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+/* userspec.c -- Parse a user and group string.
+ Copyright (C) 1989-1992, 1997-1998, 2000, 2002-2023 Free Software
+ Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* Written by David MacKenzie <djm@gnu.ai.mit.edu>. */
+
+#include <config.h>
+
+/* Specification. */
+#include "userspec.h"
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+
+#if HAVE_SYS_PARAM_H
+# include <sys/param.h>
+#endif
+
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <unistd.h>
+
+#include "intprops.h"
+#include "inttostr.h"
+#include "xalloc.h"
+#include "xstrtol.h"
+
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+#define N_(msgid) msgid
+
+#ifndef HAVE_ENDGRENT
+# define endgrent() ((void) 0)
+#endif
+
+#ifndef HAVE_ENDPWENT
+# define endpwent() ((void) 0)
+#endif
+
+#ifndef UID_T_MAX
+# define UID_T_MAX TYPE_MAXIMUM (uid_t)
+#endif
+
+#ifndef GID_T_MAX
+# define GID_T_MAX TYPE_MAXIMUM (gid_t)
+#endif
+
+/* MAXUID may come from limits.h or sys/params.h. */
+#ifndef MAXUID
+# define MAXUID UID_T_MAX
+#endif
+#ifndef MAXGID
+# define MAXGID GID_T_MAX
+#endif
+
+#ifdef __DJGPP__
+
+/* ISDIGIT differs from isdigit, as follows:
+ - Its arg may be any int or unsigned int; it need not be an unsigned char
+ or EOF.
+ - It's typically faster.
+ POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to
+ isdigit unless it's important to use the locale's definition
+ of "digit" even when the host does not conform to POSIX. */
+# define ISDIGIT(c) ((unsigned int) (c) - '0' <= 9)
+
+/* Return true if STR represents an unsigned decimal integer. */
+
+static bool
+is_number (const char *str)
+{
+ do
+ {
+ if (!ISDIGIT (*str))
+ return false;
+ }
+ while (*++str);
+
+ return true;
+}
+#endif
+
+static char const *
+parse_with_separator (char const *spec, char const *separator,
+ uid_t *uid, gid_t *gid,
+ char **username, char **groupname)
+{
+ const char *error_msg;
+ struct passwd *pwd;
+ struct group *grp;
+ char *u;
+ char const *g;
+ char *gname = NULL;
+ uid_t unum = *uid;
+ gid_t gnum = gid ? *gid : -1;
+
+ error_msg = NULL;
+ if (username)
+ *username = NULL;
+ if (groupname)
+ *groupname = NULL;
+
+ /* Set U and G to nonzero length strings corresponding to user and
+ group specifiers or to NULL. If U is not NULL, it is a newly
+ allocated string. */
+
+ u = NULL;
+ if (separator == NULL)
+ {
+ if (*spec)
+ u = xstrdup (spec);
+ }
+ else
+ {
+ idx_t ulen = separator - spec;
+ if (ulen != 0)
+ {
+ u = ximemdup (spec, ulen + 1);
+ u[ulen] = '\0';
+ }
+ }
+
+ g = (separator == NULL || *(separator + 1) == '\0'
+ ? NULL
+ : separator + 1);
+
+#ifdef __DJGPP__
+ /* Pretend that we are the user U whose group is G. This makes
+ pwd and grp functions "know" about the UID and GID of these. */
+ if (u && !is_number (u))
+ setenv ("USER", u, 1);
+ if (g && !is_number (g))
+ setenv ("GROUP", g, 1);
+#endif
+
+ if (u != NULL)
+ {
+ /* If it starts with "+", skip the look-up. */
+ pwd = (*u == '+' ? NULL : getpwnam (u));
+ if (pwd == NULL)
+ {
+ username = NULL;
+ bool use_login_group = (separator != NULL && g == NULL);
+ if (use_login_group)
+ {
+ /* If there is no group,
+ then there may not be a trailing ":", either. */
+ error_msg = N_("invalid spec");
+ }
+ else
+ {
+ unsigned long int tmp;
+ if (xstrtoul (u, NULL, 10, &tmp, "") == LONGINT_OK
+ && tmp <= MAXUID && (uid_t) tmp != (uid_t) -1)
+ unum = tmp;
+ else
+ error_msg = N_("invalid user");
+ }
+ }
+ else
+ {
+ unum = pwd->pw_uid;
+ if (g == NULL && separator != NULL)
+ {
+ /* A separator was given, but a group was not specified,
+ so get the login group. */
+ char buf[INT_BUFSIZE_BOUND (uintmax_t)];
+ gnum = pwd->pw_gid;
+ grp = getgrgid (gnum);
