cpio/cmdline.c - third_party/libarchive - Git at Google

 /*-
  * Copyright (c) 2003-2007 Tim Kientzle
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer
  *    in this position and unchanged.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */


 #include "cpio_platform.h"
 __FBSDID("$FreeBSD: src/usr.bin/cpio/cmdline.c,v 1.5 2008/12/06 07:30:40 kientzle Exp $");

 #ifdef HAVE_ERRNO_H
 #include <errno.h>
 #endif
 #ifdef HAVE_GRP_H
 #include <grp.h>
 #endif
 #ifdef HAVE_PWD_H
 #include <pwd.h>
 #endif
 #include <stdio.h>
 #ifdef HAVE_STDLIB_H
 #include <stdlib.h>
 #endif
 #ifdef HAVE_STRING_H
 #include <string.h>
 #endif

 #include "cpio.h"
 #include "err.h"

 /*
  * Short options for cpio.  Please keep this sorted.
  */
 static const char *short_options = "0AaBC:cdE:F:f:H:hI:iJjLlmnO:opR:rtuVvW:yZz";

 /*
  * Long options for cpio.  Please keep this sorted.
  */
 static const struct option {
 	const char *name;
 	int required;	/* 1 if this option requires an argument */
 	int equivalent;	/* Equivalent short option. */
 } cpio_longopts[] = {
 	{ "b64encode",			0, OPTION_B64ENCODE },
 	{ "create",			0, 'o' },
 	{ "dot",			0, 'V' },
 	{ "extract",			0, 'i' },
 	{ "file",			1, 'F' },
 	{ "format",             	1, 'H' },
 	{ "grzip",			0, OPTION_GRZIP },
 	{ "help",			0, 'h' },
 	{ "insecure",			0, OPTION_INSECURE },
 	{ "link",			0, 'l' },
 	{ "list",			0, 't' },
 	{ "lrzip",			0, OPTION_LRZIP },
 	{ "lzma",			0, OPTION_LZMA },
 	{ "lzop",			0, OPTION_LZOP },
 	{ "make-directories",		0, 'd' },
 	{ "no-preserve-owner",		0, OPTION_NO_PRESERVE_OWNER },
 	{ "null",			0, '0' },
 	{ "numeric-uid-gid",		0, 'n' },
 	{ "owner",			1, 'R' },
 	{ "pass-through",		0, 'p' },
 	{ "preserve-modification-time", 0, 'm' },
 	{ "preserve-owner",		0, OPTION_PRESERVE_OWNER },
 	{ "quiet",			0, OPTION_QUIET },
 	{ "unconditional",		0, 'u' },
 	{ "uuencode",			0, OPTION_UUENCODE },
 	{ "verbose",			0, 'v' },
 	{ "version",			0, OPTION_VERSION },
 	{ "xz",				0, 'J' },
 	{ NULL, 0, 0 }
 };

 /*
  * I used to try to select platform-provided getopt() or
  * getopt_long(), but that caused a lot of headaches.  In particular,
  * I couldn't consistently use long options in the test harness
  * because not all platforms have getopt_long().  That in turn led to
  * overuse of the -W hack in the test harness, which made it rough to
  * run the test harness against GNU cpio.  (I periodically run the
  * test harness here against GNU cpio as a sanity-check.  Yes,
  * I've found a couple of bugs in GNU cpio that way.)
  */
 int
 cpio_getopt(struct cpio *cpio)
 {
 	enum { state_start = 0, state_next_word, state_short, state_long };
 	static int state = state_start;
 	static char *opt_word;

 	const struct option *popt, *match = NULL, *match2 = NULL;
 	const char *p, *long_prefix = "--";
 	size_t optlength;
 	int opt = '?';
 	int required = 0;

 	cpio->argument = NULL;

 	/* First time through, initialize everything. */
 	if (state == state_start) {
 		/* Skip program name. */
 		++cpio->argv;
 		--cpio->argc;
 		state = state_next_word;
 	}

 	/*
 	 * We're ready to look at the next word in argv.
 	 */
 	if (state == state_next_word) {
 		/* No more arguments, so no more options. */
 		if (cpio->argv[0] == NULL)
 			return (-1);
 		/* Doesn't start with '-', so no more options. */
 		if (cpio->argv[0][0] != '-')
 			return (-1);
 		/* "--" marks end of options; consume it and return. */
 		if (strcmp(cpio->argv[0], "--") == 0) {
 			++cpio->argv;
 			--cpio->argc;
 			return (-1);
 		}
 		/* Get next word for parsing. */
 		opt_word = *cpio->argv++;
 		--cpio->argc;
 		if (opt_word[1] == '-') {
 			/* Set up long option parser. */
 			state = state_long;
 			opt_word += 2; /* Skip leading '--' */
 		} else {
 			/* Set up short option parser. */
 			state = state_short;
 			++opt_word;  /* Skip leading '-' */
 		}
 	}

