passwd: improvements

- add shadow support.
- allow passwd without argument, prompt which user password is changed.

Makefile

@@ -18,6 +18,7 @@ LIB = \
 	util/agetcwd.o        \
 	util/agetline.o       \
 	util/apathmax.o       \
+	util/concat.o         \
 	util/ealloc.o         \
 	util/eprintf.o        \
 	util/estrtol.o        \

TODO

@@ -31,4 +31,4 @@ Misc
 ====
 
  * Decide what to do with 'bool vs int' debate.
- * Beautify passwd(1) + shadow support.
+ * Beautify passwd(1).

passwd.1

@@ -2,12 +2,10 @@
 .SH NAME
 \fBpasswd\fR - Change a user's password
 .SH SYNOPSIS
-\fBpasswd\fR \fIusername\fR
+\fBpasswd\fR [\fIusername\fR]
 .SH DESCRIPTION
 \fBpasswd\fR changes the user's password. The user is prompted
 for their current password.  If the current password is correctly typed,
 a new password is requested.  The new password must be entered twice to
 avoid typing errors.  The superuser is not required to provide a user's
 current password.
-.SH BUGS
-Currently there's no shadow support.

passwd.c

@@ -11,51 +11,82 @@
 #include <string.h>
 #include <unistd.h>
 
+#include <limits.h>
+#include <shadow.h>
+
 #include "config.h"
 #include "passwd.h"
 #include "util.h"
+#include "text.h"
 
 static void
 usage(void)
 {
-	eprintf("usage: %s username\n", argv0);
+	eprintf("usage: %s [username]\n", argv0);
+}
+
+static int
+gettempfile(char *template)
+{
+	int fd;
+
+	umask(077);
+	fd = mkostemp(template, O_RDWR);
+	if (fd < 0)
+		weprintf("mkstemp:");
+	return fd;
 }
 
 int
 main(int argc, char *argv[])
 {
-	char *pass;
 	char *cryptpass1 = NULL, *cryptpass2 = NULL, *cryptpass3 = NULL;
-	char *p;
+	char shadowfile[PATH_MAX], *inpass, *p, *pwd = NULL;
 	char template[] = "/tmp/pw.XXXXXX";
-	uid_t uid;
 	struct passwd *pw;
-	int ffd, tfd;
-	int r;
+	struct spwd *spw = NULL, *spwent;
+	uid_t uid;
+	FILE *fp = NULL, *tfp = NULL;
+	int ffd = -1, tfd = -1, r, status = EXIT_FAILURE;
 
 	ARGBEGIN {
 	default:
 		usage();
 	} ARGEND;
 
-	if (argc != 1)
-		usage();
-
 	pw_init();
 
 	errno = 0;
-	pw = getpwnam(argv[0]);
-	if (errno)
-		eprintf("getpwnam: %s:", argv[0]);
-	else if (!pw)
-		eprintf("who are you?\n");
+	if (argc == 0)
+		pw = getpwuid(getuid());
+	else
+		pw = getpwnam(argv[0]);
+	if (!pw) {
+		if (errno)
+			eprintf("getpwnam: %s:", argv[0]);
+		else
+			eprintf("who are you?\n");
+	}
 
-	if (pw->pw_passwd[0] == 'x' && pw->pw_passwd[1] == '\0')
-		eprintf("no shadow support\n");
+	/* is using shadow entry ? */
+	if (pw->pw_passwd[0] == 'x') {
+		errno = 0;
+		spw = getspnam(pw->pw_name);
+		if (!spw) {
+			if (errno)
+				eprintf("getspnam: %s:", pw->pw_name);
+			else
+				eprintf("who are you?\n");
+		}
+		pwd = spw->sp_pwdp;
+	} else {
+		pwd = pw->pw_passwd;
+	}
 
 	uid = getuid();
 	if (uid == 0) {
 		if (pw->pw_passwd[0] == '!' ||
+		    pw->pw_passwd[0] == 'x' ||
 		    pw->pw_passwd[0] == '*' ||
 		    pw->pw_passwd[0] == '\0')
 			pw->pw_passwd = PW_CIPHER;
@@ -73,30 +104,29 @@ main(int argc, char *argv[])
 	/* Flush pending input */
 	ioctl(STDIN_FILENO, TCFLSH, (void *)0);
 
-	pass = getpass("Current password: ");
-	putchar('\n');
-	if (!pass)
+	printf("Changing password for %s\n", pw->pw_name);
+	inpass = getpass("Old password: ");
+	if (!inpass)
 		eprintf("getpass:");
-	if (pass[0] == '\0')
+	if (inpass[0] == '\0')
 		eprintf("no password supplied\n");
-	p = crypt(pass, pw->pw_passwd);
+	p = crypt(inpass, pwd);
 	if (!p)
 		eprintf("crypt:");
 	cryptpass1 = estrdup(p);
-	if (strcmp(cryptpass1, pw->pw_passwd) != 0)
+	if (strcmp(cryptpass1, pwd) != 0)
 		eprintf("incorrect password\n");
 
 newpass:
 	/* Flush pending input */
 	ioctl(STDIN_FILENO, TCFLSH, (void *)0);
 
-	pass = getpass("Enter new password: ");
-	putchar('\n');
-	if (!pass)
+	inpass = getpass("Enter new password: ");
+	if (!inpass)
 		eprintf("getpass:");
-	if (pass[0] == '\0')
+	if (inpass[0] == '\0')
 		eprintf("no password supplied\n");
-	p = crypt(pass, pw->pw_passwd);
+	p = crypt(inpass, pwd);
 	if (!p)
 		eprintf("crypt:");
 	cryptpass2 = estrdup(p);
@@ -106,58 +136,97 @@ newpass:
 	/* Flush pending input */
 	ioctl(STDIN_FILENO, TCFLSH, (void *)0);
 
