error_message.c revision a6ce1349539f866334ef3d5758bc2ee44a454acd 
1/*
2 * $Header$
3 * $Source$
4 * $Locker$
5 *
6 * Copyright 1987 by the Student Information Processing Board
7 * of the Massachusetts Institute of Technology
8 *
9 * Permission to use, copy, modify, and distribute this software and
10 * its documentation for any purpose is hereby granted, provided that
11 * the names of M.I.T. and the M.I.T. S.I.P.B. not be used in
12 * advertising or publicity pertaining to distribution of the software
13 * without specific, written prior permission.  M.I.T. and the
14 * M.I.T. S.I.P.B. make no representations about the suitability of
15 * this software for any purpose.  It is provided "as is" without
16 * express or implied warranty.
17 */
18
19#include <stdio.h>
20#include <stdlib.h>
21#include <string.h>
22#include <errno.h>
23#ifdef HAVE_SYS_PRCTL_H
24#include <sys/prctl.h>
25#else
26#define PR_GET_DUMPABLE 3
27#endif
28#if (!defined(HAVE_PRCTL) && defined(linux))
29#include <sys/syscall.h>
30#endif
31#ifdef HAVE_SEMAPHORE_H
32#include <semaphore.h>
33#endif
34#if HAVE_UNISTD_H
35#include <unistd.h>
36#endif
37#include <fcntl.h>
38#if HAVE_SYS_TYPES_H
39#include <sys/types.h>
40#endif
41#include "com_err.h"
42#include "error_table.h"
43#include "internal.h"
44
45#ifdef TLS
46#define THREAD_LOCAL static TLS
47#else
48#define THREAD_LOCAL static
49#endif
50
51THREAD_LOCAL char buffer[25];
52
53struct et_list * _et_list = (struct et_list *) NULL;
54struct et_list * _et_dynamic_list = (struct et_list *) NULL;
55
56#ifdef __GNUC__
57#define COMERR_ATTR(x) __attribute__(x)
58#else
59#define COMERR_ATTR(x)
60#endif
61
62#ifdef HAVE_SEM_INIT
63static sem_t _et_lock;
64static int _et_lock_initialized;
65
66static void COMERR_ATTR((constructor)) setup_et_lock(void)
67{
68	sem_init(&_et_lock, 0, 1);
69	_et_lock_initialized = 1;
70}
71
72static void COMERR_ATTR((destructor)) fini_et_lock(void)
73{
74	sem_destroy(&_et_lock);
75	_et_lock_initialized = 0;
76}
77#endif
78
79
80int et_list_lock(void)
81{
82#ifdef HAVE_SEM_INIT
83	if (!_et_lock_initialized)
84		setup_et_lock();
85	return sem_wait(&_et_lock);
86#else
87	return 0;
88#endif
89}
90
91int et_list_unlock(void)
92{
93#ifdef HAVE_SEM_INIT
94	if (_et_lock_initialized)
95		return sem_post(&_et_lock);
96#endif
97	return 0;
98}
99
100const char * error_message (errcode_t code)
101{
102    int offset;
103    struct et_list *et;
104    errcode_t table_num;
105    int started = 0;
106    char *cp;
107
108    offset = (int) (code & ((1<<ERRCODE_RANGE)-1));
109    table_num = code - offset;
110    if (!table_num) {
111#ifdef HAS_SYS_ERRLIST
112	if (offset < sys_nerr)
113	    return(sys_errlist[offset]);
114	else
115	    goto oops;
116#else
117	cp = strerror(offset);
118	if (cp)
119	    return(cp);
120	else
121	    goto oops;
122#endif
123    }
124    et_list_lock();
125    for (et = _et_list; et; et = et->next) {
126	if ((et->table->base & 0xffffffL) == (table_num & 0xffffffL)) {
127	    /* This is the right table */
128	    if (et->table->n_msgs <= offset) {
129		break;
130	    } else {
131		const char *msg = et->table->msgs[offset];
132		et_list_unlock();
133		return msg;
134	    }
135	}
136    }
137    for (et = _et_dynamic_list; et; et = et->next) {
138	if ((et->table->base & 0xffffffL) == (table_num & 0xffffffL)) {
139	    /* This is the right table */
140	    if (et->table->n_msgs <= offset) {
141		break;
142	    } else {
143		const char *msg = et->table->msgs[offset];
144		et_list_unlock();
145		return msg;
146	    }
147	}
148    }
149    et_list_unlock();
150oops:
151    strcpy (buffer, "Unknown code ");
152    if (table_num) {
153	strcat (buffer, error_table_name (table_num));
154	strcat (buffer, " ");
155    }
156    for (cp = buffer; *cp; cp++)
157	;
158    if (offset >= 100) {
159	*cp++ = '0' + offset / 100;
160	offset %= 100;
161	started++;
162    }
163    if (started || offset >= 10) {
164	*cp++ = '0' + offset / 10;
165	offset %= 10;
166    }
167    *cp++ = '0' + offset;
168    *cp = '\0';
169    return(buffer);
170}
171
172/*
173 * This routine will only return a value if the we are not running as
174 * a privileged process.
