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Diffstat (limited to 'm4/gethostname.m4')
| -rw-r--r-- | m4/gethostname.m4 | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/m4/gethostname.m4 b/m4/gethostname.m4 new file mode 100644 index 000000000..25e9eb20c --- /dev/null +++ b/m4/gethostname.m4 @@ -0,0 +1,107 @@ +# gethostname.m4 serial 15 +dnl Copyright (C) 2002, 2008-2021 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. + +# Ensure +# - the gethostname() function, +# - the HOST_NAME_MAX macro in <limits.h>. +AC_DEFUN([gl_FUNC_GETHOSTNAME], +[ + AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) + gl_PREREQ_SYS_H_WINSOCK2 + + dnl Where is gethostname() defined? + dnl - On native Windows, it is in ws2_32.dll. + dnl - Otherwise it is in libc. + GETHOSTNAME_LIB= + AC_CHECK_FUNCS([gethostname], , [ + AC_CACHE_CHECK([for gethostname in winsock2.h and -lws2_32], + [gl_cv_w32_gethostname], + [gl_cv_w32_gethostname=no + gl_save_LIBS="$LIBS" + LIBS="$LIBS -lws2_32" + AC_LINK_IFELSE([AC_LANG_PROGRAM([[ +#ifdef HAVE_WINSOCK2_H +#include <winsock2.h> +#endif +#include <stddef.h> +]], [[gethostname(NULL, 0);]])], [gl_cv_w32_gethostname=yes]) + LIBS="$gl_save_LIBS" + ]) + if test "$gl_cv_w32_gethostname" = "yes"; then + GETHOSTNAME_LIB="-lws2_32" + fi + ]) + AC_SUBST([GETHOSTNAME_LIB]) + + if test "$ac_cv_func_gethostname" = no; then + HAVE_GETHOSTNAME=0 + fi + + gl_PREREQ_HOST_NAME_MAX +]) + +# Provide HOST_NAME_MAX when <limits.h> lacks it. +AC_DEFUN([gl_PREREQ_HOST_NAME_MAX], [ + dnl - On most Unix systems, use MAXHOSTNAMELEN from <sys/param.h> instead. + dnl - On Solaris, Cygwin, BeOS, use MAXHOSTNAMELEN from <netdb.h> instead. + dnl - On mingw, use 256, because + dnl <https://docs.microsoft.com/en-us/windows/desktop/api/winsock/nf-winsock-gethostname> says: + dnl "if a buffer of 256 bytes is passed in the name parameter and + dnl the namelen parameter is set to 256, the buffer size will always + dnl be adequate." + dnl With this, there is no need to use sysconf (_SC_HOST_NAME_MAX), which + dnl is not a compile-time constant. + dnl We cannot override <limits.h> using the usual technique, because + dnl gl_CHECK_NEXT_HEADERS does not work for <limits.h>. Therefore retrieve + dnl the value of HOST_NAME_MAX at configure time. + AC_CHECK_HEADERS_ONCE([sys/param.h]) + AC_CHECK_HEADERS_ONCE([sys/socket.h]) + AC_CHECK_HEADERS_ONCE([netdb.h]) + AC_CACHE_CHECK([for HOST_NAME_MAX], [gl_cv_decl_HOST_NAME_MAX], [ + gl_cv_decl_HOST_NAME_MAX= + AC_EGREP_CPP([lucky], [ +#include <limits.h> +#ifdef HOST_NAME_MAX +lucky +#endif + ], [gl_cv_decl_HOST_NAME_MAX=yes]) + if test -z "$gl_cv_decl_HOST_NAME_MAX"; then + dnl It's not defined in <limits.h>. Substitute it. + if test "$gl_cv_w32_gethostname" = yes; then + dnl mingw. + gl_cv_decl_HOST_NAME_MAX=256 + else + AC_COMPUTE_INT([gl_cv_decl_HOST_NAME_MAX], [MAXHOSTNAMELEN], [ +#include <sys/types.h> +#if HAVE_SYS_PARAM_H +# include <sys/param.h> +#endif +#if HAVE_SYS_SOCKET_H +# include <sys/socket.h> +#endif +#if HAVE_NETDB_H +# include <netdb.h> +#endif +], + [dnl The system does not define MAXHOSTNAMELEN in any of the common + dnl headers. Use a safe fallback. + gl_cv_decl_HOST_NAME_MAX=256 + ]) + fi + fi + ]) + if test "$gl_cv_decl_HOST_NAME_MAX" != yes; then + AC_DEFINE_UNQUOTED([HOST_NAME_MAX], [$gl_cv_decl_HOST_NAME_MAX], + [Define HOST_NAME_MAX when <limits.h> does not define it.]) + fi +]) + +# Prerequisites of lib/gethostname.c. +AC_DEFUN([gl_PREREQ_GETHOSTNAME], [ + if test "$gl_cv_w32_gethostname" != "yes"; then + AC_CHECK_FUNCS([uname]) + fi +]) |