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Re: [PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
- From: Chen Gang <gang dot chen dot 5i5j at gmail dot com>
- To: Chung-Lin Tang <chunglin_tang at mentor dot com>, Jeff Law <law at redhat dot com>, cltang at codesourcery dot com, sandra at codesourcery dot com
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Sat, 26 Jul 2014 15:33:02 +0800
- Subject: Re: [PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
- Authentication-results: sourceware.org; auth=none
- References: <53D3205B dot 9050907 at gmail dot com> <53D34B8F dot 4080301 at mentor dot com>
On 07/26/2014 02:32 PM, Chung-Lin Tang wrote:
> On 14/7/26 11:28 AM, Chen Gang wrote:
>> The related strncpy() for custom_builtin_name[*] may set 5 none-zero
>> characters, which may cause custom_builtin_name[*] is none-zero
>> So add additional '\0' byte for custom_builtin_name[*].
> Where did you see this? Supposedly the snprintf of the custom function
> type string should at most be of 'xnxx' format; 4 characters at most,
I guess, your 'xnxx' means "%cn%c%c", not "%sn%s%s" (which is current
implementation), also at present, "32 - n" is 17, not 4 for snprintf()
If we are always sure it must be no more than 4 characters (at present,
it is, but in the future, I don't know). We can use strcpy() instead of
strncpy() for it -- that will let other readers no doubt.
If we need let custom_builtin_name[*] not only zero terminated, but also
zero pad, we need pass '4' to strncpy() instead of '5', that also will
clear all doubts.
> not 5. Do you have a test case where the behavior you described appears?
I find it by reading source code, for me, it is simple code, test is
welcomed, but not mandatory.
But it really needs necessary discussion (for modification, and comments).
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