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-rw-r--r--gnulib-m4/dup2.m4105
1 files changed, 105 insertions, 0 deletions
diff --git a/gnulib-m4/dup2.m4 b/gnulib-m4/dup2.m4
new file mode 100644
index 00000000..7e777cde
--- /dev/null
+++ b/gnulib-m4/dup2.m4
@@ -0,0 +1,105 @@
+#serial 27
+dnl Copyright (C) 2002, 2005, 2007, 2009-2022 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.
+
+AC_DEFUN([gl_FUNC_DUP2],
+[
+ AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+ AC_REQUIRE([AC_CANONICAL_HOST])
+ AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
+ [AC_RUN_IFELSE([
+ AC_LANG_PROGRAM(
+ [[#include <errno.h>
+ #include <fcntl.h>
+ #include <limits.h>
+ #include <sys/resource.h>
+ #include <unistd.h>
+ ]GL_MDA_DEFINES[
+ #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;
+ #ifdef FD_CLOEXEC
+ if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
+ result |= 1;
+ #endif
+ if (dup2 (1, 1) != 1)
+ result |= 2;
+ #ifdef FD_CLOEXEC
+ if (fcntl (1, F_GETFD) != FD_CLOEXEC)
+ result |= 4;
+ #endif
+ close (0);
+ if (dup2 (0, 0) != -1)
+ result |= 8;
+ /* Many gnulib modules require POSIX conformance of EBADF. */
+ if (dup2 (2, bad_fd) == -1 && errno != EBADF)
+ result |= 16;
+ /* Flush out some cygwin core dumps. */
+ if (dup2 (2, -1) != -1 || errno != EBADF)
+ result |= 32;
+ dup2 (2, 255);
+ dup2 (2, 256);
+ /* On OS/2 kLIBC, dup2() does not work on a directory fd. */
+ {
+ int fd = open (".", O_RDONLY);
+ if (fd == -1)
+ result |= 64;
+ else if (dup2 (fd, fd + 1) == -1)
+ result |= 128;
+ close (fd);
+ }
+ return result;]])
+ ],
+ [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
+ [case "$host_os" in
+ mingw*) # on this platform, dup2 always returns 0 for success
+ gl_cv_func_dup2_works="guessing no" ;;
+ cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
+ gl_cv_func_dup2_works="guessing no" ;;
+ aix* | freebsd*)
+ # on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) gives EMFILE,
+ # not EBADF.
+ gl_cv_func_dup2_works="guessing no" ;;
+ haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
+ gl_cv_func_dup2_works="guessing no" ;;
+ *-android*) # implemented using dup3(), which fails if oldfd == newfd
+ gl_cv_func_dup2_works="guessing no" ;;
+ os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd.
+ gl_cv_func_dup2_works="guessing no" ;;
+ *) gl_cv_func_dup2_works="guessing yes" ;;
+ esac])
+ ])
+ case "$gl_cv_func_dup2_works" in
+ *yes) ;;
+ *)
+ REPLACE_DUP2=1
+ AC_CHECK_FUNCS([setdtablesize])
+ ;;
+ esac
+ dnl Replace dup2() 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
+ REPLACE_DUP2=1
+ fi
+ ])
+])
+
+# Prerequisites of lib/dup2.c.
+AC_DEFUN([gl_PREREQ_DUP2], [])