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nlist_elf32.c revision 1.6 
      1 /*	$NetBSD: nlist_elf32.c,v 1.6 1997/12/15 04:21:34 mrg Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1996 Christopher G. Demetriou.  All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. All advertising materials mentioning features or use of this software
     15  *    must display the following acknowledgement:
     16  *      This product includes software developed by Christopher G. Demetriou
     17  *	for the NetBSD Project.
     18  * 4. The name of the author may not be used to endorse or promote products
     19  *    derived from this software without specific prior written permission
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 #include <sys/cdefs.h>
     34 #ifndef lint
     35 __RCSID("$NetBSD: nlist_elf32.c,v 1.6 1997/12/15 04:21:34 mrg Exp $");
     36 #endif /* not lint */
     37 
     38 /* If not included by nlist_elf64.c, ELFSIZE won't be defined. */
     39 #ifndef ELFSIZE
     40 #define	ELFSIZE		32
     41 #endif
     42 
     43 #include <sys/param.h>
     44 #include <sys/mman.h>
     45 #include <sys/stat.h>
     46 
     47 #include <a.out.h>
     48 #include <db.h>
     49 #include <err.h>
     50 #include <errno.h>
     51 #include <fcntl.h>
     52 #include <kvm.h>
     53 #include <limits.h>
     54 #include <stdio.h>
     55 #include <stdlib.h>
     56 #include <string.h>
     57 #include <unistd.h>
     58 
     59 #include "extern.h"
     60 
     61 #if defined(NLIST_ELF32) || defined(NLIST_ELF64)
     62 #include <sys/exec_elf.h>
     63 #endif
     64 
     65 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
     66     (defined(NLIST_ELF64) && (ELFSIZE == 64))
     67 
     68 #define CONCAT(x,y)     __CONCAT(x,y)
     69 #define ELFNAME(x)      CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x)))
     70 #define ELFNAME2(x,y)   CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y))))
     71 #define ELFNAMEEND(x)   CONCAT(x,CONCAT(_elf,ELFSIZE))
     72 #define ELFDEFNNAME(x)  CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x)))
     73 
     74 typedef struct nlist NLIST;
     75 #define	_strx	n_un.n_strx
     76 #define	_name	n_un.n_name
     77 
     78 #define	badfmt(str)							\
     79 	do {								\
     80 		warnx("%s: %s: %s", kfile, str, strerror(EFTYPE));	\
     81 		punt();							\
     82 	} while (0)
     83 
     84 #define	check(off, size)	((off < 0) || (off + size > mappedsize))
     85 #define	BAD			do { rv = -1; goto out; } while (0)
     86 #define	BADUNMAP		do { rv = -1; goto unmap; } while (0)
     87 
     88 static const char *kfile;
     89 
     90 int
     91 ELFNAMEEND(create_knlist)(name, db)
     92 	const char *name;
     93 	DB *db;
     94 {
     95 	struct stat st;
     96 	struct nlist nbuf;
     97 	DBT key, data;
     98 	char *mappedfile, *symname, *fsymname, *tmpcp, *strtab;
     99 	size_t mappedsize, symnamesize, fsymnamesize;
    100 	Elf_Ehdr *ehdrp;
    101 	Elf_Shdr *shdrp, *symshdrp, *symstrshdrp;
    102 	Elf_Sym *symp;
    103 	Elf_Off shdr_off;
    104 	Elf_Word shdr_size;
    105 #if (ELFSIZE == 32)
    106 	Elf32_Half nshdr;
    107 #elif (ELFSIZE == 64)
    108 	Elf64_Half nshdr;
    109 #endif
    110 	unsigned long i, nsyms;
    111 	int fd, rv;
    112 
    113 	rv = -1;
    114 #ifdef __GNUC__
    115 	/* fix compiler warnings */
    116 	symshdrp = NULL;
    117 	symstrshdrp = NULL;
    118 #endif
    119 
    120 	/*
    121 	 * Open and map the whole file.  If we can't open/stat it,
    122 	 * something bad is going on so we punt.
    123 	 */
    124 	kfile = name;
    125 	if ((fd = open(name, O_RDONLY, 0)) < 0) {
    126 		warn("%s", kfile);
    127 		punt();
    128 	}
    129 	if (fstat(fd, &st) < 0) {
    130 		warn("%s", kfile);
    131 		punt();
    132 	}
    133 	if (st.st_size > SIZE_T_MAX)
    134 		BAD;
    135 
    136 	/*
    137 	 * Map the file in its entirety.
    138 	 */
    139 	mappedsize = st.st_size;
    140 	mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE,
    141 	    fd, 0);
    142 	if (mappedfile == (char *)-1)
    143 		BAD;
    144 
    145 	/*
    146 	 * Make sure we can access the executable's header
    147 	 * directly, and make sure the recognize the executable
    148 	 * as an ELF binary.
    149 	 */
    150 	if (check(0, sizeof *ehdrp))
    151 		BADUNMAP;
    152 	ehdrp = (Elf_Ehdr *)&mappedfile[0];
    153 
    154 	if (memcmp(ehdrp->e_ident, Elf_e_ident, Elf_e_siz))
    155 		BADUNMAP;
    156 
    157 	switch (ehdrp->e_machine) {
    158 	ELFDEFNNAME(MACHDEP_ID_CASES)
    159 
    160 	default:
    161 		BADUNMAP;
    162 	}
    163 
    164 	/*
    165 	 * We've recognized it as an ELF binary.  From here
    166 	 * on out, all errors are fatal.
    167 	 */
    168 
    169 	/*
    170 	 * Find the symbol list and string table.
