Use pstat() on HP-UX to determine the tty device.

config.h.in

@@ -430,6 +430,9 @@
 /* Define to 1 if you have the <project.h> header file. */
 #undef HAVE_PROJECT_H
 
+/* Define to 1 if you have the `pstat_getproc' function. */
+#undef HAVE_PSTAT_GETPROC
+
 /* Define to 1 if you have the <pty.h> header file. */
 #undef HAVE_PTY_H
 

configure

@@ -14181,6 +14181,17 @@ $as_echo "$sudo_cv_var_daportable" >&6; }
 			    test -z "$with_pam" && AUTH_EXCL_DEF="PAM"
 			;;
 		esac
+		for ac_func in pstat_getproc
+do :
+  ac_fn_c_check_func "$LINENO" "pstat_getproc" "ac_cv_func_pstat_getproc"
+if test "x$ac_cv_func_pstat_getproc" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_PSTAT_GETPROC 1
+_ACEOF
+
+fi
+done
+
 		;;
     *-dec-osf*)
 		# ignore envariables wrt dynamic lib path

configure.in

@@ -1742,6 +1742,7 @@ case "$host" in
 			    test -z "$with_pam" && AUTH_EXCL_DEF="PAM"
 			;;
 		esac
+		AC_CHECK_FUNCS(pstat_getproc)
 		;;
     *-dec-osf*)
 		# ignore envariables wrt dynamic lib path

src/ttyname.c

@@ -82,6 +82,10 @@
 #elif defined(HAVE_SYS_PROCFS_H)
 # include <sys/procfs.h>
 #endif
+#ifdef HAVE_PSTAT_GETPROC
+# include <sys/param.h>
+# include <sys/pstat.h>
+#endif
 
 #include "sudo.h"
 
@@ -156,7 +160,7 @@ sudo_ttyname_dev(dev_t tdev)
 
     debug_return_str(estrdup(tty));
 }
-#elif defined(HAVE_STRUCT_PSINFO_PR_TTYDEV) || defined(__linux__)
+#elif defined(HAVE_STRUCT_PSINFO_PR_TTYDEV) || defined(HAVE_PSTAT_GETPROC) || defined(__linux__)
 /*
  * Devices to search before doing a breadth-first scan.
  */
@@ -335,7 +339,6 @@ sudo_ttyname_dev(dev_t rdev)
  * Return a string from ttyname() containing the tty to which the process is
  * attached or NULL if there is no tty associated with the process (or its
  * parent).  First tries sysctl using the current pid, then the parent's pid.
- * Falls back on ttyname of std{in,out,err} if that fails.
  */
 char *
 get_process_ttyname(void)
@@ -385,7 +388,6 @@ get_process_ttyname(void)
  * Return a string from ttyname() containing the tty to which the process is
  * attached or NULL if there is no tty associated with the process (or its
  * parent).  First tries /proc/pid/psinfo, then /proc/ppid/psinfo.
- * Falls back on ttyname of std{in,out,err} if that fails.
  */
 char *
 get_process_ttyname(void)
@@ -416,7 +418,6 @@ get_process_ttyname(void)
  * Return a string from ttyname() containing the tty to which the process is
  * attached or NULL if there is no tty associated with the process (or its
  * parent).  First tries field 7 in /proc/pid/stat, then /proc/ppid/stat.
- * Falls back on ttyname of std{in,out,err} if that fails.
  */
 char *
 get_process_ttyname(void)
@@ -457,6 +458,32 @@ get_process_ttyname(void)
 
     debug_return_str(tty);
 }
+#elif HAVE_PSTAT_GETPROC
+/*
+ * Return a string from ttyname() containing the tty to which the process is
+ * attached or NULL if there is no tty associated with the process (or its
+ * parent).
+ */
+char *
+get_process_ttyname(void)
+{
+    struct pst_status pstat;
+    char *tty = NULL;
+    int i;
+    debug_decl(get_process_ttyname, SUDO_DEBUG_UTIL)
+
+    /* Try to determine the tty from psdev in struct pst_status. */
+    for (i = 0; tty == NULL && i < 2; i++) {
+	const int pid = i ? (int)getppid() : (int)getpid();
+	if (pstat_getproc(&pstat, sizeof(pstat), 0, pid) != -1) {
+	    if (pstat.pst_term.psd_major != -1 && pstat.pst_term.psd_minor != -1) {
+		tty = sudo_ttyname_dev(makedev(pstat.pst_term.psd_major,
+		    pstat.pst_term.psd_minor));
+	    }
+	}
+    }
+    debug_return_str(tty);
+}
 #else
 /*
  * Return a string from ttyname() containing the tty to which the process is