ldconfig.c

linux下用PCMCIA无线网卡虚拟无线AP的程序源码

/*
 * ldconfig - update shared library symlinks
 *
 * usage: ldconfig [-DvqnNX] [-f conf] [-C cache] [-r root] dir ...
 *        ldconfig -l [-Dv] lib ...
 *        ldconfig -p
 *        -D: debug mode, don't update links
 *        -v: verbose mode, print things as we go
 *        -q: quiet mode, don't print warnings
 *        -n: don't process standard directories
 *        -N: don't update the library cache
 *        -X: don't update the library links
 *        -l: library mode, manually link libraries
 *        -p: print the current library cache
 *        -f conf: use conf instead of /etc/ld.so.conf
 *        -C cache: use cache instead of /etc/ld.so.cache
 *        -r root: first, do a chroot to the indicated directory
 *        dir ...: directories to process
 *        lib ...: libraries to link
 *
 * Copyright 1994-2000 David Engel and Mitch D'Souza
 *
 * This program may be used for any purpose as long as this
 * copyright notice is kept.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <ctype.h>
#include <getopt.h>
#include <dirent.h>
#include <unistd.h>
#include <link.h>
#include <elf.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <errno.h>
#include "../config.h"
#include "readsoname.h"

struct exec
{
  unsigned long a_info;		/* Use macros N_MAGIC, etc for access */
  unsigned a_text;		/* length of text, in bytes */
  unsigned a_data;		/* length of data, in bytes */
  unsigned a_bss;		/* length of uninitialized data area for file, in bytes */
  unsigned a_syms;		/* length of symbol table data in file, in bytes */
  unsigned a_entry;		/* start address */
  unsigned a_trsize;		/* length of relocation info for text, in bytes */
  unsigned a_drsize;		/* length of relocation info for data, in bytes */
};

#if !defined (N_MAGIC)
#define N_MAGIC(exec) ((exec).a_info & 0xffff)
#endif
/* Code indicating object file or impure executable.  */
#define OMAGIC 0407
/* Code indicating pure executable.  */
#define NMAGIC 0410
/* Code indicating demand-paged executable.  */
#define ZMAGIC 0413
/* This indicates a demand-paged executable with the header in the text. 
   The first page is unmapped to help trap NULL pointer references */
#define QMAGIC 0314
/* Code indicating core file.  */
#define CMAGIC 0421
#ifdef __GNUC__
void warn(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
void error(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
#endif

char *___strtok = NULL;

/* For SunOS */
#ifndef PATH_MAX
#include <limits.h>
#define PATH_MAX _POSIX_PATH_MAX
#endif

/* For SunOS */
#ifndef N_MAGIC
#define N_MAGIC(exec) ((exec).a_magic & 0xffff)
#endif

#define EXIT_OK    0
#define EXIT_FATAL 128

char *prog = NULL;
int debug = 0;			/* debug mode */
int verbose = 0;		/* verbose mode */
int libmode = 0;		/* library mode */
int nocache = 0;		/* don't build cache */
int nolinks = 0;		/* don't update links */

char *conffile = LDSO_CONF;	/* default conf file */
char *cachefile = LDSO_CACHE;	/* default cache file */
void cache_print(void);
void cache_dolib(const char *dir, const char *so, int libtype);
void cache_write(void);

void warn(const char *fmt, ...)
{
    va_list ap;

    if (verbose < 0)
        return;

    fflush(stdout);    /* don't mix output and error messages */
    fprintf(stderr, "%s: warning: ", prog);

    va_start(ap, fmt);
    vfprintf(stderr, fmt, ap);
    va_end(ap);

    fprintf(stderr, "\n");

    return;
}

void error(const char *fmt, ...)
{
    va_list ap;

    fflush(stdout);    /* don't mix output and error messages */
    fprintf(stderr, "%s: ", prog);

    va_start(ap, fmt);
    vfprintf(stderr, fmt, ap);
    va_end(ap);

    fprintf(stderr, "\n");

    exit(EXIT_FATAL);
}

void *xmalloc(size_t size)
{
    void *ptr;
    if ((ptr = malloc(size)) == NULL)
	error("out of memory");
    return ptr;
}

char *xstrdup(const char *str)
{
    char *ptr;
    if ((ptr = strdup(str)) == NULL)
	error("out of memory");
    return ptr;
}

/* If shared library, return a malloced copy of the soname and set the
   type, else return NULL.

   expected_type should be either LIB_ANY or one of the following:-
   LIB_DLL
   LIB_ELF
   LIB_ELF_LIBC5
   LIB_ELF_LIBC6

   If the lib is ELF and we can not deduce the type the type will
   be set based on expected_type.

