[glibc] Suppress GCC 10 true positive warnings [BZ #25967]

[Martin Sebor <msebor@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=978e8ac39f8ba2d694031e521511da1ae803ccfc

commit 978e8ac39f8ba2d694031e521511da1ae803ccfc
Author: Martin Sebor <msebor@redhat.com>
Date:   Mon May 11 11:29:39 2020 -0600

    Suppress GCC 10 true positive warnings [BZ #25967]
    
    Suppress or avoid warnings in tests that exercise failure modes by making
    calls with invalid arguments.
    
    Reviewed-by: DJ Delorie <dj@redhat.com>
    Reviewed-by: Florian Weimer <fweimer@redhat.com>
    Reviewed-by: Joseph Myers <joseph@codesourcery.com>

Diff:
---
 io/tst-getcwd.c    | 21 +++++++++++++++++++--
 posix/test-errno.c | 12 +++++++++++-
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/io/tst-getcwd.c b/io/tst-getcwd.c
index 75ecd2c7b9..c9c4713fc3 100644
--- a/io/tst-getcwd.c
+++ b/io/tst-getcwd.c
@@ -23,6 +23,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <sys/param.h>
+#include <libc-diag.h>
 
 
 #define TEST_FUNCTION do_test ()
@@ -58,7 +59,13 @@ do_test (void)
       bufs[i] = (char *) malloc (sbs);
     }
 
+  /* Avoid warnings about the first argument being null when the second
+     is nonzero.  */
+  DIAG_PUSH_NEEDS_COMMENT;
+  DIAG_IGNORE_NEEDS_COMMENT (10.1, "-Wnonnull");
   bufs[i] = getcwd (NULL, sbs);
+  DIAG_POP_NEEDS_COMMENT;
+
   lens[i] = sbs;
   if (bufs[i] == NULL)
     {
@@ -96,12 +103,17 @@ getcwd (NULL, sbs) = \"%s\", getcwd (thepath, sizeof thepath) = \"%s\"\n",
     free (bufs[i]);
 
   /* Test whether the function signals success despite the buffer
-     being too small.  */
+     being too small.
+     Avoid warnings about the first argument being null when the second
+     is nonzero.  */
+  DIAG_PUSH_NEEDS_COMMENT;
+  DIAG_IGNORE_NEEDS_COMMENT (10.1, "-Wnonnull");
   if (getcwd (NULL, len) != NULL)
     {
       puts ("getcwd (NULL, len) didn't failed");
       return 1;
     }
+  DIAG_POP_NEEDS_COMMENT;
 
   bufs[0] = malloc (len);
   bufs[1] = malloc (len);
@@ -132,13 +144,18 @@ getcwd (NULL, sbs) = \"%s\", getcwd (thepath, sizeof thepath) = \"%s\"\n",
 	return 1;
       }
 
-  /* Now test handling of correctly sized buffers.  */
+  /* Now test handling of correctly sized buffers.
+     Again. avoid warnings about the first argument being null when
+     the second is nonzero.  */
+  DIAG_PUSH_NEEDS_COMMENT;
+  DIAG_IGNORE_NEEDS_COMMENT (10.1, "-Wnonnull");
   bufs[0] = getcwd (NULL, len + 1);
   if (bufs[0] == NULL)
     {
       puts ("getcwd (NULL, len + 1) failed");
       return 1;
     }
+  DIAG_POP_NEEDS_COMMENT;
   free (bufs[0]);
 
   memset (thepath, '\xff', sizeof thepath);
diff --git a/posix/test-errno.c b/posix/test-errno.c
index 6afadcd102..492fd66bb5 100644
--- a/posix/test-errno.c
+++ b/posix/test-errno.c
@@ -34,6 +34,7 @@
 #include <sys/uio.h>
 #include <unistd.h>
 #include <netinet/in.h>
+#include <libc-diag.h>
 
 /* This is not an exhaustive test: only system calls that can be
    persuaded to fail with a consistent error code and no side effects
@@ -119,7 +120,16 @@ do_test (void)
   fails |= test_wrp (EBADF, fstatfs, -1, &sfs);
   fails |= test_wrp (EBADF, fsync, -1);
   fails |= test_wrp (EBADF, ftruncate, -1, 0);
+
+#if __GNUC_PREREQ (7, 0)
+  DIAG_PUSH_NEEDS_COMMENT;
+  /* Avoid warnings about the second (size) argument being negative.  */
+  DIAG_IGNORE_NEEDS_COMMENT (10.1, "-Wstringop-overflow");
+#endif
   fails |= test_wrp (EINVAL, getgroups, -1, 0);
+#if __GNUC_PREREQ (7, 0)
+  DIAG_POP_NEEDS_COMMENT;
+#endif
   fails |= test_wrp (EBADF, getpeername, -1, &sa, &sl);
   fails |= test_wrp (EBADF, getsockname, -1, &sa, &sl);
   fails |= test_wrp (EBADF, getsockopt, -1, 0, 0, buf, &sl);
@@ -134,7 +144,7 @@ do_test (void)
   fails |= test_wrp (EINVAL, munmap, (void *) -1, 0);
   fails |= test_wrp (EISDIR, open, "/bin", EISDIR, O_WRONLY);
   fails |= test_wrp (EBADF, read, -1, buf, 1);
-  fails |= test_wrp (EINVAL, readlink, "/", buf, -1);
+  fails |= test_wrp (EINVAL, readlink, "/", buf, sizeof buf);
   fails |= test_wrp (EBADF, readv, -1, iov, 1);
   fails |= test_wrp (EBADF, recv, -1, buf, 1, 0);
   fails |= test_wrp (EBADF, recvfrom, -1, buf, 1, 0, &sa, &sl);