Re: [PATCH 60/68] prefer memcpy to strcpy

Am 27.09.2015 um 15:06 schrieb Torsten Bögershausen:

On 2015-09-27 13.19, René Scharfe wrote:

quoted

Am 24.09.2015 um 23:08 schrieb Jeff King:

quoted

When we already know the length of a string (e.g., because
we just malloc'd to fit it), it's nicer to use memcpy than
strcpy, as it makes it more obvious that we are not going to
overflow the buffer (because the size we pass matches the
size in the allocation).

This also eliminates calls to strcpy, which make auditing
the code base harder.

Signed-off-by: Jeff King <redacted>
---
   compat/nedmalloc/nedmalloc.c | 5 +++--
   fast-import.c                | 5 +++--
   revision.c                   | 2 +-
   3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/compat/nedmalloc/nedmalloc.c b/compat/nedmalloc/nedmalloc.c
index 609ebba..a0a16eb 100644
--- a/compat/nedmalloc/nedmalloc.c
+++ b/compat/nedmalloc/nedmalloc.c

@@ -957,8 +957,9 @@ char *strdup(const char *s1)
   {
       char *s2 = 0;
       if (s1) {
-        s2 = malloc(strlen(s1) + 1);
-        strcpy(s2, s1);
+        size_t len = strlen(s1) + 1;
+        s2 = malloc(len);
+        memcpy(s2, s1, len);

This leaves the last byte uninitialized; it was set to NUL by strcpy() before.

len is == strlen() +1, which should cover the NUL:

1 byte extra for NUL is allocated,
and memcpy will copy NUL from source.
(Or do I miss somethong ?)

No, you're right.  Sorry for the noise.

I fully blame this on lack of coffeine because my electric kettle just 
broke. O_o

René