53 lines
1.2 KiB
C
53 lines
1.2 KiB
C
|
#include <u.h>
|
||
|
|
#include <libc.h>
|
||
|
|
|
||
|
|
/*
|
||
|
|
* In place, rewrite name to compress multiple /, eliminate ., and process ..
|
||
|
|
*/
|
||
|
|
#define SEP(x) ((x)=='/' || (x) == 0)
|
||
|
|
char*
|
||
|
|
cleanname(char *name)
|
||
|
|
{
|
||
|
|
char *p, *q, *dotdot;
|
||
|
|
int rooted;
|
||
|
|
|
||
|
|
rooted = name[0] == '/';
|
||
|
|
|
||
|
|
/*
|
||
|
|
* invariants:
|
||
|
|
* p points at beginning of path element we're considering.
|
||
|
|
* q points just past the last path element we wrote (no slash).
|
||
|
|
* dotdot points just past the point where .. cannot backtrack
|
||
|
|
* any further (no slash).
|
||
|
|
*/
|
||
|
|
p = q = dotdot = name+rooted;
|
||
|
|
while(*p) {
|
||
|
|
if(p[0] == '/') /* null element */
|
||
|
|
p++;
|
||
|
|
else if(p[0] == '.' && SEP(p[1]))
|
||
|
|
p += 1; /* don't count the separator in case it is nul */
|
||
|
|
else if(p[0] == '.' && p[1] == '.' && SEP(p[2])) {
|
||
|
|
p += 2;
|
||
|
|
if(q > dotdot) { /* can backtrack */
|
||
|
|
while(--q > dotdot && *q != '/')
|
||
|
|
;
|
||
|
|
} else if(!rooted) { /* /.. is / but ./../ is .. */
|
||
|
|
if(q != name)
|
||
|
|
*q++ = '/';
|
||
|
|
*q++ = '.';
|
||
|
|
*q++ = '.';
|
||
|
|
dotdot = q;
|
||
|
|
}
|
||
|
|
} else { /* real path element */
|
||
|
|
if(q != name+rooted)
|
||
|
|
*q++ = '/';
|
||
|
|
while((*q = *p) != '/' && *q != 0)
|
||
|
|
p++, q++;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
if(q == name) /* empty string is really ``.'' */
|
||
|
|
*q++ = '.';
|
||
|
|
*q = '\0';
|
||
|
|
return name;
|
||
|
|
}
|