yamt commented on code in PR #15320:
URL: https://github.com/apache/nuttx/pull/15320#discussion_r1896557246
##########
libs/libc/stdio/lib_libvsprintf.c:
##########
@@ -911,6 +915,11 @@ static int vsprintf_internal(FAR struct lib_outstream_s
*stream,
size = 1;
goto str_lpad;
+ case 'm': /* Print error message (%m) */
+ pnt = strerror(saved_errno);
+ size = strlen(pnt); /* Adjusting the size is not supported by %m */
+ goto str_lpad;
+
Review Comment:
> I'm not quite sure what process to follow. What it's clear is using those
`printf` statements within the kernel is unsafe, and should be avoided.
Literally, the Linux kernel has its own internal implementations of
`vsprintf.c` which are considered safe.
>
> `syslog`, `printf`, and friends are intended to be used from user space.
If NuttX is mixing things, it's a problem because changes focusing on achieving
POSIX compliance may break things on the kernel side, which shouldn't happen.
i personally tend to agree. (i guess i'm biased as my background is BSD)
but it's how nuttx has been. that is, use the (mostly) same api for kernel
as well.
> @yamt, do you have specific examples of NuttX kernel code using those
calls? Mainly because a bugfix should be created to actuate on those.
eg. see include/debug.h. these debug macros are usually backed by syslog.
depending on configurations, they can be used from a bit extreme contexts, like
interrupt handlers and very early on the boot process.
probably you can avoid errno access depending on the context.
(using `up_interrupt_context` etc)
although i feel it's a bit hacky, it seems like a common practice.
>
> CC/ @patacongo @xiaoxiang781216 @acassis
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