+#if defined(I_SYS_ACCESS) && !defined(R_OK)
+# include <sys/access.h>
+#endif
+
+#if defined(HAS_FCNTL) && defined(F_SETFD) && !defined(FD_CLOEXEC)
+# define FD_CLOEXEC 1 /* NeXT needs this */
+#endif
+
+#undef PERL_EFF_ACCESS_R_OK /* EFFective uid/gid ACCESS R_OK */
+#undef PERL_EFF_ACCESS_W_OK
+#undef PERL_EFF_ACCESS_X_OK
+
+/* F_OK unused: if stat() cannot find it... */
+
+#if !defined(PERL_EFF_ACCESS_R_OK) && defined(HAS_ACCESS) && defined(EFF_ONLY_OK) && !defined(NO_EFF_ONLY_OK)
+ /* Digital UNIX (when the EFF_ONLY_OK gets fixed), UnixWare */
+# define PERL_EFF_ACCESS_R_OK(p) (access((p), R_OK | EFF_ONLY_OK))
+# define PERL_EFF_ACCESS_W_OK(p) (access((p), W_OK | EFF_ONLY_OK))
+# define PERL_EFF_ACCESS_X_OK(p) (access((p), X_OK | EFF_ONLY_OK))
+#endif
+
+#if !defined(PERL_EFF_ACCESS_R_OK) && defined(HAS_EACCESS)
+# if defined(I_SYS_SECURITY)
+# include <sys/security.h>
+# endif
+ /* XXX Configure test needed for eaccess */
+# ifdef ACC_SELF
+ /* HP SecureWare */
+# define PERL_EFF_ACCESS_R_OK(p) (eaccess((p), R_OK, ACC_SELF))
+# define PERL_EFF_ACCESS_W_OK(p) (eaccess((p), W_OK, ACC_SELF))
+# define PERL_EFF_ACCESS_X_OK(p) (eaccess((p), X_OK, ACC_SELF))
+# else
+ /* SCO */
+# define PERL_EFF_ACCESS_R_OK(p) (eaccess((p), R_OK))
+# define PERL_EFF_ACCESS_W_OK(p) (eaccess((p), W_OK))
+# define PERL_EFF_ACCESS_X_OK(p) (eaccess((p), X_OK))
+# endif
+#endif
+
+#if !defined(PERL_EFF_ACCESS_R_OK) && defined(HAS_ACCESSX) && defined(ACC_SELF)
+ /* AIX */
+# define PERL_EFF_ACCESS_R_OK(p) (accessx((p), R_OK, ACC_SELF))
+# define PERL_EFF_ACCESS_W_OK(p) (accessx((p), W_OK, ACC_SELF))
+# define PERL_EFF_ACCESS_X_OK(p) (accessx((p), X_OK, ACC_SELF))
+#endif
+
+#if !defined(PERL_EFF_ACCESS_R_OK) && defined(HAS_ACCESS) \
+ && (defined(HAS_SETREUID) || defined(HAS_SETRESUID) \
+ || defined(HAS_SETREGID) || defined(HAS_SETRESGID))
+/* The Hard Way. */
+STATIC int
+S_emulate_eaccess(pTHX_ const char* path, Mode_t mode)
+{
+ Uid_t ruid = getuid();
+ Uid_t euid = geteuid();
+ Gid_t rgid = getgid();
+ Gid_t egid = getegid();
+ int res;
+
+ MUTEX_LOCK(&PL_cred_mutex);
+#if !defined(HAS_SETREUID) && !defined(HAS_SETRESUID)
+ Perl_croak(aTHX_ "switching effective uid is not implemented");
+#else
+#ifdef HAS_SETREUID
+ if (setreuid(euid, ruid))
+#else
+#ifdef HAS_SETRESUID
+ if (setresuid(euid, ruid, (Uid_t)-1))
+#endif
+#endif
+ Perl_croak(aTHX_ "entering effective uid failed");
+#endif
+
+#if !defined(HAS_SETREGID) && !defined(HAS_SETRESGID)
+ Perl_croak(aTHX_ "switching effective gid is not implemented");
+#else
+#ifdef HAS_SETREGID
+ if (setregid(egid, rgid))
+#else
+#ifdef HAS_SETRESGID
+ if (setresgid(egid, rgid, (Gid_t)-1))
+#endif
+#endif
+ Perl_croak(aTHX_ "entering effective gid failed");
+#endif
+
+ res = access(path, mode);
+
+#ifdef HAS_SETREUID
+ if (setreuid(ruid, euid))
+#else
+#ifdef HAS_SETRESUID
+ if (setresuid(ruid, euid, (Uid_t)-1))
+#endif
+#endif
+ Perl_croak(aTHX_ "leaving effective uid failed");
+
+#ifdef HAS_SETREGID
+ if (setregid(rgid, egid))
+#else
+#ifdef HAS_SETRESGID
+ if (setresgid(rgid, egid, (Gid_t)-1))
+#endif
+#endif
+ Perl_croak(aTHX_ "leaving effective gid failed");
+ MUTEX_UNLOCK(&PL_cred_mutex);
+
+ return res;
+}
+# define PERL_EFF_ACCESS_R_OK(p) (emulate_eaccess((p), R_OK))
+# define PERL_EFF_ACCESS_W_OK(p) (emulate_eaccess((p), W_OK))
+# define PERL_EFF_ACCESS_X_OK(p) (emulate_eaccess((p), X_OK))
+#endif
+
+#if !defined(PERL_EFF_ACCESS_R_OK)
+STATIC int
+S_emulate_eaccess(pTHX_ const char* path, Mode_t mode)
+{
+ Perl_croak(aTHX_ "switching effective uid is not implemented");
+ /*NOTREACHED*/
+ return -1;
+}
+#endif