175 */
176static char *safe_getenv(const char *arg)
177{
178	if ((getuid() != geteuid()) || (getgid() != getegid()))
179		return NULL;
180#if HAVE_PRCTL
181	if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
182		return NULL;
183#else
184#if (defined(linux) && defined(SYS_prctl))
185	if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
186		return NULL;
187#endif
188#endif
189
190#ifdef HAVE___SECURE_GETENV
191	return __secure_getenv(arg);
192#else
193	return getenv(arg);
194#endif
195}
196
197#define DEBUG_INIT	0x8000
198#define DEBUG_ADDREMOVE 0x0001
199
200static int debug_mask = 0;
201static FILE *debug_f = 0;
202
203static void init_debug(void)
204{
205	char	*dstr, *fn, *tmp;
206	int	fd, flags;
207
208	if (debug_mask & DEBUG_INIT)
209		return;
210
211	dstr = getenv("COMERR_DEBUG");
212	if (dstr) {
213		debug_mask = strtoul(dstr, &tmp, 0);
214		if (*tmp || errno)
215			debug_mask = 0;
216	}
217
218	debug_mask |= DEBUG_INIT;
219	if (debug_mask == DEBUG_INIT)
220		return;
221
222	fn = safe_getenv("COMERR_DEBUG_FILE");
223	if (fn)
224		debug_f = fopen(fn, "a");
225	if (!debug_f)
226		debug_f = fopen("/dev/tty", "a");
227	if (debug_f) {
228		fd = fileno(debug_f);
229		if (fd >= 0) {
230			flags = fcntl(fd, F_GETFD);
231			if (flags >= 0)
232				fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
233		}
234	} else
235		debug_mask = DEBUG_INIT;
236
237}
238
239/*
240 * New interface provided by krb5's com_err library
241 */
242errcode_t add_error_table(const struct error_table * et)
243{
244	struct et_list *el;
245
246	if (!(el = (struct et_list *) malloc(sizeof(struct et_list))))
247		return ENOMEM;
248
249	if (et_list_lock() != 0) {
250		free(el);
251		return errno;
252	}
253
254	el->table = et;
255	el->next = _et_dynamic_list;
256	_et_dynamic_list = el;
257
258	init_debug();
259	if (debug_mask & DEBUG_ADDREMOVE)
260		fprintf(debug_f, "add_error_table: %s (0x%p)\n",
261			error_table_name(et->base),
262			(const void *) et);
263
264	et_list_unlock();
265	return 0;
266}
267
268/*
269 * New interface provided by krb5's com_err library
270 */
271errcode_t remove_error_table(const struct error_table * et)
272{
273	struct et_list *el;
274	struct et_list *el2 = 0;
275
276	if (et_list_lock() != 0)
277		return ENOENT;
278
279	el = _et_dynamic_list;
280	init_debug();
281	while (el) {
282		if (el->table->base == et->base) {
283			if (el2)	/* Not the beginning of the list */
284				el2->next = el->next;
285			else
286				_et_dynamic_list = el->next;
287			(void) free(el);
288			if (debug_mask & DEBUG_ADDREMOVE)
289				fprintf(debug_f,
290					"remove_error_table: %s (0x%p)\n",
291					error_table_name(et->base),
292					(const void *) et);
293			et_list_unlock();
294			return 0;
295		}
296		el2 = el;
297		el = el->next;
298	}
299	if (debug_mask & DEBUG_ADDREMOVE)
300		fprintf(debug_f, "remove_error_table FAILED: %s (0x%p)\n",
301			error_table_name(et->base),
302			(const void *) et);
303	et_list_unlock();
304	return ENOENT;
305}
306
307/*
308 * Variant of the interface provided by Heimdal's com_err library
309 */
310void
311add_to_error_table(struct et_list *new_table)
312{
313	add_error_table(new_table->table);
314}
315