Make pw_scan(3) more compatible with getpwent(3) et. al. when processing

data from /etc/passwd rather than /etc/master.passwd.

The libc getpwent(3) and related functions automatically read master.passwd
when run by root, or passwd when run by a non-root user.  When run by non-
root, getpwent() copes with the missing data by setting the corresponding
fields in the passwd struct to known values (zeroes for numbers, or a
pointer to an empty string for literals).  When libutil's pw_scan(3) was
used to parse a line without the root-accessible data, it was leaving
garbage in the corresponding fields.

These changes rename the static pw_init() function used by getpwent() and
friends to __pw_initpwd(), and move it into pw_scan.c so that common init
code can be shared between libc and libutil.  pw_scan(3) now calls
__pw_initpwd() before __pw_scan(), just like the getpwent() family does, so
that reading an arbitrary passwd file in either format and parsing it with
pw_scan(3) returns the same results as getpwent(3) would.

This also adds a new pw_initpwd(3) function to libutil, so that code which
creates passwd structs from scratch in some manner that doesn't involve
pw_scan() can initialize the struct to the values expected by lots of
existing code, which doesn't expect to encounter NULL pointers or garbage
values in some fields.

1 files changed, 10 insertions, 1 deletions

diff --git a/libutil/pw_util.c b/libutil/pw_util.c
index 112b6d8..1659c97 100644
--- a/libutil/pw_util.c
+++ b/libutil/pw_util.c
@@ -652,8 +652,16 @@ pw_dup(const struct passwd *pw)
 #include "pw_scan.h"
 
 /*
- * Wrapper around an internal libc function
+ * Wrapper around some internal libc functions.
  */
+
+void
+pw_initpwd(struct passwd *pw)
+{
+
+	__pw_initpwd(pw);
+}
+
 struct passwd *
 pw_scan(const char *line, int flags)
 {
@@ -662,6 +670,7 @@ pw_scan(const char *line, int flags)
 
 	if ((bp = strdup(line)) == NULL)
 		return (NULL);
+	__pw_initpwd(&pw);
 	if (!__pw_scan(bp, &pw, flags)) {
 		free(bp);
 		return (NULL);