 	/*
 	 * We're parsing a group of POSIX-style single-character options.
 	 */
 	if (state == state_short) {
 		/* Peel next option off of a group of short options. */
 		opt = *opt_word++;
 		if (opt == '\0') {
 			/* End of this group; recurse to get next option. */
 			state = state_next_word;
 			return cpio_getopt(cpio);
 		}

 		/* Does this option take an argument? */
 		p = strchr(short_options, opt);
 		if (p == NULL)
 			return ('?');
 		if (p[1] == ':')
 			required = 1;

 		/* If it takes an argument, parse that. */
 		if (required) {
 			/* If arg is run-in, opt_word already points to it. */
 			if (opt_word[0] == '\0') {
 				/* Otherwise, pick up the next word. */
 				opt_word = *cpio->argv;
 				if (opt_word == NULL) {
 					lafe_warnc(0,
 					    "Option -%c requires an argument",
 					    opt);
 					return ('?');
 				}
 				++cpio->argv;
 				--cpio->argc;
 			}
 			if (opt == 'W') {
 				state = state_long;
 				long_prefix = "-W "; /* For clearer errors. */
 			} else {
 				state = state_next_word;
 				cpio->argument = opt_word;
 			}
 		}
 	}

 	/* We're reading a long option, including -W long=arg convention. */
 	if (state == state_long) {
 		/* After this long option, we'll be starting a new word. */
 		state = state_next_word;

 		/* Option name ends at '=' if there is one. */
 		p = strchr(opt_word, '=');
 		if (p != NULL) {
 			optlength = (size_t)(p - opt_word);
 			cpio->argument = (char *)(uintptr_t)(p + 1);
 		} else {
 			optlength = strlen(opt_word);
 		}

 		/* Search the table for an unambiguous match. */
 		for (popt = cpio_longopts; popt->name != NULL; popt++) {
 			/* Short-circuit if first chars don't match. */
 			if (popt->name[0] != opt_word[0])
 				continue;
 			/* If option is a prefix of name in table, record it.*/
 			if (strncmp(opt_word, popt->name, optlength) == 0) {
 				match2 = match; /* Record up to two matches. */
 				match = popt;
 				/* If it's an exact match, we're done. */
 				if (strlen(popt->name) == optlength) {
 					match2 = NULL; /* Forget the others. */
 					break;
 				}
 			}
 		}

 		/* Fail if there wasn't a unique match. */
 		if (match == NULL) {
 			lafe_warnc(0,
 			    "Option %s%s is not supported",
 			    long_prefix, opt_word);
 			return ('?');
 		}
 		if (match2 != NULL) {
 			lafe_warnc(0,
 			    "Ambiguous option %s%s (matches --%s and --%s)",
 			    long_prefix, opt_word, match->name, match2->name);
 			return ('?');
 		}

 		/* We've found a unique match; does it need an argument? */
 		if (match->required) {
 			/* Argument required: get next word if necessary. */
 			if (cpio->argument == NULL) {
 				cpio->argument = *cpio->argv;
 				if (cpio->argument == NULL) {
 					lafe_warnc(0,
 					    "Option %s%s requires an argument",
 					    long_prefix, match->name);
 					return ('?');
 				}
 				++cpio->argv;
 				--cpio->argc;
 			}
 		} else {
 			/* Argument forbidden: fail if there is one. */
 			if (cpio->argument != NULL) {
 				lafe_warnc(0,
 				    "Option %s%s does not allow an argument",
 				    long_prefix, match->name);
 				return ('?');
 			}
 		}
 		return (match->equivalent);
 	}

 	return (opt);
 }


 /*
  * Parse the argument to the -R or --owner flag.
  *
  * The format is one of the following:
  *   <username|uid>    - Override user but not group
  *   <username>:   - Override both, group is user's default group
  *   <uid>:    - Override user but not group
  *   <username|uid>:<groupname|gid> - Override both
  *   :<groupname|gid>  - Override group but not user
  *
  * Where uid/gid are decimal representations and groupname/username
  * are names to be looked up in system database.  Note that we try
  * to look up an argument as a name first, then try numeric parsing.
  *
  * A period can be used instead of the colon.
  *
  * Sets uid/gid return as appropriate, -1 indicates uid/gid not specified.
  * TODO: If the spec uses uname/gname, then return those to the caller
  * as well.  If the spec provides uid/gid, just return names as NULL.
  *
  * Returns NULL if no error, otherwise returns error string for display.
  *
  */
 const char *
 owner_parse(const char *spec, int *uid, int *gid)
 {
 	static char errbuff[128];
 	const char *u, *ue, *g;

