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lib: Add memcat_p(): paste 2 pointer arrays together

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This adds a helper to paste 2 pointer arrays together, useful for merging
various types of attribute arrays. There are a few places in the kernel
tree where this is open coded, and I just added one more in the STM class.

The naming is inspired by memset_p() and memcat(), and partial credit for
it goes to Andy Shevchenko.

This patch adds the function wrapped in a type-enforcing macro and a test
module.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexander Shishkin
2018-10-05 15:43:05 +03:00
committed by Greg Kroah-Hartman
parent 6c7e4b6882
commit ce76d938dd
5 changed files with 162 additions and 0 deletions
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31
lib/string.c
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@@ -27,6 +27,7 @@
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <asm/byteorder.h>
#include <asm/word-at-a-time.h>
@@ -890,6 +891,36 @@ void *memscan(void *addr, int c, size_t size)
EXPORT_SYMBOL(memscan);
#endif
/*
* Merge two NULL-terminated pointer arrays into a newly allocated
* array, which is also NULL-terminated. Nomenclature is inspired by
* memset_p() and memcat() found elsewhere in the kernel source tree.
*/
void **__memcat_p(void **a, void **b)
{
void **p = a, **new;
int nr;
/* count the elements in both arrays */
for (nr = 0, p = a; *p; nr++, p++)
;
for (p = b; *p; nr++, p++)
;
/* one for the NULL-terminator */
nr++;
new = kmalloc_array(nr, sizeof(void *), GFP_KERNEL);
if (!new)
return NULL;
/* nr -> last index; p points to NULL in b[] */
for (nr--; nr >= 0; nr--, p = p == b ? &a[nr] : p - 1)
new[nr] = *p;
return new;
}
EXPORT_SYMBOL_GPL(__memcat_p);
#ifndef __HAVE_ARCH_STRSTR
/**
* strstr - Find the first substring in a %NUL terminated string