Re: setpassent(1) not working

[Philip Guenther]

On Thu, Nov 14, 2013 at 1:00 PM, Erik Lax e...@halon.se wrote:
 I noticed that setpassent(1) probably doesn't work as intended, as this
 program should open the spwd.db file once, not four times?
...
 This following patch fixes this.

This has been committed; thanks!


Philip Guenther

setpassent(1) not working

[Erik Lax]

Hi,

I noticed that setpassent(1) probably doesn't work as intended, as this
program should open the spwd.db file once, not four times?

int main() {
setpassent(1);
getpwnam(root); getpwnam(root); getpwuid(0); getpwuid(0);
return 0;
}

It seems to be due to faulty logic in libc/gen/getpwent.c. In short

...
savedb = _pw_db;
if (!_pw_db  !__initdb())
...
_pw_db begin as NULL
so savedb is set to NULL
_pw_db is NULL and __initdb() is run, _pw_db is set
...
if (savedb != _pw_db || !_pw_stayopen) {
...
savedb is still NULL, _pwd_db is not, so the first condition is true
_pw_db get closed, and set to NULL

This following patch fixes this.

--- lib/libc/gen/getpwent.c.origThu Nov 14 21:06:13 2013
+++ lib/libc/gen/getpwent.c Thu Nov 14 21:18:45 2013
@@ -708,10 +708,8 @@
 {
struct passwd *pwret = NULL;
int flags = 0, *flagsp;
-   DB *savedb;

_THREAD_PRIVATE_MUTEX_LOCK(pw);
-   savedb = _pw_db;
if (!_pw_db  !__initdb())
goto fail;

@@ -728,7 +726,7 @@
if (!pwret)
pwret = _pwhashbyname(name, buf, buflen, pw, flagsp);

-   if (savedb != _pw_db || !_pw_stayopen) {
+   if (!_pw_stayopen) {
(void)(_pw_db-close)(_pw_db);
_pw_db = NULL;
}
@@ -755,10 +753,8 @@
 {
struct passwd *pwret = NULL;
int flags = 0, *flagsp;
-   DB *savedb;

_THREAD_PRIVATE_MUTEX_LOCK(pw);
-   savedb = _pw_db;
if (!_pw_db  !__initdb())
goto fail;

@@ -775,7 +771,7 @@
if (!pwret)
pwret = _pwhashbyuid(uid, buf, buflen, pw, flagsp);

-   if (savedb != _pw_db || !_pw_stayopen) {
+   if (!_pw_stayopen) {
(void)(_pw_db-close)(_pw_db);
_pw_db = NULL;
}