lib/libdll/dlfcn.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1997-2011 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                 Eclipse Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*          http://www.eclipse.org/org/documents/epl-v10.html           *
*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * provide dlopen/dlsym/dlerror interface
 *
 * David Korn
 * Glenn Fowler
 * AT&T Research
 */

static const char id[] = "\n@(#)$Id: dll library (AT&T Research) 2010-10-20 $\0\n";

#include <ast.h>
#include <dlldefs.h>
#include <error.h>

#define T(x)    ERROR_dictionary(x)

#if _BLD_dll && defined(__EXPORT__)
#define extern  __EXPORT__
#endif

#if _hdr_dlfcn && _lib_dlopen

    /*
     * standard
     */

#   include <dlfcn.h>

#else
#if _hdr_dl

    /*
     * HP-UX
     */

#   include <dl.h>
#   ifndef BIND_FIRST
#   define BIND_FIRST   0x4
#   endif
#   ifndef BIND_NOSTART
#   define BIND_NOSTART 0x10
#   endif

    static shl_t    all;
    static int  err;

    extern void* dlopen(const char* path, int mode)
    {
        void*   dll;

        if (!path)
            return (void*)&all;
        if (mode)
            mode = (BIND_IMMEDIATE|BIND_FIRST|BIND_NOSTART);
        if (!(dll = (void*)shl_load(path, mode, 0L)))
            err = errno;
        return dll;
    }

    extern int dlclose(void* dll)
    {
        return 0;
    }

    extern void* dlsym(void* dll, const char* name)
    {
        shl_t   handle;
        long    addr;

        handle = dll == (void*)&all ? (shl_t)0 : (shl_t)dll;
        if (shl_findsym(&handle, name, TYPE_UNDEFINED, &addr))
        {
            err = errno;
            return 0;
        }
        return (void*)addr;
    }

    extern char* dlerror(void)
    {
        char*   msg;

        if (!err)
            return 0;
        msg = fmterror(err);
        err = 0;
        return msg;
    }

#else
#if _sys_ldr && _lib_loadbind

    /*
     * rs6000
     */

#   include <sys/ldr.h>
#   include <xcoff.h>

    /* xcoff module header */
    struct hdr
    {
        struct filehdr  f;
        struct aouthdr  a;
        struct scnhdr   s[1];
    };

    static struct ld_info*  ld_info;
    static unsigned int ld_info_size = 1024;
    static void*        last_module;
    static int      err;

    extern void* dlopen(const char* path, int mode)
    {
        void*   dll;

        if (!(dll = (void*)load((char*)path, mode, getenv("LIBPATH"))))
            err = errno;
        return dll;
    }

    extern int dlclose(void* dll)
    {
        return 0;
    }

    static int getquery(void)
    {
        if (!ld_info)
            ld_info = malloc(ld_info_size);
        for (;;)
        {
            if (!ld_info)
                return 1;
            if (!loadquery(L_GETINFO, ld_info, ld_info_size))
                return 0;
            if (errno != ENOMEM)
                return 1;
            ld_info = realloc(ld_info, ld_info_size *= 2);
        }
    }

    /* find the loaded module whose data area contains the
     * address passed in. Remember that procedure pointers
     * are implemented as pointers to descriptors in the
     * data area of the module defining the procedure
     */
    static struct ld_info* getinfo(void* module)
    {
        struct ld_info* info = ld_info;
        register int    n = 1;

        if (!ld_info || module != last_module)
        {
            last_module = module;
            if (getquery())
                return 0;
            info = ld_info;
        }
        while (n)
        {
            if ((char*)(info->ldinfo_dataorg) <= (char*)module &&
                (char*)module <= ((char*)(info->ldinfo_dataorg)
                + (unsigned)(info->ldinfo_datasize)))
                return info;
            if (n=info->ldinfo_next)
                info = (void*)((char*)info + n);
        }
        return 0;
    }

    static char* getloc(struct hdr* hdr, char* data, char* name)
    {
        struct ldhdr*   ldhdr;
        struct ldsym*   ldsym;
        ulong       datareloc;
        ulong       textreloc;
        int     i;

        /* data is relocated by the difference between
         * its virtual origin and where it was
         * actually placed
         */
        /*N.B. o_sndata etc. are one based */
        datareloc = (ulong)data - hdr->s[hdr->a.o_sndata-1].s_vaddr;
        /*hdr is address of header, not text, so add text s_scnptr */
        textreloc = (ulong)hdr + hdr->s[hdr->a.o_sntext-1].s_scnptr
            - hdr->s[hdr->a.o_sntext-1].s_vaddr;
        ldhdr = (void*)((char*)hdr+ hdr->s[hdr->a.o_snloader-1].s_scnptr);
        ldsym = (void*) (ldhdr+1);
        /* search the exports symbols */
        for(i=0; i < ldhdr->l_nsyms;ldsym++,i++)
        {
            char *symname,symbuf[9];
            char *loc;
            /* the symbol name representation is a nuisance since
             * 8 character names appear in l_name but may
             * not be null terminated. This code works around
             * that by brute force
             */
            if (ldsym->l_zeroes)
            {
                symname = symbuf;
                memcpy(symbuf,ldsym->l_name,8);
                symbuf[8] = 0;
            }
            else
                symname = (void*)(ldsym->l_offset + (ulong)ldhdr + ldhdr->l_stoff);
            if (strcmp(symname,name))
                continue;
            loc = (char*)ldsym->l_value;
            if ((ldsym->l_scnum==hdr->a.o_sndata) ||
                (ldsym->l_scnum==hdr->a.o_snbss))
                loc += datareloc;
            else if (ldsym->l_scnum==hdr->a.o_sntext)
                loc += textreloc;
            return loc;
        }
        return 0;
    }

    extern void* dlsym(void* handle, const char* name)
    {
        void*       addr;
        struct ld_info* info;

        if (!(info = getinfo(handle)) || !(addr = getloc(info->ldinfo_textorg,info->ldinfo_dataorg,(char*)name)))
        {
            err = errno;
            return 0;
        }
        return addr;
    }

    extern char* dlerror(void)
    {
        char*   msg;

        if (!err)
            return 0;
        msg = fmterror(err);
        err = 0;
        return msg;
    }

