readelflib1.c

linux下用PCMCIA无线网卡虚拟无线AP的程序源码

/* Load an ELF sharable library into memory.

   Copyright (C) 1993-1996, Eric Youngdale.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */



/* This file contains the helper routines to load an ELF sharable
   library into memory and add the symbol table info to the chain. */

#include <elf.h>
#include "linuxelf.h"
#include "string.h"
#include "hash.h"
#include "sysdep.h"
#include "syscall.h"
#include <sys/mman.h>
#ifdef USE_CACHE
#include "../config.h"
#endif

extern char *_dl_progname;

#ifdef USE_CACHE

static caddr_t _dl_cache_addr = NULL;
static size_t _dl_cache_size = 0;

int _dl_map_cache(void)
{
	int fd;
	struct stat st;
	header_t *header;
	libentry_t *libent;
	int i, strtabsize;

	if (_dl_cache_addr == (caddr_t) - 1)
		return -1;
	else if (_dl_cache_addr != NULL)
		return 0;

	if (_dl_stat(LDSO_CACHE, &st)
		|| (fd = _dl_open(LDSO_CACHE, O_RDONLY)) < 0) {
		_dl_dprintf(2, "%s: can't open cache '%s'\n", _dl_progname, LDSO_CACHE);
		_dl_cache_addr = (caddr_t) - 1;	/* so we won't try again */
		return -1;
	}

	_dl_cache_size = st.st_size;
	_dl_cache_addr = (caddr_t) _dl_mmap(0, _dl_cache_size, PROT_READ, MAP_SHARED, fd, 0);
	_dl_close(fd);
	if (_dl_cache_addr == (caddr_t) - 1) {
		_dl_dprintf(2, "%s: can't map cache '%s'\n", 
			_dl_progname, LDSO_CACHE);
		return -1;
	}

	header = (header_t *) _dl_cache_addr;

	if (_dl_cache_size < sizeof(header_t) ||
		_dl_memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
		|| _dl_memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
		|| _dl_cache_size <
		(sizeof(header_t) + header->nlibs * sizeof(libentry_t))
		|| _dl_cache_addr[_dl_cache_size - 1] != '\0') 
	{
		_dl_dprintf(2, "%s: cache '%s' is corrupt\n", _dl_progname, 
			LDSO_CACHE);
		goto fail;
	}

	strtabsize = _dl_cache_size - sizeof(header_t) -
		header->nlibs * sizeof(libentry_t);
	libent = (libentry_t *) & header[1];

	for (i = 0; i < header->nlibs; i++) {
		if (libent[i].sooffset >= strtabsize || 
			libent[i].liboffset >= strtabsize) 
		{
			_dl_dprintf(2, "%s: cache '%s' is corrupt\n", _dl_progname, LDSO_CACHE);
			goto fail;
		}
	}

	return 0;

  fail:
	_dl_munmap(_dl_cache_addr, _dl_cache_size);
	_dl_cache_addr = (caddr_t) - 1;
	return -1;
}

int _dl_unmap_cache(void)
{
	if (_dl_cache_addr == NULL || _dl_cache_addr == (caddr_t) - 1)
		return -1;

#if 1
	_dl_munmap(_dl_cache_addr, _dl_cache_size);
	_dl_cache_addr = NULL;
#endif

	return 0;
}

#endif

/* This function's behavior must exactly match that 
 * in uClibc/ldso/util/ldd.c */
static struct elf_resolve * 
search_for_named_library(char *name, int secure, const char *path_list)
{
	int i, count = 0;
	char *path, *path_n;
	char mylibname[2050];
	struct elf_resolve *tpnt1;


	/* We need a writable copy of this string */
	path = _dl_strdup(path_list);
	if (!path) {
		_dl_dprintf(2, "Out of memory!\n");
		_dl_exit(0);
	}
	

	/* Unlike ldd.c, don't bother to eliminate double //s */


	/* Replace colons with zeros in path_list and count them */
	for(i=_dl_strlen(path); i > 0; i--) {
		if (path[i]==':') {
			path[i]=0;
			count++;
		}
	}

	path_n = path;
	for (i = 0; i < count; i++) {
		_dl_strcpy(mylibname, path_n); 
		_dl_strcat(mylibname, "/"); 
		_dl_strcat(mylibname, name);
		if ((tpnt1 = _dl_load_elf_shared_library(secure, mylibname, 0)) != NULL)
		    return tpnt1;
		path_n += (_dl_strlen(path_n) + 1);
	}
	return NULL;
}


