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/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2009 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* Glenn Fowler
* AT&T Research
*
* in-place path name canonicalization -- preserves the logical view
* pointer to trailing 0 in path returned
*
* remove redundant .'s and /'s
* move ..'s to the front
* /.. preserved (for pdu and newcastle hacks)
* FS_3D handles ...
* if (flags&PATH_PHYSICAL) then symlinks resolved at each component
* if (flags&PATH_DOTDOT) then each .. checked for access
* if (flags&PATH_EXISTS) then path must exist at each component
* if (flags&PATH_VERIFIED(n)) then first n chars of path exist
*
* longer pathname possible if (flags&PATH_PHYSICAL) or FS_3D ... involved
* 0 returned on error and if (flags&(PATH_DOTDOT|PATH_EXISTS)) then path
* will contain the components following the failure point
*/
#include <ast.h>
#include <ls.h>
#include <fs3d.h>
#include <error.h>
char*
pathcanon(char* path, int flags)
{
register char* p;
register char* r;
register char* s;
register char* t;
register int dots;
char* phys;
char* v;
int loop;
int oerrno;
#if defined(FS_3D)
long visits = 0;
#endif
oerrno = errno;
dots = loop = 0;
phys = path;
v = path + ((flags >> 5) & 01777);
if (*path == '/')
{
if (*(path + 1) == '/' && *astconf("PATH_LEADING_SLASHES", NiL, NiL) == '1')
do path++; while (*path == '/' && *(path + 1) == '/');
if (!*(path + 1))
return path + 1;
}
p = r = s = t = path;
for (;;) switch (*t++ = *s++)
{
case '.':
dots++;
break;
case 0:
s--;
/*FALLTHROUGH*/
case '/':
while (*s == '/') s++;
switch (dots)
{
case 1:
t -= 2;
break;
case 2:
if ((flags & (PATH_DOTDOT|PATH_EXISTS)) == PATH_DOTDOT && (t - 2) >= v)
{
struct stat st;
*(t - 2) = 0;
if (stat(phys, &st))
{
strcpy(path, s);
return 0;
}
*(t - 2) = '.';
}
#if PRESERVE_TRAILING_SLASH
if (t - 5 < r) r = t;
#else
if (t - 5 < r)
{
if (t - 4 == r) t = r + 1;
else r = t;
}
#endif
else for (t -= 5; t > r && *(t - 1) != '/'; t--);
break;
case 3:
#if defined(FS_3D)
{
char* x;
char* o;
int c;
o = t;
if ((t -= 5) <= path) t = path + 1;
c = *t;
*t = 0;
if (x = pathnext(phys, s - (*s != 0), &visits))
{
r = path;
if (t == r + 1) x = r;
v = s = t = x;
}
else
{
*t = c;
t = o;
}
}
#else
r = t;
#endif
break;
default:
if ((flags & PATH_PHYSICAL) && loop < 32 && (t - 1) > path)
{
int c;
char buf[PATH_MAX];
c = *(t - 1);
*(t - 1) = 0;
dots = pathgetlink(phys, buf, sizeof(buf));
*(t - 1) = c;
if (dots > 0)
{
loop++;
strcpy(buf + dots, s - (*s != 0));
if (*buf == '/') p = r = path;
v = s = t = p;
strcpy(p, buf);
}
else if (dots < 0 && errno == ENOENT)
{
if (flags & PATH_EXISTS)
{
strcpy(path, s);
return 0;
}
flags &= ~(PATH_PHYSICAL|PATH_DOTDOT);
}
dots = 4;
}
break;
}
if (dots >= 4 && (flags & PATH_EXISTS) && (t - 1) >= v && (t > path + 1 || t > path && *(t - 1) && *(t - 1) != '/'))
{
struct stat st;
*(t - 1) = 0;
if (stat(phys, &st))
{
strcpy(path, s);
return 0;
}
v = t;
if (*s) *(t - 1) = '/';
}
if (!*s)
{
if (t > path && !*(t - 1)) t--;
if (t == path) *t++ = '.';
#if DONT_PRESERVE_TRAILING_SLASH
else if (t > path + 1 && *(t - 1) == '/') t--;
#else
else if ((s <= path || *(s - 1) != '/') && t > path + 1 && *(t - 1) == '/') t--;
#endif
*t = 0;
errno = oerrno;
return t;
}
dots = 0;
p = t;
break;
default:
dots = 4;
break;
}
}
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