Is there a C API to get the:
- Current used file descriptors system wide
- Current used file descriptors of the current process
Is there a C API to get the: Current used file descriptors system wide
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Is there a C API to get the:
For the current process count, you can use
getrlimitto get the file descriptor limit, then iterate over all integers from 0 to that limit and try callingfcntlwith theF_GETFDcommand. It will succeed only on the file descriptors which are actually open, letting you count them.Edit: I now have a better way to do it. After getting the
rlimit, make a large array ofstruct pollfd(as large as the limit if possible; otherwise you can break it down into multiple runs/calls) with each fd in the range and theeventsmember set to 0. Callpollon the array with 0 timeout, and look for thePOLLNVALflag in thereventsfor each member. This will tell you which among a potentially-huge set of fds are invalid with a single syscall, rather than one syscall per fd.