   If the expected, actual/deduced types missmatch we display a warning
   and use the actual/deduced type.
*/
char *is_shlib(const char *dir, const char *name, int *type,
	int *islink, int expected_type)
{
    char *good = NULL;
    char *cp, *cp2;
    FILE *file;
    struct exec exec;
    ElfW(Ehdr) *elf_hdr;
    struct stat statbuf;
    char buff[4096];

    /* see if name is of the form libZ.so* */
    if ((strncmp(name, "lib", 3) == 0 || strncmp(name, "ld-", 3) == 0) && \
	name[strlen(name)-1] != '~' && (cp = strstr(name, ".so")))
    {
	/* find the start of the Vminor part, if any */
	if (cp[3] == '.' && (cp2 = strchr(cp + 4, '.')))
	    cp = cp2;
	else
	    cp = cp + strlen(cp);

	/* construct the full path name */
	sprintf(buff, "%s%s%s", dir, (*dir && strcmp(dir, "/")) ?
		"/" : "", name);

	/* first, make sure it's a regular file */
	if (lstat(buff, &statbuf))
	    warn("can't lstat %s (%s), skipping", buff, strerror(errno));
	else if (!S_ISREG(statbuf.st_mode) && !S_ISLNK(statbuf.st_mode))
	    warn("%s is not a regular file or symlink, skipping", buff);
	else
	{
	    /* is it a regular file or a symlink */
	    *islink = S_ISLNK(statbuf.st_mode);

	    /* then try opening it */
	    if (!(file = fopen(buff, "rb")))
		warn("can't open %s (%s), skipping", buff, strerror(errno));
	    else
	    {
		/* now make sure it's a shared library */
		if (fread(&exec, sizeof exec, 1, file) < 1)
		    warn("can't read header from %s, skipping", buff);
		else if (N_MAGIC(exec) != ZMAGIC && N_MAGIC(exec) != QMAGIC)
		{
		    elf_hdr = (ElfW(Ehdr) *) &exec;
		    if (elf_hdr->e_ident[0] != 0x7f ||
			strncmp(&elf_hdr->e_ident[1], "ELF",3) != 0)
		    {
		        /* silently ignore linker scripts */
		        if (strncmp((char *)&exec, "/* GNU ld", 9) != 0)
			    warn("%s is not a shared library, skipping", buff);
		    }
		    else
		    {
		        /* always call readsoname to update type */
			if(expected_type == LIB_DLL){
			    warn("%s is not an a.out library, its ELF!\n", buff);
			    expected_type=LIB_ANY;
			}
		        *type = LIB_ELF;
		        good = readsoname(buff, file, expected_type, type, 
					  elf_hdr->e_ident[EI_CLASS]);
			if (good == NULL || *islink)
			{
			    if (good != NULL)
			        free(good);
			    good = xstrdup(name);
			}
			else
			{
			    /* if the soname does not match the filename,
			       issue a warning, but only in debug mode. */
			    int len = strlen(good);
			    if (debug && (strncmp(good, name, len) != 0 ||
				(name[len] != '\0' && name[len] != '.')))
			        warn("%s has inconsistent soname (%s)",
				     buff, good);
			}
		    }
		}
		else
		{
		    if (*islink)
		        good = xstrdup(name);
		    else
		    {
		        good = xmalloc(cp - name + 1);
			strncpy(good, name, cp - name);
			good[cp - name] = '\0';
		    }
		    if(expected_type != LIB_ANY && expected_type != LIB_DLL)
		    {
			warn("%s is not an ELF library, its an a.out DLL!", buff);
			expected_type=LIB_ANY;
		    }
		    
