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- #include "lib9.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, erasedprefix;
- rooted = name[0] == '/';
- erasedprefix = 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])) {
- if(p == name)
- erasedprefix = 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;
- }
- if(q == name)
- erasedprefix = 1; /* erased entire path via dotdot */
- } 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';
- if(erasedprefix && name[0] == '#'){
- /* this was not a #x device path originally - make it not one now */
- memmove(name+2, name, strlen(name)+1);
- name[0] = '.';
- name[1] = '/';
- }
- return name;
- }
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