/*  $OpenBSD: readpassphrase.c,v 1.32 2026/10/15 16:40:50 millert Exp $ */

/*

 * Copyright (c) 2000-2002, 2007, 2010

 *  Todd C. Miller <millert@openbsd.org>

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 *

 * Sponsored in part by the Defense Advanced Research Projects

 * Agency (DARPA) and Air Force Research Laboratory, Air Force

 * Materiel Command, USAF, under agreement number F39502-99-1-0512.

 */

/* OPENBSD ORIGINAL: lib/libc/gen/readpassphrase.c */

#include "includes.h"

#ifndef HAVE_READPASSPHRASE

#include <termios.h>

#include <signal.h>

#include <ctype.h>

#include <fcntl.h>

#include <readpassphrase.h>

#include <errno.h>

#include <string.h>

#include <unistd.h>

#ifndef TCSASOFT

/* If we don't have TCSASOFT define it so that ORing it it below is a no-op. */

# define TCSASOFT 0

#endif

/* SunOS 4.x which lacks _POSIX_VDISABLE, but has VDISABLE */

#if !defined(_POSIX_VDISABLE) && defined(VDISABLE)

#  define _POSIX_VDISABLE       VDISABLE

#endif

static volatile sig_atomic_t signo[_NSIG];

static void handler(int);

/* Like sigaction(2) but preserves SIG_IGN */

static void

sigaction_except_ign(int signum, struct sigaction *act, struct sigaction *old)

{

  struct sigaction sabuf;

  if (old == NULL)

    old = &sabuf;

  (void)sigaction(signum, act, old);

  /* Reinstate SIG_IGN; we don't want to override this */

  if (old->sa_handler == SIG_IGN && act->sa_handler != SIG_IGN)

    (void)sigaction(signum, old, NULL);

}

char *

readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags)

{

  ssize_t nr;

  int input, output, save_errno, i, need_restart;

  char ch, *p, *end;

  struct termios term, oterm;

  struct sigaction sa, savealrm, saveint, savehup, savequit, saveterm;

  struct sigaction savetstp, savettin, savettou, savepipe;

  /* I suppose we could alloc on demand in this case (XXX). */

  if (bufsiz == 0) {

    errno = EINVAL;

    return(NULL);

  }

restart:

  for (i = 0; i < _NSIG; i++)

    signo[i] = 0;

  nr = -1;

  save_errno = 0;

  need_restart = 0;

  /*

   * Read and write to /dev/tty if available.  If not, read from

   * stdin and write to stderr unless a tty is required.

   */

#ifndef O_CLOEXEC

# define O_CLOEXEC 0

#endif

  if ((flags & RPP_STDIN) ||

      (input = output = open(_PATH_TTY, O_RDWR | O_CLOEXEC)) == -1) {

    if (flags & RPP_REQUIRE_TTY) {

      errno = ENOTTY;

      return(NULL);

    }

    input = STDIN_FILENO;

    output = STDERR_FILENO;

  }

  /*

   * Turn off echo if possible.

   * If we are using a tty but are not the foreground pgrp this will

   * generate SIGTTOU, so do it *before* installing the signal handlers.

   */

  if (input != STDIN_FILENO && tcgetattr(input, &oterm) == 0) {

    memcpy(&term, &oterm, sizeof(term));

    if (!(flags & RPP_ECHO_ON))

      term.c_lflag &= ~(ECHO | ECHONL);

#ifdef VSTATUS

    if (term.c_cc[VSTATUS] != _POSIX_VDISABLE)

      term.c_cc[VSTATUS] = _POSIX_VDISABLE;

#endif

    (void)tcsetattr(input, TCSAFLUSH|TCSASOFT, &term);

  } else {

    memset(&term, 0, sizeof(term));

    term.c_lflag |= ECHO;

    memset(&oterm, 0, sizeof(oterm));

    oterm.c_lflag |= ECHO;

  }

  /*

   * Catch signals that would otherwise cause the user to end

   * up with echo turned off in the shell.  Don't worry about

   * things like SIGXCPU and SIGVTALRM for now.