/*
 * Used to return error codes back to dlopen et. al.
 */

unsigned long _dl_error_number;
unsigned long _dl_internal_error_number;

struct elf_resolve *_dl_load_shared_library(int secure, 
	struct elf_resolve *tpnt, char *full_libname)
{
	char *pnt;
	struct elf_resolve *tpnt1;
	char *libname;

	_dl_internal_error_number = 0;

	/* quick hack to ensure mylibname buffer doesn't overflow.  don't 
	   allow full_libname or any directory to be longer than 1024. */
	if (_dl_strlen(full_libname) > 1024)
		goto goof;

	pnt = libname = full_libname;
	while (*pnt) {
		if (*pnt == '/')
			libname = pnt + 1;
		pnt++;
	}

	/* If the filename has any '/', try it straight and leave it at that.
	   For IBCS2 compatibility under linux, we substitute the string 
	   /usr/i486-sysv4/lib for /usr/lib in library names. */

	if (libname != full_libname) {
		tpnt1 = _dl_load_elf_shared_library(secure, full_libname, 0);
		if (tpnt1)
			return tpnt1;
		goto goof;
	}

	/*
	 * The ABI specifies that RPATH is searched before LD_*_PATH or
	 * the default path of /usr/lib.  Check in rpath directories.
	 */
	for (tpnt = _dl_loaded_modules; tpnt; tpnt = tpnt->next) {
		if (tpnt->libtype == elf_executable) {
			pnt = (char *) tpnt->dynamic_info[DT_RPATH];
			if (pnt) {
				pnt += (unsigned long) tpnt->loadaddr +
					tpnt->dynamic_info[DT_STRTAB];
				if ((tpnt1 = search_for_named_library(libname, secure, pnt)) != NULL) 
				{
				    return tpnt1;
				}
			}
		}
	}

	/* Check in LD_{ELF_}LIBRARY_PATH, if specified and allowed */
	if (_dl_library_path) {
	    if ((tpnt1 = search_for_named_library(libname, secure, _dl_library_path)) != NULL) 
	    {
		return tpnt1;
	    }
	}

	/*
	 * Where should the cache be searched?  There is no such concept in the
	 * ABI, so we have some flexibility here.  For now, search it before
	 * the hard coded paths that follow (i.e before /lib and /usr/lib).
	 */
#ifdef USE_CACHE
	if (_dl_cache_addr != NULL && _dl_cache_addr != (caddr_t) - 1) {
		int i;
		header_t *header = (header_t *) _dl_cache_addr;
		libentry_t *libent = (libentry_t *) & header[1];
		char *strs = (char *) &libent[header->nlibs];

		for (i = 0; i < header->nlibs; i++) {
			if ((libent[i].flags == LIB_ELF ||
				 libent[i].flags == LIB_ELF_LIBC5) &&
				_dl_strcmp(libname, strs + libent[i].sooffset) == 0 &&
				(tpnt1 = _dl_load_elf_shared_library(secure, 
				     strs + libent[i].liboffset, 0)))
				return tpnt1;
		}
	}
#endif

	/* Lastly, search the standard list of paths for the library.
	   This list must exactly match the list in uClibc/ldso/util/ldd.c */
	if ((tpnt1 = search_for_named_library(libname, secure, 
			UCLIBC_TARGET_PREFIX "/usr/lib:"
			UCLIBC_TARGET_PREFIX "/lib:"
			UCLIBC_DEVEL_PREFIX "/lib:"
			UCLIBC_BUILD_DIR "/lib:"
			"/usr/lib:"
			"/lib")
		    ) != NULL) 
	{
	    return tpnt1;
	}

  goof:
	/* Well, we shot our wad on that one.  All we can do now is punt */
	if (_dl_internal_error_number)
		_dl_error_number = _dl_internal_error_number;
	else
		_dl_error_number = DL_ERROR_NOFILE;
	return NULL;
}

/*
 * Read one ELF library into memory, mmap it into the correct locations and
 * add the symbol info to the symbol chain.  Perform any relocations that
 * are required.
 */

//extern _elf_rtbndr(void);

struct elf_resolve *_dl_load_elf_shared_library(int secure, 
	char *libname, int flag)
{
	elfhdr *epnt;
	unsigned long dynamic_addr = 0;
	unsigned long dynamic_size = 0;
	Elf32_Dyn *dpnt;
	struct elf_resolve *tpnt;
	elf_phdr *ppnt;
	int piclib;
	char *status;