+ gname = xstrdup (grp ? grp->gr_name : umaxtostr (gnum, buf));
+ endgrent ();
+ }
+ }
+ endpwent ();
+ }
+
+ if (g != NULL && error_msg == NULL)
+ {
+ /* Explicit group. */
+ /* If it starts with "+", skip the look-up. */
+ grp = (*g == '+' ? NULL : getgrnam (g));
+ if (grp == NULL)
+ {
+ groupname = NULL;
+ unsigned long int tmp;
+ if (xstrtoul (g, NULL, 10, &tmp, "") == LONGINT_OK
+ && tmp <= MAXGID && (gid_t) tmp != (gid_t) -1)
+ gnum = tmp;
+ else
+ error_msg = N_("invalid group");
+ }
+ else
+ gnum = grp->gr_gid;
+ endgrent (); /* Save a file descriptor. */
+ gname = xstrdup (g);
+ }
+
+ if (error_msg == NULL)
+ {
+ *uid = unum;
+ if (gid)
+ *gid = gnum;
+ if (username)
+ {
+ *username = u;
+ u = NULL;
+ }
+ if (groupname)
+ {
+ *groupname = gname;
+ gname = NULL;
+ }
+ }
+
+ free (u);
+ free (gname);
+ return error_msg ? _(error_msg) : NULL;
+}
+
+/* Extract from SPEC, which has the form "[user][:.][group]",
+ a USERNAME, UID U, GROUPNAME, and GID G.
+ If the GID parameter is NULL the entire SPEC is treated as a user.
+ If the USERNAME and GROUPNAME parameters are NULL they're ignored.
+ Either user or group, or both, must be present.
+ If the group is omitted but the separator is given,
+ use the given user's login group.
+ If SPEC contains a ':', then use that as the separator, ignoring
+ any '.'s. If there is no ':', but there is a '.', then first look
+ up the entire SPEC as a login name. If that look-up fails, then
+ try again interpreting the '.' as a separator.
+
+ USERNAME and GROUPNAME will be in newly malloc'd memory.
+ Either one might be NULL instead, indicating that it was not
+ given and the corresponding numeric ID was left unchanged.
+
+ Return NULL if successful, a static error message string if not.
+ If PWARN is null, return NULL instead of a warning;
+ otherwise, set *PWARN to true depending on whether returning a warning. */
+
+char const *
+parse_user_spec_warn (char const *spec, uid_t *uid, gid_t *gid,
+ char **username, char **groupname, bool *pwarn)
+{
+ char const *colon = gid ? strchr (spec, ':') : NULL;
+ char const *error_msg =
+ parse_with_separator (spec, colon, uid, gid, username, groupname);
+ bool warn = false;
+
+ if (gid && !colon && error_msg)
+ {
+ /* If there's no colon but there is a dot, and if looking up the
+ whole spec failed (i.e., the spec is not an owner name that
+ includes a dot), then try again, but interpret the dot as a
+ separator. This is a compatible extension to POSIX, since
+ the POSIX-required behavior is always tried first. */
+
+ char const *dot = strchr (spec, '.');
+ if (dot
+ && ! parse_with_separator (spec, dot, uid, gid, username, groupname))
+ {
+ warn = true;
+ error_msg = pwarn ? N_("warning: '.' should be ':'") : NULL;
+ }
+ }
+
+ if (pwarn)
+ *pwarn = warn;
+ return error_msg;
+}
+
+/* Like parse_user_spec_warn, but generate only errors; no warnings. */
+
+char const *
+parse_user_spec (char const *spec, uid_t *uid, gid_t *gid,
+ char **username, char **groupname)
+{
+ return parse_user_spec_warn (spec, uid, gid, username, groupname, NULL);
+}
+
+#ifdef TEST
+
+# define NULL_CHECK(s) ((s) == NULL ? "(null)" : (s))
+
+int
+main (int argc, char **argv)
+{
+ int i;
+
+ for (i = 1; i < argc; i++)
+ {
+ const char *e;
+ char *username, *groupname;
+ uid_t uid;
+ gid_t gid;
+ char *tmp;
+
+ tmp = strdup (argv[i]);
+ e = parse_user_spec (tmp, &uid, &gid, &username, &groupname);
+ free (tmp);
+ printf ("%s: %lu %lu %s %s %s\n",
+ argv[i],
+ (unsigned long int) uid,
+ (unsigned long int) gid,
+ NULL_CHECK (username),
+ NULL_CHECK (groupname),
+ NULL_CHECK (e));
+ }
+
+ exit (0);
+}
+
+#endif
+
+/*
+Local Variables:
+indent-tabs-mode: nil
+End:
+*/
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