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agent/src/os/linux/symtab.c@9fae07c31641 (annotated)

agent/src/os/linux/symtab.c

Fri, 25 Jan 2013 16:50:33 -0800

author

morris

date

Fri, 25 Jan 2013 16:50:33 -0800

changeset 4535

9fae07c31641

parent 2384

0a8e0d4345b3

child 5797

f2512d89ad0c

permissions

-rw-r--r--

6518907: cleanup IA64 specific code in Hotspot
Summary: removed unused IA64 specific code
Reviewed-by: twisti, kvn, dholmes

duke@435	1	/*
trims@2384	2	* Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
trims@1907	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907	20	* or visit www.oracle.com if you need additional information or have any
trims@1907	21	* questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	#include <unistd.h>
duke@435	26	#include <sys/procfs.h>
duke@435	27	#include <search.h>
duke@435	28	#include <stdlib.h>
duke@435	29	#include <string.h>
duke@435	30	#include "symtab.h"
duke@435	31	#include "salibelf.h"
duke@435	32
duke@435	33
duke@435	34	// ----------------------------------------------------
duke@435	35	// functions for symbol lookups
duke@435	36	// ----------------------------------------------------
duke@435	37
duke@435	38	struct elf_section {
duke@435	39	ELF_SHDR *c_shdr;
duke@435	40	void *c_data;
duke@435	41	};
duke@435	42
duke@435	43	struct elf_symbol {
duke@435	44	char *name;
duke@435	45	uintptr_t offset;
duke@435	46	uintptr_t size;
duke@435	47	};
duke@435	48
duke@435	49	typedef struct symtab {
duke@435	50	char *strs;
duke@435	51	size_t num_symbols;
duke@435	52	struct elf_symbol *symbols;
duke@435	53	struct hsearch_data *hash_table;
duke@435	54	} symtab_t;
duke@435	55
never@1729	56
never@1729	57	// Directory that contains global debuginfo files. In theory it
never@1729	58	// should be possible to change this, but in a Java environment there
never@1729	59	// is no obvious place to put a user interface to do it. Maybe this
never@1729	60	// could be set with an environment variable.
never@1729	61	static const char debug_file_directory[] = "/usr/lib/debug";
never@1729	62
never@1729	63	/* The CRC used in gnu_debuglink, retrieved from
never@1729	64	http://sourceware.org/gdb/current/onlinedocs/gdb/Separate-Debug-Files.html#Separate-Debug-Files. */
never@1729	65	unsigned int gnu_debuglink_crc32 (unsigned int crc,
never@1729	66	unsigned char *buf, size_t len)
never@1729	67	{
never@1729	68	static const unsigned int crc32_table[256] =
never@1729	69	{
never@1729	70	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
never@1729	71	0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
never@1729	72	0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
never@1729	73	0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
never@1729	74	0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
never@1729	75	0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
never@1729	76	0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
never@1729	77	0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
never@1729	78	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
never@1729	79	0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
never@1729	80	0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
never@1729	81	0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
never@1729	82	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
never@1729	83	0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
never@1729	84	0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
never@1729	85	0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
never@1729	86	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
never@1729	87	0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
never@1729	88	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
