diff mbox series

memmem.c, strstr.c: use unsigned int instead of size_t for small needles

Message ID 20231214142005.48670-1-tirtajames45@gmail.com
State New
Headers show
Series memmem.c, strstr.c: use unsigned int instead of size_t for small needles | expand

Commit Message

James Tirta Halim Dec. 14, 2023, 2:20 p.m. UTC 
---
 string/memmem.c | 10 +++++++---
 string/strstr.c | 10 +++++++---
 2 files changed, 14 insertions(+), 6 deletions(-)

Comments

Carlos O'Donell Dec. 18, 2023, 2:22 p.m. UTC | #1 
On 12/14/23 09:20, James Tirta Halim wrote:
> ---
>  string/memmem.c | 10 +++++++---
>  string/strstr.c | 10 +++++++---
>  2 files changed, 14 insertions(+), 6 deletions(-)

The feedback at this point is that these kinds of activities need performance
microbenchmark data to show the benefit across target machines.

Likewise this needs copyright assignment or DCO.

Thank you!

> 
> diff --git a/string/memmem.c b/string/memmem.c
> index 13df3bcdd4..d5548e5f71 100644
> --- a/string/memmem.c
> +++ b/string/memmem.c
> @@ -80,9 +80,13 @@ __memmem (const void *haystack, size_t hs_len,
>      return two_way_long_needle (hs, hs_len, ne, ne_len);
>  
>    uint8_t shift[256];
> -  size_t tmp, shift1;
> -  size_t m1 = ne_len - 1;
> -  size_t offset = 0;
> +
> +  typedef unsigned int Idx;
> +  _Static_assert (sizeof (shift) / sizeof (shift[0]) == 256 && sizeof (shift[0]) <= sizeof (Idx), "Index type is too small.");
> +
> +  Idx tmp, shift1;
> +  Idx m1 = ne_len - 1;
> +  Idx offset = 0;
>  
>    memset (shift, 0, sizeof (shift));
>    for (int i = 1; i < m1; i++)
> diff --git a/string/strstr.c b/string/strstr.c
> index 23618e2eb2..132a115214 100644
> --- a/string/strstr.c
> +++ b/string/strstr.c
> @@ -108,9 +108,13 @@ STRSTR (const char *haystack, const char *needle)
>  
>    const unsigned char *end = hs + hs_len - ne_len;
>    uint8_t shift[256];
> -  size_t tmp, shift1;
> -  size_t m1 = ne_len - 1;
> -  size_t offset = 0;
> +
> +  typedef unsigned int Idx;
> +  _Static_assert (sizeof (shift) / sizeof (shift[0]) == 256 && sizeof (shift[0]) <= sizeof (Idx), "Index type is too small.");
> +
> +  Idx tmp, shift1;
> +  Idx m1 = ne_len - 1;
> +  Idx offset = 0;
>  
>    /* Initialize bad character shift hash table.  */
>    memset (shift, 0, sizeof (shift));
diff mbox series

Patch

diff --git a/string/memmem.c b/string/memmem.c
index 13df3bcdd4..d5548e5f71 100644
--- a/string/memmem.c
+++ b/string/memmem.c
@@ -80,9 +80,13 @@  __memmem (const void *haystack, size_t hs_len,
     return two_way_long_needle (hs, hs_len, ne, ne_len);
 
   uint8_t shift[256];
-  size_t tmp, shift1;
-  size_t m1 = ne_len - 1;
-  size_t offset = 0;
+
+  typedef unsigned int Idx;
+  _Static_assert (sizeof (shift) / sizeof (shift[0]) == 256 && sizeof (shift[0]) <= sizeof (Idx), "Index type is too small.");
+
+  Idx tmp, shift1;
+  Idx m1 = ne_len - 1;
+  Idx offset = 0;
 
   memset (shift, 0, sizeof (shift));
   for (int i = 1; i < m1; i++)
diff --git a/string/strstr.c b/string/strstr.c
index 23618e2eb2..132a115214 100644
--- a/string/strstr.c
+++ b/string/strstr.c
@@ -108,9 +108,13 @@  STRSTR (const char *haystack, const char *needle)
 
   const unsigned char *end = hs + hs_len - ne_len;
   uint8_t shift[256];
-  size_t tmp, shift1;
-  size_t m1 = ne_len - 1;
-  size_t offset = 0;
+
+  typedef unsigned int Idx;
+  _Static_assert (sizeof (shift) / sizeof (shift[0]) == 256 && sizeof (shift[0]) <= sizeof (Idx), "Index type is too small.");
+
+  Idx tmp, shift1;
+  Idx m1 = ne_len - 1;
+  Idx offset = 0;
 
   /* Initialize bad character shift hash table.  */
   memset (shift, 0, sizeof (shift));