error_message.c revision d7f45af802330a0e1450afa05185d3722e77a76c 
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#if HAVE_SYS_TYPES_H
38#include <sys/types.h>
39#endif
40#include "com_err.h"
41#include "error_table.h"
42#include "internal.h"
43
44#ifdef TLS
45#define THREAD_LOCAL static TLS
46#else
47#define THREAD_LOCAL static
48#endif
49
50THREAD_LOCAL char buffer[25];
51
52struct et_list * _et_list = (struct et_list *) NULL;
53struct et_list * _et_dynamic_list = (struct et_list *) NULL;
54
55#ifdef __GNUC__
56#define COMERR_ATTR(x) __attribute__(x)
57#else
58#define COMERR_ATTR(x)
59#endif
60
61#ifdef HAVE_SEM_INIT
62static sem_t _et_lock;
63static _et_lock_initialized;
64
65static COMERR_ATTR((constructor)) setup_et_lock()
66{
67	sem_init(&_et_lock, 0, 1);
68	_et_lock_initialized = 1;
69}
70
71static COMERR_ATTR((destructor)) fini_et_lock()
72{
73	sem_destroy(&_et_lock);
74	_et_lock_initialized = 0;
75}
76#endif
77
78
79int et_list_lock()
80{
81#ifdef HAVE_SEM_INIT
82	if (!_et_lock_initialized)
83		setup_et_lock();
84	return sem_wait(&_et_lock);
85#else
86	return 0;
87#endif
88}
89
90int et_list_unlock()
91{
92#ifdef HAVE_SEM_INIT
93	if (_et_lock_initialized)
94		return sem_post(&_et_lock);
95#endif
96	return 0;
97}
98
99const char * error_message (errcode_t code)
100{
101    int offset;
102    struct et_list *et;
103    errcode_t table_num;
104    int started = 0;
105    char *cp;
106
107    offset = (int) (code & ((1<<ERRCODE_RANGE)-1));
108    table_num = code - offset;
109    if (!table_num) {
110#ifdef HAS_SYS_ERRLIST
111	if (offset < sys_nerr)
112	    return(sys_errlist[offset]);
113	else
114	    goto oops;
115#else
116	cp = strerror(offset);
117	if (cp)
118	    return(cp);
119	else
120	    goto oops;
121#endif
122    }
123    et_list_lock();
124    for (et = _et_list; et; et = et->next) {
125	if ((et->table->base & 0xffffffL) == (table_num & 0xffffffL)) {
126	    /* This is the right table */
127	    if (et->table->n_msgs <= offset) {
128		break;
129	    } else {
130		const char *msg = et->table->msgs[offset];
131		et_list_unlock();
132		return msg;
133	    }
134	}
135    }
136    for (et = _et_dynamic_list; et; et = et->next) {
137	if ((et->table->base & 0xffffffL) == (table_num & 0xffffffL)) {
138	    /* This is the right table */
139	    if (et->table->n_msgs <= offset) {
140		break;
141	    } else {
142		const char *msg = et->table->msgs[offset];
143		et_list_unlock();
144		return msg;
145	    }
146	}
147    }
148    et_list_unlock();
149oops:
150    strcpy (buffer, "Unknown code ");
151    if (table_num) {
152	strcat (buffer, error_table_name (table_num));
153	strcat (buffer, " ");
154    }
155    for (cp = buffer; *cp; cp++)
156	;
157    if (offset >= 100) {
158	*cp++ = '0' + offset / 100;
159	offset %= 100;
160	started++;
161    }
162    if (started || offset >= 10) {
163	*cp++ = '0' + offset / 10;
164	offset %= 10;
165    }
166    *cp++ = '0' + offset;
167    *cp = '\0';
168    return(buffer);
169}
170
171/*
172 * This routine will only return a value if the we are not running as
173 * a privileged process.
174 */
175static char *safe_getenv(const char *arg)
176{
177	if ((getuid() != geteuid()) || (getgid() != getegid()))
178		return NULL;
179#if HAVE_PRCTL
180	if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
181		return NULL;
182#else
183#if (defined(linux) && defined(SYS_prctl))
184	if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
185		return NULL;
186#endif
187#endif
188
189#ifdef HAVE___SECURE_GETENV
190	return __secure_getenv(arg);
191#else
192	return getenv(arg);
193#endif
194}
195
196#define DEBUG_INIT	0x8000
197#define DEBUG_ADDREMOVE 0x0001
198
199static int debug_mask = 0;
200static FILE *debug_f = 0;
201
202static void init_debug(void)
203{
204	char *dstr;
205	char *fn;
206
207	if (debug_mask & DEBUG_INIT)
208		return;
209
210	dstr = getenv("COMERR_DEBUG");
211	if (dstr)
212		debug_mask = strtoul(dstr, 0, 0);
213
214	fn = safe_getenv("COMERR_DEBUG_FILE");
215	if (fn)
216		debug_f = fopen(fn, "a");
217	if (!debug_f)
218		debug_f = fopen("/dev/tty", "a");
219	if (!debug_f)
220		debug_mask = 0;
221
222	debug_mask |= DEBUG_INIT;
223}
224
225/*
226 * New interface provided by krb5's com_err library
227 */
228errcode_t add_error_table(const struct error_table * et)
229{
230	struct et_list *el;
231
232	if (!(el = (struct et_list *) malloc(sizeof(struct et_list))))
233		return ENOMEM;
234
235	if (et_list_lock() != 0) {
236		free(el);
237		return errno;
238	}
239
240	el->table = et;
241	el->next = _et_dynamic_list;
242	_et_dynamic_list = el;
243
244	init_debug();
245	if (debug_mask & DEBUG_ADDREMOVE)
246		fprintf(debug_f, "add_error_table: %s (0x%p)\n",
247			error_table_name(et->base),
248			(const void *) et);
249
250	et_list_unlock();
251	return 0;
252}
253
254/*
255 * New interface provided by krb5's com_err library
256 */
257errcode_t remove_error_table(const struct error_table * et)
258{
259	struct et_list *el;
260	struct et_list *el2 = 0;
261
262	if (et_list_lock() != 0)
263		return ENOENT;
264
265	el = _et_dynamic_list;
266	init_debug();
267	while (el) {
268		if (el->table->base == et->base) {
269			if (el2)	/* Not the beginning of the list */
270				el2->next = el->next;
271			else
272				_et_dynamic_list = el->next;
273			(void) free(el);
274			if (debug_mask & DEBUG_ADDREMOVE)
275				fprintf(debug_f,
276					"remove_error_table: %s (0x%p)\n",
277					error_table_name(et->base),
278					(const void *) et);
279			et_list_unlock();
280			return 0;
281		}
282		el2 = el;
283		el = el->next;
284	}
285	if (debug_mask & DEBUG_ADDREMOVE)
286		fprintf(debug_f, "remove_error_table FAILED: %s (0x%p)\n",
287			error_table_name(et->base),
288			(const void *) et);
289	et_list_unlock();
290	return ENOENT;
291}
292
293/*
294 * Variant of the interface provided by Heimdal's com_err library
295 */
296void
297add_to_error_table(struct et_list *new_table)
298{
299	add_error_table(new_table->table);
300}
301