Re: [PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
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 terminated. 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, not 5. Do you have a test case where the behavior you described appears? Thanks, Chung-Lin ChangeLog: * config/nios2/nios2.c (custom_builtin_name): Let it always be zero terminated string. Signed-off-by: Chen Gang gang.chen.5...@gmail.com --- gcc/config/nios2/nios2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gcc/config/nios2/nios2.c b/gcc/config/nios2/nios2.c index a4e60c6..e4e005b 100644 --- a/gcc/config/nios2/nios2.c +++ b/gcc/config/nios2/nios2.c @@ -2510,7 +2510,7 @@ nios2_expand_fpu_builtin (tree exp, unsigned int code, rtx target) total of (3 + 1) * (1 + 3 + 9) == 52 custom builtin functions. */ #define NUM_CUSTOM_BUILTINS ((3 + 1) * (1 + 3 + 9)) -static char custom_builtin_name[NUM_CUSTOM_BUILTINS][5]; +static char custom_builtin_name[NUM_CUSTOM_BUILTINS][6]; static void nios2_init_custom_builtins (int start_code)
Re: [PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
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 terminated. 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() length limitation. 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). Thanks. -- Chen Gang Open, share, and attitude like air, water, and life which God blessed
Re: [PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
Chen Gang gang.chen.5...@gmail.com writes: 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. If you pass 5 to strncpy to copy a string of at most 4 characters you get zero-termination for free. Andreas. -- Andreas Schwab, sch...@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 And now for something completely different.
Re: [PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
On 2014/7/26 03:33 PM, Chen Gang wrote: 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 terminated. 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() length limitation. The use of %sn%s%s is intentional. That allows me to print directly using snprintf. '32 - n' is to represent the rest of the 32-byte buffer, harmless really, as it is at most 4 chars. Also, if I were to restrict it in the snprintf argument, it would be 5 (including the null char) not 4. 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. I don't understand what point you're trying to make here, really. As Andreas has noted in the other mail, strncpy does zero-termination automatically. Chung-Lin 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).
Re: [PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
On 07/26/2014 03:59 PM, Andreas Schwab wrote: Chen Gang gang.chen.5...@gmail.com writes: 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. If you pass 5 to strncpy to copy a string of at most 4 characters you get zero-termination for free. Yes. So at least, at present, it is no issue, so if we are focusing on solving issues, this patch can be skipped. And then I will continue discussing it in the other thread, please check that. Thanks. -- Chen Gang Open, share, and attitude like air, water, and life which God blessed
Re: [PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
On 07/26/2014 05:07 PM, Chung-Lin Tang wrote: On 2014/7/26 03:33 PM, Chen Gang wrote: 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 terminated. 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() length limitation. The use of %sn%s%s is intentional. That allows me to print directly using snprintf. OK, thanks. '32 - n' is to represent the rest of the 32-byte buffer, harmless really, as it is at most 4 chars. Also, if I were to restrict it in the snprintf argument, it would be 5 (including the null char) not 4. OK, thanks. And for me, I'd like to use 'sizeof(custom_builtin_name[0])' instead of 32 - n 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. I don't understand what point you're trying to make here, really. As Andreas has noted in the other mail, strncpy does zero-termination automatically. strncpy will zero pad, but not be sure of the dest string will be zero terminated, please man strncpy to get more details. So for me, I'd like to use '4' instead of '5' for strncpy(), that will clear all doubts (although, at present, it is not a bug, so this patch can be skipped, if we are only focus on bug fix). Thanks. -- Chen Gang Open, share, and attitude like air, water, and life which God blessed
[PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
The related strncpy() for custom_builtin_name[*] may set 5 none-zero characters, which cause custom_builtin_name[*] none-zero terminated. But error() assumes custom_builtin_name[*] is always zero terminated. So add additional '\0' byte for custom_builtin_name[*]. ChangeLog: * config/nios2/nios2.c (custom_builtin_name): Let it always be zero terminated string. Signed-off-by: Chen Gang gang.chen.5...@gmail.com --- gcc/config/nios2/nios2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gcc/config/nios2/nios2.c b/gcc/config/nios2/nios2.c index a4e60c6..e4e005b 100644 --- a/gcc/config/nios2/nios2.c +++ b/gcc/config/nios2/nios2.c @@ -2510,7 +2510,7 @@ nios2_expand_fpu_builtin (tree exp, unsigned int code, rtx target) total of (3 + 1) * (1 + 3 + 9) == 52 custom builtin functions. */ #define NUM_CUSTOM_BUILTINS ((3 + 1) * (1 + 3 + 9)) -static char custom_builtin_name[NUM_CUSTOM_BUILTINS][5]; +static char custom_builtin_name[NUM_CUSTOM_BUILTINS][6]; static void nios2_init_custom_builtins (int start_code) -- 1.9.2.459.g68773ac
[PATCH] gcc/config/nios2/nios2.c: Let custom_builtin_name[*] always be zero terminated string
The related strncpy() for custom_builtin_name[*] may set 5 none-zero characters, which may cause custom_builtin_name[*] is none-zero terminated. So add additional '\0' byte for custom_builtin_name[*]. ChangeLog: * config/nios2/nios2.c (custom_builtin_name): Let it always be zero terminated string. Signed-off-by: Chen Gang gang.chen.5...@gmail.com --- gcc/config/nios2/nios2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gcc/config/nios2/nios2.c b/gcc/config/nios2/nios2.c index a4e60c6..e4e005b 100644 --- a/gcc/config/nios2/nios2.c +++ b/gcc/config/nios2/nios2.c @@ -2510,7 +2510,7 @@ nios2_expand_fpu_builtin (tree exp, unsigned int code, rtx target) total of (3 + 1) * (1 + 3 + 9) == 52 custom builtin functions. */ #define NUM_CUSTOM_BUILTINS ((3 + 1) * (1 + 3 + 9)) -static char custom_builtin_name[NUM_CUSTOM_BUILTINS][5]; +static char custom_builtin_name[NUM_CUSTOM_BUILTINS][6]; static void nios2_init_custom_builtins (int start_code) -- 1.9.2.459.g68773ac