never@1729	89	0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
never@1729	90	0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
never@1729	91	0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
never@1729	92	0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
never@1729	93	0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
never@1729	94	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
never@1729	95	0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
never@1729	96	0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
never@1729	97	0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
never@1729	98	0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
never@1729	99	0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
never@1729	100	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
never@1729	101	0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
never@1729	102	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
never@1729	103	0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
never@1729	104	0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
never@1729	105	0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
never@1729	106	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
never@1729	107	0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
never@1729	108	0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
never@1729	109	0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
never@1729	110	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
never@1729	111	0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
never@1729	112	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
never@1729	113	0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
never@1729	114	0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
never@1729	115	0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
never@1729	116	0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
never@1729	117	0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
never@1729	118	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
never@1729	119	0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
never@1729	120	0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
never@1729	121	0x2d02ef8d
never@1729	122	};
never@1729	123	unsigned char *end;
never@1729	124
never@1729	125	crc = ~crc & 0xffffffff;
never@1729	126	for (end = buf + len; buf < end; ++buf)
never@1729	127	crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
never@1729	128	return ~crc & 0xffffffff;
never@1729	129	}
never@1729	130
never@1729	131	/* Open a debuginfo file and check its CRC. If it exists and the CRC
never@1729	132	matches return its fd. */
never@1729	133	static int
never@1729	134	open_debug_file (const char *pathname, unsigned int crc)
never@1729	135	{
never@1729	136	unsigned int file_crc = 0;
never@1729	137	unsigned char buffer[8 * 1024];
never@1729	138
never@1729	139	int fd = pathmap_open(pathname);
never@1729	140
never@1729	141	if (fd < 0)
never@1729	142	return -1;
never@1729	143
never@1729	144	lseek(fd, 0, SEEK_SET);
never@1729	145
never@1729	146	for (;;) {
never@1729	147	int len = read(fd, buffer, sizeof buffer);
never@1729	148	if (len <= 0)
never@1729	149	break;
never@1729	150	file_crc = gnu_debuglink_crc32(file_crc, buffer, len);
never@1729	151	}
never@1729	152
never@1729	153	if (crc == file_crc)
never@1729	154	return fd;
never@1729	155	else {
never@1729	156	close(fd);
never@1729	157	return -1;
never@1729	158	}
never@1729	159	}
never@1729	160
never@1729	161	/* Find an ELF section. */
never@1729	162	static struct elf_section *find_section_by_name(char *name,
never@1729	163	int fd,
never@1729	164	ELF_EHDR *ehdr,
