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ldconfig.c

/*
 * 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 <a.out.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 "readelf.h"

#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;

      /* have we already seen one with the same so name? */
      for (lp = libs; lp; lp = lp->next)
      {
          if (strcmp(so, lp->so) == 0)
          {
              /* we have, which one do we want to use? */
              if ((!islink && lp->islink) ||
                (islink == lp->islink && 
                 libcmp(ent->d_name, lp->name) > 0))
            {
                /* let's use the new one */
                free(lp->name);
                lp->name = xstrdup(ent->d_name);
                lp->libtype = libtype;
                lp->islink = islink;
            } 
            break;
          }
      }

      /* congratulations, you're the first one we've seen */
      if (!lp)
      {
          lp = xmalloc(sizeof *lp);
          lp->so = xstrdup(so);
          lp->name = xstrdup(ent->d_name);
          lp->libtype = libtype;
          lp->islink = islink;
          lp->next = libs;
          libs = lp;
      }

      free(so);
    }

    /* don't need this any more */
    closedir(dir);

    /* now we have all the latest libs, update the links */
    for (lp = libs; lp; lp = lp->next)
    {
        if (!lp->islink)
          link_shlib(name, lp->name, lp->so);
      if (!nocache)
          cache_dolib(name, lp->so, lp->libtype);
    }

    /* always try to clean up after ourselves */
    while (libs)
    {
      lp = libs->next;
      free(libs->so);
      free(libs->name);
      free(libs);
      libs = lp;
    }

    return;
}

/* return the list of system-specific directories */
char *get_extpath(void)
{
    char *res = NULL, *cp;
    FILE *file;
    struct stat stat;

    if ((file = fopen(conffile, "r")) != NULL)
    {
      fstat(fileno(file), &stat);
      res = xmalloc(stat.st_size + 1);
      fread(res, 1, stat.st_size, file);
      fclose(file);
      res[stat.st_size] = '\0';

      /* convert comments fo spaces */
      for (cp = res; *cp; /*nada*/) {
        if (*cp == '#') {
          do
            *cp++ = ' ';
          while (*cp && *cp != '\n');
        } else {
          cp++;
        }
      }       
    }

    return res;
}

void usage(void)
{
    fprintf(stderr,
          "ldconfig - update shared library symlinks\n"
          "\n"
          "usage: ldconfig [-DvqnNX] [-f conf] [-C cache] [-r root] dir ...\n"
          "       ldconfig -l [-Dv] lib ...\n"
          "       ldconfig -p\n"
          "\t-D:\t\tdebug mode, don't update links\n"
          "\t-v:\t\tverbose mode, print things as we go\n"
          "\t-q:\t\tquiet mode, don't print warnings\n"
          "\t-n:\t\tdon't process standard directories\n"
          "\t-N:\t\tdon't update the library cache\n"
          "\t-X:\t\tdon't update the library links\n"
          "\t-l:\t\tlibrary mode, manually link libraries\n"
          "\t-p:\t\tprint the current library cache\n"
          "\t-f conf :\tuse conf instead of %s\n"
          "\t-C cache:\tuse cache instead of %s\n"
          "\t-r root :\tfirst, do a chroot to the indicated directory\n"
          "\tdir ... :\tdirectories to process\n"
          "\tlib ... :\tlibraries to link\n"
          "\n"
          "Copyright 1994-2000 David Engel and Mitch D'Souza\n",
          LDSO_CONF, LDSO_CACHE
          );
    exit(EXIT_FATAL);
}

int main(int argc, char **argv)
{
    int i, c;
    int nodefault = 0;
    int printcache = 0;
    char *cp, *dir, *so;
    char *extpath;
    int libtype, islink;
    char *chroot_dir = NULL;

    prog = argv[0];
    opterr = 0;

    while ((c = getopt(argc, argv, "DvqnNXlpf:C:r:")) != EOF)
      switch (c)
      {
      case 'D':
          debug = 1;          /* debug mode */
          nocache = 1;
          nolinks = 1;
          verbose = 1;
          break;
      case 'v':
          verbose = 1;  /* verbose mode */
          break;
      case 'q':
          if (verbose <= 0)
              verbose = -1;   /* quiet mode */
          break;
      case 'n':
          nodefault = 1;      /* no default dirs */
          nocache = 1;
          break;
      case 'N':
          nocache = 1;  /* don't build cache */
          break;
      case 'X':
          nolinks = 1;  /* don't update links */
          break;
      case 'l':
          libmode = 1;  /* library mode */
          break;
      case 'p':
          printcache = 1;     /* print cache */
          break;
      case 'f':
          conffile = optarg;  /* alternate conf file */
          break;
      case 'C':
          cachefile = optarg; /* alternate cache file */
          break;
      case 'r':
          chroot_dir = optarg;
          break;
      default:
          usage();
          break;