-	pass = getpass("Retype new password: ");
-	putchar('\n');
-	if (!pass)
+	inpass = getpass("Retype new password: ");
+	if (!inpass)
 		eprintf("getpass:");
-	if (pass[0] == '\0')
+	if (inpass[0] == '\0')
 		eprintf("no password supplied\n");
-	p = crypt(pass, pw->pw_passwd);
+	p = crypt(inpass, pwd);
 	if (!p)
 		eprintf("crypt:");
 	cryptpass3 = estrdup(p);
 	if (strcmp(cryptpass2, cryptpass3) != 0)
 		eprintf("passwords don't match\n");
 
-	pw->pw_passwd = cryptpass3;
-
-	ffd = open("/etc/passwd", O_RDWR);
-	if (ffd < 0)
-		eprintf("open %s:", "/etc/passwd");
-
-	tfd = mkostemp(template, O_RDWR);
-	if (tfd < 0)
-		eprintf("mkstemp:");
-
-	r = pw_copy(ffd, tfd, pw);
-	if (r < 0) {
-		unlink(template);
-		exit(EXIT_FAILURE);
+	r = snprintf(shadowfile, sizeof(shadowfile), "/etc/tcb/%s/shadow", pw->pw_name);
+	if (r < 0 || (size_t)r >= sizeof(shadowfile))
+		eprintf("snprintf:");
+	fp = fopen(shadowfile, "r+");
+	if (!fp) {
+		strlcpy(shadowfile, "/etc/shadow", sizeof(shadowfile));
+		fp = fopen(shadowfile, "r+");
 	}
+	if (fp) {
+		if ((tfd = gettempfile(template)) == -1)
+			goto cleanup;
 
-	r = lseek(ffd, 0, SEEK_SET);
-	if (r < 0) {
-		unlink(template);
-		exit(EXIT_FAILURE);
-	}
-	r = lseek(tfd, 0, SEEK_SET);
-	if (r < 0) {
-		unlink(template);
-		exit(EXIT_FAILURE);
-	}
+		/* write to (tcb) shadow file. */
+		if (!(tfp = fdopen(tfd, "w+"))) {
+			weprintf("fdopen:");
+			goto cleanup;
+		}
+		while ((spwent = fgetspent(fp))) {
+			/* update entry on name match */
+			if (strcmp(spwent->sp_namp, spw->sp_namp) == 0)
+				spwent->sp_pwdp = cryptpass3;
+			errno = 0;
+			if (putspent(spwent, tfp) == -1) {
+				weprintf("putspent:");
+				goto cleanup;
+			}
+		}
+		fflush(tfp);
 
-	r = pw_copy(tfd, ffd, NULL);
-	if (r < 0) {
-		unlink(template);
-		exit(EXIT_FAILURE);
-	}
+		if (fseek(fp, 0, SEEK_SET) == -1 || fseek(tfp, 0, SEEK_SET) == -1) {
+			weprintf("rewind:");
+			goto cleanup;
+		}
 
-	close(tfd);
-	close(ffd);
-	unlink(template);
+		/* old shadow file with temporary file data. */
+		concat(tfp, template, fp, shadowfile);
+		ftruncate(tfd, ftell(tfp));
+	} else {
+		/* write to /etc/passwd file. */
+		ffd = open("/etc/passwd", O_RDWR);
+		if (ffd < 0) {
+			weprintf("open %s:", "/etc/passwd");
+			goto cleanup;
+		}
+		pw->pw_passwd = cryptpass3;
+
+		if ((tfd = gettempfile(template)) == -1)
+			goto cleanup;
+
+		r = pw_copy(ffd, tfd, pw);
+		if (r < 0)
+			goto cleanup;
+		r = lseek(ffd, 0, SEEK_SET);
+		if (r < 0)
+			goto cleanup;
+		r = lseek(tfd, 0, SEEK_SET);
+		if (r < 0)
+			goto cleanup;
+		r = pw_copy(tfd, ffd, NULL);
+		if (r < 0)
+			goto cleanup;
+		close(ffd);
+	}
+	status = EXIT_SUCCESS;
+
+cleanup:
+	if (fp)
+		fclose(fp);
+	if (tfp)
+		fclose(tfp);
+	if (tfd != -1) {
+		close(tfd);
+		unlink(template);
+	}
+	if (ffd != -1)
+		close(ffd);
 	free(cryptpass3);
 	free(cryptpass2);
 	free(cryptpass1);
 
-	return EXIT_SUCCESS;
+	return status;
 }

text.h

@@ -9,3 +9,5 @@ struct linebuf {
 void getlines(FILE *, struct linebuf *);
 
 ssize_t agetline(char **, size_t *, FILE *);
+
+void concat(FILE *, const char *, FILE *, const char *);

util/concat.c

@@ -0,0 +1,21 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+
+#include "../text.h"
+#include "../util.h"
+
+void
+concat(FILE *fp1, const char *s1, FILE *fp2, const char *s2)
+{
+	char buf[BUFSIZ];
+	size_t n;
+
+	while ((n = fread(buf, 1, sizeof buf, fp1)) > 0) {
+		if (fwrite(buf, 1, n, fp2) != n)
+			eprintf("%s: write error:", s2);
+		if (feof(fp1))
+			break;
+	}
+	if (ferror(fp1))
+		eprintf("%s: read error:", s1);
+}