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/*-
* Copyright 2009 Colin Percival
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "scrypt_platform.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include "warn.h"
#include "readpass.h"
#define MAXPASSLEN 2048
/**
* tarsnap_getpass(passwd, prompt, confirmprompt, devtty)
* If ${devtty} is non-zero, read a password from /dev/tty if possible; if
* not, read from stdin. If reading from a tty (either /dev/tty or stdin),
* disable echo and prompt the user by printing ${prompt} to stderr. If
* ${confirmprompt} is non-NULL, read a second password (prompting if a
* terminal is being used) and repeat until the user enters the same password
* twice. Return the password as a malloced NUL-terminated string via
* ${passwd}. The obscure name is to avoid namespace collisions due to the
* getpass / readpass / readpassphrase / etc. functions in various libraries.
*/
int
tarsnap_readpass(char ** passwd, const char * prompt,
const char * confirmprompt, int devtty)
{
FILE * readfrom;
char passbuf[MAXPASSLEN];
char confpassbuf[MAXPASSLEN];
struct termios term, term_old;
int usingtty;
/*
* If devtty != 0, try to open /dev/tty; if that fails, or if devtty
* is zero, we'll read the password from stdin instead.
*/
if ((devtty == 0) || ((readfrom = fopen("/dev/tty", "r")) == NULL))
readfrom = stdin;
/* If we're reading from a terminal, try to disable echo. */
if ((usingtty = isatty(fileno(readfrom))) != 0) {
if (tcgetattr(fileno(readfrom), &term_old)) {
warn("Cannot read terminal settings");
goto err1;
}
memcpy(&term, &term_old, sizeof(struct termios));
term.c_lflag = (term.c_lflag & ~ECHO) | ECHONL;
if (tcsetattr(fileno(readfrom), TCSANOW, &term)) {
warn("Cannot set terminal settings");
goto err1;
}
}
retry:
/* If we have a terminal, prompt the user to enter the password. */
if (usingtty)
fprintf(stderr, "%s: ", prompt);
/* Read the password. */
if (fgets(passbuf, MAXPASSLEN, readfrom) == NULL) {
warn("Cannot read password");
goto err2;
}
/* Confirm the password if necessary. */
if (confirmprompt != NULL) {
if (usingtty)
fprintf(stderr, "%s: ", confirmprompt);
if (fgets(confpassbuf, MAXPASSLEN, readfrom) == NULL) {
warn("Cannot read password");
goto err2;
}
if (strcmp(passbuf, confpassbuf)) {
fprintf(stderr,
"Passwords mismatch, please try again\n");
goto retry;
}
}
/* Terminate the string at the first "\r" or "\n" (if any). */
passbuf[strcspn(passbuf, "\r\n")] = '\0';
/* If we changed terminal settings, reset them. */
if (usingtty)
tcsetattr(fileno(readfrom), TCSANOW, &term_old);
/* Close /dev/tty if we opened it. */
if (readfrom != stdin)
fclose(readfrom);
/* Copy the password out. */
if ((*passwd = strdup(passbuf)) == NULL) {
warn("Cannot allocate memory");
goto err1;
}
/* Zero any stored passwords. */
memset(passbuf, 0, MAXPASSLEN);
memset(confpassbuf, 0, MAXPASSLEN);
/* Success! */
return (0);
err2:
/* Reset terminal settings if necessary. */
if (usingtty)
tcsetattr(fileno(readfrom), TCSAFLUSH, &term_old);
err1:
/* Close /dev/tty if we opened it. */
if (readfrom != stdin)
fclose(readfrom);
/* Failure! */
return (-1);
}
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