never@1729	165	ELF_SHDR *shbuf,
never@1729	166	struct elf_section *scn_cache)
never@1729	167	{
never@1729	168	ELF_SHDR* cursct = NULL;
never@1729	169	char *strtab;
never@1729	170	int cnt;
never@1729	171
never@1729	172	if (scn_cache[ehdr->e_shstrndx].c_data == NULL) {
never@1729	173	if ((scn_cache[ehdr->e_shstrndx].c_data
never@1729	174	= read_section_data(fd, ehdr, cursct)) == NULL) {
never@1729	175	return NULL;
never@1729	176	}
never@1729	177	}
never@1729	178
never@1729	179	strtab = scn_cache[ehdr->e_shstrndx].c_data;
never@1729	180
never@1729	181	for (cursct = shbuf, cnt = 0;
never@1729	182	cnt < ehdr->e_shnum;
never@1729	183	cnt++, cursct++) {
never@1729	184	if (strcmp(cursct->sh_name + strtab, name) == 0) {
never@1729	185	scn_cache[cnt].c_data = read_section_data(fd, ehdr, cursct);
never@1729	186	return &scn_cache[cnt];
never@1729	187	}
never@1729	188	}
never@1729	189
never@1729	190	return NULL;
never@1729	191	}
never@1729	192
never@1729	193	/* Look for a ".gnu_debuglink" section. If one exists, try to open a
never@1729	194	suitable debuginfo file. */
never@1729	195	static int open_file_from_debug_link(const char *name,
never@1729	196	int fd,
never@1729	197	ELF_EHDR *ehdr,
never@1729	198	ELF_SHDR *shbuf,
never@1729	199	struct elf_section *scn_cache)
never@1729	200	{
never@1729	201	int debug_fd;
never@1729	202	struct elf_section *debug_link = find_section_by_name(".gnu_debuglink", fd, ehdr,
never@1729	203	shbuf, scn_cache);
never@1729	204	if (debug_link == NULL)
never@1729	205	return -1;
never@1729	206	char *debug_filename = debug_link->c_data;
never@1729	207	int offset = (strlen(debug_filename) + 4) >> 2;
never@1729	208	static unsigned int crc;
never@1729	209	crc = ((unsigned int*)debug_link->c_data)[offset];
never@1729	210	char *debug_pathname = malloc(strlen(debug_filename)
never@1729	211	+ strlen(name)
never@1729	212	+ strlen(".debug/")
never@1729	213	+ strlen(debug_file_directory)
never@1729	214	+ 2);
never@1729	215	strcpy(debug_pathname, name);
never@1729	216	char *last_slash = strrchr(debug_pathname, '/');
never@1729	217	if (last_slash == NULL)
never@1729	218	return -1;
never@1729	219
never@1729	220	/* Look in the same directory as the object. */
never@1729	221	strcpy(last_slash+1, debug_filename);
never@1729	222
never@1729	223	debug_fd = open_debug_file(debug_pathname, crc);
never@1729	224	if (debug_fd >= 0) {
never@1729	225	free(debug_pathname);
never@1729	226	return debug_fd;
never@1729	227	}
never@1729	228
never@1729	229	/* Look in a subdirectory named ".debug". */
never@1729	230	strcpy(last_slash+1, ".debug/");
never@1729	231	strcat(last_slash, debug_filename);
never@1729	232
never@1729	233	debug_fd = open_debug_file(debug_pathname, crc);
never@1729	234	if (debug_fd >= 0) {
never@1729	235	free(debug_pathname);
never@1729	236	return debug_fd;
never@1729	237	}
never@1729	238
never@1729	239	/* Look in /usr/lib/debug + the full pathname. */
never@1729	240	strcpy(debug_pathname, debug_file_directory);
never@1729	241	strcat(debug_pathname, name);
never@1729	242	last_slash = strrchr(debug_pathname, '/');
never@1729	243	strcpy(last_slash+1, debug_filename);
never@1729	244
never@1729	245	debug_fd = open_debug_file(debug_pathname, crc);
never@1729	246	if (debug_fd >= 0) {
never@1729	247	free(debug_pathname);
never@1729	248	return debug_fd;
never@1729	249	}
never@1729	250
never@1729	251	free(debug_pathname);
never@1729	252	return -1;
never@1729	253	}
never@1729	254
never@1729	255	static struct symtab* build_symtab_internal(int fd, const char *filename, bool try_debuginfo);
never@1729	256
never@1729	257	/* Look for a ".gnu_debuglink" section. If one exists, try to open a
never@1729	258	suitable debuginfo file and read a symbol table from it. */
