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      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 #if HAVE_SECURE_GETENV
     20 #define _GNU_SOURCE
     21 #endif
     22 #include <stdio.h>
     23 #include <stdlib.h>
     24 #include <string.h>
     25 #include <errno.h>
     26 #ifdef HAVE_SYS_PRCTL_H
     27 #include <sys/prctl.h>
     28 #else
     29 #define PR_GET_DUMPABLE 3
     30 #endif
     31 #if (!defined(HAVE_PRCTL) && defined(linux))
     32 #include <sys/syscall.h>
     33 #endif
     34 #ifdef HAVE_SEMAPHORE_H
     35 #include <semaphore.h>
     36 #endif
     37 #if HAVE_UNISTD_H
     38 #include <unistd.h>
     39 #endif
     40 #include <fcntl.h>
     41 #if HAVE_SYS_TYPES_H
     42 #include <sys/types.h>
     43 #endif
     44 #include "com_err.h"
     45 #include "error_table.h"
     46 #include "internal.h"
     47 
     48 #ifdef TLS
     49 #define THREAD_LOCAL static TLS
     50 #else
     51 #define THREAD_LOCAL static
     52 #endif
     53 
     54 THREAD_LOCAL char buffer[25];
     55 
     56 struct et_list * _et_list = (struct et_list *) NULL;
     57 struct et_list * _et_dynamic_list = (struct et_list *) NULL;
     58 
     59 #ifdef __GNUC__
     60 #define COMERR_ATTR(x) __attribute__(x)
     61 #else
     62 #define COMERR_ATTR(x)
     63 #endif
     64 
     65 #ifdef HAVE_SEM_INIT
     66 static sem_t _et_lock;
     67 static int _et_lock_initialized;
     68 
     69 static void COMERR_ATTR((constructor)) setup_et_lock(void)
     70 {
     71 	sem_init(&_et_lock, 0, 1);
     72 	_et_lock_initialized = 1;
     73 }
     74 
     75 static void COMERR_ATTR((destructor)) fini_et_lock(void)
     76 {
     77 	sem_destroy(&_et_lock);
     78 	_et_lock_initialized = 0;
     79 }
     80 #endif
     81 
     82 
     83 int et_list_lock(void)
     84 {
     85 #ifdef HAVE_SEM_INIT
     86 	if (!_et_lock_initialized)
     87 		setup_et_lock();
     88 	return sem_wait(&_et_lock);
     89 #else
     90 	return 0;
     91 #endif
     92 }
     93 
     94 int et_list_unlock(void)
     95 {
     96 #ifdef HAVE_SEM_INIT
     97 	if (_et_lock_initialized)
     98 		return sem_post(&_et_lock);
     99 #endif
    100 	return 0;
    101 }
    102 
    103 typedef char *(*gettextf) (const char *);
    104 
    105 static gettextf com_err_gettext = NULL;
    106 
    107 gettextf set_com_err_gettext(gettextf new_proc)
    108 {
    109     gettextf x = com_err_gettext;
    110 
    111     com_err_gettext = new_proc;
    112 
    113     return x;
    114 }
    115 
    116 
    117 const char * error_message (errcode_t code)
    118 {
    119     int offset;
    120     struct et_list *et;
    121     errcode_t table_num;
    122     int started = 0;
    123     char *cp;
    124 
    125     offset = (int) (code & ((1<<ERRCODE_RANGE)-1));
    126     table_num = code - offset;
    127     if (!table_num) {
    128 #ifdef HAS_SYS_ERRLIST
    129 	if (offset < sys_nerr)
    130 	    return(sys_errlist[offset]);
    131 	else
    132 	    goto oops;
    133 #else
    134 	cp = strerror(offset);
    135 	if (cp)
    136 	    return(cp);
    137 	else
    138 	    goto oops;
    139 #endif
    140     }
    141     et_list_lock();
    142     for (et = _et_list; et; et = et->next) {
    143 	if ((et->table->base & 0xffffffL) == (table_num & 0xffffffL)) {
    144 	    /* This is the right table */
    145 	    if (et->table->n_msgs <= offset) {
    146 		break;
    147 	    } else {
    148 		const char *msg = et->table->msgs[offset];
    149 		et_list_unlock();
    150 		if (com_err_gettext)
    151 		    return (*com_err_gettext)(msg);
    152 		else
    153 		    return msg;
    154 	    }
    155 	}
    156     }
    157     for (et = _et_dynamic_list; et; et = et->next) {
    158 	if ((et->table->base & 0xffffffL) == (table_num & 0xffffffL)) {
    159 	    /* This is the right table */
    160 	    if (et->table->n_msgs <= offset) {
    161 		break;
    162 	    } else {
    163 		const char *msg = et->table->msgs[offset];
    164 		et_list_unlock();
    165 		if (com_err_gettext)
    166 		    return (*com_err_gettext)(msg);
    167 		else
    168 		    return msg;
    169 	    }
    170 	}
    171     }
    172     et_list_unlock();
    173 oops:
    174     strcpy (buffer, "Unknown code ");
    175     if (table_num) {
    176 	strcat (buffer, error_table_name (table_num));
    177 	strcat (buffer, " ");
    178     }
    179     for (cp = buffer; *cp; cp++)
    180 	;
    181     if (offset >= 100) {
    182 	*cp++ = '0' + offset / 100;
    183 	offset %= 100;
    184 	started++;
    185     }
    186     if (started || offset >= 10) {
    187 	*cp++ = '0' + offset / 10;
    188 	offset %= 10;
    189     }
    190     *cp++ = '0' + offset;
    191     *cp = '\0';
    192     return(buffer);
    193 }
    194 
    195 /*
    196  * This routine will only return a value if the we are not running as
    197  * a privileged process.
