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Fix string/tester.c build with GCC 8.

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GCC 8 warns about more cases of string functions truncating their
output or not copying a trailing NUL byte.

This patch fixes testsuite build failures caused by such warnings in
string/tester.c.  In general, the warnings are disabled around the
relevant calls using DIAG_* macros, since the relevant cases are being
deliberately tested.  In one case, the warning is with
-Wstringop-overflow= instead of -Wstringop-truncation; in that case,
the conditional is __GNUC_PREREQ (7, 0) (being the version where
-Wstringop-overflow= was introduced), to allow the conditional to be
removed sooner, since it's harmless to disable the warning for a
GCC version where it doesn't actually occur.  In the case of warnings
for strncpy calls in test_memcmp, the calls in question are changed to
use memcpy, as they don't copy a trailing NUL and the point of that
code is to test memcmp rather than strncpy.

Tested (compilation) with GCC 8 for x86_64-linux-gnu with
build-many-glibcs.py (in conjunction with Martin's patch to allow
glibc to build).

	* string/tester.c (test_stpncpy): Disable -Wstringop-truncation
	for stpncpy calls for GCC 8.
	(test_strncat): Disable -Wstringop-truncation warning for strncat
	calls for GCC 8.  Disable -Wstringop-overflow= warning for one
	strncat call for GCC 7.
	(test_strncpy): Disable -Wstringop-truncation warning for strncpy
	calls for GCC 8.
	(test_memcmp): Use memcpy instead of strncpy for calls not copying
	trailing NUL.
This commit is contained in:
Joseph Myers 2017-11-14 17:52:26 +00:00
parent ec72135e5f
commit 2e64ec9c9e
2 changed files with 54 additions and 2 deletions
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10
ChangeLog
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@ -1,5 +1,15 @@
2017-11-14 Joseph Myers <joseph@codesourcery.com>
* string/tester.c (test_stpncpy): Disable -Wstringop-truncation
for stpncpy calls for GCC 8.
(test_strncat): Disable -Wstringop-truncation warning for strncat
calls for GCC 8. Disable -Wstringop-overflow= warning for one
strncat call for GCC 7.
(test_strncpy): Disable -Wstringop-truncation warning for strncpy
calls for GCC 8.
(test_memcmp): Use memcpy instead of strncpy for calls not copying
trailing NUL.
* string/bug-strncat1.c: Include <libc-diag.h>.
(main): Disable -Wstringop-truncation for strncat call for GCC 8.

46
string/tester.c
View File

@ -264,8 +264,15 @@ test_stpncpy (void)
{
it = "stpncpy";
memset (one, 'x', sizeof (one));
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (8, 0)
/* GCC 8 warns about stpncpy truncating output; this is deliberately
tested here. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
#endif
check (stpncpy (one, "abc", 2) == one + 2, 1);
check (stpncpy (one, "abc", 3) == one + 3, 2);
DIAG_POP_NEEDS_COMMENT;
check (stpncpy (one, "abc", 4) == one + 3, 3);
check (one[3] == '\0' && one[4] == 'x', 4);
check (stpncpy (one, "abcd", 5) == one + 4, 5);
@ -420,13 +427,27 @@ test_strncat (void)
equal (one, "cd", 9);
(void) strcpy (one, "ab");
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (8, 0)
/* GCC 8 warns about strncat truncating output; this is deliberately
tested here. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
#endif
(void) strncat (one, "cdef", 2);
DIAG_POP_NEEDS_COMMENT;
equal (one, "abcd", 10); /* Count-limited. */
(void) strncat (one, "gh", 0);
equal (one, "abcd", 11); /* Zero count. */
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (7, 0)
/* GCC 8 warns about strncat bound equal to source length; this is
deliberately tested here. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-overflow=");
#endif
(void) strncat (one, "gh", 2);
DIAG_POP_NEEDS_COMMENT;
equal (one, "abcdgh", 12); /* Count and length equal. */
DIAG_PUSH_NEEDS_COMMENT;
@ -523,11 +544,25 @@ test_strncpy (void)
equal (one, "abc", 2); /* Did the copy go right? */
(void) strcpy (one, "abcdefgh");
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (8, 0)
/* GCC 8 warns about strncpy truncating output; this is deliberately
tested here. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
#endif
(void) strncpy (one, "xyz", 2);
DIAG_POP_NEEDS_COMMENT;
equal (one, "xycdefgh", 3); /* Copy cut by count. */
(void) strcpy (one, "abcdefgh");
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (8, 0)
/* GCC 8 warns about strncpy truncating output; this is deliberately
tested here. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
#endif
(void) strncpy (one, "xyz", 3); /* Copy cut just before NUL. */
DIAG_POP_NEEDS_COMMENT;
equal (one, "xyzdefgh", 4);
(void) strcpy (one, "abcdefgh");
@ -542,7 +577,14 @@ test_strncpy (void)
equal (one+5, "fgh", 9);
(void) strcpy (one, "abc");
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (8, 0)
/* GCC 8 warns about strncpy truncating output; this is deliberately
tested here. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
#endif
(void) strncpy (one, "xyz", 0); /* Zero-length copy. */
DIAG_POP_NEEDS_COMMENT;
equal (one, "abc", 10);
(void) strncpy (one, "", 2); /* Zero-length source. */
@ -1151,8 +1193,8 @@ test_memcmp (void)
{
char *a = one + i;
char *b = two + i;
strncpy(a, "--------11112222", 16);
strncpy(b, "--------33334444", 16);
memcpy(a, "--------11112222", 16);
memcpy(b, "--------33334444", 16);
check(memcmp(b, a, 16) > 0, cnt++);
check(memcmp(a, b, 16) < 0, cnt++);
}