- AC_LANG_PROGRAM([[#include <unistd.h>
-#include <fcntl.h>
-#include <errno.h>]],
- [int result = 0;
-#ifdef FD_CLOEXEC
- if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
- result |= 1;
-#endif
- if (dup2 (1, 1) == 0)
- 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, 1000000) == -1 && errno != EBADF)
- result |= 16;
- /* Flush out a cygwin core dump. */
- if (dup2 (2, -1) != -1 || errno != EBADF)
- result |= 32;
- return result;
- ])
+ 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;
+ #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;]])