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comparison lib/idcache.c @ 5:41c9d08b09d7

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Initial revision
author Jim Meyering <jim@meyering.net>
date Sat, 31 Oct 1992 20:42:48 +0000
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children 395da10fb137 b4ef1c1a0171
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4:9087e62f9efd 5:41c9d08b09d7
1 /* idcache.c -- map user and group IDs, cached for speed
2 Copyright (C) 1985, 1988, 1989, 1990 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
17
18 #include <stdio.h>
19 #include <sys/types.h>
20 #include <pwd.h>
21 #include <grp.h>
22
23 #if defined(USG) || defined(STDC_HEADERS)
24 #include <string.h>
25 #else
26 #include <strings.h>
27 #endif
28
29 #ifdef HAVE_UNISTD_H
30 #include <unistd.h>
31 #endif
32 #ifndef _POSIX_VERSION
33 struct passwd *getpwuid ();
34 struct passwd *getpwnam ();
35 struct group *getgrgid ();
36 struct group *getgrnam ();
37 #endif
38
39 char *xmalloc ();
40 char *xstrdup ();
41
42 struct userid
43 {
44 union
45 {
46 uid_t u;
47 gid_t g;
48 } id;
49 char *name;
50 struct userid *next;
51 };
52
53 static struct userid *user_alist;
54
55 /* The members of this list have names not in the local passwd file. */
56 static struct userid *nouser_alist;
57
58 /* Translate UID to a login name or a stringified number,
59 with cache. */
60
61 char *
62 getuser (uid)
63 uid_t uid;
64 {
65 register struct userid *tail;
66 struct passwd *pwent;
67 char usernum_string[20];
68
69 for (tail = user_alist; tail; tail = tail->next)
70 if (tail->id.u == uid)
71 return tail->name;
72
73 pwent = getpwuid (uid);
74 tail = (struct userid *) xmalloc (sizeof (struct userid));
75 tail->id.u = uid;
76 if (pwent == 0)
77 {
78 sprintf (usernum_string, "%u", (unsigned) uid);
79 tail->name = xstrdup (usernum_string);
80 }
81 else
82 tail->name = xstrdup (pwent->pw_name);
83
84 /* Add to the head of the list, so most recently used is first. */
85 tail->next = user_alist;
86 user_alist = tail;
87 return tail->name;
88 }
89
90 /* Translate USER to a UID, with cache.
91 Return NULL if there is no such user.
92 (We also cache which user names have no passwd entry,
93 so we don't keep looking them up.) */
94
95 uid_t *
96 getuidbyname (user)
97 char *user;
98 {
99 register struct userid *tail;
100 struct passwd *pwent;
101
102 for (tail = user_alist; tail; tail = tail->next)
103 /* Avoid a function call for the most common case. */
104 if (*tail->name == *user && !strcmp (tail->name, user))
105 return &tail->id.u;
106
107 for (tail = nouser_alist; tail; tail = tail->next)
108 /* Avoid a function call for the most common case. */
109 if (*tail->name == *user && !strcmp (tail->name, user))
110 return 0;
111
112 pwent = getpwnam (user);
113
114 tail = (struct userid *) xmalloc (sizeof (struct userid));
115 tail->name = xstrdup (user);
116
117 /* Add to the head of the list, so most recently used is first. */
118 if (pwent)
119 {
120 tail->id.u = pwent->pw_uid;
121 tail->next = user_alist;
122 user_alist = tail;
123 return &tail->id.u;
124 }
125
126 tail->next = nouser_alist;
127 nouser_alist = tail;
128 return 0;
129 }
130
131 /* Use the same struct as for userids. */
132 static struct userid *group_alist;
133 static struct userid *nogroup_alist;
134
135 /* Translate GID to a group name or a stringified number,
136 with cache. */
137
138 char *
139 getgroup (gid)
140 gid_t gid;
141 {
142 register struct userid *tail;
143 struct group *grent;
144 char groupnum_string[20];
145
146 for (tail = group_alist; tail; tail = tail->next)
147 if (tail->id.g == gid)
148 return tail->name;
149
150 grent = getgrgid (gid);
151 tail = (struct userid *) xmalloc (sizeof (struct userid));
152 tail->id.g = gid;
153 if (grent == 0)
154 {
155 sprintf (groupnum_string, "%u", (unsigned int) gid);
156 tail->name = xstrdup (groupnum_string);
157 }
158 else
159 tail->name = xstrdup (grent->gr_name);
160
161 /* Add to the head of the list, so most recently used is first. */
162 tail->next = group_alist;
163 group_alist = tail;
164 return tail->name;
165 }
166
167 /* Translate GROUP to a UID, with cache.
168 Return NULL if there is no such group.
169 (We also cache which group names have no group entry,
170 so we don't keep looking them up.) */
171
172 gid_t *
173 getgidbyname (group)
174 char *group;
175 {
176 register struct userid *tail;
177 struct group *grent;
178
179 for (tail = group_alist; tail; tail = tail->next)
180 /* Avoid a function call for the most common case. */
181 if (*tail->name == *group && !strcmp (tail->name, group))
182 return &tail->id.g;
183
184 for (tail = nogroup_alist; tail; tail = tail->next)
185 /* Avoid a function call for the most common case. */
186 if (*tail->name == *group && !strcmp (tail->name, group))
187 return 0;
188
189 grent = getgrnam (group);
190
191 tail = (struct userid *) xmalloc (sizeof (struct userid));
192 tail->name = xstrdup (group);
193
194 /* Add to the head of the list, so most recently used is first. */
195 if (grent)
196 {
197 tail->id.g = grent->gr_gid;
198 tail->next = group_alist;
199 group_alist = tail;
200 return &tail->id.g;
201 }
202
203 tail->next = nogroup_alist;
204 nogroup_alist = tail;
205 return 0;
206 }