Password file routines with DBM support [ repost ]

[John F. Haugh II]

[ This is the second time I'm posting this.  The first post included a very
  nasty bug which I hadn't caught.  So, if you have managed to get a copy of
  that version, trash it ... ]

I keep seeing password file routines get posted which have no support
for DBM files.  I decided to collect a few sources I had hanging around
and send them out to the world.  To use this stuff, compile with

	cc -c -O getpwent.c pwpack.c

or whatever other magical incantations you use, and then link whatever
you want these to be a part of with these two files.  The routines which
get defined here are getpwent, getpwuid, getpwnam, setpwent, endpwent,
fgetpwent, and sgetpwent.  Two additional routines, pw_pack and pw_unpack
are defined to pack and unpack DBM records containing password file
entries.

If anyone manages to put NDBM stuff in here, please send back the
patches.

DISCLAIMER: Also, this is alt.sources stuff, don't expect it to actually
work.  I wouldn't use it in the ICBM controller you've been working on
without first making sure it works correctly in your environment.

Unshar and enjoy!
------ cut here ------
#! /bin/sh
# This is a shell archive, meaning:
# 1. Remove everything above the #! /bin/sh line.
# 2. Save the resulting text in a file.
# 3. Execute the file with /bin/sh (not csh) to create:
#	getpwent.c
#	pwpack.c
# This archive created: Sat Jul 21 17:42:05 1990
# By:	John F. Haugh II (River Parishes Programming, Austin TX)
export PATH; PATH=/bin:/usr/bin:$PATH
echo shar: "extracting 'getpwent.c'" '(6614 characters)'
if test -f 'getpwent.c'
then
	echo shar: "will not over-write existing file 'getpwent.c'"
else
sed 's/^X//' << \SHAR_EOF > 'getpwent.c'
X/*
X * Copyright 1990, John F. Haugh II
X * All rights reserved.
X *
X * Use, duplication, and disclosure prohibited without
X * the express written permission of the author.
X *
X * Duplication is permitted for non-commercial [ non-profit making ]
X * purposes provided this and other copyright notices remain
X * intact.
X */
X
X#include <stdio.h>
X#include <pwd.h>
X#include <string.h>
X#include <dbm.h>
X
X#define	SBUFSIZ	64
X#define	NFIELDS	7
X
Xstatic	FILE	*pwdfp;
Xstatic	char	pwdbuf[BUFSIZ];
Xstatic	char	*pwdfile = "/etc/passwd";
Xstatic	int	dbmopened;
Xstatic	int	dbmerror;
Xstatic	char	*pwdfields[NFIELDS];
Xstatic	struct	passwd	pwent;
X
X/*
X * sgetpwent - convert a string to a (struct passwd)
X *
X * sgetpwent() parses a string into the parts required for a password
X * structure.  Strict checking is made for the UID and GID fields and
X * presence of the correct number of colons.  Any failing tests result
X * in a NULL pointer being returned.
X */
X
Xstruct	passwd	*sgetpwent (buf)
Xchar	*buf;
X{
X	int	i;
X	char	*cp;
X
X	/*
X	 * Copy the string to a static buffer so the pointers into
X	 * the password structure remain valid.
X	 */
X
X	strncpy (pwdbuf, buf, BUFSIZ);
X	pwdbuf[BUFSIZ-1] = '\0';
X
X	/*
X	 * Save a pointer to the start of each colon separated
X	 * field.  The fields are converted into NUL terminated strings.
X	 */
X
X	for (cp = pwdbuf, i = 0;i < NFIELDS && cp;i++) {
X		pwdfields[i] = cp;
X		if (cp = strchr (cp, ':'))
X			*cp++ = 0;
X	}
X
X	/*
X	 * There must be exactly NFIELDS colon separated fields or
X	 * the entry is invalid.  Also, the UID and GID must be non-blank.
X	 */
X
X	if (i != NFIELDS || *pwdfields[2] == '\0' || *pwdfields[3] == '\0')
X		return 0;
X
X	/*
X	 * Each of the fields is converted the appropriate data type
X	 * and the result assigned to the password structure.  If the
X	 * UID or GID does not convert to an integer value, a NULL
X	 * pointer is returned.
X	 */
X
