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authorMark H Weaver <mhw@netris.org>2019-04-01 22:11:35 -0400
committerMark H Weaver <mhw@netris.org>2019-04-16 16:54:55 -0400
commit6b1de860ab2360e8679205aecdc1c837744a4b9c (patch)
tree0357dcee473b12ca590343ad513d876eca1e8199 /libguile/bytevectors.c
parent275c96dd1fbc392e43423e91f08d2cf2fcc538a1 (diff)
downloadguile-6b1de860ab2360e8679205aecdc1c837744a4b9c.tar.gz
Avoid passing NULL to 'memcpy' and 'memcmp'.
Reported by Jeffrey Walton <noloader@gmail.com> in <https://lists.gnu.org/archive/html/guile-devel/2019-03/msg00001.html>. Note that C11 section 7.1.4 (Use of library functions) states that: "unless explicitly stated otherwise in the detailed descriptions [of library functions] that follow: If an argument to a function has an invalid value (such as ... a null pointer ...) ..., the behavior is undefined." Note that 'strxfrm' is an example of a standard C function that explicitly states otherwise, allowing NULL to be passed in the first argument if the size argument is zero, but no similar allowance is specified for 'memcpy' or 'memcmp'. * libguile/bytevectors.c (scm_uniform_array_to_bytevector): Call memcpy only if 'byte_len' is non-zero. * libguile/srfi-14.c (charsets_equal): Call memcmp only if the number of ranges is non-zero. * libguile/stime.c (setzone): Pass 1-character buffer to 'scm_to_locale_stringbuf', instead of NULL. * libguile/strings.c (scm_to_locale_stringbuf): Call memcpy only if the number of bytes to copy is non-zero.
Diffstat (limited to 'libguile/bytevectors.c')
-rw-r--r--libguile/bytevectors.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/libguile/bytevectors.c b/libguile/bytevectors.c
index 1d4129705..e42a48c4e 100644
--- a/libguile/bytevectors.c
+++ b/libguile/bytevectors.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2009-2015 Free Software Foundation, Inc.
+/* Copyright (C) 2009-2015, 2019 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
@@ -662,7 +662,11 @@ SCM_DEFINE (scm_uniform_array_to_bytevector, "uniform-array->bytevector",
SCM_MISC_ERROR ("uniform elements larger than 8 bits must fill whole bytes", SCM_EOL);
ret = make_bytevector (byte_len, SCM_ARRAY_ELEMENT_TYPE_VU8);
- memcpy (SCM_BYTEVECTOR_CONTENTS (ret), elts, byte_len);
+ if (byte_len != 0)
+ /* Empty arrays may have elements == NULL. We must avoid passing
+ NULL to memcpy, even if the length is zero, to avoid undefined
+ behavior. */
+ memcpy (SCM_BYTEVECTOR_CONTENTS (ret), elts, byte_len);
scm_array_handle_release (&h);