silence implicit conversions and overflows found by ubsan

src/parser.c:530:16: runtime error: implicit conversion from type 'int' of value 232 (32-bit, signed) to type 'char' changed the value to -24 (8-bit, signed)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior src/parser.c:530:16 in

src/parser.c:1620:19: runtime error: unsigned integer overflow: 1 - 10 cannot be represented in type 'unsigned int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior src/parser.c:1620:19 in

src/parser.c:1606:17: runtime error: unsigned integer overflow: 1 - 10 cannot be represented in type 'unsigned int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior src/parser.c:1606:17 in

src/settings.c:353:12: runtime error: implicit conversion from type 'int' of value -1 (32-bit, signed) to type 'size_t' (aka 'unsigned long') changed the value to 18446744073709551615 (64-bit, unsigned)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior src/settings.c:353:12 in

src/util.c:194:13: runtime error: unsigned integer overflow: 0 - 1 cannot be represented in type 'size_t' (aka 'unsigned long')
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior src/util.c:194:13 in

src/parser.c

@@ -527,7 +527,7 @@ decode_hex (char *url, char *out)
     if (*c != '%' || !isxdigit (c[1]) || !isxdigit (c[2])) {
       *ptr++ = *c;
     } else {
-      *ptr++ = (B16210 (c[1]) * 16) + (B16210 (c[2]));
+      *ptr++ = (char)((B16210 (c[1]) * 16) + (B16210 (c[2])));
       c += 2;
     }
   }
@@ -1603,7 +1603,10 @@ count_invalid (GLog * glog, const char *line)
 static void
 uncount_invalid (GLog * glog)
 {
-  glog->invalid -= conf.num_tests;
+  if (glog->invalid > conf.num_tests)
+    glog->invalid -= conf.num_tests;
+  else
+    glog->invalid = 0;
 #ifdef TCB_BTREE
   ht_replace_genstats ("failed_requests", glog->invalid);
 #endif
@@ -1617,7 +1620,10 @@ uncount_invalid (GLog * glog)
 static void
 uncount_processed (GLog * glog)
 {
-  glog->processed -= conf.num_tests;
+  if (glog->processed > conf.num_tests)
+    glog->processed -= conf.num_tests;
+  else
+    glog->processed = 0;
 #ifdef TCB_BTREE
   ht_replace_genstats ("total_requests", glog->processed);
 #endif

src/settings.c

@@ -350,7 +350,7 @@ size_t
 get_selected_format_idx (void)
 {
   if (conf.log_format == NULL)
-    return -1;
+    return (size_t)-1;
   if (strcmp (conf.log_format, logs.common) == 0)
     return COMMON;
   else if (strcmp (conf.log_format, logs.vcommon) == 0)
@@ -372,7 +372,7 @@ get_selected_format_idx (void)
   else if (strcmp (conf.log_format, logs.awss3) == 0)
     return AWSS3;
   else
-    return -1;
+    return (size_t)-1;
 }
 
 /* Determine the selected log format from the config file or command line

src/util.c

@@ -191,7 +191,7 @@ genstr (char *dest, size_t len)
 {
   char set[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
 
-  while (len-- > 0)
+  for (; len > 0; --len)
     *dest++ = set[rand () % (sizeof (set) - 1)];
   *dest = '\0';
 }