From f6747ba6d9e0d45b2006e34f49112ed441af9946 Mon Sep 17 00:00:00 2001
From: Evgeny Zinoviev <me@ch1p.com>
Date: Fri, 4 Jan 2019 16:45:45 +0300
Subject: refactor code

---
 sketchtrial.c | 86 +++++++++++++++++++++++++++++++----------------------------
 1 file changed, 45 insertions(+), 41 deletions(-)

diff --git a/sketchtrial.c b/sketchtrial.c
index 85354c9..56175cb 100644
--- a/sketchtrial.c
+++ b/sketchtrial.c
@@ -9,7 +9,7 @@
 #include <pthread.h>
 
 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
-static int nstime_calls_left = 3;
+static int calls_left = 3; // actually 2 seems to be enough. use 3 just for safety
 static bool done = false;
 static char buf[32];
 static long days = -5000;
@@ -49,51 +49,55 @@ int gettimeofday(struct timeval *restrict tp, void *restrict tzp) {
     }
 
     int result = orig_gettimeofday(tp, tzp);
-    if (result == 0 && !done) {
-        pthread_mutex_lock(&mutex);
-        if (nstime_calls_left > 0) {
-            void *callstack[128];
-            int frames = backtrace(callstack, 128);
-            char **strs = backtrace_symbols(callstack, frames);
-            
-            bool is_sketch = false, is_nstime = false, is_cfnet = false, is_nt = false;
-            int i;
+    if (result != 0 || done) {
+        return result;
+    }
 
-            for (i = 0; i < frames; ++i) {
-                parse_bt_source(strs[i], buf, 32);
-                if (!is_nstime && strstr(strs[i], "NSDate") != NULL) {
-                    is_nstime = true;
-                }
-                if (!is_nt && strstr(strs[i], "NSNotification") != NULL) {
-                    is_nt = true;
-                }
-                if (!is_sketch && !strcmp(buf, "Sketch")) {
-                    is_sketch = true;
-                }
-                if (!is_cfnet && !strcmp(buf, "CFNetwork")) {
-                    is_cfnet = true;
-                }
-            }
+    pthread_mutex_lock(&mutex);
+    if (!calls_left) {
+        goto end;
+    }
 
-            if (is_sketch && is_nstime && !is_cfnet && !is_nt) {
-                tp->tv_sec += days * 86400;
-                tp->tv_usec = tp->tv_sec * 1000000;
-                nstime_calls_left--;
+    void *callstack[128];
+    int frames = backtrace(callstack, 128);
+    char **strs = backtrace_symbols(callstack, frames);
+    int i;
+    bool call_sketch = false;
+    bool call_nsdate = false;
 
-                printf("spoofed time on call stack:\n");
-                for (i = 0; i < frames; i++) {
-                    printf("    %s\n", strs[i]);
-                }
-                printf("\n");
-            }
-            
-            free(strs);
-            if (!nstime_calls_left) {
-                done = true;
-            }
+    for (i = 0; i < frames; ++i) {
+        parse_bt_source(strs[i], buf, 32);
+        if (strstr(strs[i], "NSNotification") != NULL || !strcmp(buf, "CFNetwork")) {
+            call_sketch = false;
+            break;
+        }
+        if (!call_nsdate && strstr(strs[i], "NSDate") != NULL) {
+            call_nsdate = true;
+        }
+        if (!call_sketch && !strcmp(buf, "Sketch")) {
+            call_sketch = true;
         }
-        pthread_mutex_unlock(&mutex);
     }
 
+    if (call_sketch && call_nsdate) {
+        tp->tv_sec += days * 86400;
+        tp->tv_usec = tp->tv_sec * 1000000;
+        calls_left--;
+
+        printf("spoofed time on call stack:\n");
+        for (i = 0; i < frames; i++) {
+            printf("    %s\n", strs[i]);
+        }
+        printf("\n");
+    }
+
+    free(strs);
+    if (!calls_left) {
+        done = true;
+    }
+
+end:
+    pthread_mutex_unlock(&mutex);
+
     return result;
 }
-- 
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