[glibc] Sync timespec-{add,sub} with gnulib

[Adhemerval Zanella <azanella at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c1dac8f83ecda0d23f92ddacad52818f658988a4

commit c1dac8f83ecda0d23f92ddacad52818f658988a4
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Thu Oct 31 14:46:44 2019 -0300

    Sync timespec-{add,sub} with gnulib
    
    It sync with gnulib commit 06011ed74e978613422aca43c0bd92dc44213933.
    
    Reviewed-by: Paul Eggert <eggert@cs.ucla.edu>

Diff:
---
 support/timespec-add.c | 20 +++++++-------------
 support/timespec-sub.c | 20 +++++++-------------
 2 files changed, 14 insertions(+), 26 deletions(-)

diff --git a/support/timespec-add.c b/support/timespec-add.c
index ea9791d..8efb8a6 100644
--- a/support/timespec-add.c
+++ b/support/timespec-add.c
@@ -33,36 +33,30 @@ timespec_add (struct timespec a, struct timespec b)
   int ns = a.tv_nsec + b.tv_nsec;
   int nsd = ns - TIMESPEC_HZ;
   int rns = ns;
-  time_t tmin = TYPE_MINIMUM (time_t);
-  time_t tmax = TYPE_MAXIMUM (time_t);
 
   if (0 <= nsd)
     {
       rns = nsd;
-      if (bs < tmax)
-        bs++;
+      time_t bs1;
+      if (!INT_ADD_WRAPV (bs, 1, &bs1))
+        bs = bs1;
       else if (rs < 0)
         rs++;
       else
         goto high_overflow;
     }
 
-  /* INT_ADD_WRAPV is not appropriate since time_t might be unsigned.
-     In theory time_t might be narrower than int, so plain
-     INT_ADD_OVERFLOW does not suffice.  */
-  if (! INT_ADD_OVERFLOW (rs, bs) && tmin <= rs + bs && rs + bs <= tmax)
-    rs += bs;
-  else
+  if (INT_ADD_WRAPV (rs, bs, &rs))
     {
-      if (rs < 0)
+      if (bs < 0)
         {
-          rs = tmin;
+          rs = TYPE_MINIMUM (time_t);
           rns = 0;
         }
       else
         {
         high_overflow:
-          rs = tmax;
+          rs = TYPE_MAXIMUM (time_t);
           rns = TIMESPEC_HZ - 1;
         }
     }
diff --git a/support/timespec-sub.c b/support/timespec-sub.c
index 0fe6517..cf16ed7 100644
--- a/support/timespec-sub.c
+++ b/support/timespec-sub.c
@@ -33,36 +33,30 @@ timespec_sub (struct timespec a, struct timespec b)
   time_t bs = b.tv_sec;
   int ns = a.tv_nsec - b.tv_nsec;
   int rns = ns;
-  time_t tmin = TYPE_MINIMUM (time_t);
-  time_t tmax = TYPE_MAXIMUM (time_t);
 
   if (ns < 0)
     {
       rns = ns + TIMESPEC_HZ;
-      if (bs < tmax)
-        bs++;
+      time_t bs1;
+      if (!INT_ADD_WRAPV (bs, 1, &bs1))
+        bs = bs1;
       else if (- TYPE_SIGNED (time_t) < rs)
         rs--;
       else
         goto low_overflow;
     }
 
-  /* INT_SUBTRACT_WRAPV is not appropriate since time_t might be unsigned.
-     In theory time_t might be narrower than int, so plain
-     INT_SUBTRACT_OVERFLOW does not suffice.  */
-  if (! INT_SUBTRACT_OVERFLOW (rs, bs) && tmin <= rs - bs && rs - bs <= tmax)
-    rs -= bs;
-  else
+  if (INT_SUBTRACT_WRAPV (rs, bs, &rs))
     {
-      if (rs < 0)
+      if (0 < bs)
         {
         low_overflow:
-          rs = tmin;
+          rs = TYPE_MINIMUM (time_t);
           rns = 0;
         }
       else
         {
-          rs = tmax;
+          rs = TYPE_MAXIMUM (time_t);
           rns = TIMESPEC_HZ - 1;
         }
     }