    171 	 */
    172 	nshdr = ehdrp->e_shnum;
    173 	shdr_off = ehdrp->e_shoff;
    174 	shdr_size = ehdrp->e_shentsize * nshdr;
    175 
    176 	if (check(shdr_off, shdr_size) ||
    177 	    (sizeof *shdrp != ehdrp->e_shentsize))
    178 		badfmt("bogus section header table");
    179 	shdrp = (Elf_Shdr *)&mappedfile[shdr_off];
    180 
    181 	for (i = 0; i < nshdr; i++) {
    182 		if (shdrp[i].sh_type == Elf_sht_symtab) {
    183 			symshdrp = &shdrp[i];
    184 			symstrshdrp = &shdrp[shdrp[i].sh_link];
    185 		}
    186 	}
    187 
    188 	if (symshdrp->sh_offset == 0)
    189 		badfmt("stripped");
    190 	if (check(symshdrp->sh_offset, symshdrp->sh_size))
    191 		badfmt("bogus symbol section header");
    192 	if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size))
    193 		badfmt("bogus symbol string section header");
    194 
    195 	symp = (Elf_Sym *)&mappedfile[symshdrp->sh_offset];
    196 	nsyms = symshdrp->sh_size / sizeof(*symp);
    197 	strtab = &mappedfile[symstrshdrp->sh_offset];
    198 
    199 	/*
    200 	 * Set up the data item, pointing to a nlist structure.
    201 	 * which we fill in for each symbol.
    202 	 */
    203 	data.data = (u_char *)&nbuf;
    204 	data.size = sizeof(nbuf);
    205 
    206 	/*
    207 	 * Create a buffer (to be expanded later, if necessary)
    208 	 * to hold symbol names after we've added underscores
    209 	 * to them.
    210 	 */
    211 	symnamesize = 1024;
    212 	if ((symname = malloc(symnamesize)) == NULL) {
    213 		warn("malloc");
    214 		punt();
    215 	}
    216 
    217 	/*
    218 	 * Read each symbol and enter it into the database.
    219 	 */
    220 	for (i = 0; i < nsyms; i++) {
    221 
    222 		/*
    223 		 * No symbol name; ignore this symbol.
    224 		 */
    225 		if (symp[i].st_name == 0)
    226 			continue;
    227 
    228 		/*
    229 		 * Find symbol name, copy it (with added underscore) to
    230 		 * temporary buffer, and prepare the database key for
    231 		 * insertion.
    232 		 */
    233 		fsymname = &strtab[symp[i].st_name];
    234 		fsymnamesize = strlen(fsymname) + 1;
    235 		while (symnamesize < fsymnamesize + 1) {
    236 			symnamesize *= 2;
    237 			if ((symname = realloc(symname, symnamesize)) == NULL) {
    238 				warn("malloc");
    239 				punt();
    240 			}
    241 		}
    242 		strcpy(symname, "_");
    243 		strcat(symname, fsymname);
    244 
    245 		key.data = symname;
    246 		key.size = strlen((char *)key.data);
    247 
    248 		/*
    249 		 * Convert the symbol information into an nlist structure,
    250 		 * as best we can.
    251 		 */
    252 		nbuf.n_value = symp[i].st_value;
    253 		switch (ELF_SYM_TYPE(symp[i].st_info)) {
    254 		default:
    255 		case Elf_estt_notype:
    256 			nbuf.n_type = N_UNDF;
    257 			break;
    258 		case Elf_estt_object:
    259 			nbuf.n_type = N_DATA;
    260 			break;
    261 		case Elf_estt_func:
    262 			nbuf.n_type = N_TEXT;
    263 			break;
    264 		case Elf_estt_file:
    265 			nbuf.n_type = N_FN;
    266 			break;
    267 		}
    268 		if (ELF_SYM_BIND(symp[i].st_info) != Elf_estb_local)
    269 			nbuf.n_type |= N_EXT;
    270 		nbuf.n_desc = 0;				/* XXX */
    271 		nbuf.n_other = 0;				/* XXX */
    272 
    273 		/*
    274 		 * Enter the symbol into the database.
    275 		 */
    276 		if (db->put(db, &key, &data, 0)) {
    277 			warn("record enter");
    278 			punt();
    279 		}
    280 
    281 		/*
    282 		 * If it's the kernel version string, we've gotta keep
    283 		 * some extra data around.  Under a seperate key,
    284 		 * we enter the first line (i.e. up to the first newline,
    285 		 * with the newline replaced by a NUL to terminate the
    286 		 * entered string) of the version string.
    287 		 */
    288 		if (strcmp((char *)key.data, VRS_SYM) == 0) {
    289 			key.data = (u_char *)VRS_KEY;
    290 			key.size = sizeof(VRS_KEY) - 1;
    291 			/* Find the version string, relative to its section */
    292 			data.data = strdup(&mappedfile[nbuf.n_value -
    293 			    shdrp[symp[i].st_shndx].sh_addr +
    294 			    shdrp[symp[i].st_shndx].sh_offset]);
    295 			/* assumes newline terminates version. */
    296 			if ((tmpcp = strchr(data.data, '\n')) != NULL)
    297 				*tmpcp = '\0';
    298 			data.size = strlen((char *)data.data);
    299 
    300 			if (db->put(db, &key, &data, 0)) {
    301 				warn("record enter");
    302 				punt();
    303 			}
    304 
    305 			/* free pointer created by strdup(). */
    306 			free(data.data);
    307 
    308 			/* Restore to original values */
    309 			data.data = (u_char *)&nbuf;
    310 			data.size = sizeof(nbuf);
    311 		}
    312 	}
    313 
    314 	rv = 0;
    315 
    316 unmap:
    317 	munmap(mappedfile, mappedsize);
    318 out:
    319 	return (rv);
    320 }
    321 
    322 #endif
    323