   */

  sigemptyset(&sa.sa_mask);

  sa.sa_flags = 0;    /* don't restart system calls */

  sa.sa_handler = handler;

  sigaction(SIGINT, &sa, &saveint);

  sigaction(SIGQUIT, &sa, &savequit);

  sigaction_except_ign(SIGALRM, &sa, &savealrm);

  sigaction_except_ign(SIGHUP, &sa, &savehup);

  sigaction_except_ign(SIGPIPE, &sa, &savepipe);

  sigaction_except_ign(SIGTERM, &sa, &saveterm);

  sigaction_except_ign(SIGTSTP, &sa, &savetstp);

  sigaction_except_ign(SIGTTIN, &sa, &savettin);

  sigaction_except_ign(SIGTTOU, &sa, &savettou);

  if (!(flags & RPP_STDIN))

    (void)write(output, prompt, strlen(prompt));

  end = buf + bufsiz - 1;

  p = buf;

  while ((nr = read(input, &ch, 1)) == 1 && ch != '\n' && ch != '\r') {

    if (p < end) {

      if ((flags & RPP_SEVENBIT))

        ch &= 0x7f;

      if (isalpha((unsigned char)ch)) {

        if ((flags & RPP_FORCELOWER))

          ch = (char)tolower((unsigned char)ch);

        if ((flags & RPP_FORCEUPPER))

          ch = (char)toupper((unsigned char)ch);

      }

      *p++ = ch;

    }

  }

  *p = '\0';

  save_errno = errno;

  if (!(term.c_lflag & ECHO) && !(nr == -1 && errno == EINTR))

    (void)write(output, "\n", 1);

  /* Restore old terminal settings and signals. */

  if (memcmp(&term, &oterm, sizeof(term)) != 0) {

    const int sigttou = signo[SIGTTOU];

    /* Ignore SIGTTOU generated when we are not the fg pgrp. */

    while (tcsetattr(input, TCSAFLUSH|TCSASOFT, &oterm) == -1 &&

        errno == EINTR && !signo[SIGTTOU])

      continue;

    signo[SIGTTOU] = sigttou;

  }

  sigaction(SIGINT, &saveint, NULL);

  sigaction(SIGQUIT, &savequit, NULL);

  sigaction_except_ign(SIGALRM, &savealrm, NULL);

  sigaction_except_ign(SIGHUP, &savehup, NULL);

  sigaction_except_ign(SIGPIPE, &savepipe, NULL);

  sigaction_except_ign(SIGTERM, &saveterm, NULL);

  sigaction_except_ign(SIGTSTP, &savetstp, NULL);

  sigaction_except_ign(SIGTTIN, &savettin, NULL);

  sigaction_except_ign(SIGTTOU, &savettou, NULL);

  if (input != STDIN_FILENO)

    (void)close(input);

  /*

   * If we were interrupted by a signal, resend it to ourselves

   * now that we have restored the signal handlers.

   */

  for (i = 0; i < _NSIG; i++) {

    if (signo[i]) {

      kill(getpid(), i);

      switch (i) {

      case SIGTSTP:

      case SIGTTIN:

      case SIGTTOU:

        need_restart = 1;

      }

    }

  }

  if (need_restart)

    goto restart;

  if (save_errno)

    errno = save_errno;

  return(nr == -1 ? NULL : buf);

}

DEF_WEAK(readpassphrase);

#if 0

char *

getpass(const char *prompt)

{

  static char buf[_PASSWORD_LEN + 1];

  return(readpassphrase(prompt, buf, sizeof(buf), RPP_ECHO_OFF));

}

#endif

static void handler(int s)

{

  signo[s] = 1;

}

#endif /* HAVE_READPASSPHRASE */