		    *type = LIB_DLL;
		}
		fclose(file);
	    }
	}
    }

    return good;
}

/* update the symlink to new library */
void link_shlib(const char *dir, const char *file, const char *so)
{
    int change = 1;
    char libname[4096];
    char linkname[4096];
    struct stat libstat;
    struct stat linkstat;

    /* construct the full path names */
    sprintf(libname, "%s/%s", dir, file);
    sprintf(linkname, "%s/%s", dir, so);

    /* see if a link already exists */
    if (!stat(linkname, &linkstat))
    {
	/* now see if it's the one we want */
	if (stat(libname, &libstat))
	    warn("can't stat %s (%s)", libname, strerror(errno));
	else if (libstat.st_dev == linkstat.st_dev &&
	    libstat.st_ino == linkstat.st_ino)
	    change = 0;
    }

    /* then update the link, if required */
    if (change > 0 && !nolinks)
    {
	if (!lstat(linkname, &linkstat))
	{
	  if (!S_ISLNK(linkstat.st_mode))
	  {
	    warn("%s is not a symlink", linkname);
	    change = -1;
	  }
	  else if (remove(linkname))
	  {
	    warn("can't unlink %s (%s)", linkname, strerror(errno));
	    change = -1;
	  }
	}
	if (change > 0)
	{
	  if (symlink(file, linkname))
	  {
	    warn("can't link %s to %s (%s)", linkname, file, strerror(errno));
	    change = -1;
	  }
	}
    }

    /* some people like to know what we're doing */
    if (verbose > 0)
	printf("\t%s => %s%s\n", so, file,
	       change < 0 ? " (SKIPPED)" :
	       (change > 0 ? " (changed)" : ""));

    return;
}

/* figure out which library is greater */
int libcmp(char *p1, char *p2)
{
    while (*p1)
    {
	if (isdigit(*p1) && isdigit(*p2))
	{
	    /* must compare this numerically */
	    int v1, v2;
	    v1 = strtoul(p1, &p1, 10);
	    v2 = strtoul(p2, &p2, 10);
	    if (v1 != v2)
		return v1 - v2;
	}
	else if (isdigit(*p1) && !isdigit(*p2))
	    return 1;
	else if (!isdigit(*p1) && isdigit(*p2))
	    return -1;
	else if (*p1 != *p2)
	    return *p1 - *p2;
	else
	    p1++, p2++;
    }

    return *p1 - *p2;
}

struct lib
{
    char *so;			/* soname of a library */
    char *name;			/* name of a library */
    int libtype;		/* type of a library */
    int islink;			/* is it a symlink */
    struct lib *next;		/* next library in list */
};

/* update all shared library links in a directory */
void scan_dir(const char *name)
{
    DIR *dir;
    struct dirent *ent;
    char *so;
    struct lib *lp, *libs = NULL;
    int libtype, islink;
    int expected_type = LIB_ANY;
    char *t;

    /* Check for an embedded expected type */
    t=strrchr(name, '=');
    if( t )
    {
	*t++ = '\0'; /* Skip = char */
	if(strcasecmp(t, "libc4") == 0)
	{
	    expected_type = LIB_DLL;
	} 
	else
	{
	    if(strcasecmp(t, "libc5") == 0)
	    {
		expected_type = LIB_ELF_LIBC5; 
	    }
	    else
	    {
		if(strcasecmp(t, "libc6") == 0)
		{
		    expected_type = LIB_ELF_LIBC6;
		}
		else
		{
		    warn("Unknown type field '%s' for dir '%s' - ignored\n", t, name);
		    expected_type = LIB_ANY;
		}
	    }
	}
    }

    /* let 'em know what's going on */
    if (verbose > 0)
	printf("%s:\n", name);

    /* if we can't open it, we can't do anything */
    if ((dir = opendir(name)) == NULL)
    {
	warn("can't open %s (%s), skipping", name, strerror(errno));
	return;
    }

    /* yes, we have to look at every single file */
    while ((ent = readdir(dir)) != NULL)
    {
	/* if it's not a shared library, don't bother */
	if ((so = is_shlib(name, ent->d_name, &libtype, &islink, expected_type)) == NULL)
	    continue;