    198  */
    199 static char *safe_getenv(const char *arg)
    200 {
    201 	if ((getuid() != geteuid()) || (getgid() != getegid()))
    202 		return NULL;
    203 #if HAVE_PRCTL
    204 	if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
    205 		return NULL;
    206 #else
    207 #if (defined(linux) && defined(SYS_prctl))
    208 	if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
    209 		return NULL;
    210 #endif
    211 #endif
    212 
    213 #if defined(HAVE_SECURE_GETENV)
    214 	return secure_getenv(arg);
    215 #elif defined(HAVE___SECURE_GETENV)
    216 	return __secure_getenv(arg);
    217 #else
    218 	return getenv(arg);
    219 #endif
    220 }
    221 
    222 #define DEBUG_INIT	0x8000
    223 #define DEBUG_ADDREMOVE 0x0001
    224 
    225 static int debug_mask = 0;
    226 static FILE *debug_f = 0;
    227 
    228 static void init_debug(void)
    229 {
    230 	char	*dstr, *fn, *tmp;
    231 	int	fd, flags;
    232 
    233 	if (debug_mask & DEBUG_INIT)
    234 		return;
    235 
    236 	dstr = getenv("COMERR_DEBUG");
    237 	if (dstr) {
    238 		debug_mask = strtoul(dstr, &tmp, 0);
    239 		if (*tmp || errno)
    240 			debug_mask = 0;
    241 	}
    242 
    243 	debug_mask |= DEBUG_INIT;
    244 	if (debug_mask == DEBUG_INIT)
    245 		return;
    246 
    247 	fn = safe_getenv("COMERR_DEBUG_FILE");
    248 	if (fn)
    249 		debug_f = fopen(fn, "a");
    250 	if (!debug_f)
    251 		debug_f = fopen("/dev/tty", "a");
    252 	if (debug_f) {
    253 		fd = fileno(debug_f);
    254 		if (fd >= 0) {
    255 			flags = fcntl(fd, F_GETFD);
    256 			if (flags >= 0)
    257 				fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
    258 		}
    259 	} else
    260 		debug_mask = DEBUG_INIT;
    261 
    262 }
    263 
    264 /*
    265  * New interface provided by krb5's com_err library
    266  */
    267 errcode_t add_error_table(const struct error_table * et)
    268 {
    269 	struct et_list *el;
    270 
    271 	if (!(el = (struct et_list *) malloc(sizeof(struct et_list))))
    272 		return ENOMEM;
    273 
    274 	if (et_list_lock() != 0) {
    275 		free(el);
    276 		return errno;
    277 	}
    278 
    279 	el->table = et;
    280 	el->next = _et_dynamic_list;
    281 	_et_dynamic_list = el;
    282 
    283 	init_debug();
    284 	if (debug_mask & DEBUG_ADDREMOVE)
    285 		fprintf(debug_f, "add_error_table: %s (0x%p)\n",
    286 			error_table_name(et->base),
    287 			(const void *) et);
    288 
    289 	et_list_unlock();
    290 	return 0;
    291 }
    292 
    293 /*
    294  * New interface provided by krb5's com_err library
    295  */
    296 errcode_t remove_error_table(const struct error_table * et)
    297 {
    298 	struct et_list *el;
    299 	struct et_list *el2 = 0;
    300 
    301 	if (et_list_lock() != 0)
    302 		return ENOENT;
    303 
    304 	el = _et_dynamic_list;
    305 	init_debug();
    306 	while (el) {
    307 		if (el->table->base == et->base) {
    308 			if (el2)	/* Not the beginning of the list */
    309 				el2->next = el->next;
    310 			else
    311 				_et_dynamic_list = el->next;
    312 			(void) free(el);
    313 			if (debug_mask & DEBUG_ADDREMOVE)
    314 				fprintf(debug_f,
    315 					"remove_error_table: %s (0x%p)\n",
    316 					error_table_name(et->base),
    317 					(const void *) et);
    318 			et_list_unlock();
    319 			return 0;
    320 		}
    321 		el2 = el;
    322 		el = el->next;
    323 	}
    324 	if (debug_mask & DEBUG_ADDREMOVE)
    325 		fprintf(debug_f, "remove_error_table FAILED: %s (0x%p)\n",
    326 			error_table_name(et->base),
    327 			(const void *) et);
    328 	et_list_unlock();
    329 	return ENOENT;
    330 }
    331 
    332 /*
    333  * Variant of the interface provided by Heimdal's com_err library
    334  */
    335 void
    336 add_to_error_table(struct et_list *new_table)
    337 {
    338 	add_error_table(new_table->table);
    339 }
    340