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#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include "norm.h"
#define SKP() \
do { \
s++; \
} while (0)
#define CPY() \
do { \
*d++ = *s++; \
} while (0)
#define MRK() \
do { \
PUSH(); \
} while (0)
#define BKP() \
do { \
POP(); \
} while (0)
#define BKP2() \
do { \
POP(); \
POP(); \
} while (0)
#define PUSH() \
do { \
stk[top++] = d; \
} while (0)
#define POP() \
do { \
if (top == 0) \
{ \
dest[0] = '\0'; \
return -1; \
} \
d = stk[--top]; \
} while (0)
/*
* Normalize the unix pathname in src eliminating . and .. sequences
* to yield an absolute path. Returns 0 on success, and -1 on error.
*/
int norm(char* dest, int len, const char* src)
{
const char* s = src;
char* d = dest;
char* stk[256];
int top = 0;
enum { L0, L1, L2, L3, L4 } state = L0;
assert(strlen(src) <= len);
while (*s)
{
char c = *s;
enum { slash, dot, other } cls;
switch (c)
{
case '/':
{
cls = slash;
break;
}
case '.':
{
cls = dot;
break;
}
default:
{
cls = other;
}
}
switch (state)
{
case L0:
{
switch (cls)
{
case slash:
{
CPY();
state = L1;
break;
}
case dot:
case other:
{
dest[0] = '\0';
return -1;
}
}
break;
}
case L1:
{
switch (cls)
{
case slash:
{
SKP();
break;
}
case dot:
{
MRK();
CPY();
state = L2;
break;
}
case other:
{
MRK();
CPY();
state = L4;
break;
}
}
break;
}
case L2:
{
switch (cls)
{
case slash:
{
BKP();
state = L1;
break;
}
case dot:
{
CPY();
state = L3;
break;
}
case other:
{
CPY();
state = L4;
break;
}
}
break;
}
case L3:
{
switch (cls)
{
case slash:
{
BKP2();
state = L1;
break;
}
case dot:
case other:
{
CPY();
state = L4;
break;
}
}
break;
}
case L4:
{
switch (cls)
{
case slash:
{
CPY();
state = L1;
break;
}
case dot:
case other:
{
CPY();
break;
}
}
break;
}
}
}
*d = '\0';
return 0;
}
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