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Diffstat (limited to '')
| -rw-r--r-- | m4/dup2.m4 | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/m4/dup2.m4 b/m4/dup2.m4 new file mode 100644 index 0000000..e1cc73e --- /dev/null +++ b/m4/dup2.m4 @@ -0,0 +1,105 @@ +#serial 27 +dnl Copyright (C) 2002, 2005, 2007, 2009-2023 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], []) |