X	pwent.pw_name = pwdfields[0];
X	pwent.pw_passwd = pwdfields[1];
X	if ((pwent.pw_uid = strtol (pwdfields[2], &cp, 10)) == 0 && *cp)
X		return 0;
X
X	if ((pwent.pw_gid = strtol (pwdfields[3], &cp, 10)) == 0 && *cp)
X		return 0;
X
X	if (cp = strchr (pwent.pw_passwd, ',')) {
X		pwent.pw_age = cp + 1;
X		*cp = '\0';
X	}
X	pwent.pw_gecos = pwdfields[4];
X	pwent.pw_dir = pwdfields[5];
X	pwent.pw_shell = pwdfields[6];
X
X	return (&pwent);
X}
X
X/*
X * fgetpwent - get a password file entry from a stream
X *
X * fgetpwent() reads the next line from a password file formatted stream
X * and returns a pointer to the password structure for that line.
X */
X
Xstruct	passwd	*fgetpwent (fp)
XFILE	*fp;
X{
X	char	buf[BUFSIZ];
X	char	*cp;
X
X	if (! fgets (buf, BUFSIZ, fp))
X		return 0;
X
X	if (cp = strrchr (buf, '\n'))
X		*cp = '\0';
X
X	return sgetpwent (buf);
X}
X
X/*
X * endpwent - close a password file
X *
X * endpwent() closes the password file if open.
X */
X
Xint	endpwent ()
X{
X	if (pwdfp)
X		if (fclose (pwdfp))
X			return -1;
X
X	return 0;
X}
X
X/*
X * getpwent - get a password entry from the password file
X *
X * getpwent() opens the password file, if not already opened, and reads
X * a single entry.  NULL is returned if any errors are encountered reading
X * the password file.
X */
X
Xstruct	passwd	*getpwent ()
X{
X	if (! pwdfp && setpwent ())
X		return 0;
X
X	return fgetpwent (pwdfp);
X}
X
X/*
X * getpwuid - locate the password entry for a given UID
X *
X * getpwuid() locates the first password file entry for the given UID.
X * If there is a valid DBM file, the DBM files are queried first for
X * the entry.  Otherwise, a linear search is begun of the password file
X * searching for an entry which matches the provided UID.
X */
X
Xstruct	passwd	*getpwuid (uid)
Xint	uid;
X{
X	struct	passwd	*pwd;
X	datum	key;
X	datum	content;
X
X	/*
X	 * Attempt to open the DBM files if they have never been opened
X	 * and an error has never been returned.
X	 */
X
X	if (! dbmerror && ! dbmopened)
X		if (dbminit (pwdfile) == 0)
X			dbmopened = 1;
X		else
X			dbmerror = 1;
X
X	/*
X	 * If the DBM file are now open, create a key for this UID and
X	 * try to fetch the entry from the database.  A matching record
X	 * will be unpacked into a static structure and returned to
X	 * the user.
X	 */
X
X	if (dbmopened) {
X		pwent.pw_uid = uid;
X		key.dsize = sizeof pwent.pw_uid;
X		key.dptr = (char *) &pwent.pw_uid;
X		content = fetch (key);
X		if (content.dptr != 0) {
X			memcpy (pwdbuf, content.dptr, content.dsize);
X			pw_unpack (pwdbuf, content.dsize, &pwent);
X			return &pwent;
X		}
X	}
X
X	/*
X	 * Rewind the database and begin searching for an entry which
X	 * matches the UID.  Return the entry when a match is found.
X	 */
X
X	if (setpwent ())
X		return 0;
X
X	while (pwd = getpwent ())
X		if (pwd->pw_uid == uid)
X			return pwd;
X
X	return 0;
X}
X
X/*
X * getpwuid - locate the password entry for a given name
X *
X * getpwuid() locates the first password file entry for the given name.
X * If there is a valid DBM file, the DBM files are queried first for
X * the entry.  Otherwise, a linear search is begun of the password file
X * searching for an entry which matches the provided name.
X */
X
Xstruct	passwd	*getpwnam (name)
Xchar	*name;
X{
X	struct	passwd	*pwd;
X	datum	key;
X	datum	content;
X
X	/*
X	 * Attempt to open the DBM files if they have never been opened
X	 * and an error has never been returned.
X	 */
X
X	if (! dbmerror && ! dbmopened)
X		if (dbminit (pwdfile) == 0)
X			dbmopened = 1;
X		else
X			dbmerror = 1;
X
X	/*
X	 * If the DBM file are now open, create a key for this name and
X	 * try to fetch the entry from the database.  A matching record
