcname = ret; // use possibly realloc()-ed string
-		fprintf(out, "  %s : %s+%s %s\n",
-			symbollist[i], funcname, begin_offset, ++end_offset);
-	    }
-	    else {
-		// demangling failed. Output function name as a C function with
-		// no arguments.
-		fprintf(out, "  %s : %s()+%s %s\n",
-			symbollist[i], begin_name, begin_offset, ++end_offset);
-	    }
-	}
-	else
-	{
-	    // couldn't parse the line? print the whole line.
-	    fprintf(out, "  %s\n", symbollist[i]);
-	}
+            int status;
+            char *ret = abi::__cxa_demangle(begin_name,
+                                            funcname, &funcnamesize, &status);
+            if (status == 0) {
+                funcname = ret; // use possibly realloc()-ed string
+                fprintf(out, "  %s : %s+%s %s\n",
+                        symbollist[i], funcname, begin_offset, ++end_offset);
+            }
+            else {
+                // demangling failed. Output function name as a C function with
+                // no arguments.
+                fprintf(out, "  %s : %s()+%s %s\n",
+                        symbollist[i], begin_name, begin_offset, ++end_offset);
+            }
+            ++functionNamesFound;
+        }
+        else {
+            // couldn't parse the line? print the whole line.
+            fprintf(out, "  %s\n", symbollist[i]);
+        }
     }
 
+    if (!functionNamesFound) {
+        fprintf(out, "There were no function names found in the stack trace\n."
+            "Seems like debug symbols are not installed, and the stack trace is useless.\n");
+    }
+    if (functionNamesFound < addrlen - 2) {
+        fprintf(out, "Consider installing debug symbols for packages containing files with empty"
+            " function names (i.e. empty braces \"()\") to make your stack trace more useful\n");
+    }
     free(funcname);
     free(symbollist);
 }