non-critical impact:

O_NDELAY - different usage (NcWn123)

Problem description

The open, creat, read, readv, pread, write, writev, and pwrite system calls all deal with aspects of file manipulation. However, there are some differences regarding the use of the O_NDELAY flag.

When attempting to read a file (other than a pipe) that supports nonblocking reads and that has no data currently available, the read and pread calls have different behavior on Tru64 UNIX and HP-UX. On Tru64 UNIX, if O_NDELAY is set and the file is a serial device, the function returns -1 and sets errno to [EAGAIN]. On HP-UX, the function returns 0 and sets errno to 0.

Identifiers

O_NDELAY

See also

• Background information on Input/Output (files, devices) impacts
• creat(2)
• open(2)
• pread(2)
• pwrite(2)
• read(2)
• readv(2)
• write(2)
• writev(2)

Solution description

Review the applicable manpages and code.

Applications that use O_NDELAY may or may not work properly depending on how the flag is used. Review the applicable manpages and your code to determine if unexpected behavior will result.

See also

• creat(2)
• open(2)
• read(2)
• readv(2)
• write(2)
• writev(2)

Problem summary