[PATCH 4/6] maint: fix overflow checking in nap.h

[Paul Eggert]

* modules/chown-tests:
* modules/fchownat-tests, modules/fdutimensat-tests:
* modules/futimens-tests, modules/lchown-tests:
* modules/stat-time-tests, modules/utime-tests:
* modules/utimens-tests, modules/utimensat-tests:
Depend on intprops.
* tests/nap.h: Include intprops.h.
(diff_timespec): Handle overflow properly.
---
 ChangeLog                 | 10 ++++++++++
 modules/chown-tests       |  1 +
 modules/fchownat-tests    |  1 +
 modules/fdutimensat-tests |  1 +
 modules/futimens-tests    |  1 +
 modules/lchown-tests      |  1 +
 modules/stat-time-tests   |  1 +
 modules/utime-tests       |  1 +
 modules/utimens-tests     |  1 +
 modules/utimensat-tests   |  1 +
 tests/nap.h               | 21 +++++++++++++--------
 11 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 0995e5d53..9935941df 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,15 @@
 2017-09-25  Paul Eggert  <address@hidden>
 
+       maint: fix overflow checking in nap.h
+       * modules/chown-tests:
+       * modules/fchownat-tests, modules/fdutimensat-tests:
+       * modules/futimens-tests, modules/lchown-tests:
+       * modules/stat-time-tests, modules/utime-tests:
+       * modules/utimens-tests, modules/utimensat-tests:
+       Depend on intprops.
+       * tests/nap.h: Include intprops.h.
+       (diff_timespec): Handle overflow properly.
+
        sys_types: update URL
        * m4/sys_types_h.m4: Use https: URL.
 
diff --git a/modules/chown-tests b/modules/chown-tests
index 58b965682..13138f438 100644
--- a/modules/chown-tests
+++ b/modules/chown-tests
@@ -7,6 +7,7 @@ tests/macros.h
 
 Depends-on:
 ignore-value
+intprops
 lstat
 mgetgroups
 nanosleep
diff --git a/modules/fchownat-tests b/modules/fchownat-tests
index 4e289bda5..81adf7fe8 100644
--- a/modules/fchownat-tests
+++ b/modules/fchownat-tests
@@ -8,6 +8,7 @@ tests/macros.h
 
 Depends-on:
 ignore-value
+intprops
 mgetgroups
 nanosleep
 openat-h
diff --git a/modules/fdutimensat-tests b/modules/fdutimensat-tests
index a77ada4f0..37f70c652 100644
--- a/modules/fdutimensat-tests
+++ b/modules/fdutimensat-tests
@@ -10,6 +10,7 @@ tests/macros.h
 Depends-on:
 fcntl-h
 ignore-value
+intprops
 nanosleep
 openat
 timespec
diff --git a/modules/futimens-tests b/modules/futimens-tests
index c7e9db2f0..519141300 100644
--- a/modules/futimens-tests
+++ b/modules/futimens-tests
@@ -10,6 +10,7 @@ Depends-on:
 gettext-h
 fcntl-h
 ignore-value
+intprops
 nanosleep
 timespec
 dup
diff --git a/modules/lchown-tests b/modules/lchown-tests
index d7288fea6..c5bba89d5 100644
--- a/modules/lchown-tests
+++ b/modules/lchown-tests
@@ -7,6 +7,7 @@ tests/macros.h
 
 Depends-on:
 ignore-value
+intprops
 mgetgroups
 nanosleep
 stat-time
diff --git a/modules/stat-time-tests b/modules/stat-time-tests
index 18843de5a..c512eca76 100644
--- a/modules/stat-time-tests
+++ b/modules/stat-time-tests
@@ -4,6 +4,7 @@ tests/macros.h
 tests/nap.h
 
 Depends-on:
+intprops
 nanosleep
 time
 
diff --git a/modules/utime-tests b/modules/utime-tests
index 1d3da120e..a64d0a006 100644
--- a/modules/utime-tests
+++ b/modules/utime-tests
@@ -8,6 +8,7 @@ Depends-on:
 dup
 gettext-h
 ignore-value
+intprops
 nanosleep
 symlink
 timespec
diff --git a/modules/utimens-tests b/modules/utimens-tests
index d5e3085d2..2a95346a0 100644
--- a/modules/utimens-tests
+++ b/modules/utimens-tests
@@ -11,6 +11,7 @@ Depends-on:
 dup
 gettext-h
 ignore-value
+intprops
 nanosleep
 symlink
 timespec
diff --git a/modules/utimensat-tests b/modules/utimensat-tests
index 09e5cb15b..15c79407e 100644
--- a/modules/utimensat-tests
+++ b/modules/utimensat-tests
@@ -9,6 +9,7 @@ tests/macros.h
 
 Depends-on:
 ignore-value
+intprops
 nanosleep
 timespec
 utimecmp
diff --git a/tests/nap.h b/tests/nap.h
index c16ee904e..24043c612 100644
--- a/tests/nap.h
+++ b/tests/nap.h
@@ -22,6 +22,8 @@
 # include <limits.h>
 # include <stdbool.h>
 
+# include <intprops.h>
+
 /* Name of the witness file.  */
 #define TEMPFILE BASE "nap.tmp"
 
@@ -38,17 +40,20 @@ diff_timespec (struct timespec a, struct timespec b)
   time_t bs = b.tv_sec;
   int ans = a.tv_nsec;
   int bns = b.tv_nsec;
+  int sdiff;
+
+  ASSERT (0 <= ans && ans < 2000000000);
+  ASSERT (0 <= bns && bns < 2000000000);
 
   if (! (bs < as || (bs == as && bns < ans)))
     return 0;
-  if (as - bs <= INT_MAX / 1000000000)
-    {
-      int sdiff = (as - bs) * 1000000000;
-      int usdiff = ans - bns;
-      if (usdiff < INT_MAX - sdiff)
-        return sdiff + usdiff;
-    }
-  return INT_MAX;
+
+  if (INT_SUBTRACT_WRAPV (as, bs, &sdiff)
+      || INT_MULTIPLY_WRAPV (sdiff, 1000000000, &sdiff)
+      || INT_ADD_WRAPV (sdiff, ans - bns, &sdiff))
+    return INT_MAX;
+
+  return sdiff;
 }
 
 /* If DO_WRITE, bump the modification time of the file designated by NAP_FD.
-- 
2.13.5