From cd83b5b613a0559bf9c83dc970a8446bf1164e95 Mon Sep 17 00:00:00 2001
From: JoYo <rndpwn+bitbucket@gmail.com>
Date: Wed, 13 Jan 2016 18:32:51 -0500
Subject: [PATCH] SIGSEGV recovery? and drand48 for RNG

---
 pic-linux.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/pic-linux.c b/pic-linux.c
index 0e16098..ca46f5a 100644
--- a/pic-linux.c
+++ b/pic-linux.c
@@ -10,11 +10,15 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <openssl/sha.h>
+#include <signal.h>
+#include <setjmp.h>
 
 #pragma comment(lib, "openssl/sha.lib")
 
 #define SHA_SUM_LENGTH (SHA_DIGEST_LENGTH + SHA_DIGEST_LENGTH + 1)
 
+jmp_buf jmpBuf;
+
 void picProto(void *picAddr, size_t picSize, void *clonePtr, char *checksum) {
   void (*cloneFunc)(void *, size_t, char *) = clonePtr;
   cloneFunc(picAddr, picSize, checksum);
@@ -24,10 +28,13 @@ void picProto(void *picAddr, size_t picSize, void *clonePtr, char *checksum) {
 void clone(void *picAddr, size_t picSize, char *checksum) {
   auto retVal = EX_SOFTWARE;
 
-  srand(time(NULL));
+  struct drand48_data drand_data;
+  srand48_r(time(NULL), &drand_data);
+  long int randVal;
+  lrand48_r(&drand_data, &randVal);
 
-  unsigned int picOffset = (rand() % (picSize + 1));
-  unsigned char picFlip = ((char *)picAddr)[picOffset] & (rand() % 2);
+  unsigned int picOffset = (randVal % (picSize + 1));
+  unsigned char picFlip = ((char *)picAddr)[picOffset] & (randVal % 2);
 
   printf("%x\t%x\n", picOffset, picFlip);
 
@@ -60,6 +67,16 @@ CLONE_CLEANUP:
   return;
 }
 
+void magic_handler(int sig) {
+
+  switch (sig) {
+
+  case SIGSEGV:
+    longjmp(jmpBuf, 1);
+    break;
+  }
+}
+
 int main(int argc, const char **argv) {
   auto retVal = EX_SOFTWARE;
   char fileInPath[SHA_SUM_LENGTH];
@@ -105,7 +122,14 @@ int main(int argc, const char **argv) {
     void (*cloneFunc)(void *, size_t, char *) = clone;
     void (*picFunc)(void *, size_t, void *, char *) = picBuffer;
 
-    picFunc(picBuffer, picStat.st_size, cloneFunc, checksum);
+    signal(SIGSEGV, magic_handler);
+
+    if (!setjmp(jmpBuf)) {
+      picFunc(picBuffer, picStat.st_size, cloneFunc, checksum);
+    } else {
+      retVal = errno;
+      goto MAIN_CLEANUP;
+    }
 
     strncpy(fileInPath, checksum, SHA_SUM_LENGTH);