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nlist_elf32.c revision 1.14 
      1 /* $NetBSD: nlist_elf32.c,v 1.14 2001/07/22 13:34:17 wiz Exp $ */
      2 
      3 /*
      4  * Copyright (c) 1996 Christopher G. Demetriou
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *          This product includes software developed for the
     18  *          NetBSD Project.  See http://www.netbsd.org/ for
     19  *          information about NetBSD.
     20  * 4. The name of the author may not be used to endorse or promote products
     21  *    derived from this software without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     33  *
     34  * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
     35  */
     36 
     37 #include <sys/cdefs.h>
     38 #ifndef lint
     39 __RCSID("$NetBSD: nlist_elf32.c,v 1.14 2001/07/22 13:34:17 wiz Exp $");
     40 #endif /* not lint */
     41 
     42 /* If not included by nlist_elf64.c, ELFSIZE won't be defined. */
     43 #ifndef ELFSIZE
     44 #define	ELFSIZE		32
     45 #endif
     46 
     47 #include <sys/param.h>
     48 #include <sys/mman.h>
     49 #include <sys/stat.h>
     50 
     51 #include <a.out.h>
     52 #include <db.h>
     53 #include <err.h>
     54 #include <errno.h>
     55 #include <fcntl.h>
     56 #include <kvm.h>
     57 #include <limits.h>
     58 #include <stdio.h>
     59 #include <stdlib.h>
     60 #include <string.h>
     61 #include <unistd.h>
     62 
     63 #include "extern.h"
     64 
     65 #if defined(NLIST_ELF32) || defined(NLIST_ELF64)
     66 #include <sys/exec_elf.h>
     67 #endif
     68 
     69 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
     70     (defined(NLIST_ELF64) && (ELFSIZE == 64))
     71 
     72 typedef struct nlist NLIST;
     73 #define	_strx	n_un.n_strx
     74 #define	_name	n_un.n_name
     75 
     76 #define	badfmt(str)							\
     77 	do {								\
     78 		warnx("%s: %s: %s", kfile, str, strerror(EFTYPE));	\
     79 		punt();							\
     80 	} while (0)
     81 
     82 #define	check(off, size)	((off < 0) || (off + size > mappedsize))
     83 #define	BAD			do { rv = -1; goto out; } while (0)
     84 #define	BADUNMAP		do { rv = -1; goto unmap; } while (0)
     85 
     86 static const char *kfile;
     87 
     88 int
     89 ELFNAMEEND(create_knlist)(name, db)
     90 	const char *name;
     91 	DB *db;
     92 {
     93 	struct stat st;
     94 	struct nlist nbuf;
     95 	DBT key, data;
     96 	char *mappedfile, *symname, *fsymname, *tmpcp, *strtab;
     97 	size_t mappedsize, symnamesize, fsymnamesize;
     98 	Elf_Ehdr *ehdrp;
     99 	Elf_Shdr *shdrp, *symshdrp, *symstrshdrp;
    100 	Elf_Sym *symp;
    101 	Elf_Off shdr_off;
    102 	Elf_Word shdr_size;
    103 #if (ELFSIZE == 32)
    104 	Elf32_Half nshdr;
    105 #elif (ELFSIZE == 64)
    106 	Elf64_Half nshdr;
    107 #endif
    108 	unsigned long i, nsyms;
    109 	int fd, rv;
    110 
    111 	rv = -1;
    112 #ifdef __GNUC__
    113 	/* fix compiler warnings */
    114 	symshdrp = NULL;
    115 	symstrshdrp = NULL;
    116 #endif
    117 
    118 	/*
    119 	 * Open and map the whole file.  If we can't open/stat it,
    120 	 * something bad is going on so we punt.
    121 	 */
    122 	kfile = name;
    123 	if ((fd = open(name, O_RDONLY, 0)) < 0) {
    124 		warn("%s", kfile);
    125 		punt();
    126 	}
    127 	if (fstat(fd, &st) < 0) {
    128 		warn("%s", kfile);
    129 		punt();
    130 	}
    131 	if (st.st_size > SIZE_T_MAX)
    132 		BAD;
    133 
    134 	/*
    135 	 * Map the file in its entirety.
    136 	 */
    137 	mappedsize = st.st_size;
    138 	mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE,
    139 	    fd, 0);
    140 	if (mappedfile == (char *)-1)
    141 		BAD;
    142 
    143 	/*
    144 	 * Make sure we can access the executable's header
    145 	 * directly, and make sure the recognize the executable
    146 	 * as an ELF binary.
    147 	 */
    148 	if (check(0, sizeof *ehdrp))
    149 		BADUNMAP;
    150 	ehdrp = (Elf_Ehdr *)&mappedfile[0];
    151 
    152 	if (memcmp(ehdrp->e_ident, ELFMAG, SELFMAG) != 0 ||
    153 	    ehdrp->e_ident[EI_CLASS] != ELFCLASS)
    154 		BADUNMAP;
    155 
    156 	switch (ehdrp->e_machine) {
    157 	ELFDEFNNAME(MACHDEP_ID_CASES)
    158 
    159 	default:
    160 		BADUNMAP;
    161 	}
    162 
    163 	/*
    164 	 * We've recognized it as an ELF binary.  From here
    165 	 * on out, all errors are fatal.
    166 	 */
    167 
    168 	/*
    169 	 * Find the symbol list and string table.
