Paul Eggert wrote:
> malloc can fail with EAGAIN
> on GNU/Linux and I assume other errno values are also possible.
Indeed [1], although the glibc manual [2] and the Linux man page [3]
don't mention it.
The meaning of EAGAIN in this case is as documented for the mmap()
system call [4]:
"too much memory has been locked"
The usual meaning of EAGAIN [5] does not apply here:
- Stating in an error message that "Resource temporarily unavailable"
is bad, because the error does not come from outside the process, it
originates in the process itself.
- Similarly, trying again later (e.g. in a loop) will not help, since
the situation originates in the process itself.
So, IMO, applications should
- better print "Out of memory" or "Cannot allocate memory", rather than
"Resource temporarily unavailable".
- just fail, never retry.
I would argue that glibc should use a different errno value in this case.
What do you think?
Bruno
[1] https://stackoverflow.com/questions/34165276/malloc-setting-errno-to-eagain
[2] https://www.gnu.org/software/libc/manual/html_mono/libc.html
[3] https://www.kernel.org/doc/man-pages/online/pages/man3/malloc.3.html
[4] https://www.kernel.org/doc/man-pages/online/pages/man2/mmap.2.html
[5] https://www.gnu.org/software/libc/manual/html_node/Error-Codes.html
