tests: replace read by xread

With fortification enabled, read calls return result needs to be checked,
has it gets the __wur macro enabled.

Note on read call removal from  sysdeps/pthread/tst-cancel20.c and
sysdeps/pthread/tst-cancel21.c:
It is assumed that this second read call was there to overcome the race
condition between pipe closure and thread cancellation that could happen
in the original code. Since this race condition got fixed by
d0e3ffb7a58854248f1d5e737610d50cd0a60f46 the second call seems
superfluous. Hence, instead of checking for the return value of read, it
looks reasonable to simply remove it.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/support/xunistd.h b/support/xunistd.h
index 43a1e69fcb..0aa2638a8d 100644
--- a/support/xunistd.h
+++ b/support/xunistd.h
@@ -77,6 +77,9 @@ void xclose (int);
 /* Write the buffer.  Retry on short writes.  */
 void xwrite (int, const void *, size_t);
 
+/* Read to buffer.  Retry on short reads.  */
+void xread (int, void *, size_t);
+
 /* Invoke mmap with a zero file offset.  */
 void *xmmap (void *addr, size_t length, int prot, int flags, int fd);
 void xmprotect (void *addr, size_t length, int prot);