fcntl: use to simplify other modules Let fcntl do the work, instead of copying code into other modules. * modules/cloexec (Depends-on): Add fcntl. * modules/fchdir (Depends-on): Likewise. * modules/fd-safer-flag (Depends-on): Likewise. * modules/unistd-safer (Depends-on): Likewise. * modules/dup3 (configure.ac): Set module indicator. * m4/fchdir.m4 (gl_FUNC_FCHDIR): Replace fcntl if fchdir is missing. * lib/fchdir.c (_gl_register_dup): Fix comment. * lib/cloexec.c (dup_cloexec): Simplify, by relying on fcntl. * lib/dup-safer.c (dup_safer): Likewise. * lib/dup-safer-flag.c (dup_safer_flag): Likewise. * lib/dup3.c (dup3): Likewise. * tests/test-fchdir.c (main): Enhance test. Fixes a dup_cloexec bug reported by Ondřej Vašík. Signed-off-by: Eric Blake <ebb9@byu.net>

Description:
fd_safer_flag() function: adjust a file descriptor result so that it avoids
clobbering STD{IN,OUT,ERR}_FILENO, with specific flags.

Files:
lib/fd-safer-flag.c
lib/dup-safer-flag.c

Depends-on:
cloexec
fcntl
unistd-safer

configure.ac:
gl_MODULE_INDICATOR([fd-safer-flag])

Makefile.am:
lib_SOURCES += fd-safer-flag.c dup-safer-flag.c

Include:
"unistd-safer.h"

License:
GPL

Maintainer:
Eric Blake