diff options
| -rw-r--r-- | usr.sbin/pwd_mkdb/pwd_mkdb.8 | 7 | ||||
| -rw-r--r-- | usr.sbin/pwd_mkdb/pwd_mkdb.c | 42 |
2 files changed, 43 insertions, 6 deletions
diff --git a/usr.sbin/pwd_mkdb/pwd_mkdb.8 b/usr.sbin/pwd_mkdb/pwd_mkdb.8 index 54abc76..7beecd7 100644 --- a/usr.sbin/pwd_mkdb/pwd_mkdb.8 +++ b/usr.sbin/pwd_mkdb/pwd_mkdb.8 @@ -40,6 +40,7 @@ .Sh SYNOPSIS .Nm pwd_mkdb .Op Fl C +.Op Fl N .Op Fl p .Op Fl d Ar directory .Op Fl s Ar cachesize @@ -67,6 +68,12 @@ The options are as follows: .It Fl C Check if the password file is in the correct format. Do not change, add, or remove any files. +.It Fl N +Tell +.Nm Pwd_mkdb +to exit with an error if it cannot obtain a lock on the file. By default, +we block waiting for a lock on the source file. The lock is held through +the rebuilding of the database. .It Fl p Create a Version 7 style password file and install it into .Pa /etc/passwd . diff --git a/usr.sbin/pwd_mkdb/pwd_mkdb.c b/usr.sbin/pwd_mkdb/pwd_mkdb.c index 9df6680..4c5a518 100644 --- a/usr.sbin/pwd_mkdb/pwd_mkdb.c +++ b/usr.sbin/pwd_mkdb/pwd_mkdb.c @@ -42,7 +42,7 @@ static const char copyright[] = static char sccsid[] = "@(#)pwd_mkdb.c 8.5 (Berkeley) 4/20/94"; #endif static const char rcsid[] = - "$Id: pwd_mkdb.c,v 1.27 1998/09/29 20:01:21 dt Exp $"; + "$Id: pwd_mkdb.c,v 1.28 1998/12/12 16:08:41 foxfair Exp $"; #endif /* not lint */ #include <sys/param.h> @@ -109,6 +109,7 @@ main(argc, argv) char *username; u_int method, methoduid; int Cflag; + int nblock = 0; Cflag = 0; strcpy(prefix, _PATH_PWD); @@ -133,6 +134,9 @@ main(argc, argv) break; case 'v': /* backward compatible */ break; + case 'N': /* do not wait for lock */ + nblock = LOCK_NB; + break; default: usage(); } @@ -158,9 +162,30 @@ main(argc, argv) (void)umask(0); pname = *argv; - /* Open the original password file */ - if (!(fp = fopen(pname, "r"))) - error(pname); + + /* + * Open and lock the original password file. We have to check + * the hardlink count after we get the lock to handle any potential + * unlink/rename race. + * + * This lock is necessary when someone runs pwd_mkdb manually, directly + * on master.passwd, to handle the case where a user might try to + * change his password while pwd_mkdb is running. + */ + for (;;) { + struct stat st; + + if (!(fp = fopen(pname, "r"))) + error(pname); + if (flock(fileno(fp), LOCK_EX|nblock) < 0) + error("flock"); + if (fstat(fileno(fp), &st) < 0) + error(pname); + if (st.st_nlink != 0) + break; + fclose(fp); + fp = NULL; + } /* check only if password database is valid */ if (Cflag) { @@ -431,8 +456,6 @@ main(argc, argv) /* Set master.passwd permissions, in case caller forgot. */ (void)fchmod(fileno(fp), S_IRUSR|S_IWUSR); - if (fclose(fp) == EOF) - error("close fp"); /* Install as the real password files. */ (void)snprintf(buf, sizeof(buf), "%s/%s.tmp", prefix, _MP_DB); @@ -454,6 +477,13 @@ main(argc, argv) */ (void)snprintf(buf, sizeof(buf), "%s/%s", prefix, _MASTERPASSWD); mv(pname, buf); + + /* + * Close locked password file after rename() + */ + if (fclose(fp) == EOF) + error("close fp"); + exit(0); } |