 	*uid = -1;
 	*gid = -1;

 	if (spec[0] == '\0')
 		return ("Invalid empty user/group spec");

 	/*
 	 * Split spec into [user][:.][group]
 	 *  u -> first char of username, NULL if no username
 	 *  ue -> first char after username (colon, period, or \0)
 	 *  g -> first char of group name
 	 */
 	if (*spec == ':' || *spec == '.') {
 		/* If spec starts with ':' or '.', then just group. */
 		ue = u = NULL;
 		g = spec + 1;
 	} else {
 		/* Otherwise, [user] or [user][:] or [user][:][group] */
 		ue = u = spec;
 		while (*ue != ':' && *ue != '.' && *ue != '\0')
 			++ue;
 		g = ue;
 		if (*g != '\0') /* Skip : or . to find first char of group. */
 			++g;
 	}

 	if (u != NULL) {
 		/* Look up user: ue is first char after end of user. */
 		char *user;
 		struct passwd *pwent;

 		user = (char *)malloc(ue - u + 1);
 		if (user == NULL)
 			return ("Couldn't allocate memory");
 		memcpy(user, u, ue - u);
 		user[ue - u] = '\0';
 		if ((pwent = getpwnam(user)) != NULL) {
 			*uid = pwent->pw_uid;
 			if (*ue != '\0')
 				*gid = pwent->pw_gid;
 		} else {
 			char *end;
 			errno = 0;
 			*uid = (int)strtoul(user, &end, 10);
 			if (errno || *end != '\0') {
 				snprintf(errbuff, sizeof(errbuff),
 				    "Couldn't lookup user ``%s''", user);
 				errbuff[sizeof(errbuff) - 1] = '\0';
 				free(user);
 				return (errbuff);
 			}
 		}
 		free(user);
 	}

 	if (*g != '\0') {
 		struct group *grp;
 		if ((grp = getgrnam(g)) != NULL) {
 			*gid = grp->gr_gid;
 		} else {
 			char *end;
 			errno = 0;
 			*gid = (int)strtoul(g, &end, 10);
 			if (errno || *end != '\0') {
 				snprintf(errbuff, sizeof(errbuff),
 				    "Couldn't lookup group ``%s''", g);
 				errbuff[sizeof(errbuff) - 1] = '\0';
 				return (errbuff);
 			}
 		}
 	}
 	return (NULL);
 }
	/*-
	* Copyright (c) 2003-2007 Tim Kientzle
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer
	* in this position and unchanged.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/


	#include "cpio_platform.h"
	__FBSDID("$FreeBSD: src/usr.bin/cpio/cmdline.c,v 1.5 2008/12/06 07:30:40 kientzle Exp $");

	#ifdef HAVE_ERRNO_H
	#include <errno.h>
	#endif
	#ifdef HAVE_GRP_H
	#include <grp.h>
	#endif
	#ifdef HAVE_PWD_H
	#include <pwd.h>
	#endif
	#include <stdio.h>
	#ifdef HAVE_STDLIB_H
	#include <stdlib.h>
	#endif
	#ifdef HAVE_STRING_H
	#include <string.h>
	#endif

	#include "cpio.h"
	#include "err.h"

	/*
	* Short options for cpio. Please keep this sorted.
	*/
	static const char *short_options = "0AaBC:cdE:F:f:H:hI:iJjLlmnO:opR:rtuVvW:yZz";

	/*
	* Long options for cpio. Please keep this sorted.
	*/
	static const struct option {
	const char *name;
	int required; /* 1 if this option requires an argument */
	int equivalent; /* Equivalent short option. */
	} cpio_longopts[] = {
	{ "b64encode", 0, OPTION_B64ENCODE },
	{ "create", 0, 'o' },
	{ "dot", 0, 'V' },
	{ "extract", 0, 'i' },
	{ "file", 1, 'F' },
	{ "format", 1, 'H' },
	{ "grzip", 0, OPTION_GRZIP },
	{ "help", 0, 'h' },
	{ "insecure", 0, OPTION_INSECURE },
	{ "link", 0, 'l' },
	{ "list", 0, 't' },
	{ "lrzip", 0, OPTION_LRZIP },
	{ "lzma", 0, OPTION_LZMA },
	{ "lzop", 0, OPTION_LZOP },
	{ "make-directories", 0, 'd' },
	{ "no-preserve-owner", 0, OPTION_NO_PRESERVE_OWNER },
	{ "null", 0, '0' },
	{ "numeric-uid-gid", 0, 'n' },
	{ "owner", 1, 'R' },
	{ "pass-through", 0, 'p' },
	{ "preserve-modification-time", 0, 'm' },
	{ "preserve-owner", 0, OPTION_PRESERVE_OWNER },
	{ "quiet", 0, OPTION_QUIET },
	{ "unconditional", 0, 'u' },
	{ "uuencode", 0, OPTION_UUENCODE },
	{ "verbose", 0, 'v' },
	{ "version", 0, OPTION_VERSION },
	{ "xz", 0, 'J' },
	{ NULL, 0, 0 }
	};

