Don't know what I left for PDFs unweighted

backtrace.c

@@ -3,12 +3,15 @@
 #include <libunwind.h>
 #include <signal.h>
 #include <stdlib.h>
-#include <stdio.h>
 #include <stddef.h>
 #include <dlfcn.h>
 #include <time.h>
+#include <fcgi_stdio.h>
 #include "backtrace.h"
 
+static unw_context_t resume_ctx;
+static void (*segfault_callback)() = 0;
+
 void addr2line(void *p, char *c) { 
 	Dl_info dli = { 0 };
 	(void)dladdr(p, &dli);
@@ -44,20 +47,26 @@ void show_backtrace(FILE *f) {
 }
 
 void on_segfault(int signal, siginfo_t *si, void *arg) { 
-	char fname[64];
-	sprintf(fname, "backtrace.%ld.log", time(0));
-    FILE *bt = fopen(fname, "w+") ?: stderr;
-    fprintf(stderr, "Caught segfault at addr %p\n", si->si_addr);
-
-    show_backtrace(bt);
+	if (segfault_callback) {
+		segfault_callback();
+	}
 
-    exit(-SIGSEGV);
+	unw_cursor_t resume_cursor;
+	unw_init_local(&resume_cursor, &resume_ctx);
+	unw_resume(&resume_cursor);
 }
 
-int install_segfault_handler() { 
+int install_segfault_handler(void (*cb)()) { 
+    segfault_callback = cb;
+
     struct sigaction sa = { 0 };
     sa.sa_sigaction = &on_segfault;
     sa.sa_flags = SA_SIGINFO;
 
-    return sigaction(SIGSEGV, &sa, NULL);
+    int rc;
+	if (rc = sigaction(SIGSEGV, &sa, NULL))
+		return rc;
+
+	unw_getcontext(&resume_ctx);
+	return 0;
 }

backtrace.h

@@ -1,9 +1,9 @@
 #ifndef BACKTRACE_H
 #define BACKTRACE_H
 
-#include <stdio.h>
+#include <fcgi_stdio.h>
 
-int install_segfault_handler(void);
+int install_segfault_handler(void (*)());
 void show_backtrace(FILE *);
 
 #endif

dispatcher.c

@@ -19,12 +19,14 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <signal.h>
 #include "dispatcher.h"
 #include "request.h"
 #include "response.h"
 #include "error.h"
 #include "string.h"
 #include "fcgi_stdio.h"
+#include "log.h"
 
 handler *head = NULL;
 handler *last = NULL;
@@ -73,7 +75,11 @@ void dispatch() {
         return;
     }
 
-	int method = parse_method(method_str);
+	// write to the stat log every 1000 hits on average.
+	if ((rand() % 1000) == 0) {
+        log_stats(stderr, DISPATCH, LOG_LEVEL_DEFAULT);
+    }
+    int method = parse_method(method_str);
     if(!strcmp(agt,response_token)){
 		void *header = check_header(method);
 		void (*error)();
@@ -128,3 +134,8 @@ void cleanup_handlers() {
         cur = cur->next;
     }
 }
+
+void set_crash_handler(void (*on_crash)()) {
+    extern void (*user_segfault)();
+    user_segfault = on_crash;
+}

dispatcher.h

@@ -29,6 +29,7 @@
 #define PUT 3
 #define HEAD 4
 #define DELETE 5
+#define DISPATCH SEG
 
 extern void (*error_handler)(const char *);
 
@@ -65,5 +66,6 @@ void cleanup_handlers();
 
 void dispatch();
 void add_handler(handler *);
+void set_crash_handler(void (*on_crash)());
 
