timediff: return timediff_t from the time diff functions

... to cater for systems with unsigned time_t variables.

- Renamed the functions to curlx_timediff and Curl_timediff_us.

- Added overflow protection for both of them in either direction for
  both 32 bit and 64 bit time_ts

- Reprefixed the curlx_time functions to use Curl_*

Reported-by: Peter Piekarski
Fixes #2004
Closes #2005

1 files changed, 12 insertions, 15 deletions

diff --git a/lib/timeval.h b/lib/timeval.h
index 1ee4b3044..b2f0e0d97 100644
--- a/lib/timeval.h
+++ b/lib/timeval.h
@@ -22,19 +22,21 @@
  *
  ***************************************************************************/
 
-/*
- * CAUTION: this header is designed to work when included by the app-side
- * as well as the library. Do not mix with library internals!
- */
-
 #include "curl_setup.h"
 
+#if SIZEOF_TIME_T < 8
+typedef int timediff_t;
+#else
+typedef ssize_t timediff_t;
+#endif
+
+
 struct curltime {
-  time_t       tv_sec;     /* seconds */
-  unsigned int tv_usec;    /* microseconds */
+  time_t tv_sec; /* seconds */
+  int tv_usec;   /* microseconds */
 };
 
-struct curltime curlx_tvnow(void);
+struct curltime Curl_tvnow(void);
 
 /*
  * Make sure that the first argument (t1) is the more recent time and t2 is
@@ -42,7 +44,7 @@ struct curltime curlx_tvnow(void);
  *
  * Returns: the time difference in number of milliseconds.
  */
-time_t curlx_tvdiff(struct curltime t1, struct curltime t2);
+timediff_t Curl_timediff(struct curltime t1, struct curltime t2);
 
 /*
  * Make sure that the first argument (t1) is the more recent time and t2 is
@@ -50,12 +52,7 @@ time_t curlx_tvdiff(struct curltime t1, struct curltime t2);
  *
  * Returns: the time difference in number of microseconds.
  */
-time_t Curl_tvdiff_us(struct curltime newer, struct curltime older);
-
-/* These two defines below exist to provide the older API for library
-   internals only. */
-#define Curl_tvnow() curlx_tvnow()
-#define Curl_tvdiff(x,y) curlx_tvdiff(x,y)
+timediff_t Curl_timediff_us(struct curltime newer, struct curltime older);
 
 #endif /* HEADER_CURL_TIMEVAL_H */