Initial code.

src/lib/util/readpass.c

+/*-
+ * 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);
+}