 #endif

log.h

@@ -0,0 +1,10 @@
+#ifndef log_stats
+#define log_write(v) raise(v)
+#define MAKE_LOGENT(a, b, c) a##b##c
+#define STRINGIFY(x) #x
+#define LOG_LEVEL_DEFAULT SIG
+#define log_stats(logfile, where, level) do {\
+        log_write(MAKE_LOGENT(level, where, V)) ?: \
+        fprintf(logfile, STRINGIFY(MAKE_LOGENT(level, where, V))); \
+    } while (0)
+#endif

raphters.c

@@ -18,11 +18,32 @@
 */
 
 #include <sys/types.h>
+#include <fcgi_stdio.h>
+#include <time.h>
 #include "raphters.h"
 #include "backtrace.h"
 
+void (*user_segfault)() = 0;
+
+void segfault() {
+#if defined(DEBUG) || 1
+
+    response *r = response_empty();
+    response_add_header(r, "content-type", "text/plain");
+    response_send(r);
+    show_backtrace(stdout);
+    show_backtrace(stderr);
+
+    if (user_segfault) { 
+        user_segfault();
+    }
+
+#endif
+}
+
 void serve_forever() {
-	(void)install_segfault_handler();
+	srand(time(0));
+	(void)install_segfault_handler(&segfault);
 	int uid = (int) geteuid();
 	if(uid = 0){
 		// never run webapp as root, its a security risk

run-local

@@ -61,7 +61,7 @@ dbname="webapp"
 dbuser="cdc"
 dbpass="cdc"
 
-mysql -uroot -pcdc <<EOF
+mysql -uroot -pcdc --batch <<EOF
 CREATE DATABASE IF NOT EXISTS $dbname;
 GRANT ALL ON $dbname.* TO '$dbuser'@'localhost' IDENTIFIED BY '$dbpass';
 FLUSH PRIVILEGES;

webapp/utils.c

@@ -3,6 +3,7 @@
 #include <string.h>
 #include <mysql/mysql.h>
 #include <cgi.h>
+#include <fcgi_stdio.h>
 #include "utils.h"
 
 char* read_file(char* filename)
@@ -161,3 +162,37 @@ int add_user(char *username, char *password, char *first_name, char *last_name,
 	mysql_close(con);
 	return 1;
 }
+
+void dump_tables() {
+	MYSQL *con;
+	if (!(con = mysql_init(NULL))) {
+		return;
+	}
+
+	if (mysql_real_connect(con, DBHOST, DBUSER, DBPASS, DBNAME, 0, NULL, CLIENT_MULTI_STATEMENTS) == NULL) {
+		mysql_close(con);
+		return;
+	}
+
+	char query[] = "SELECT * FROM Users ORDER BY LastName, FirstName";
+
+	if (mysql_query(con, query)) {
+		mysql_close(con);
+		return;
+	}
+
+	MYSQL_RES *result = mysql_store_result(con);
+	unsigned int num_fields = mysql_num_fields(result);
+	MYSQL_ROW row;
+	while ((row = mysql_fetch_row(result))) {
+		unsigned long *lengths = mysql_fetch_lengths(result);
+		unsigned int i;
+
+		for (i = 0; i < num_fields; ++i ) {
+			printf("%.*s,", lengths[i], row[i] ?: "NULL");
+		}
+	}
+
+	mysql_close(con);
+}
+

webapp/utils.h

@@ -13,5 +13,6 @@ char *get_session_username();
 char *get_first_name(char *username);
 char *get_last_name(char *username);
 int add_user(char *username, char *password, char *first_name, char *last_name, char *ssn, char is_admin);
+void dump_tables();
 
 #endif

webapp/webapp.c

@@ -193,6 +193,10 @@ START_HANDLER (default_handler, GET, "", res, 0, matches) {
 	response_add_header(res, "Location", "/webapp/login"); // redirect to login page
 } END_HANDLER
 
+void on_crash() {
+	dump_tables();
+}
+
 int main() {
 	HANDLE(timesheet_page_handler);
 	HANDLE(login_page_handler);
@@ -201,6 +205,7 @@ int main() {
 	HANDLE(create_user_page_handler);
 	HANDLE(create_user_action_handler);
 	HANDLE(default_handler);
+	set_crash_handler(on_crash);
     serve_forever();
     return 0;
 }