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#include <kernel/vfs/path.h>
#include <kernel/panic.h>
int path_simplify(const char *in, char *out, size_t len) {
if (len == 0) return -1; // empty paths are invalid
if (in[0] != '/') return -1; // so are relative paths
int depth = 0; // shouldn't be needed!
int seg_len; // the length of the current path segment
int out_pos = 0;
bool directory = 0;
for (int i = 0; i < len; i += seg_len + 1) {
assert(in[i] == '/');
seg_len = 0;
directory = false;
for (int j = i + 1; j < len; j++) {
if (in[j] == '/') {
directory = true;
break;
}
seg_len++;
}
/* example iteration, illustrated with terrible ASCII art
*
* |i=5 |next i = i + seg_len + 1 = 10
* v v
* /some/path/asdf
* |--|
* seg_len = 4
* (segment starts at i+1) */
if (seg_len == 0 || (seg_len == 1 && in[i + 1] == '.')) {
// the segment is // or /./
directory = true;
} else if (seg_len == 2 && in[i + 1] == '.' && in[i + 2] == '.') {
// the segment is /../
if (--depth < 0)
return -1;
// backtrack to last slash
while (out[--out_pos] != '/');
} else {
// normal segment
out[out_pos] = '/';
memcpy(&out[out_pos + 1], &in[i + 1], seg_len);
out_pos += seg_len + 1;
depth++;
}
}
/* if we were backtracking, out_pos can become 0. i don't like this,
* it feels sloppy. this algorithm should be implemented differently. TODO? */
if (out_pos == 0)
out[out_pos++] = '/';
if (directory) // if the path refers to a directory, append a trailing slash
if (out[out_pos-1] != '/') // unless it's already there
out[out_pos++] = '/';
return out_pos;
}
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