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extmod/vfs_lfsx: Normalize path name in chdir.

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This change scans for '.', '..' and multiple '/' and normalizes the new
path name.  If the resulting path does not exist, an error is raised.
Non-existing interim path elements are ignored if they are removed during
normalization.
This commit is contained in:
robert
2020-05-03 21:05:08 +02:00
committed by Damien George
parent a5ea4b9f3f
commit d3ea28d04a
3 changed files with 81 additions and 0 deletions
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37
extmod/vfs_lfsx.c
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@@ -283,8 +283,45 @@ STATIC mp_obj_t MP_VFS_LFSx(chdir)(mp_obj_t self_in, mp_obj_t path_in) {
}
// If not at root add trailing / to make it easy to build paths
// and then normalise the path
if (vstr_len(&self->cur_dir) != 1) {
vstr_add_byte(&self->cur_dir, '/');
#define CWD_LEN (vstr_len(&self->cur_dir))
size_t to = 1;
size_t from = 1;
char *cwd = vstr_str(&self->cur_dir);
while (from < CWD_LEN) {
for (; cwd[from] == '/' && from < CWD_LEN; ++from) {
// Scan for the start
}
if (from > to) {
// Found excessive slash chars, squeeze them out
vstr_cut_out_bytes(&self->cur_dir, to, from - to);
from = to;
}
for (; cwd[from] != '/' && from < CWD_LEN; ++from) {
// Scan for the next /
}
if ((from - to) == 1 && cwd[to] == '.') {
// './', ignore
vstr_cut_out_bytes(&self->cur_dir, to, ++from - to);
from = to;
} else if ((from - to) == 2 && cwd[to] == '.' && cwd[to + 1] == '.') {
// '../', skip back
if (to > 1) {
// Only skip back if not at the tip
for (--to; to > 1 && cwd[to - 1] != '/'; --to) {
// Skip back
}
}
vstr_cut_out_bytes(&self->cur_dir, to, ++from - to);
from = to;
} else {
// Normal element, keep it and just move the offset
to = ++from;
}
}
}
return mp_const_none;