    170 	 */
    171 	nshdr = ehdrp->e_shnum;
    172 	shdr_off = ehdrp->e_shoff;
    173 	shdr_size = ehdrp->e_shentsize * nshdr;
    174 
    175 	if (check(shdr_off, shdr_size) ||
    176 	    (sizeof *shdrp != ehdrp->e_shentsize))
    177 		badfmt("bogus section header table");
    178 	shdrp = (Elf_Shdr *)&mappedfile[shdr_off];
    179 
    180 	for (i = 0; i < nshdr; i++) {
    181 		if (shdrp[i].sh_type == SHT_SYMTAB) {
    182 			symshdrp = &shdrp[i];
    183 			symstrshdrp = &shdrp[shdrp[i].sh_link];
    184 		}
    185 	}
    186 
    187 	if (symshdrp == NULL)
    188 		badfmt("no symbol section header found");
    189 	if (symshdrp->sh_offset == 0)
    190 		badfmt("stripped");
    191 	if (check(symshdrp->sh_offset, symshdrp->sh_size))
    192 		badfmt("bogus symbol section header");
    193 	if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size))
    194 		badfmt("bogus symbol string section header");
    195 
    196 	symp = (Elf_Sym *)&mappedfile[symshdrp->sh_offset];
    197 	nsyms = symshdrp->sh_size / sizeof(*symp);
    198 	strtab = &mappedfile[symstrshdrp->sh_offset];
    199 
    200 	/*
    201 	 * Set up the data item, pointing to a nlist structure.
    202 	 * which we fill in for each symbol.
    203 	 */
    204 	data.data = (u_char *)&nbuf;
    205 	data.size = sizeof(nbuf);
    206 
    207 	/*
    208 	 * Create a buffer (to be expanded later, if necessary)
    209 	 * to hold symbol names after we've added underscores
    210 	 * to them.
    211 	 */
    212 	symnamesize = 1024;
    213 	if ((symname = malloc(symnamesize)) == NULL) {
    214 		warn("malloc");
    215 		punt();
    216 	}
    217 
    218 	/*
    219 	 * Read each symbol and enter it into the database.
    220 	 */
    221 	for (i = 0; i < nsyms; i++) {
    222 
    223 		/*
    224 		 * No symbol name; ignore this symbol.
    225 		 */
    226 		if (symp[i].st_name == 0)
    227 			continue;
    228 
    229 		/*
    230 		 * Find symbol name, copy it (with added underscore) to
    231 		 * temporary buffer, and prepare the database key for
    232 		 * insertion.
    233 		 */
    234 		fsymname = &strtab[symp[i].st_name];
    235 		fsymnamesize = strlen(fsymname) + 1;
    236 		while (symnamesize < fsymnamesize + 1) {
    237 			symnamesize *= 2;
    238 			if ((symname = realloc(symname, symnamesize)) == NULL) {
    239 				warn("malloc");
    240 				punt();
    241 			}
    242 		}
    243 		strcpy(symname, "_");
    244 		strcat(symname, fsymname);
    245 
    246 		key.data = symname;
    247 		key.size = strlen((char *)key.data);
    248 
    249 		/*
    250 		 * Convert the symbol information into an nlist structure,
    251 		 * as best we can.
    252 		 */
    253 		nbuf.n_value = symp[i].st_value;
    254 		switch (ELFDEFNNAME(ST_TYPE)(symp[i].st_info)) {
    255 		default:
    256 		case STT_NOTYPE:
    257 			nbuf.n_type = N_UNDF;
    258 			break;
    259 		case STT_OBJECT:
    260 			nbuf.n_type = N_DATA;
    261 			break;
    262 		case STT_FUNC:
    263 			nbuf.n_type = N_TEXT;
    264 			break;
    265 		case STT_FILE:
    266 			nbuf.n_type = N_FN;
    267 			break;
    268 		}
    269 		if (ELFDEFNNAME(ST_BIND)(symp[i].st_info) != STB_LOCAL)
    270 			nbuf.n_type |= N_EXT;
    271 		nbuf.n_desc = 0;				/* XXX */
    272 		nbuf.n_other = 0;				/* XXX */
    273 
    274 		/*
    275 		 * Enter the symbol into the database.
    276 		 */
    277 		if (db->put(db, &key, &data, 0)) {
    278 			warn("record enter");
    279 			punt();
    280 		}
    281 
    282 		/*
    283 		 * If it's the kernel version string, we've gotta keep
    284 		 * some extra data around.  Under a separate key,
    285 		 * we enter the first line (i.e. up to the first newline,
    286 		 * with the newline replaced by a NUL to terminate the
    287 		 * entered string) of the version string.
    288 		 */
    289 		if (strcmp((char *)key.data, VRS_SYM) == 0) {
    290 			key.data = (u_char *)VRS_KEY;
    291 			key.size = sizeof(VRS_KEY) - 1;
    292 			/* Find the version string, relative to its section */
    293 			data.data = strdup(&mappedfile[nbuf.n_value -
    294 			    shdrp[symp[i].st_shndx].sh_addr +
    295 			    shdrp[symp[i].st_shndx].sh_offset]);
    296 			/* assumes newline terminates version. */
    297 			if ((tmpcp = strchr(data.data, '\n')) != NULL)
    298 				*tmpcp = '\0';
    299 			data.size = strlen((char *)data.data);
    300 
    301 			if (db->put(db, &key, &data, 0)) {
    302 				warn("record enter");
    303 				punt();
    304 			}
    305 
    306 			/* free pointer created by strdup(). */
    307 			free(data.data);
    308 
    309 			/* Restore to original values */
    310 			data.data = (u_char *)&nbuf;
    311 			data.size = sizeof(nbuf);
    312 		}
    313 	}
    314 
    315 	rv = 0;
    316 
    317 unmap:
    318 	munmap(mappedfile, mappedsize);
    319 out:
    320 	return (rv);
    321 }
    322 
    323 #endif
    324