      /* THE REST OF THESE ARE UNDOCUMENTED AND MAY BE REMOVED
         IN FUTURE VERSIONS. */
      }

    if (chroot_dir && *chroot_dir) {
      if (chroot(chroot_dir) < 0)
          error("couldn't chroot to %s (%s)", chroot_dir, strerror(errno));
        if (chdir("/") < 0)
          error("couldn't chdir to / (%s)", strerror(errno));
    }

    /* allow me to introduce myself, hi, my name is ... */
    if (verbose > 0)
      printf("%s: version %s\n", argv[0], VERSION);

    if (printcache)
    {
      /* print the cache -- don't you trust me? */
      cache_print();
      exit(EXIT_OK);
    }
    else if (libmode)
    {
      /* so you want to do things manually, eh? */

      /* ok, if you're so smart, which libraries do we link? */
      for (i = optind; i < argc; i++)
      {
          /* split into directory and file parts */
          if (!(cp = strrchr(argv[i], '/')))
          {
            dir = ".";  /* no dir, only a filename */
            cp = argv[i];
          }
          else
          {
            if (cp == argv[i])
                dir = "/";    /* file in root directory */
            else
                dir = argv[i];
            *cp++ = '\0';     /* neither of the above */
          }

          /* we'd better do a little bit of checking */
          if ((so = is_shlib(dir, cp, &libtype, &islink, LIB_ANY)) == NULL)
            error("%s%s%s is not a shared library", dir,
                  (*dir && strcmp(dir, "/")) ? "/" : "", cp);

          /* so far, so good, maybe he knows what he's doing */
          link_shlib(dir, cp, so);
      }
    }
    else
    {
      /* the lazy bum want's us to do all the work for him */

      /* don't cache dirs on the command line */
      int nocache_save = nocache;
      nocache = 1;

      /* OK, which directories should we do? */
      for (i = optind; i < argc; i++)
          scan_dir(argv[i]);

      /* restore the desired caching state */
      nocache = nocache_save;

      /* look ma, no defaults */
      if (!nodefault)
      {
          /* I guess the defaults aren't good enough */
          if ((extpath = get_extpath()))
          {
            for (cp = strtok(extpath, DIR_SEP); cp;
                 cp = strtok(NULL, DIR_SEP))
                scan_dir(cp);
            free(extpath);
          }

          /* everybody needs these, don't they? */
          scan_dir("/usr/lib");
          scan_dir("/lib");
      }

      if (!nocache)
          cache_write();
    }

    exit(EXIT_OK);
}

typedef struct liblist
{
    int flags;
    int sooffset;
    int liboffset;
    char *soname;
    char *libname;
    struct liblist *next;
} liblist_t;

static header_t magic = { LDSO_CACHE_MAGIC, LDSO_CACHE_VER, 0 };
static liblist_t *lib_head = NULL;

static int liblistcomp(liblist_t *x, liblist_t *y)
{
    int res;

    if ((res = libcmp(x->soname, y->soname)) == 0)
    {
        res = libcmp(strrchr(x->libname, '/') + 1,
                 strrchr(y->libname, '/') + 1);
    }

    return res;
}

void cache_dolib(const char *dir, const char *so, int libtype)
{
    char fullpath[PATH_MAX];
    liblist_t *new_lib, *cur_lib;

    magic.nlibs++;
    sprintf(fullpath, "%s/%s", dir, so);
    new_lib = xmalloc(sizeof (liblist_t));
    new_lib->flags = libtype;
    new_lib->soname = xstrdup(so);
    new_lib->libname = xstrdup(fullpath);

