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py: Change vstr so that it doesn't null terminate buffer by default.

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This cleans up vstr so that it's a pure "variable buffer", and the user
can decide whether they need to add a terminating null byte.  In most
places where vstr is used, the vstr did not need to be null terminated
and so this patch saves code size, a tiny bit of RAM, and makes vstr
usage more efficient.  When null termination is needed it must be
done explicitly using vstr_null_terminate.
This commit is contained in:
Damien George
2015-01-28 23:43:01 +00:00
parent 57aebe1714
commit 0d3cb6726d
14 changed files with 67 additions and 70 deletions
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21
py/stream.c
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@@ -177,7 +177,6 @@ STATIC mp_obj_t stream_read(mp_uint_t n_args, const mp_obj_t *args) {
nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(error)));
} else {
vstr.len = out_sz;
vstr.buf[vstr.len] = '\0';
return mp_obj_new_str_from_vstr(STREAM_CONTENT_TYPE(o->type->stream_p), &vstr);
}
}
@@ -289,7 +288,6 @@ STATIC mp_obj_t stream_readall(mp_obj_t self_in) {
}
vstr.len = total_size;
vstr.buf[total_size] = '\0';
return mp_obj_new_str_from_vstr(STREAM_CONTENT_TYPE(o->type->stream_p), &vstr);
}
@@ -306,15 +304,15 @@ STATIC mp_obj_t stream_unbuffered_readline(mp_uint_t n_args, const mp_obj_t *arg
max_size = MP_OBJ_SMALL_INT_VALUE(args[1]);
}
vstr_t *vstr;
vstr_t vstr;
if (max_size != -1) {
vstr = vstr_new_size(max_size);
vstr_init(&vstr, max_size);
} else {
vstr = vstr_new();
vstr_init(&vstr, 16);
}
while (max_size == -1 || max_size-- != 0) {
char *p = vstr_add_len(vstr, 1);
char *p = vstr_add_len(&vstr, 1);
if (p == NULL) {
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_MemoryError, "out of memory"));
}
@@ -323,14 +321,14 @@ STATIC mp_obj_t stream_unbuffered_readline(mp_uint_t n_args, const mp_obj_t *arg
mp_uint_t out_sz = o->type->stream_p->read(o, p, 1, &error);
if (out_sz == MP_STREAM_ERROR) {
if (is_nonblocking_error(error)) {
if (vstr->len == 1) {
if (vstr.len == 1) {
// We just incremented it, but otherwise we read nothing
// and immediately got EAGAIN. This is case is not well
// specified in
// https://docs.python.org/3/library/io.html#io.IOBase.readline
// unlike similar case for read(). But we follow the latter's
// behavior - return None.
vstr_free(vstr);
vstr_clear(&vstr);
return mp_const_none;
} else {
goto done;
@@ -343,16 +341,15 @@ done:
// Back out previously added byte
// Consider, what's better - read a char and get OutOfMemory (so read
// char is lost), or allocate first as we do.
vstr_cut_tail_bytes(vstr, 1);
vstr_cut_tail_bytes(&vstr, 1);
break;
}
if (*p == '\n') {
break;
}
}
mp_obj_t ret = mp_obj_new_str_from_vstr(STREAM_CONTENT_TYPE(o->type->stream_p), vstr);
vstr_free(vstr);
return ret;
return mp_obj_new_str_from_vstr(STREAM_CONTENT_TYPE(o->type->stream_p), &vstr);
}
// TODO take an optional extra argument (what does it do exactly?)