never@1729	259	static struct symtab *build_symtab_from_debug_link(const char *name,
never@1729	260	int fd,
never@1729	261	ELF_EHDR *ehdr,
never@1729	262	ELF_SHDR *shbuf,
never@1729	263	struct elf_section *scn_cache)
never@1729	264	{
never@1729	265	fd = open_file_from_debug_link(name, fd, ehdr, shbuf, scn_cache);
never@1729	266
never@1729	267	if (fd >= 0) {
never@1729	268	struct symtab *symtab = build_symtab_internal(fd, NULL, /* try_debuginfo */ false);
never@1729	269	close(fd);
never@1729	270	return symtab;
never@1729	271	}
never@1729	272
never@1729	273	return NULL;
never@1729	274	}
never@1729	275
never@1729	276	// Given a build_id, find the associated debuginfo file
never@1729	277	static char *
never@1729	278	build_id_to_debug_filename (size_t size, unsigned char *data)
never@1729	279	{
never@1729	280	char *filename, *s;
never@1729	281
never@1729	282	filename = malloc(strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1
never@1729	283	+ 2 * size + (sizeof ".debug" - 1) + 1);
never@1729	284	s = filename + sprintf (filename, "%s/.build-id/", debug_file_directory);
never@1729	285	if (size > 0)
never@1729	286	{
never@1729	287	size--;
never@1729	288	s += sprintf (s, "%02x", *data++);
never@1729	289	}
never@1729	290	if (size > 0)
never@1729	291	*s++ = '/';
never@1729	292	while (size-- > 0)
never@1729	293	s += sprintf (s, "%02x", *data++);
never@1729	294	strcpy (s, ".debug");
never@1729	295
never@1729	296	return filename;
never@1729	297	}
never@1729	298
never@1729	299	// Read a build ID note. Try to open any associated debuginfo file
never@1729	300	// and return its symtab
never@1729	301	static struct symtab* build_symtab_from_build_id(Elf64_Nhdr *note)
never@1729	302	{
never@1729	303	int fd;
never@1729	304	struct symtab *symtab = NULL;
never@1729	305
never@1729	306	unsigned char *bytes
never@1729	307	= (unsigned char*)(note+1) + note->n_namesz;
never@1729	308	unsigned char *filename
never@1729	309	= (build_id_to_debug_filename (note->n_descsz, bytes));
never@1729	310
never@1729	311	fd = pathmap_open(filename);
never@1729	312	if (fd >= 0) {
never@1729	313	symtab = build_symtab_internal(fd, NULL, /* try_debuginfo */ false);
never@1729	314	close(fd);
never@1729	315	}
never@1729	316	free(filename);
never@1729	317
never@1729	318	return symtab;
never@1729	319	}
never@1729	320
never@1729	321	// read symbol table from given fd. If try_debuginfo) is true, also
never@1729	322	// try to open an associated debuginfo file
never@1729	323	static struct symtab* build_symtab_internal(int fd, const char *filename, bool try_debuginfo) {
duke@435	324	ELF_EHDR ehdr;
duke@435	325	char *names = NULL;
duke@435	326	struct symtab* symtab = NULL;
duke@435	327
duke@435	328	// Reading of elf header
duke@435	329	struct elf_section *scn_cache = NULL;
duke@435	330	int cnt = 0;
duke@435	331	ELF_SHDR* shbuf = NULL;
duke@435	332	ELF_SHDR* cursct = NULL;
duke@435	333	ELF_PHDR* phbuf = NULL;
duke@435	334	ELF_PHDR* phdr = NULL;
never@1729	335	int sym_section = SHT_DYNSYM;
duke@435	336
duke@435	337	uintptr_t baseaddr = (uintptr_t)-1;
duke@435	338
duke@435	339	lseek(fd, (off_t)0L, SEEK_SET);
duke@435	340	if (! read_elf_header(fd, &ehdr)) {
duke@435	341	// not an elf
duke@435	342	return NULL;
duke@435	343	}
duke@435	344
duke@435	345	// read ELF header
duke@435	346	if ((shbuf = read_section_header_table(fd, &ehdr)) == NULL) {
duke@435	347	goto quit;
duke@435	348	}
duke@435	349
duke@435	350	baseaddr = find_base_address(fd, &ehdr);
duke@435	351
duke@435	352	scn_cache = (struct elf_section *)
duke@435	353	calloc(ehdr.e_shnum * sizeof(struct elf_section), 1);
duke@435	354	if (scn_cache == NULL) {
duke@435	355	goto quit;
duke@435	356	}
duke@435	357
duke@435	358	for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) {
