load.c revision 1.8
1 /* $NetBSD: load.c,v 1.8 1999/12/13 10:47:38 christos Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by John Polstra. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 /* 35 * Dynamic linker for ELF. 36 * 37 * John Polstra <jdp (at) polstra.com>. 38 */ 39 40 #include <err.h> 41 #include <errno.h> 42 #include <fcntl.h> 43 #include <stdarg.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <unistd.h> 48 #include <sys/types.h> 49 #include <sys/param.h> 50 #include <sys/mman.h> 51 #include <sys/sysctl.h> 52 #include <dirent.h> 53 54 #include "debug.h" 55 #include "rtld.h" 56 57 static bool _rtld_load_by_name __P((const char *, Obj_Entry *, Needed_Entry **, 58 bool)); 59 60 /* 61 * Load a shared object into memory, if it is not already loaded. The 62 * argument must be a string allocated on the heap. This function assumes 63 * responsibility for freeing it when necessary. 64 * 65 * Returns a pointer to the Obj_Entry for the object. Returns NULL 66 * on failure. 67 */ 68 Obj_Entry * 69 _rtld_load_object(filepath, dodebug) 70 char *filepath; 71 bool dodebug; 72 { 73 Obj_Entry *obj; 74 int fd = -1; 75 struct stat sb; 76 77 for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next) 78 if (strcmp(obj->path, filepath) == 0) 79 break; 80 81 /* 82 * If we didn't find a match by pathname, open the file and check 83 * again by device and inode. This avoids false mismatches caused 84 * by multiple links or ".." in pathnames. 85 * 86 * To avoid a race, we open the file and use fstat() rather than 87 * using stat(). 88 */ 89 if (obj == NULL) { 90 if ((fd = open(filepath, O_RDONLY)) == -1) { 91 _rtld_error("Cannot open \"%s\"", filepath); 92 return NULL; 93 } 94 if (fstat(fd, &sb) == -1) { 95 _rtld_error("Cannot fstat \"%s\"", filepath); 96 close(fd); 97 return NULL; 98 } 99 for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next) { 100 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 101 close(fd); 102 break; 103 } 104 } 105 } 106 107 if (obj == NULL) { /* First use of this object, so we must map it in */ 108 obj = _rtld_map_object(filepath, fd, &sb); 109 (void)close(fd); 110 if (obj == NULL) { 111 free(filepath); 112 return NULL; 113 } 114 obj->path = filepath; 115 _rtld_digest_dynamic(obj); 116 117 *_rtld_objtail = obj; 118 _rtld_objtail = &obj->next; 119 #ifdef RTLD_LOADER 120 _rtld_linkmap_add(obj); /* for GDB */ 121 #endif 122 if (dodebug) { 123 dbg((" %p .. %p: %s", obj->mapbase, 124 obj->mapbase + obj->mapsize - 1, obj->path)); 125 if (obj->textrel) 126 dbg((" WARNING: %s has impure text", 127 obj->path)); 128 } 129 } else 130 free(filepath); 131 132 ++obj->refcount; 133 return obj; 134 } 135 136 static bool 137 _rtld_load_by_name(name, obj, needed, dodebug) 138 const char *name; 139 Obj_Entry *obj; 140 Needed_Entry **needed; 141 bool dodebug; 142 { 143 Library_Xform *x = _rtld_xforms; 144 Obj_Entry *o = NULL; 145 size_t i, j; 146 int ctlname[2]; 147 char *libpath; 148 bool got = false; 149 union { 150 int i; 151 char s[16]; 152 } val; 153 154 ctlname[0] = CTL_MACHDEP; 155 if (dodebug) 156 dbg(("load by name %s %p", name, x)); 157 for (; x; x = x->next) { 158 if (strcmp(x->name, name) != 0) 159 continue; 160 161 ctlname[1] = x->ctl; 162 163 i = sizeof(val); 164 165 if (sysctl(ctlname, 2, &val, &i, NULL, 0) == -1) { 166 warn("sysctl"); 167 break; 168 } 169 170 switch (x->ctltype) { 171 case CTLTYPE_INT: 172 xsnprintf(val.s, sizeof(val.s), "%d", val.i); 173 break; 174 case CTLTYPE_STRING: 175 break; 176 default: 177 warnx("unsupported sysctl type %d", x->ctltype); 178 break; 179 } 180 181 if (dodebug) 182 dbg(("sysctl returns %s", val.s)); 183 184 for (i = 0; i < RTLD_MAX_ENTRY && x->entry[i].value != NULL; 185 i++) { 186 if (dodebug) 187 dbg(("entry %d", i)); 188 if (strcmp(x->entry[i].value, val.s) == 0) 189 break; 190 } 191 192 if (i == RTLD_MAX_ENTRY) { 193 warnx("sysctl value %s not found for lib%s", 194 val.s, name); 195 break; 196 } 197 /* XXX: This can mess up debuggers, cause we lie about 198 * what we loaded in the needed objects */ 199 for (j = 0; j < RTLD_MAX_LIBRARY && 200 x->entry[i].library[j] != NULL; j++) { 201 libpath = _rtld_find_library( 202 x->entry[i].library[j], obj); 203 if (libpath == NULL) { 204 warnx("could not load lib%s for lib%s", 205 x->entry[i].library[j], name); 206 continue; 207 } 208 o = _rtld_load_object(libpath, true); 209 if (o == NULL) 210 continue; 211 got = true; 212 if (j == 0) 213 (*needed)->obj = o; 214 else { 215 /* make a new one and put it in the chain */ 216 Needed_Entry *ne = xmalloc(sizeof(*ne)); 217 ne->name = (*needed)->name; 218 ne->obj = o; 219 ne->next = (*needed)->next; 220 (*needed)->next = ne; 221 *needed = ne; 222 } 223 224 } 225 226 } 227 228 if (got) 229 return true; 230 231 libpath = _rtld_find_library(name, obj); 232 if (libpath == NULL) 233 return false; 234 return ((*needed)->obj = _rtld_load_object(libpath, true)) != NULL; 235 } 236 237 238 /* 239 * Given a shared object, traverse its list of needed objects, and load 240 * each of them. Returns 0 on success. Generates an error message and 241 * returns -1 on failure. 242 */ 243 int 244 _rtld_load_needed_objects(first, dodebug) 245 Obj_Entry *first; 246 bool dodebug; 247 { 248 Obj_Entry *obj; 249 int status = 0; 250 251 for (obj = first; obj != NULL; obj = obj->next) { 252 Needed_Entry *needed; 253 254 for (needed = obj->needed; needed != NULL; 255 needed = needed->next) { 256 const char *name = obj->strtab + needed->name; 257 if (!_rtld_load_by_name(name, obj, &needed, dodebug)) 258 status = -1; /* FIXME - cleanup */ 259 #ifdef RTLD_LOADER 260 if (status == -1) 261 return status; 262 #endif 263 } 264 } 265 266 return status; 267 } 268 269 #ifdef RTLD_LOADER 270 int 271 _rtld_preload(preload_path, dodebug) 272 const char *preload_path; 273 bool dodebug; 274 { 275 const char *path; 276 char *cp, *buf; 277 int status = 0; 278 279 if (preload_path != NULL) { 280 cp = buf = xstrdup(preload_path); 281 while ((path = strsep(&cp, " ")) != NULL && status == 0) { 282 if (_rtld_load_object(xstrdup(path), dodebug) == NULL) 283 status = -1; 284 else if (dodebug) 285 dbg((" preloaded \"%s\"", path)); 286 } 287 free(buf); 288 } 289 290 return (status); 291 } 292 #endif 293
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