src: major cleanups, introduce new eXtended Span class

- initial minimally invasive eXtended Span implementation
- rename ptr_diff to ptr_diff_bytes
- move some files to util subdir
- lots of cleanups
- start using the new checked pointers - this needs some real-world testing

src/util/util.h

@@ -0,0 +1,125 @@
+/* util.h --
+
+   This file is part of the UPX executable compressor.
+
+   Copyright (C) 1996-2022 Markus Franz Xaver Johannes Oberhumer
+   Copyright (C) 1996-2022 Laszlo Molnar
+   All Rights Reserved.
+
+   UPX and the UCL library are free software; you can redistribute them
+   and/or modify them under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2 of
+   the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING.
+   If not, write to the Free Software Foundation, Inc.,
+   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+   Markus F.X.J. Oberhumer              Laszlo Molnar
+   <markus@oberhumer.com>               <ezerotven+github@gmail.com>
+ */
+
+#pragma once
+#ifndef UPX_UTIL_H__
+#define UPX_UTIL_H__ 1
+
+/*************************************************************************
+// assert sane memory buffer sizes to protect against integer overflows
+// and malicious header fields
+// see C 11 standard, Annex K
+**************************************************************************/
+
+inline bool mem_size_valid_bytes(upx_uint64_t bytes) noexcept { return bytes <= UPX_RSIZE_MAX; }
+
+bool mem_size_valid(upx_uint64_t element_size, upx_uint64_t n, upx_uint64_t extra1 = 0,
+                    upx_uint64_t extra2 = 0) noexcept;
+
+// new with asserted size; will throw on failure
+#define New(type, n) new type[mem_size_get_n(sizeof(type), n)]
+
+// will throw on invalid size
+upx_rsize_t mem_size(upx_uint64_t element_size, upx_uint64_t n, upx_uint64_t extra1,
+                     upx_uint64_t extra2 = 0);
+
+// inline fast paths:
+
+// will throw on invalid size
+inline upx_rsize_t mem_size(upx_uint64_t element_size, upx_uint64_t n) {
+    upx_uint64_t bytes = element_size * n;
+    if __acc_very_unlikely (element_size == 0 || element_size > UPX_RSIZE_MAX ||
+                            n > UPX_RSIZE_MAX || bytes > UPX_RSIZE_MAX)
+        return mem_size(element_size, n, 0, 0); // this will throw
+    return ACC_ICONV(upx_rsize_t, bytes);
+}
+
+// will throw on invalid size
+inline upx_rsize_t mem_size_get_n(upx_uint64_t element_size, upx_uint64_t n) {
+    (void) mem_size(element_size, n); // assert size
+    return ACC_ICONV(upx_rsize_t, n); // and return n
+}
+
+// will throw on invalid size
+inline void mem_size_assert(upx_uint64_t element_size, upx_uint64_t n) {
+    (void) mem_size(element_size, n); // assert size
+}
+
+// will throw on invalid size
+inline void mem_clear(void *p, size_t n) {
+    (void) mem_size(1, n); // assert size
+    memset(p, 0, n);
+}
+
+// ptrdiff_t with nullptr check and asserted size; will throw on failure
+// WARNING: returns size_in_bytes, not number of elements!
+int ptr_diff_bytes(const void *a, const void *b);
+unsigned ptr_udiff_bytes(const void *a, const void *b); // asserts a >= b
+
+// short names "ptr_diff" and "ptr_udiff" for types with sizeof(X) == 1
+template <class T, class U>
+inline typename std::enable_if<sizeof(T) == 1 && sizeof(U) == 1, int>::type ptr_diff(const T *a,
+                                                                                     const U *b) {
+    return ptr_diff_bytes(a, b);
+}
+template <class T, class U>
+inline typename std::enable_if<sizeof(T) == 1 && sizeof(U) == 1, unsigned>::type
+ptr_udiff(const T *a, const U *b) {
+    return ptr_udiff_bytes(a, b);
+}
+
+/*************************************************************************
+// misc. support functions
+**************************************************************************/
+
+char *fn_basename(const char *name);
+int fn_strcmp(const char *n1, const char *n2);
+char *fn_strlwr(char *n);
+bool fn_has_ext(const char *name, const char *ext, bool ignore_case = true);
+
+bool file_exists(const char *name);
+bool maketempname(char *ofilename, size_t size, const char *ifilename, const char *ext,
+                  bool force = true);
+bool makebakname(char *ofilename, size_t size, const char *ifilename, bool force = true);
+
+unsigned get_ratio(upx_uint64_t u_len, upx_uint64_t c_len);
+bool set_method_name(char *buf, size_t size, int method, int level);
+void center_string(char *buf, size_t size, const char *s);
+
+int find(const void *b, int blen, const void *what, int wlen);
+int find_be16(const void *b, int blen, unsigned what);
+int find_be32(const void *b, int blen, unsigned what);
+int find_be64(const void *b, int blen, upx_uint64_t what);
+int find_le16(const void *b, int blen, unsigned what);
+int find_le32(const void *b, int blen, unsigned what);
+int find_le64(const void *b, int blen, upx_uint64_t what);
+
+int mem_replace(void *b, int blen, const void *what, int wlen, const void *r);
+
+#endif /* already included */
+
+/* vim:set ts=4 sw=4 et: */