duke@435	359	scn_cache[cnt].c_shdr = cursct;
never@1729	360	if (cursct->sh_type == SHT_SYMTAB || cursct->sh_type == SHT_STRTAB
never@1729	361	|| cursct->sh_type == SHT_NOTE || cursct->sh_type == SHT_DYNSYM) {
duke@435	362	if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) {
duke@435	363	goto quit;
duke@435	364	}
duke@435	365	}
never@1729	366	if (cursct->sh_type == SHT_SYMTAB) {
never@1729	367	// Full symbol table available so use that
never@1729	368	sym_section = cursct->sh_type;
never@1729	369	}
duke@435	370	cursct++;
duke@435	371	}
duke@435	372
duke@435	373	for (cnt = 1; cnt < ehdr.e_shnum; cnt++) {
duke@435	374	ELF_SHDR *shdr = scn_cache[cnt].c_shdr;
duke@435	375
never@1729	376	if (shdr->sh_type == sym_section) {
duke@435	377	ELF_SYM *syms;
duke@435	378	int j, n, rslt;
duke@435	379	size_t size;
duke@435	380
duke@435	381	// FIXME: there could be multiple data buffers associated with the
duke@435	382	// same ELF section. Here we can handle only one buffer. See man page
duke@435	383	// for elf_getdata on Solaris.
duke@435	384
duke@435	385	// guarantee(symtab == NULL, "multiple symtab");
duke@435	386	symtab = (struct symtab*)calloc(1, sizeof(struct symtab));
duke@435	387	if (symtab == NULL) {
duke@435	388	goto quit;
duke@435	389	}
duke@435	390	// the symbol table
duke@435	391	syms = (ELF_SYM *)scn_cache[cnt].c_data;
duke@435	392
duke@435	393	// number of symbols
duke@435	394	n = shdr->sh_size / shdr->sh_entsize;
duke@435	395
duke@435	396	// create hash table, we use hcreate_r, hsearch_r and hdestroy_r to
duke@435	397	// manipulate the hash table.
duke@435	398	symtab->hash_table = (struct hsearch_data*) calloc(1, sizeof(struct hsearch_data));
duke@435	399	rslt = hcreate_r(n, symtab->hash_table);
duke@435	400	// guarantee(rslt, "unexpected failure: hcreate_r");
duke@435	401
duke@435	402	// shdr->sh_link points to the section that contains the actual strings
duke@435	403	// for symbol names. the st_name field in ELF_SYM is just the
duke@435	404	// string table index. we make a copy of the string table so the
duke@435	405	// strings will not be destroyed by elf_end.
duke@435	406	size = scn_cache[shdr->sh_link].c_shdr->sh_size;
duke@435	407	symtab->strs = (char *)malloc(size);
duke@435	408	memcpy(symtab->strs, scn_cache[shdr->sh_link].c_data, size);
duke@435	409
duke@435	410	// allocate memory for storing symbol offset and size;
duke@435	411	symtab->num_symbols = n;
duke@435	412	symtab->symbols = (struct elf_symbol *)calloc(n , sizeof(struct elf_symbol));
duke@435	413
duke@435	414	// copy symbols info our symtab and enter them info the hash table
duke@435	415	for (j = 0; j < n; j++, syms++) {
duke@435	416	ENTRY item, *ret;
duke@435	417	char *sym_name = symtab->strs + syms->st_name;
duke@435	418
duke@435	419	// skip non-object and non-function symbols
duke@435	420	int st_type = ELF_ST_TYPE(syms->st_info);
duke@435	421	if ( st_type != STT_FUNC && st_type != STT_OBJECT)
duke@435	422	continue;
duke@435	423	// skip empty strings and undefined symbols
duke@435	424	if (*sym_name == '\0' || syms->st_shndx == SHN_UNDEF) continue;
duke@435	425
duke@435	426	symtab->symbols[j].name = sym_name;
duke@435	427	symtab->symbols[j].offset = syms->st_value - baseaddr;
duke@435	428	symtab->symbols[j].size = syms->st_size;
duke@435	429
duke@435	430	item.key = sym_name;
duke@435	431	item.data = (void *)&(symtab->symbols[j]);
duke@435	432
duke@435	433	hsearch_r(item, ENTER, &ret, symtab->hash_table);
duke@435	434	}
duke@435	435	}
duke@435	436	}
duke@435	437
never@1729	438	// Look for a separate debuginfo file.
never@1729	439	if (try_debuginfo) {
never@1729	440
never@1729	441	// We prefer a debug symtab to an object's own symtab, so look in
never@1729	442	// the debuginfo file. We stash a copy of the old symtab in case