    if (lib_head == NULL || liblistcomp(new_lib, lib_head) > 0)
    {
        new_lib->next = lib_head;
      lib_head = new_lib;
    }
    else
    {
        for (cur_lib = lib_head; cur_lib->next != NULL &&
           liblistcomp(new_lib, cur_lib->next) <= 0;
           cur_lib = cur_lib->next)
          /* nothing */;
      new_lib->next = cur_lib->next;
      cur_lib->next = new_lib;
    }
}

void cache_write(void)
{
    int cachefd;
    int stroffset = 0;
    char tempfile[4096];
    liblist_t *cur_lib;

    if (!magic.nlibs)
      return;

    sprintf(tempfile, "%s~", cachefile);

    if (unlink(tempfile) && errno != ENOENT)
        error("can't unlink %s (%s)", tempfile, strerror(errno));

    if ((cachefd = creat(tempfile, 0644)) < 0)
      error("can't create %s (%s)", tempfile, strerror(errno));

    if (write(cachefd, &magic, sizeof (header_t)) != sizeof (header_t))
      error("can't write %s (%s)", tempfile, strerror(errno));

    for (cur_lib = lib_head; cur_lib != NULL; cur_lib = cur_lib->next)
    {
        cur_lib->sooffset = stroffset;
      stroffset += strlen(cur_lib->soname) + 1;
      cur_lib->liboffset = stroffset;
      stroffset += strlen(cur_lib->libname) + 1;
      if (write(cachefd, cur_lib, sizeof (libentry_t)) !=
          sizeof (libentry_t))
          error("can't write %s (%s)", tempfile, strerror(errno));
    }

    for (cur_lib = lib_head; cur_lib != NULL; cur_lib = cur_lib->next)
    {
      if (write(cachefd, cur_lib->soname, strlen(cur_lib->soname) + 1)
        != strlen(cur_lib->soname) + 1)
        error("can't write %s (%s)", tempfile, strerror(errno));
      if (write(cachefd, cur_lib->libname, strlen(cur_lib->libname) + 1)
        != strlen(cur_lib->libname) + 1)
        error("can't write %s (%s)", tempfile, strerror(errno));
    }

    if (close(cachefd))
        error("can't close %s (%s)", tempfile, strerror(errno));

    if (chmod(tempfile, 0644))
      error("can't chmod %s (%s)", tempfile, strerror(errno));

    if (rename(tempfile, cachefile))
      error("can't rename %s (%s)", tempfile, strerror(errno));
}

void cache_print(void)
{
    caddr_t c;
    struct stat st;
    int fd = 0;
    char *strs;
    header_t *header;
    libentry_t *libent;

    if (stat(cachefile, &st) || (fd = open(cachefile, O_RDONLY))<0)
      error("can't read %s (%s)", cachefile, strerror(errno));
    if ((c = mmap(0,st.st_size, PROT_READ, MAP_SHARED ,fd, 0)) == (caddr_t)-1)
      error("can't map %s (%s)", cachefile, strerror(errno));
    close(fd);

    if (memcmp(((header_t *)c)->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN))
      error("%s cache corrupt", cachefile);

    if (memcmp(((header_t *)c)->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN))
      error("wrong cache version - expected %s", LDSO_CACHE_VER);

    header = (header_t *)c;
    libent = (libentry_t *)(c + sizeof (header_t));
    strs = (char *)&libent[header->nlibs];

    printf("%d libs found in cache `%s' (version %s)\n",
          header->nlibs, cachefile, LDSO_CACHE_VER);

    for (fd = 0; fd < header->nlibs; fd++)
    {
      printf("\t%s ", strs + libent[fd].sooffset);
      switch (libent[fd].flags & ~LIB_ELF64) 
      {
        case LIB_DLL:
          printf("(libc4)");
          break;
        case LIB_ELF:
          printf("(ELF%s)", libent[fd].flags & LIB_ELF64 ? "/64" : "");
          break;
        case LIB_ELF_LIBC5:
        case LIB_ELF_LIBC6:
          printf("(libc%d%s)", (libent[fd].flags & ~LIB_ELF64) + 3,
               libent[fd].flags & LIB_ELF64 ? "/64" : "");
          break;
        default:
          printf("(unknown)");
          break;
      }
      printf(" => %s\n", strs + libent[fd].liboffset);
    }

    munmap (c,st.st_size);
}


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