Hi, On 2023-03-01 14:47:51 -0800, Nathan Bossart wrote: > On Tue, Feb 28, 2023 at 08:36:03PM -0800, Nathan Bossart wrote: > > On Sun, Feb 26, 2023 at 12:12:27PM -0800, Andres Freund wrote: > >> Partially I just want something that can easily be searched for, that can > >> have > >> comments attached to it documenting why what it is doing is safe. > >> > >> It'd not be a huge amount of work to have a slow and restricted string > >> interpolation support, to make it easier to write messages. Converting > >> floats > >> is probably too hard to do safely, and I'm not sure %m can safely be > >> supported. But basic things like %d would be pretty simple. > >> > >> Basically a loop around the format string that directly writes to stderr > >> using > >> write(), and only supports a signal safe subset of normal format strings. > > > > Got it, thanks. I will try to put something together along these lines, > > although I don't know if I'll pick up the interpolation support in this > > thread. > > Here is an attempt at adding a signal safe function for writing to STDERR.
Cool. > I didn't add support for format strings, but looking ahead, I think one > challenge will be avoiding va_start() and friends. In any case, IMO format > string support probably deserves its own thread. Makes sense to split that off. FWIW, I think we could rely on va_start() et al to be signal safe. The standardese isn't super clear about this, because they aren't functions, and posix only talks about functions being async signal safe... Greetings, Andres Freund
