getdtablesize - get file descriptor table size
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.12:
/* Glibc since 2.19: */
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
|| ! (_POSIX_C_SOURCE >= 200112L)
Before glibc 2.12:
_BSD_SOURCE || _XOPEN_SOURCE >= 500
getdtablesize() returns the maximum number of files a process can have open, one more than the largest possible value for a file descriptor.
The current limit on the number of open files per process.
On Linux, getdtablesize() can return any of the errors described for getrlimit(2); see NOTES below.
For an explanation of the terms used in this section, see attributes(7).
SVr4, 4.4BSD (the getdtablesize() function first appeared in 4.2BSD). It is not specified in POSIX.1; portable applications should employ sysconf(_SC_OPEN_MAX) instead of this call.
getdtablesize() is implemented as a libc library function. The glibc version calls getrlimit(2) and returns the current RLIMIT_NOFILE limit, or OPEN_MAX when that fails.
close(2), dup(2), getrlimit(2), open(2)
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