diff options
Diffstat (limited to '')
| -rw-r--r-- | m4/fcntl.m4 | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/m4/fcntl.m4 b/m4/fcntl.m4 new file mode 100644 index 0000000..46b2445 --- /dev/null +++ b/m4/fcntl.m4 @@ -0,0 +1,126 @@ +# fcntl.m4 serial 9 +dnl Copyright (C) 2009-2018 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +# For now, this module ensures that fcntl() +# - supports F_DUPFD correctly +# - supports or emulates F_DUPFD_CLOEXEC +# - supports F_GETFD +# Still to be ported to mingw: +# - F_SETFD +# - F_GETFL, F_SETFL +# - F_GETOWN, F_SETOWN +# - F_GETLK, F_SETLK, F_SETLKW +AC_DEFUN([gl_FUNC_FCNTL], +[ + dnl Persuade glibc to expose F_DUPFD_CLOEXEC. + AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) + AC_REQUIRE([gl_FCNTL_H_DEFAULTS]) + AC_REQUIRE([AC_CANONICAL_HOST]) + AC_CHECK_FUNCS_ONCE([fcntl]) + if test $ac_cv_func_fcntl = no; then + gl_REPLACE_FCNTL + else + dnl cygwin 1.5.x F_DUPFD has wrong errno, and allows negative target + dnl haiku alpha 2 F_DUPFD has wrong errno + AC_CACHE_CHECK([whether fcntl handles F_DUPFD correctly], + [gl_cv_func_fcntl_f_dupfd_works], + [AC_RUN_IFELSE( + [AC_LANG_PROGRAM( + [[#include <errno.h> + #include <fcntl.h> + #include <limits.h> + #include <sys/resource.h> + #include <unistd.h> + #ifndef RLIM_SAVED_CUR + # define RLIM_SAVED_CUR RLIM_INFINITY + #endif + #ifndef RLIM_SAVED_MAX + # define RLIM_SAVED_MAX RLIM_INFINITY + #endif + ]], + [[int result = 0; + int bad_fd = INT_MAX; + struct rlimit rlim; + if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 + && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX + && rlim.rlim_cur != RLIM_INFINITY + && rlim.rlim_cur != RLIM_SAVED_MAX + && rlim.rlim_cur != RLIM_SAVED_CUR) + bad_fd = rlim.rlim_cur; + if (fcntl (0, F_DUPFD, -1) != -1) result |= 1; + if (errno != EINVAL) result |= 2; + if (fcntl (0, F_DUPFD, bad_fd) != -1) result |= 4; + if (errno != EINVAL) result |= 8; + /* On OS/2 kLIBC, F_DUPFD does not work on a directory fd */ + { + int fd; + fd = open (".", O_RDONLY); + if (fd == -1) + result |= 16; + else if (fcntl (fd, F_DUPFD, STDERR_FILENO + 1) == -1) + result |= 32; + + close (fd); + } + return result;]])], + [gl_cv_func_fcntl_f_dupfd_works=yes], + [gl_cv_func_fcntl_f_dupfd_works=no], + [case $host_os in + aix* | cygwin* | haiku*) + gl_cv_func_fcntl_f_dupfd_works="guessing no" ;; + *) gl_cv_func_fcntl_f_dupfd_works="guessing yes" ;; + esac])]) + case $gl_cv_func_fcntl_f_dupfd_works in + *yes) ;; + *) gl_REPLACE_FCNTL + AC_DEFINE([FCNTL_DUPFD_BUGGY], [1], [Define this to 1 if F_DUPFD + behavior does not match POSIX]) ;; + esac + + dnl Many systems lack F_DUPFD_CLOEXEC + AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC], + [gl_cv_func_fcntl_f_dupfd_cloexec], + [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ +#include <fcntl.h> +#ifndef F_DUPFD_CLOEXEC +choke me +#endif + ]])], + [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ +#ifdef __linux__ +/* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace + it to support the semantics on older kernels that failed with EINVAL. */ +choke me +#endif + ]])], + [gl_cv_func_fcntl_f_dupfd_cloexec=yes], + [gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])], + [gl_cv_func_fcntl_f_dupfd_cloexec=no])]) + if test "$gl_cv_func_fcntl_f_dupfd_cloexec" != yes; then + gl_REPLACE_FCNTL + dnl No witness macro needed for this bug. + fi + fi + dnl Replace fcntl() for supporting the gnulib-defined fchdir() function, + dnl to keep fchdir's bookkeeping up-to-date. + m4_ifdef([gl_FUNC_FCHDIR], [ + gl_TEST_FCHDIR + if test $HAVE_FCHDIR = 0; then + gl_REPLACE_FCNTL + fi + ]) +]) + +AC_DEFUN([gl_REPLACE_FCNTL], +[ + AC_REQUIRE([gl_FCNTL_H_DEFAULTS]) + AC_CHECK_FUNCS_ONCE([fcntl]) + if test $ac_cv_func_fcntl = no; then + HAVE_FCNTL=0 + else + REPLACE_FCNTL=1 + fi +]) |