gnulib/import/m4/readlink.m4

   1 # readlink.m4 serial 15
   2 dnl Copyright (C) 2003, 2007, 2009-2019 Free Software Foundation, Inc.
   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_READLINK],
   8 [
   9   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
  10   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  11   AC_CHECK_FUNCS_ONCE([readlink])
  12   if test $ac_cv_func_readlink = no; then
  13     HAVE_READLINK=0
  14   else
  15     AC_CACHE_CHECK([whether readlink signature is correct],
  16       [gl_cv_decl_readlink_works],
  17       [AC_COMPILE_IFELSE(
  18          [AC_LANG_PROGRAM(
  19            [[#include <unistd.h>
  20       /* Cause compilation failure if original declaration has wrong type.  */
  21       ssize_t readlink (const char *, char *, size_t);]])],
  22          [gl_cv_decl_readlink_works=yes], [gl_cv_decl_readlink_works=no])])
  23     dnl Solaris 9 ignores trailing slash.
  24     dnl FreeBSD 7.2 dereferences only one level of links with trailing slash.
  25     AC_CACHE_CHECK([whether readlink handles trailing slash correctly],
  26       [gl_cv_func_readlink_works],
  27       [# We have readlink, so assume ln -s works.
  28        ln -s conftest.no-such conftest.link
  29        ln -s conftest.link conftest.lnk2
  30        AC_RUN_IFELSE(
  31          [AC_LANG_PROGRAM(
  32            [[#include <unistd.h>
  33 ]], [[char buf[20];
  34       return readlink ("conftest.lnk2/", buf, sizeof buf) != -1;]])],
  35          [gl_cv_func_readlink_works=yes], [gl_cv_func_readlink_works=no],
  36          [case "$host_os" in
  37                              # Guess yes on Linux systems.
  38             linux-* | linux) gl_cv_func_readlink_works="guessing yes" ;;
  39                              # Guess yes on glibc systems.
  40             *-gnu* | gnu*)   gl_cv_func_readlink_works="guessing yes" ;;
  41                              # If we don't know, obey --enable-cross-guesses.
  42             *)               gl_cv_func_readlink_works="$gl_cross_guess_normal" ;;
  43           esac
  44          ])
  45       rm -f conftest.link conftest.lnk2])
  46     case "$gl_cv_func_readlink_works" in
  47       *yes)
  48         if test "$gl_cv_decl_readlink_works" != yes; then
  49           REPLACE_READLINK=1
  50         fi
  51         ;;
  52       *)
  53         AC_DEFINE([READLINK_TRAILING_SLASH_BUG], [1], [Define to 1 if readlink
  54           fails to recognize a trailing slash.])
  55         REPLACE_READLINK=1
  56         ;;
  57     esac
  58   fi
  59 ])
  60
  61 # Like gl_FUNC_READLINK, except prepare for separate compilation
  62 # (no REPLACE_READLINK, no AC_LIBOBJ).
  63 AC_DEFUN([gl_FUNC_READLINK_SEPARATE],
  64 [
  65   AC_CHECK_FUNCS_ONCE([readlink])
  66   gl_PREREQ_READLINK
  67 ])
  68
  69 # Prerequisites of lib/readlink.c.
  70 AC_DEFUN([gl_PREREQ_READLINK],
  71 [
  72   :
  73 ])