nanosleep: Work around bug on newer 32-bit mingw

[Bruno Haible]

On mingw, there is a 'nanosleep' function in libwinpthread. On 32-bit mingw,
it does not fail when the tv_nsec argument is negative. This is currently
not being caught at configure time, and causes the 'test-nanosleep' test
to hang (more precisely, to hang for 1000 seconds).

This patch
  - adds a faster unit test, that fails within 1 second instead of 1000
    seconds,
  - adds a workaround.


2022-09-03  Bruno Haible  <bruno@clisp.org>

        nanosleep: Work around bug on newer 32-bit mingw.
        * m4/nanosleep.m4 (gl_FUNC_NANOSLEEP): Test for 32-bit mingw bug.
        * tests/test-nanosleep.c (main): Add another test.
        * doc/posix-functions/nanosleep.texi: Mention the mingw bug.

diff --git a/m4/nanosleep.m4 b/m4/nanosleep.m4
index 1964b1ea47..dfe21f56d5 100644
--- a/m4/nanosleep.m4
+++ b/m4/nanosleep.m4
@@ -1,4 +1,4 @@
-# serial 41
+# serial 42
 
 dnl From Jim Meyering.
 dnl Check for the nanosleep function.
@@ -100,15 +100,22 @@ AC_DEFUN([gl_FUNC_NANOSLEEP],
             #else /* A simpler test for native Windows.  */
             if (nanosleep (&ts_sleep, &ts_remaining) < 0)
               return 3;
+            /* Test for 32-bit mingw bug: negative nanosecond values do not
+               cause failure.  */
+            ts_sleep.tv_sec = 1;
+            ts_sleep.tv_nsec = -1;
+            if (nanosleep (&ts_sleep, &ts_remaining) != -1)
+              return 7;
             #endif
             return 0;
           }]])],
        [gl_cv_func_nanosleep=yes],
-       [case $? in dnl (
-        4|5|6) gl_cv_func_nanosleep='no (mishandles large arguments)';; dnl (
-        *)   gl_cv_func_nanosleep=no;;
+       [case $? in
+        4|5|6) gl_cv_func_nanosleep='no (mishandles large arguments)' ;;
+        7)     gl_cv_func_nanosleep='no (mishandles negative tv_nsec)' ;;
+        *)     gl_cv_func_nanosleep=no ;;
         esac],
-       [case "$host_os" in dnl ((
+       [case "$host_os" in
           linux*) # Guess it halfway works when the kernel is Linux.
             gl_cv_func_nanosleep='guessing no (mishandles large arguments)' ;;
           mingw*) # Guess no on native Windows.
diff --git a/tests/test-nanosleep.c b/tests/test-nanosleep.c
index e7edeffc0e..c208161559 100644
--- a/tests/test-nanosleep.c
+++ b/tests/test-nanosleep.c
@@ -43,16 +43,27 @@ main (void)
 {
   struct timespec ts;
 
+  /* Check that negative nanosecond values cause failure.  */
+  ts.tv_sec = 1;
+  ts.tv_nsec = -1;
+  errno = 0;
+  ASSERT (nanosleep (&ts, NULL) == -1);
+  ASSERT (errno == EINVAL);
+
   ts.tv_sec = 1000;
   ts.tv_nsec = -1;
   errno = 0;
   ASSERT (nanosleep (&ts, NULL) == -1);
   ASSERT (errno == EINVAL);
+
+  /* Check that too large nanosecond values cause failure.  */
+  ts.tv_sec = 1000;
   ts.tv_nsec = 1000000000;
   errno = 0;
   ASSERT (nanosleep (&ts, NULL) == -1);
   ASSERT (errno == EINVAL);
 
+  /* Check successful call.  */
   ts.tv_sec = 0;
   ts.tv_nsec = 1;
   ASSERT (nanosleep (&ts, &ts) == 0);
diff --git a/doc/posix-functions/nanosleep.texi 
b/doc/posix-functions/nanosleep.texi
index 8ede0b01f9..be54aef571 100644
--- a/doc/posix-functions/nanosleep.texi
+++ b/doc/posix-functions/nanosleep.texi
@@ -18,6 +18,10 @@ Linux 64-bit, Solaris 64-bit.
 @item
 This function cannot sleep longer than 49.7 days on some platforms:
 Cygwin 1.5.x.
+@item
+This function does not fail when passed a negative nanosecond value on some
+platforms:
+newer 32-bit mingw.
 @end itemize
 
 Portability problems not fixed by Gnulib: