load_lib.c

[詳解]

/*++
/* NAME
/*  load_lib 3
/* SUMMARY
/*  library loading wrappers
/* SYNOPSIS
/*  #include <load_lib.h>
/*
/*  void    load_library_symbols(const char *, LIB_FN *, LIB_DP *);
/*  const char *libname;
/*  LIB_FN  *libfuncs;
/*  LIB_DP  *libdata;
/* DESCRIPTION
/*  load_library_symbols() loads the specified shared object
/*  and looks up the function or data pointers for the specified
/*  symbols. All errors are fatal.
/*
/*  Arguments:
/* .IP libname
/*  shared-library pathname.
/* .IP libfuncs
/*  Array of LIB_FN strucures. The last name member must be null.
/* .IP libdata
/*  Array of LIB_DP strucures. The last name member must be null.
/* SEE ALSO
/*  msg(3) diagnostics interface
/* DIAGNOSTICS
/*  Problems are reported via the msg(3) diagnostics routines:
/*  library not found, symbols not found, other fatal errors.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  LaMont Jones
/*  Hewlett-Packard Company
/*  3404 Harmony Road
/*  Fort Collins, CO 80528, USA
/*
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

 /*
  * System libraries.
  */
#include "sys_defs.h"
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#ifdef USE_DYNAMIC_MAPS
#if defined(HAS_DLOPEN)
#include <dlfcn.h>
#elif defined(HAS_SHL_LOAD)
#include <dl.h>
#else
#error "USE_DYNAMIC_LIBS requires HAS_DLOPEN or HAS_SHL_LOAD"
#endif

 /*
  * Utility library.
  */
#include <msg.h>
#include <load_lib.h>

/* load_library_symbols - load shared library and look up symbols */

void    load_library_symbols(const char *libname, LIB_FN *libfuncs,
                         LIB_DP *libdata)
{
    static const char myname[] = "load_library_symbols";
    LIB_FN *fn;
    LIB_DP *dp;

#if defined(HAS_DLOPEN)
    void   *handle;
    char   *emsg;

    /*
     * XXX This is basically how FreeBSD dlfunc() silences a compiler warning
     * about a data/function pointer conversion. The solution below is non-
     * portable: it assumes that both data and function pointers are the same
     * in size, and that both have the same representation.
     */
    union {
    void   *dptr;           /* data pointer */
    void    (*fptr) (void);     /* function pointer */
    }       non_portable_union;

    if ((handle = dlopen(libname, RTLD_NOW)) == 0) {
    emsg = dlerror();
    msg_fatal("%s: dlopen failure loading %s: %s", myname, libname,
          emsg ? emsg : "don't know why");
    }
    if (libfuncs) {
    for (fn = libfuncs; fn->name; fn++) {
        if ((non_portable_union.dptr = dlsym(handle, fn->name)) == 0) {
        emsg = dlerror();
        msg_fatal("%s: dlsym failure looking up %s in %s: %s", myname,
              fn->name, libname, emsg ? emsg : "don't know why");
        }
        fn->fptr = non_portable_union.fptr;
        if (msg_verbose > 1)
        msg_info("loaded %s = %p", fn->name, non_portable_union.dptr);
    }
    }
    if (libdata) {
    for (dp = libdata; dp->name; dp++) {
        if ((dp->dptr = dlsym(handle, dp->name)) == 0) {
        emsg = dlerror();
        msg_fatal("%s: dlsym failure looking up %s in %s: %s", myname,
              dp->name, libname, emsg ? emsg : "don't know why");
        }
        if (msg_verbose > 1)
        msg_info("loaded %s = %p", dp->name, dp->dptr);
    }
    }
#elif defined(HAS_SHL_LOAD)
    shl_t   handle;

    handle = shl_load(libname, BIND_IMMEDIATE, 0);

    if (libfuncs) {
    for (fn = libfuncs; fn->name; fn++) {
        if (shl_findsym(&handle, fn->name, TYPE_PROCEDURE, &fn->fptr) != 0)
        msg_fatal("%s: shl_findsym failure looking up %s in %s: %m",
              myname, fn->name, libname);
        if (msg_verbose > 1)
        msg_info("loaded %s = %p", fn->name, (void *) fn->fptr);
    }
    }
    if (libdata) {
    for (dp = libdata; dp->name; dp++) {
        if (shl_findsym(&handle, dp->name, TYPE_DATA, &dp->dptr) != 0)
        msg_fatal("%s: shl_findsym failure looking up %s in %s: %m",
              myname, dp->name, libname);
        if (msg_verbose > 1)
        msg_info("loaded %s = %p", dp->name, dp->dptr);
    }
    }
#endif
}

#endif