	/*
	* I used to try to select platform-provided getopt() or
	* getopt_long(), but that caused a lot of headaches. In particular,
	* I couldn't consistently use long options in the test harness
	* because not all platforms have getopt_long(). That in turn led to
	* overuse of the -W hack in the test harness, which made it rough to
	* run the test harness against GNU cpio. (I periodically run the
	* test harness here against GNU cpio as a sanity-check. Yes,
	* I've found a couple of bugs in GNU cpio that way.)
	*/
	int
	cpio_getopt(struct cpio *cpio)
	{
	enum { state_start = 0, state_next_word, state_short, state_long };
	static int state = state_start;
	static char *opt_word;

	const struct option popt, match = NULL, *match2 = NULL;
	const char p, long_prefix = "--";
	size_t optlength;
	int opt = '?';
	int required = 0;

	cpio->argument = NULL;

	/* First time through, initialize everything. */
	if (state == state_start) {
	/* Skip program name. */
	++cpio->argv;
	--cpio->argc;
	state = state_next_word;
	}

	/*
	* We're ready to look at the next word in argv.
	*/
	if (state == state_next_word) {
	/* No more arguments, so no more options. */
	if (cpio->argv[0] == NULL)
	return (-1);
	/* Doesn't start with '-', so no more options. */
	if (cpio->argv[0][0] != '-')
	return (-1);
	/* "--" marks end of options; consume it and return. */
	if (strcmp(cpio->argv[0], "--") == 0) {
	++cpio->argv;
	--cpio->argc;
	return (-1);
	}
	/* Get next word for parsing. */
	opt_word = *cpio->argv++;
	--cpio->argc;
	if (opt_word[1] == '-') {
	/* Set up long option parser. */
	state = state_long;
	opt_word += 2; /* Skip leading '--' */
	} else {
	/* Set up short option parser. */
	state = state_short;
	++opt_word; /* Skip leading '-' */
	}
	}

	/*
	* We're parsing a group of POSIX-style single-character options.
	*/
	if (state == state_short) {
	/* Peel next option off of a group of short options. */
	opt = *opt_word++;
	if (opt == '\0') {
	/* End of this group; recurse to get next option. */
	state = state_next_word;
	return cpio_getopt(cpio);
	}

	/* Does this option take an argument? */
	p = strchr(short_options, opt);
	if (p == NULL)
	return ('?');
	if (p[1] == ':')
	required = 1;

	/* If it takes an argument, parse that. */
	if (required) {
	/* If arg is run-in, opt_word already points to it. */
	if (opt_word[0] == '\0') {
	/* Otherwise, pick up the next word. */
	opt_word = *cpio->argv;
	if (opt_word == NULL) {
	lafe_warnc(0,
	"Option -%c requires an argument",
	opt);
	return ('?');
	}
	++cpio->argv;
	--cpio->argc;
	}
	if (opt == 'W') {
	state = state_long;
	long_prefix = "-W "; /* For clearer errors. */
	} else {
	state = state_next_word;
	cpio->argument = opt_word;
	}
	}
	}

	/* We're reading a long option, including -W long=arg convention. */
	if (state == state_long) {
	/* After this long option, we'll be starting a new word. */
	state = state_next_word;

	/* Option name ends at '=' if there is one. */
	p = strchr(opt_word, '=');
	if (p != NULL) {
	optlength = (size_t)(p - opt_word);
	cpio->argument = (char *)(uintptr_t)(p + 1);
	} else {
	optlength = strlen(opt_word);
	}

