passwd: Respect --prefix/-P options

Add prefix_getpwnam_r() and xprefix_getpwnam() and make passwd
use prefix-aware functions when handling the database.

lib/prototypes.h

@@ -326,6 +326,8 @@ extern struct group *prefix_getgrnam(const char *name);
 extern struct group *prefix_getgrgid(gid_t gid);
 extern struct passwd *prefix_getpwuid(uid_t uid);
 extern struct passwd *prefix_getpwnam(const char* name);
+extern int prefix_getpwnam_r(const char* name, struct passwd* pwd,
+                             char* buf, size_t buflen, struct passwd** result);
 extern struct spwd *prefix_getspnam(const char* name);
 extern struct group *prefix_getgr_nam_gid(const char *grname);
 extern void prefix_setpwent(void);
@@ -481,6 +483,8 @@ extern bool valid (const char *, const struct passwd *);
 
 /* xgetpwnam.c */
 extern /*@null@*/ /*@only@*/struct passwd *xgetpwnam (const char *);
+/* xprefix_getpwnam.c */
+extern /*@null@*/ /*@only@*/struct passwd *xprefix_getpwnam (const char *);
 /* xgetpwuid.c */
 extern /*@null@*/ /*@only@*/struct passwd *xgetpwuid (uid_t);
 /* xgetgrnam.c */

libmisc/Makefile.am

@@ -75,6 +75,7 @@ libmisc_la_SOURCES = \
 	utmp.c \
 	valid.c \
 	xgetpwnam.c \
+	xprefix_getpwnam.c \
 	xgetpwuid.c \
 	xgetgrnam.c \
 	xgetgrgid.c \

libmisc/prefix_flag.c

@@ -238,6 +238,27 @@ extern struct passwd *prefix_getpwnam(const char* name)
 		return getpwnam(name);
 	}
 }
+extern int prefix_getpwnam_r(const char* name, struct passwd* pwd,
+                             char* buf, size_t buflen, struct passwd** result)
+{
+	if (passwd_db_file) {
+		FILE* fg;
+		int ret = 0;
+
+		fg = fopen(passwd_db_file, "rt");
+		if (!fg)
+			return errno;
+		while ((ret = fgetpwent_r(fg, pwd, buf, buflen, result)) == 0) {
+			if (!strcmp(name, pwd->pw_name))
+				break;
+		}
+		fclose(fg);
+		return ret;
+	}
+	else {
+		return getpwnam_r(name, pwd, buf, buflen, result);
+	}
+}
 extern struct spwd *prefix_getspnam(const char* name)
 {
 	if (spw_db_file) {

libmisc/xprefix_getpwnam.c

@@ -0,0 +1,41 @@
+/*
+ * SPDX-FileCopyrightText: 2007 - 2009, Nicolas François
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/*
+ * According to the Linux-PAM documentation:
+ *
+ *  4.1. Care about standard library calls
+ *
+ *  In general, writers of authorization-granting applications should
+ *  assume that each module is likely to call any or all 'libc' functions.
+ *  For 'libc' functions that return pointers to static/dynamically
+ *  allocated structures (ie.  the library allocates the memory and the
+ *  user is not expected to 'free()' it) any module call to this function
+ *  is likely to corrupt a pointer previously obtained by the application.
+ *  The application programmer should either re-call such a 'libc'
+ *  function after a call to the Linux-PAM library, or copy the structure
+ *  contents to some safe area of memory before passing control to the
+ *  Linux-PAM library.
+ *
+ *  Two important function classes that fall into this category are
+ *  getpwnam(3) and syslog(3).
+ *
+ * This file provides wrapper to the prefix_getpwnam or prefix_getpwnam_r functions.
+ */
+
+#include <config.h>
+
+#include "pwio.h"
+
+#define LOOKUP_TYPE	struct passwd
+#define FUNCTION_NAME	prefix_getpwnam
+#define ARG_TYPE	const char *
+#define ARG_NAME	name
+#define DUP_FUNCTION	__pw_dup
+#define HAVE_FUNCTION_R 1
+
+#include "xgetXXbyYY.c"
+

src/passwd.c

@@ -452,7 +452,7 @@ static void print_status (const struct passwd *pw)
 	char         date[80];
 	struct spwd *sp;
 
-	sp = getspnam (pw->pw_name); /* local, no need for xgetspnam */
+	sp = prefix_getspnam (pw->pw_name); /* local, no need for xprefix_getspnam */
 	if (NULL != sp) {
 		date_to_str (sizeof(date), date, sp->sp_lstchg * SCALE),
 		(void) printf ("%s %s %s %lld %lld %lld %lld\n",
@@ -781,7 +781,7 @@ int main (int argc, char **argv)
 			{NULL, 0, NULL, '\0'}
 		};
 
-		while ((c = getopt_long (argc, argv, "adehi:kln:qr:R:Suw:x:",
+		while ((c = getopt_long (argc, argv, "adehi:kln:qr:R:P:Suw:x:",
 		                         long_options, NULL)) != -1) {
 			switch (c) {
 			case 'a':
@@ -922,11 +922,11 @@ int main (int argc, char **argv)
 			                Prog);
 			exit (E_NOPERM);
 		}
-		setpwent ();
-		while ( (pw = getpwent ()) != NULL ) {
+		prefix_setpwent ();
+		while ( (pw = prefix_getpwent ()) != NULL ) {
 			print_status (pw);
 		}
-		endpwent ();
+		prefix_endpwent ();
 		exit (E_SUCCESS);
 	}
 #if 0
@@ -963,7 +963,7 @@ int main (int argc, char **argv)
 		exit (E_NOPERM);
 	}
 
-	pw = xgetpwnam (name);
+	pw = xprefix_getpwnam (name);
 	if (NULL == pw) {
 		(void) fprintf (stderr,
 		                _("%s: user '%s' does not exist\n"),
@@ -1007,7 +1007,7 @@ int main (int argc, char **argv)
 	/*
 	 * The user name is valid, so let's get the shadow file entry.
 	 */
-	sp = getspnam (name); /* !USE_PAM, no need for xgetspnam */
+	sp = prefix_getspnam (name); /* !USE_PAM, no need for xprefix_getspnam */
 	if (NULL == sp) {
 		if (errno == EACCES) {
 			(void) fprintf (stderr,