Having assertion macros that are disabled by default, is not
only useful for our glib code, but should also be available
for nm-std-aux. Move the macros.
- add unit test for nm_utils_parse_next_line()
- as line delimiter also accept "\r\n" and "\r" (beside "\n", "\0" and
EOF).
- fix returning lines with embedded "\0" characters. The line ends
on the first "\n" or "\0", whatever comes first. The code before
didn't ensure that with:
line_end = memchr (line_start, '\n', *inout_len);
if (!line_end)
line_end = memchr (line_start, '\0', *inout_len);
We want to parse "/proc/cmdline". That is space separated with support
for quoting and escaping. Our implementation becomes part of stable
behavior, and we should interpret the kernel command line the same way
as the system does. That means, our implementation should match
systemd's.
In the previous form, NM_STR_BUF_INIT() was a macro. That makes sense,
however it's not really possible to make that a macro without evaluating
the reservation length multiple times. That means,
NMStrBuf strbuf = NM_STR_BUF_INIT (nmtst_get_rand_uint32 () % 100, FALSE);
leads to a crash. That is unfortunate, so instead make it an inline
function that returns a NMStrBut struct. Usually, we avoid functions
that returns structs, but here we do it.
If g_vsnprintf() returns that it wants to write 5 characters, it
really needs space for 5+1 characters. If we have 5 characters
available, it would have written "0123\0", which leaves the buffer
broken.
Fixes: eda47170ed ('shared: add NMStrBuf util')
Previously, for simplicity, NMStrBuf did not support buffers without any
data allocated. However, supporting that has very little
overhead/complexity, so do it.
Now you can initialize buffers to have no data allocated, and when
appending data, it will automatically grow.
Iterating hash tables gives an undefined order. Often we want to have
a stable order, for example when printing the content of a hash or
when converting it to a "a{sv}" variant.
How to achieve that best? I think we should only iterate the hash once,
and not require additional lookups. nm_utils_named_values_from_strdict()
achieves that by returning the key and the value together. Also, often
we only need the list for a short time, so we can avoid heap allocating
the list, if it is short enough. This works by allowing the caller to
provide a pre-allocated buffer (usually on the stack) and only as fallback
allocate a new list.
If the value pointer is const, it is commonly inconvenient and requires
a cast. Requiring casts on a common base does not increase type safety,
but is annoying.
g_steal_pointer() is marked as GLIB_AVAILABLE_STATIC_INLINE_IN_2_44,
that means we get a deprecated warning. Avoid that. We anyway
re-implement the macro so that we can use it before 2.44 and so
that it always does the typeof() cast.
When parsing user input if is often convenient to allow stripping whitespace.
Especially with escaped strings, the user could still escape the whitespace,
if the space should be taken literally.
Add support for that to nm_utils_buf_utf8safe_unescape().
Note that this is not the same as calling g_strstrip() before/after
unescape. That is, because nm_utils_buf_utf8safe_unescape() correctly
preserves escaped whitespace. If you call g_strstrip() before/after
the unescape, you don't know whether the whitespace is escaped.
We want to use the function to unescape (compress) secrets. As such, we want
to be sure that no secrets are leaked in memory due to growing the buffer with
realloc. In fact, reallocation should never happen. Assert for that.
As reallocation cannot happen, we could directly fill a buffer with
API like nm_utils_strbuf_*(). But NMStrBuf has low overhead even in this
case.
We have nm_str_not_empty() which is the inverse of that. The purpose
of nm_str_not_empty() is to normalize a string to either return
%NULL or a non-empty string, like
const char *
get_name (Object *obj)
{
return nm_str_not_empty (obj->name);
}
Sometimes, we however want to check whether a string is not empty.
So, we previously had two choices:
1) use a temporary variable:
const char *tmp;
tmp = get_string ();
if (tmp && tmp[0])
...
The problem with this variant is that it's more verbose (by requiring a
temporary variable). Another downside is that there are multiple ways
how to check for an empty string (!tmp[0], tmp[0] == '\0', !strlen (tmp),
strlen (tmp) == 0), and sure enough they are all in use.
2) use !nm_str_not_empty(). But this double negation looks really odd
and confusing.
Add nm_str_is_empty() instead.
Macros preferably behave function-like, for example in that they evaluate
arguments exactly ones. Sometimes, we want to evaluate arguments
lazily, like in NM_IN_SET() or nm_g_set_error_take_lazy(). But it
is almost always undesirable to evaluate an argument more than once.
Fix NM_STR_HAS_PREFIX() for that.
Also, rename the local variable to not use the name "_str",
which may be a common name that the caller would like to use.
GPtrArray does not support NULL terminating the pointer array. That
makes it cumbersome to use it for tracking a strv array. Add a few
helper functions nm_strvarray_*() that help using a GArray instead.
When handling a GCancellable, you make decisions based on when the cancelled
property of a GCancellable changes. Correctly handling a cancellable becoming
uncancelled again is really complicated, nor is it clear what it even means:
should the flipping be treated as cancellation or not? Probably if the
cancelled property gets reset, you already start aborting and there is
no way back. So, you would want that a cancellation is always handled.
But it's hard to implement that correctly, and it's odd to claim
something was cancelled, if g_cancellable_is_cancelled() doesn't agree
(anymore).
Avoid such problems by preventing users to call g_cancellable_reset().
Add nm_utils_invoke_on_timeout() beside nm_utils_invoke_on_idle().
They are fundamentally similar, except one schedules an idle handler
and the other a timeout.
Also, use the current g_main_context_get_thread_default() as context
instead of the singleton instance. That is a change in behavior, but
the only caller of nm_utils_invoke_on_idle() is the daemon, which
doesn't use different main contexts. Anyway, to avoid anybody being
tripped up by this also change the order of arguments. It anyway
seems nicer to first pass the cancellable, and the callback and user
data as last arguments. It's more in line with glib's asynchronous
methods.
Also, in the unlikely case that the cancellable is already cancelled
from the start, always schedule an idle action to complete fast.
