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Re: [Minios-devel] [UNIKRAFT PATCHv3 24/25] nolibc: Clear a -Wstringop-overflow warning for strncpy



Hello Wei Chen,

Please find my comments inline.

Thanks & Regards
Sharan

On 12/13/18 10:15 AM, Wei Chen wrote:
The strncpy needs a signed integer for 3rd parameter, but the SIZE_MAX
is unsigned integer. We will get following error:
/lib/nolibc/string.c:155:9: warning: ‘strncpy’: specified size
18446744073709551615 exceeds maximum object size 9223372036854775807
[-Wstringop-overflow=]
   return strncpy(dst, src, SIZE_MAX);


[1] show the posix standard function declaration strncpy using size_t[2] as the third parameter. The upstream code seems to be correct. I am not sure if we need this patch.


          ^
Using SSIZE_MAX to replace SIZE_MAX to fix this warning.

Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
---
  lib/nolibc/string.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/nolibc/string.c b/lib/nolibc/string.c
index 6f853ba..fa450c9 100644
--- a/lib/nolibc/string.c
+++ b/lib/nolibc/string.c
@@ -152,7 +152,7 @@ char *strncpy(char *dst, const char *src, size_t len)
char *strcpy(char *dst, const char *src)
  {
-       return strncpy(dst, src, SIZE_MAX);
+       return strncpy(dst, src, SSIZE_MAX);
  }
int strncmp(const char *str1, const char *str2, size_t len)


[1] http://pubs.opengroup.org/onlinepubs/009696899/functions/strncpy.html
[2] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stddef.h.html

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