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py/builtinimport: Remove unreachable code for relative imports. 

The while-loop that calls chop_component will guarantee that level==-1 at
the end of the loop.  Hence the code following it is unnecessary.

The check for p==this_name will catch imports that are beyond the
top-level, and also covers the case of new_mod_q==MP_QSTR_ (equivalent to
new_mod_l==0) so that check is removed.

There is also a new check at the start for level>=0 to guard against
__import__ being called with bad level values.
This commit is contained in:
Damien George 2017-01-16 16:54:56 +11:00
parent ebb9396274
commit 2f7fad66a2
1 changed files with 6 additions and 21 deletions
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27
py/builtinimport.c
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@ -261,6 +261,9 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
fromtuple = args[3];
if (n_args >= 5) {
level = MP_OBJ_SMALL_INT_VALUE(args[4]);
if (level < 0) {
mp_raise_ValueError(NULL);
}
}
}
@ -305,28 +308,13 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
chop_component(this_name, &p);
}
uint dots_seen = 0;
while (level--) {
chop_component(this_name, &p);
dots_seen++;
}
if (dots_seen == 0 && level >= 1) {
// http://legacy.python.org/dev/peps/pep-0328/#relative-imports-and-name
// "If the module's name does not contain any package information
// (e.g. it is set to '__main__') then relative imports are
// resolved as if the module were a top level module, regardless
// of where the module is actually located on the file system."
// Supposedly this if catches this condition and resolve it properly
// TODO: But nobody knows for sure. This condition happens when
// package's __init__.py does something like "import .submod". So,
// maybe we should check for package here? But quote above doesn't
// talk about packages, it talks about dot-less module names.
DEBUG_printf("Warning: no dots in current module name and level>0\n");
p = this_name + this_name_l;
} else if (level != -1) {
mp_raise_msg(&mp_type_ImportError, "invalid relative import");
// We must have some component left over to import from
if (p == this_name) {
mp_raise_ValueError("cannot perform relative import");
}
uint new_mod_l = (mod_len == 0 ? (size_t)(p - this_name) : (size_t)(p - this_name) + 1 + mod_len);
@ -339,9 +327,6 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
qstr new_mod_q = qstr_from_strn(new_mod, new_mod_l);
DEBUG_printf("Resolved base name for relative import: '%s'\n", qstr_str(new_mod_q));
if (new_mod_q == MP_QSTR_) {
mp_raise_ValueError("cannot perform relative import");
}
module_name = MP_OBJ_NEW_QSTR(new_mod_q);
mod_str = new_mod;
mod_len = new_mod_l;