From ce76d938dd98817f998c905e01fbb99b072c0bf6 Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Fri, 5 Oct 2018 15:43:05 +0300 Subject: lib: Add memcat_p(): paste 2 pointer arrays together 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 Reviewed-by: Andy Shevchenko Tested-by: Mathieu Poirier Signed-off-by: Greg Kroah-Hartman --- lib/string.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'lib/string.c') diff --git a/lib/string.c b/lib/string.c index 2c0900a5d51a..453f35994eb6 100644 --- a/lib/string.c +++ b/lib/string.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include @@ -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 -- cgit v1.2.3