Mercurial > cpython-lru_cache-weakref

annotate Python/memmove.c @ 5758:bfe9ba74c19e legacy-trunk

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Fix problem discovered by Greg McFarlane: when an imported module replaces its own entry in sys.module, reference count errors ensue; even if there is no reference count problem, it would be preferable for the import to yield the new thing in sys.modules anyway (if only because that's what later imports will yield). This opens the road to an official hack to implement a __getattr__ like feature for modules: stick an instance in sys.modules[__name__].
author Guido van Rossum <guido@python.org>
date Thu, 10 Jul 1997 18:00:45 +0000
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children 916fb024ce94
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1 /***********************************************************
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2 Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
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3 The Netherlands.
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4
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5 All Rights Reserved
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6
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7 Permission to use, copy, modify, and distribute this software and its
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8 documentation for any purpose and without fee is hereby granted,
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9 provided that the above copyright notice appear in all copies and that
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10 both that copyright notice and this permission notice appear in
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11 supporting documentation, and that the names of Stichting Mathematisch
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12 Centrum or CWI or Corporation for National Research Initiatives or
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13 CNRI not be used in advertising or publicity pertaining to
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14 distribution of the software without specific, written prior
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15 permission.
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16
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17 While CWI is the initial source for this software, a modified version
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18 is made available by the Corporation for National Research Initiatives
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19 (CNRI) at the Internet address ftp://ftp.python.org.
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20
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21 STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
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22 REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
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23 MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
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24 CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
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25 DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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26 PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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27 TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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28 PERFORMANCE OF THIS SOFTWARE.
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29
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30 ******************************************************************/
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31
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32 /* A perhaps slow but I hope correct implementation of memmove */
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33
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34 extern char *memcpy();
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35
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36 char *
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37 memmove(dst, src, n)
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38 char *dst;
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39 char *src;
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40 int n;
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41 {
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42 char *realdst = dst;
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43 if (n <= 0)
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44 return dst;
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45 if (src >= dst+n || dst >= src+n)
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46 return memcpy(dst, src, n);
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47 if (src > dst) {
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48 while (--n >= 0)
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49 *dst++ = *src++;
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50 }
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51 else if (src < dst) {
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52 src += n;
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53 dst += n;
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54 while (--n >= 0)
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55 *--dst = *--src;
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56 }
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57 return realdst;
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58 }