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9c9d63b1 PM |
1 | #serial 27 |
2 | dnl Copyright (C) 2002, 2005, 2007, 2009-2021 Free Software Foundation, Inc. | |
6ec2e0f5 SDJ |
3 | dnl This file is free software; the Free Software Foundation |
4 | dnl gives unlimited permission to copy and/or distribute it, | |
5 | dnl with or without modifications, as long as this notice is preserved. | |
6 | ||
7 | AC_DEFUN([gl_FUNC_DUP2], | |
8 | [ | |
9 | AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) | |
10 | AC_REQUIRE([AC_CANONICAL_HOST]) | |
9c9d63b1 PM |
11 | AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works], |
12 | [AC_RUN_IFELSE([ | |
13 | AC_LANG_PROGRAM( | |
14 | [[#include <errno.h> | |
15 | #include <fcntl.h> | |
16 | #include <limits.h> | |
17 | #include <sys/resource.h> | |
18 | #include <unistd.h> | |
19 | ]GL_MDA_DEFINES[ | |
20 | #ifndef RLIM_SAVED_CUR | |
21 | # define RLIM_SAVED_CUR RLIM_INFINITY | |
22 | #endif | |
23 | #ifndef RLIM_SAVED_MAX | |
24 | # define RLIM_SAVED_MAX RLIM_INFINITY | |
25 | #endif | |
26 | ]], | |
27 | [[int result = 0; | |
28 | int bad_fd = INT_MAX; | |
29 | struct rlimit rlim; | |
30 | if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 | |
31 | && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX | |
32 | && rlim.rlim_cur != RLIM_INFINITY | |
33 | && rlim.rlim_cur != RLIM_SAVED_MAX | |
34 | && rlim.rlim_cur != RLIM_SAVED_CUR) | |
35 | bad_fd = rlim.rlim_cur; | |
36 | #ifdef FD_CLOEXEC | |
37 | if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1) | |
38 | result |= 1; | |
39 | #endif | |
40 | if (dup2 (1, 1) != 1) | |
41 | result |= 2; | |
42 | #ifdef FD_CLOEXEC | |
43 | if (fcntl (1, F_GETFD) != FD_CLOEXEC) | |
44 | result |= 4; | |
45 | #endif | |
46 | close (0); | |
47 | if (dup2 (0, 0) != -1) | |
48 | result |= 8; | |
49 | /* Many gnulib modules require POSIX conformance of EBADF. */ | |
50 | if (dup2 (2, bad_fd) == -1 && errno != EBADF) | |
51 | result |= 16; | |
52 | /* Flush out some cygwin core dumps. */ | |
53 | if (dup2 (2, -1) != -1 || errno != EBADF) | |
54 | result |= 32; | |
55 | dup2 (2, 255); | |
56 | dup2 (2, 256); | |
57 | /* On OS/2 kLIBC, dup2() does not work on a directory fd. */ | |
58 | { | |
59 | int fd = open (".", O_RDONLY); | |
60 | if (fd == -1) | |
61 | result |= 64; | |
62 | else if (dup2 (fd, fd + 1) == -1) | |
63 | result |= 128; | |
64 | close (fd); | |
65 | } | |
66 | return result;]]) | |
67 | ], | |
68 | [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no], | |
69 | [case "$host_os" in | |
70 | mingw*) # on this platform, dup2 always returns 0 for success | |
71 | gl_cv_func_dup2_works="guessing no" ;; | |
72 | cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0 | |
73 | gl_cv_func_dup2_works="guessing no" ;; | |
74 | aix* | freebsd*) | |
75 | # on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) gives EMFILE, | |
76 | # not EBADF. | |
77 | gl_cv_func_dup2_works="guessing no" ;; | |
78 | haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC. | |
79 | gl_cv_func_dup2_works="guessing no" ;; | |
80 | *-android*) # implemented using dup3(), which fails if oldfd == newfd | |
81 | gl_cv_func_dup2_works="guessing no" ;; | |
82 | os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd. | |
83 | gl_cv_func_dup2_works="guessing no" ;; | |
84 | *) gl_cv_func_dup2_works="guessing yes" ;; | |
85 | esac]) | |
86 | ]) | |
87 | case "$gl_cv_func_dup2_works" in | |
88 | *yes) ;; | |
89 | *) | |
90 | REPLACE_DUP2=1 | |
91 | AC_CHECK_FUNCS([setdtablesize]) | |
92 | ;; | |
93 | esac | |
6ec2e0f5 SDJ |
94 | dnl Replace dup2() for supporting the gnulib-defined fchdir() function, |
95 | dnl to keep fchdir's bookkeeping up-to-date. | |
96 | m4_ifdef([gl_FUNC_FCHDIR], [ | |
97 | gl_TEST_FCHDIR | |
98 | if test $HAVE_FCHDIR = 0; then | |
9c9d63b1 | 99 | REPLACE_DUP2=1 |
6ec2e0f5 SDJ |
100 | fi |
101 | ]) | |
102 | ]) | |
103 | ||
104 | # Prerequisites of lib/dup2.c. | |
105 | AC_DEFUN([gl_PREREQ_DUP2], []) |