diff options
Diffstat (limited to '')
| -rw-r--r-- | m4/fcntl-o.m4 | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/m4/fcntl-o.m4 b/m4/fcntl-o.m4 new file mode 100644 index 0000000..b0605e4 --- /dev/null +++ b/m4/fcntl-o.m4 @@ -0,0 +1,134 @@ +# fcntl-o.m4 serial 4 +dnl Copyright (C) 2006-2018 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. + +dnl Written by Paul Eggert. + +# Test whether the flags O_NOATIME and O_NOFOLLOW actually work. +# Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise. +# Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise. +AC_DEFUN([gl_FCNTL_O_FLAGS], +[ + dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW. + dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes + dnl AC_GNU_SOURCE. + m4_ifdef([AC_USE_SYSTEM_EXTENSIONS], + [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])], + [AC_REQUIRE([AC_GNU_SOURCE])]) + + AC_CHECK_HEADERS_ONCE([unistd.h]) + AC_CHECK_FUNCS_ONCE([symlink]) + AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h], + [AC_RUN_IFELSE( + [AC_LANG_PROGRAM( + [[#include <sys/types.h> + #include <sys/stat.h> + #if HAVE_UNISTD_H + # include <unistd.h> + #else /* on Windows with MSVC */ + # include <io.h> + # include <stdlib.h> + # defined sleep(n) _sleep ((n) * 1000) + #endif + #include <fcntl.h> + #ifndef O_NOATIME + #define O_NOATIME 0 + #endif + #ifndef O_NOFOLLOW + #define O_NOFOLLOW 0 + #endif + static int const constants[] = + { + O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND, + O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY + }; + ]], + [[ + int result = !constants; + #if HAVE_SYMLINK + { + static char const sym[] = "conftest.sym"; + if (symlink ("/dev/null", sym) != 0) + result |= 2; + else + { + int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0); + if (fd >= 0) + { + close (fd); + result |= 4; + } + } + if (unlink (sym) != 0 || symlink (".", sym) != 0) + result |= 2; + else + { + int fd = open (sym, O_RDONLY | O_NOFOLLOW); + if (fd >= 0) + { + close (fd); + result |= 4; + } + } + unlink (sym); + } + #endif + { + static char const file[] = "confdefs.h"; + int fd = open (file, O_RDONLY | O_NOATIME); + if (fd < 0) + result |= 8; + else + { + struct stat st0; + if (fstat (fd, &st0) != 0) + result |= 16; + else + { + char c; + sleep (1); + if (read (fd, &c, 1) != 1) + result |= 24; + else + { + if (close (fd) != 0) + result |= 32; + else + { + struct stat st1; + if (stat (file, &st1) != 0) + result |= 40; + else + if (st0.st_atime != st1.st_atime) + result |= 64; + } + } + } + } + } + return result;]])], + [gl_cv_header_working_fcntl_h=yes], + [case $? in #( + 4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #( + 64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #( + 68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #( + *) gl_cv_header_working_fcntl_h='no';; + esac], + [gl_cv_header_working_fcntl_h=cross-compiling])]) + + case $gl_cv_header_working_fcntl_h in #( + *O_NOATIME* | no | cross-compiling) ac_val=0;; #( + *) ac_val=1;; + esac + AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val], + [Define to 1 if O_NOATIME works.]) + + case $gl_cv_header_working_fcntl_h in #( + *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #( + *) ac_val=1;; + esac + AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val], + [Define to 1 if O_NOFOLLOW works.]) +]) |