	/* Search the table for an unambiguous match. */
	for (popt = cpio_longopts; popt->name != NULL; popt++) {
	/* Short-circuit if first chars don't match. */
	if (popt->name[0] != opt_word[0])
	continue;
	/* If option is a prefix of name in table, record it.*/
	if (strncmp(opt_word, popt->name, optlength) == 0) {
	match2 = match; /* Record up to two matches. */
	match = popt;
	/* If it's an exact match, we're done. */
	if (strlen(popt->name) == optlength) {
	match2 = NULL; /* Forget the others. */
	break;
	}
	}
	}

	/* Fail if there wasn't a unique match. */
	if (match == NULL) {
	lafe_warnc(0,
	"Option %s%s is not supported",
	long_prefix, opt_word);
	return ('?');
	}
	if (match2 != NULL) {
	lafe_warnc(0,
	"Ambiguous option %s%s (matches --%s and --%s)",
	long_prefix, opt_word, match->name, match2->name);
	return ('?');
	}

	/* We've found a unique match; does it need an argument? */
	if (match->required) {
	/* Argument required: get next word if necessary. */
	if (cpio->argument == NULL) {
	cpio->argument = *cpio->argv;
	if (cpio->argument == NULL) {
	lafe_warnc(0,
	"Option %s%s requires an argument",
	long_prefix, match->name);
	return ('?');
	}
	++cpio->argv;
	--cpio->argc;
	}
	} else {
	/* Argument forbidden: fail if there is one. */
	if (cpio->argument != NULL) {
	lafe_warnc(0,
	"Option %s%s does not allow an argument",
	long_prefix, match->name);
	return ('?');
	}
	}
	return (match->equivalent);
	}

	return (opt);
	}


	/*
	* Parse the argument to the -R or --owner flag.
	*
	* The format is one of the following:
	* <username\|uid> - Override user but not group
	* <username>: - Override both, group is user's default group
	* <uid>: - Override user but not group
	* <username\|uid>:<groupname\|gid> - Override both
	* :<groupname\|gid> - Override group but not user
	*
	* Where uid/gid are decimal representations and groupname/username
	* are names to be looked up in system database. Note that we try
	* to look up an argument as a name first, then try numeric parsing.
	*
	* A period can be used instead of the colon.
	*
	* Sets uid/gid return as appropriate, -1 indicates uid/gid not specified.
	* TODO: If the spec uses uname/gname, then return those to the caller
	* as well. If the spec provides uid/gid, just return names as NULL.
	*
	* Returns NULL if no error, otherwise returns error string for display.
	*
	*/
	const char *
	owner_parse(const char spec, int uid, int *gid)
	{
	static char errbuff[128];
	const char u, ue, *g;

	*uid = -1;
	*gid = -1;

	if (spec[0] == '\0')
	return ("Invalid empty user/group spec");

	/*
	* Split spec into [user][:.][group]
	* u -> first char of username, NULL if no username
	* ue -> first char after username (colon, period, or \0)
	* g -> first char of group name
	*/
	if (spec == ':' \|\| spec == '.') {
	/* If spec starts with ':' or '.', then just group. */
	ue = u = NULL;
	g = spec + 1;
	} else {
	/* Otherwise, [user] or [user][:] or [user][:][group] */
	ue = u = spec;
	while (ue != ':' && ue != '.' && *ue != '\0')
	++ue;
	g = ue;
	if (g != '\0') / Skip : or . to find first char of group. */
	++g;
	}

	if (u != NULL) {
	/* Look up user: ue is first char after end of user. */
	char *user;
	struct passwd *pwent;

	user = (char *)malloc(ue - u + 1);
	if (user == NULL)
	return ("Couldn't allocate memory");
	memcpy(user, u, ue - u);
	user[ue - u] = '\0';
	if ((pwent = getpwnam(user)) != NULL) {
	*uid = pwent->pw_uid;
	if (*ue != '\0')
	*gid = pwent->pw_gid;
	} else {
	char *end;
	errno = 0;
	*uid = (int)strtoul(user, &end, 10);
	if (errno \|\| *end != '\0') {
	snprintf(errbuff, sizeof(errbuff),
	"Couldn't lookup user ``%s''", user);
	errbuff[sizeof(errbuff) - 1] = '\0';
	free(user);
	return (errbuff);
	}
	}
	free(user);
	}

	if (*g != '\0') {
	struct group *grp;
	if ((grp = getgrnam(g)) != NULL) {
	*gid = grp->gr_gid;
	} else {
	char *end;
	errno = 0;
	*gid = (int)strtoul(g, &end, 10);
	if (errno \|\| *end != '\0') {
	snprintf(errbuff, sizeof(errbuff),
	"Couldn't lookup group ``%s''", g);
	errbuff[sizeof(errbuff) - 1] = '\0';
	return (errbuff);
	}
	}
	}
	return (NULL);
	}