On 06/05/21 08:23AM, Simon Glass wrote:
Add a function to duplicate a memory region, a little like strdup().
Signed-off-by: Simon Glass sjg@chromium.org
Changes in v2:
- Add a patch to introduce a memdup() function
include/linux/string.h | 13 +++++++++++++ lib/string.c | 13 +++++++++++++ test/lib/string.c | 32 ++++++++++++++++++++++++++++++++ 3 files changed, 58 insertions(+)
diff --git a/include/linux/string.h b/include/linux/string.h index dd255f21633..3169c93796e 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -129,6 +129,19 @@ extern void * memchr(const void *,int,__kernel_size_t); void *memchr_inv(const void *, int, size_t); #endif
+/**
- memdup() - allocate a buffer and copy in the contents
- Note that this returns a valid pointer even if @len is 0
I'm uneducated about U-Boot's memory allocator. But I wonder how it returns a valid pointer even on 0 length allocations. What location does it point to? What are users expected to do with that pointer? They obviously can't read/write to it since it is supposed to be a 0 byte long allocation. If another positive length allocation happens before the said pointer is freed, will it point to the same memory location? If not, isn't the 0-length pointer actually at least a 1-length pointer?
- @src: data to copy in
- @len: number of bytes to copy
- @return allocated buffer with the copied contents, or NULL if not enough
- memory is available
- */
+char *memdup(const void *src, size_t len);
unsigned long ustrtoul(const char *cp, char **endp, unsigned int base); unsigned long long ustrtoull(const char *cp, char **endp, unsigned int base);
diff --git a/lib/string.c b/lib/string.c index a0cff8fe88e..1be61ee0499 100644 --- a/lib/string.c +++ b/lib/string.c @@ -658,6 +658,19 @@ void * memscan(void * addr, int c, size_t size) } #endif
+char *memdup(const void *src, size_t len) +{
- char *p;
- p = malloc(len);
- if (!p)
return NULL;- memcpy(p, src, len);
- return p;
+}
#ifndef __HAVE_ARCH_STRSTR /**
- strstr - Find the first substring in a %NUL terminated string
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