Re: courier-imap unable to open INBOX

On 2025-02-16 13:52, Benjamin Lutz wrote:
> In order to better understand it, I built courier-imap with debugging 
> flags and added some debugging code around the line above:
> 
>     errno=-999;
>     int stat_retval=stat( info->tmpname, &stat_buf);
>     fprintf(stderr, "stat=%p, stat(%p, %p), stat_retval=%d, errno=%d,
>         strerror(errno)=%s\n", stat, info->tmpname, &stat_buf,
>         stat_retval, errno, strerror(errno));
>     if (stat_retval == 0)
> 
> When SELECTing the INBOX now, I get:
> 
>     stat=0x823bc4f70, stat(0x2f67a4269000, 0x820949b40), 
> stat_retval=-1,
>         errno=-999, strerror(errno)=Unknown error: -999
>     a NO Unable to open this mailbox.
> 
> So errno isn't changed by stat(2) (confirmed with other values than 
> -999). This has me rather perplexed. How can a stat(2) call not set 
> errno? As far as I can tell using GDB, that stat() call really is a 
> call into libc, not some other function that might shadow stat(2).
> 

Perplexing indeed. I've just verified libc for FreeBSD 14.2 does indeed 
set errno (which isn't exactly an int, BTW). It would correctly leave 
the error code alone if there was no error, but your return value of -1 
means there is an error.

FWIW, the next thing I'd explore is whether the "errno" in the code is 
the same as the system errno, which is defined in sys/errno.h. As I 
said, it's not an int so if it's declared as "extern int errno" you may 
see strange things happen.

Regards, Frank.