Make pw(8) showuser work the same with or without -R <path> for non-root

users.  Without -R, pw(8) uses getpwnam(3), which will open master.passwd
for the root user or passwd for non-root users.  With -R <path> pw(8) was
always opening <path>/master.passwd, which would fail for a non-root user,
then falsely claim the userid you're trying to show doesn't exist.

Now for a non-root user it opens <path>/passwd and zeroes out the 3 fields
that aren't available in the passwd file, which duplicates the behavior of
getpwnam(3).  The net effect is that the showuser output is identical
whether using -R or not.

1 files changed, 29 insertions, 3 deletions

diff --git a/pw/pw_vpw.c b/pw/pw_vpw.c
index ea87f71..4517a74 100644
--- a/pw/pw_vpw.c
+++ b/pw/pw_vpw.c
@@ -39,10 +39,13 @@ static const char rcsid[] =
 #include <string.h>
 #include <stdlib.h>
 #include <err.h>
+#include <unistd.h>
 
 #include "pwupd.h"
 
 static FILE * pwd_fp = NULL;
+static int pwd_scanflag;
+static const char *pwd_filename;
 
 void
 vendpwent(void)
@@ -71,7 +74,18 @@ vnextpwent(char const *nam, uid_t uid, int doclose)
 	line = NULL;
 	linecap = 0;
 
-	if (pwd_fp != NULL || (pwd_fp = fopen(getpwpath(_MASTERPASSWD), "r")) != NULL) {
+	if (pwd_fp == NULL) {
+		if (geteuid() == 0) {
+			pwd_filename = _MASTERPASSWD;
+			pwd_scanflag = PWSCAN_MASTER;
+		} else {
+			pwd_filename = _PASSWD;
+			pwd_scanflag = 0;
+		}
+		pwd_fp = fopen(getpwpath(pwd_filename), "r");
+	}
+	 
+	if (pwd_fp != NULL) {
 		while ((linelen = getline(&line, &linecap, pwd_fp)) > 0) {
 			/* Skip comments and empty lines */
 			if (*line == '\n' || *line == '#')
@@ -79,10 +93,10 @@ vnextpwent(char const *nam, uid_t uid, int doclose)
 			/* trim latest \n */
 			if (line[linelen - 1 ] == '\n')
 				line[linelen - 1] = '\0';
-			pw = pw_scan(line, PWSCAN_MASTER);
+			pw = pw_scan(line, pwd_scanflag);
 			if (pw == NULL)
 				errx(EXIT_FAILURE, "Invalid user entry in '%s':"
-				    " '%s'", getpwpath(_MASTERPASSWD), line);
+				    " '%s'", getpwpath(pwd_filename), line);
 			if (uid != (uid_t)-1) {
 				if (uid == pw->pw_uid)
 					break;
@@ -99,6 +113,18 @@ vnextpwent(char const *nam, uid_t uid, int doclose)
 	}
 	free(line);
 
+	/*
+	 * If we read the non-master passwd, some fields may not have been
+	 * populated.  Clean them up so that the output looks the same as that
+	 * generated using getpwnam() which also inits them to these values.
+	 */
+	if (!(pw->pw_fields & _PWF_CLASS))
+		pw->pw_class = "";
+	if (!(pw->pw_fields & _PWF_CHANGE))
+		pw->pw_change = 0;
+	if (!(pw->pw_fields & _PWF_EXPIRE))
+		pw->pw_expire = 0;
+
 	return (pw);
 }