never@1729	443	// there is no debuginfo.
never@1729	444	struct symtab* prev_symtab = symtab;
never@1729	445	symtab = NULL;
never@1729	446
never@1729	447	#ifdef NT_GNU_BUILD_ID
never@1729	448	// First we look for a Build ID
never@1729	449	for (cursct = shbuf, cnt = 0;
never@1729	450	symtab == NULL && cnt < ehdr.e_shnum;
never@1729	451	cnt++) {
never@1729	452	if (cursct->sh_type == SHT_NOTE) {
never@1729	453	Elf64_Nhdr *note = (Elf64_Nhdr *)scn_cache[cnt].c_data;
never@1729	454	if (note->n_type == NT_GNU_BUILD_ID) {
never@1729	455	symtab = build_symtab_from_build_id(note);
never@1729	456	}
never@1729	457	}
never@1729	458	cursct++;
never@1729	459	}
never@1729	460	#endif
never@1729	461
never@1729	462	// Then, if that doesn't work, the debug link
never@1729	463	if (symtab == NULL) {
never@1729	464	symtab = build_symtab_from_debug_link(filename, fd, &ehdr, shbuf,
never@1729	465	scn_cache);
never@1729	466	}
never@1729	467
never@1729	468	// If we still haven't found a symtab, use the object's own symtab.
never@1729	469	if (symtab != NULL) {
never@1729	470	if (prev_symtab != NULL)
never@1729	471	destroy_symtab(prev_symtab);
never@1729	472	} else {
never@1729	473	symtab = prev_symtab;
never@1729	474	}
never@1729	475	}
never@1729	476
duke@435	477	quit:
duke@435	478	if (shbuf) free(shbuf);
duke@435	479	if (phbuf) free(phbuf);
duke@435	480	if (scn_cache) {
duke@435	481	for (cnt = 0; cnt < ehdr.e_shnum; cnt++) {
duke@435	482	if (scn_cache[cnt].c_data != NULL) {
duke@435	483	free(scn_cache[cnt].c_data);
duke@435	484	}
duke@435	485	}
duke@435	486	free(scn_cache);
duke@435	487	}
duke@435	488	return symtab;
duke@435	489	}
duke@435	490
never@1729	491	struct symtab* build_symtab(int fd, const char *filename) {
never@1729	492	return build_symtab_internal(fd, filename, /* try_debuginfo */ true);
never@1729	493	}
never@1729	494
never@1729	495
duke@435	496	void destroy_symtab(struct symtab* symtab) {
duke@435	497	if (!symtab) return;
duke@435	498	if (symtab->strs) free(symtab->strs);
duke@435	499	if (symtab->symbols) free(symtab->symbols);
duke@435	500	if (symtab->hash_table) {
duke@435	501	hdestroy_r(symtab->hash_table);
duke@435	502	free(symtab->hash_table);
duke@435	503	}
duke@435	504	free(symtab);
duke@435	505	}
duke@435	506
duke@435	507	uintptr_t search_symbol(struct symtab* symtab, uintptr_t base,
duke@435	508	const char *sym_name, int *sym_size) {
duke@435	509	ENTRY item;
duke@435	510	ENTRY* ret = NULL;
duke@435	511
duke@435	512	// library does not have symbol table
duke@435	513	if (!symtab || !symtab->hash_table)
duke@435	514	return (uintptr_t)NULL;
duke@435	515
duke@435	516	item.key = (char*) strdup(sym_name);
duke@435	517	hsearch_r(item, FIND, &ret, symtab->hash_table);
duke@435	518	if (ret) {
duke@435	519	struct elf_symbol * sym = (struct elf_symbol *)(ret->data);
duke@435	520	uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset);
duke@435	521	if (sym_size) *sym_size = sym->size;
duke@435	522	free(item.key);
duke@435	523	return rslt;
duke@435	524	}
duke@435	525
duke@435	526	quit:
duke@435	527	free(item.key);
duke@435	528	return (uintptr_t) NULL;
duke@435	529	}
duke@435	530
duke@435	531	const char* nearest_symbol(struct symtab* symtab, uintptr_t offset,
duke@435	532	uintptr_t* poffset) {
duke@435	533	int n = 0;
duke@435	534	if (!symtab) return NULL;
duke@435	535	for (; n < symtab->num_symbols; n++) {
duke@435	536	struct elf_symbol* sym = &(symtab->symbols[n]);
duke@435	537	if (sym->name != NULL &&
duke@435	538	offset >= sym->offset && offset < sym->offset + sym->size) {
duke@435	539	if (poffset) *poffset = (offset - sym->offset);
duke@435	540	return sym->name;
duke@435	541	}
duke@435	542	}
duke@435	543	return NULL;
duke@435	544	}