pgsql-hackers
❮
Why should I use fileno(stderr) instead of STDERR_FILENO
- Jump to comment-1Dima Rybakov (Tlt)<dim001r@gmail.com>Apr 13, 2024, 10:58 PM UTCDear pgsql hackers,
I found a mixture of fileno(stderr) and STDERR_FILENO in PostgreSQL source
code which in most cases mean the same. But I have found recently that
Microsoft's fileno() _fileno() can return -2 sometimes. After some
experiments I found that applications running as windows service have
problems with stderr. I.e. fileno(stderr) returns -2 (negative two) in
windows service mode. That causes some issues with the logging collector.
Meanwhile the value of STDERR_FILENO always equals 2 and does not depend on
application mode because it is a macro.
I wonder if there are hidden advantages of using fileno(stderr) ?? Should I
use only "fileno(stderr)" or using STDERR_FILENO is acceptable too ?? Are
there cases when I should not use STDERR_FILENO ??
Sincerely,
Dmitry
Additional references
1. BUG #18400
2.
https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/fileno?view=msvc-170
Quote: "If stdout or stderr is not associated with an output stream (for
example, in a Windows application without a console window), the file
descriptor returned is -2. ..."