X	 * will be unpacked into a static structure and returned to
X	 * the user.
X	 */
X
X	if (dbmopened) {
X		key.dsize = strlen (name);
X		key.dptr = name;
X		content = fetch (key);
X		if (content.dptr != 0) {
X			memcpy (pwdbuf, content.dptr, content.dsize);
X			pw_unpack (pwdbuf, content.dsize, &pwent);
X			return &pwent;
X		}
X	}
X
X	/*
X	 * Rewind the database and begin searching for an entry which
X	 * matches the name.  Return the entry when a match is found.
X	 */
X
X	if (setpwent ())
X		return 0;
X
X	while (pwd = getpwent ())
X		if (strcmp (pwd->pw_name, name) == 0)
X			return pwd;
X
X	return 0;
X}
X
X/*
X * setpwent - open the password file
X *
X * setpwent() opens the system password file, and the DBM password files
X * if they are present.  The system password file is rewound if it was
X * open already.
X */
X
Xint	setpwent ()
X{
X	if (! pwdfp) {
X		if (! (pwdfp = fopen (pwdfile, "r")))
X			return -1;
X	} else {
X		if (fseek (pwdfp, 0L, 0) != 0)
X			return -1;
X	}
X
X	/*
X	 * Attempt to open the DBM files if they have never been opened
X	 * and an error has never been returned.
X	 */
X
X	if (! dbmerror && ! dbmopened)
X		if (dbminit (pwdfile) == 0)
X			dbmopened = 1;
X		else
X			dbmerror = 1;
X	return 0;
X}
SHAR_EOF
if test 6614 -ne "`wc -c < 'getpwent.c'`"
then
	echo shar: "error transmitting 'getpwent.c'" '(should have been 6614 characters)'
fi
fi
echo shar: "extracting 'pwpack.c'" '(1791 characters)'
if test -f 'pwpack.c'
then
	echo shar: "will not over-write existing file 'pwpack.c'"
else
sed 's/^X//' << \SHAR_EOF > 'pwpack.c'
X/*
X * Copyright 1990, John F. Haugh II
X * All rights reserved.
X *
X * Use, duplication, and disclosure prohibited without
X * the express written permission of the author.
X *
X * Duplication is permitted for non-commercial [ profit making ]
X * purposes provided this and other copyright notices remain
X * intact.
X */
X
X#include <pwd.h>
X
Xint	pw_pack (passwd, buf)
Xstruct	passwd	*passwd;
Xchar	*buf;
X{
X	char	*cp;
X
X	cp = buf;
X	strcpy (cp, passwd->pw_name);
X	cp += strlen (cp) + 1;
X
X	strcpy (cp, passwd->pw_passwd);
X	cp += strlen (cp) + 1;
X
X	memcpy (cp, (void *) &passwd->pw_uid, sizeof passwd->pw_uid);
X	cp += sizeof passwd->pw_uid;
X
X	memcpy (cp, (void *) &passwd->pw_gid, sizeof passwd->pw_gid);
X	cp += sizeof passwd->pw_gid;
X
X	strcpy (cp, passwd->pw_gecos);
X	cp += strlen (cp) + 1;
X
X	strcpy (cp, passwd->pw_dir);
X	cp += strlen (cp) + 1;
X
X	strcpy (cp, passwd->pw_shell);
X		cp += strlen (cp) + 1;
X
X	return cp - buf;
X}
X
Xint	pw_unpack (buf, len, passwd)
Xchar	*buf;
Xint	len;
Xstruct	passwd	*passwd;
X{
X	char	*org = buf;
X
X	passwd->pw_name = buf;
X	buf += strlen (buf) + 1;
X	if (buf - org > len)
X		return -1;
X
X	passwd->pw_passwd = buf;
X	buf += strlen (buf) + 1;
X	if (buf - org > len)
X		return -1;
X
X	memcpy ((void *) &passwd->pw_uid, (void *) buf, sizeof passwd->pw_uid);
X	buf += sizeof passwd->pw_uid;
X	if (buf - org > len)
X		return -1;
X
X	memcpy ((void *) &passwd->pw_gid, (void *) buf, sizeof passwd->pw_gid);
X	buf += sizeof passwd->pw_gid;
X	if (buf - org > len)
X		return -1;
X
X	passwd->pw_gecos = buf;
X	buf += strlen (buf) + 1;
X	if (buf - org > len)
X		return -1;
X
X	passwd->pw_dir = buf;
X	buf += strlen (buf) + 1;
X	if (buf - org > len)
X		return -1;
X
X	passwd->pw_shell = buf;
X	buf += strlen (buf) + 1;
X	if (buf - org > len)
X		return -1;
X
X	return 0;
X}
SHAR_EOF
if test 1791 -ne "`wc -c < 'pwpack.c'`"
then
	echo shar: "error transmitting 'pwpack.c'" '(should have been 1791 characters)'
fi
fi
exit 0
#	End of shell archive
-- 
John F. Haugh II                             UUCP: ...!cs.utexas.edu!rpp386!jfh
Ma Bell: (512) 832-8832                           Domain: jfh at rpp386.cactus.org