libbb: provide usleep() fallback implementation

POSIX.1-2008 removed the usleep function, provide a fallback
implementaion using the recommended nanosleep().

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/libbb/platform.c b/libbb/platform.c
index 19734517b..8d90ca4e9 100644
--- a/libbb/platform.c
+++ b/libbb/platform.c
@@ -17,6 +17,24 @@ char* FAST_FUNC strchrnul(const char *s, int c)
 }
 #endif
 
+#ifndef HAVE_USLEEP
+int FAST_FUNC usleep(unsigned usec)
+{
+        struct timespec ts;
+        ts.tv_sec = usec / 1000000u;
+        ts.tv_nsec = (usec % 1000000u) * 1000u;
+        /*
+         * If a signal has non-default handler, nanosleep returns early.
+         * Our version of usleep doesn't return early
+         * if interrupted by such signals:
+         *
+         */
+        while (nanosleep(&ts, &ts) != 0)
+                continue;
+        return 0;
+}
+#endif
+
 #ifndef HAVE_VASPRINTF
 int FAST_FUNC vasprintf(char **string_ptr, const char *format, va_list p)
 {