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79 lines
2.4 KiB
C
79 lines
2.4 KiB
C
/*
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Inferno libkern/cleanname.c
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http://code.google.com/p/inferno-os/source/browse/libkern/cleanname.c
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Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
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Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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#include <u.h>
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#include <libc.h>
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/*
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* In place, rewrite name to compress multiple /, eliminate ., and process ..
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*/
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#define SEP(x) ((x)=='/' || (x) == 0)
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char*
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cleanname(char *name)
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{
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char *p, *q, *dotdot;
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int rooted;
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rooted = name[0] == '/';
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/*
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* invariants:
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* p points at beginning of path element we're considering.
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* q points just past the last path element we wrote (no slash).
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* dotdot points just past the point where .. cannot backtrack
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* any further (no slash).
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*/
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p = q = dotdot = name+rooted;
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while(*p) {
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if(p[0] == '/') /* null element */
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p++;
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else if(p[0] == '.' && SEP(p[1]))
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p += 1; /* don't count the separator in case it is nul */
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else if(p[0] == '.' && p[1] == '.' && SEP(p[2])) {
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p += 2;
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if(q > dotdot) { /* can backtrack */
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while(--q > dotdot && *q != '/')
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;
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} else if(!rooted) { /* /.. is / but ./../ is .. */
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if(q != name)
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*q++ = '/';
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*q++ = '.';
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*q++ = '.';
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dotdot = q;
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}
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} else { /* real path element */
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if(q != name+rooted)
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*q++ = '/';
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while((*q = *p) != '/' && *q != 0)
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p++, q++;
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}
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}
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if(q == name) /* empty string is really ``.'' */
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*q++ = '.';
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*q = '\0';
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return name;
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}
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