#else
#if _hdr_dll && _lib_dllload

    /*
     * MVS
     */

#   include <dll.h>

    static int  err;

    extern void* dlopen(const char* path, int mode)
    {
        void*   dll;

        NoP(mode);
        if (!(dll = (void*)dllload(path)))
            err = errno;
        return dll;
    }

    extern int dlclose(void* dll)
    {
        return 0;
    }

    extern void* dlsym(void* handle, const char* name)
    {
        void*   addr;

        if (!(addr = (void*)dllqueryfn(handle, (char*)name)))
            err = errno;
        return addr;
    }

    extern char* dlerror(void)
    {
        char*   msg;

        if (!err)
            return 0;
        msg = fmterror(err);
        err = 0;
        return msg;
    }

#else
#if _hdr_mach_o_dyld

    /*
     * mac[h]
     */

#   include <mach-o/dyld.h>

    typedef const struct mach_header* NSImage;

    typedef struct Dll_s
    {
        unsigned long   magic;
        NSImage     image;
        NSModule    module;
        char        path[1];
    } Dll_t;

    #define DL_MAGIC    0x04190c04
    #define DL_NEXT     ((Dll_t*)RTLD_NEXT)

    static const char*  dlmessage = "no error";

    static const char   e_cover[] = T("cannot access covered library");
    static const char   e_handle[] = T("invalid handle");
    static const char   e_space[] = T("out of space");
    static const char   e_static[] = T("image statically linked");
    static const char   e_undefined[] = T("undefined symbol");

    static Dll_t global = { DL_MAGIC };

    static void undefined(const char* name)
    {
    }

    static NSModule multiple(NSSymbol sym, NSModule om, NSModule nm)
    {
        return om;
    }

    static void linkedit(NSLinkEditErrors c, int n, const char* f, const char* m)
    {
        dlmessage = m;
    }

    static NSLinkEditErrorHandlers handlers =
    {
        undefined, multiple, linkedit
    };

    extern void* dlopen(const char* path, int mode)
    {
        Dll_t*          dll;
        int         i;
        NSObjectFileImage   image;

        static int      init = 0;

        if (!_dyld_present())
        {
            dlmessage = e_static;
            return 0;
        }
        if (!init)
        {
            init = 1;
            NSInstallLinkEditErrorHandlers(&handlers);
        }
        if (!path)
            dll = &global;
        else if (!(dll = newof(0, Dll_t, 1, strlen(path))))
        {
            dlmessage = e_space;
            return 0;
        }
        else
        {
            switch (NSCreateObjectFileImageFromFile(path, &image))
            {
            case NSObjectFileImageSuccess:
                dll->module = NSLinkModule(image, path, (mode & RTLD_LAZY) ? 0 : NSLINKMODULE_OPTION_BINDNOW);
                NSDestroyObjectFileImage(image);
                if (!dll->module)
                {
                    free(dll);
                    return 0;
                }
                break;
            case NSObjectFileImageInappropriateFile:
                dll->image = NSAddImage(path, 0);
                if (!dll->image)
                {
                    free(dll);
                    return 0;
                }
                break;
            default:
                free(dll);
                return 0;
            }
            strcpy(dll->path, path);
            dll->magic = DL_MAGIC;
        }
        return (void*)dll;
    }

    extern int dlclose(void* handle)
    {
        Dll_t*  dll = (Dll_t*)handle;

        if (!dll || dll == DL_NEXT || dll->magic != DL_MAGIC)
        {
            dlmessage = e_handle;
            return -1;
        }
        if (dll->module)
            NSUnLinkModule(dll->module, 0);
        free(dll);
        return 0;
    }

    static NSSymbol
    lookup(Dll_t* dll, const char* name)
    {
        unsigned long   pun;
        void*       address;

        if (dll == DL_NEXT)
        {
            if (!_dyld_func_lookup(name, &pun))
                return 0;
            address = (NSSymbol)pun;
        }
        else if (dll->module)
            address = NSLookupSymbolInModule(dll->module, name);
        else if (dll->image)
        {
            if (!NSIsSymbolNameDefinedInImage(dll->image, name))
                return 0;
            address = NSLookupSymbolInImage(dll->image, name, 0);
        }
        else
        {
            if (!NSIsSymbolNameDefined(name))
                return 0;
            address = NSLookupAndBindSymbol(name);
        }
        if (address)
            address = NSAddressOfSymbol(address);
        return address;
    }

    extern void* dlsym(void* handle, const char* name)
    {
        Dll_t*      dll = (Dll_t*)handle;
        NSSymbol    address;
        char        buf[1024];

        if (!dll || dll != DL_NEXT && (dll->magic != DL_MAGIC || !dll->image && !dll->module))
        {
            dlmessage = e_handle;
            return 0;
        }
        if (!(address = lookup(dll, name)) && name[0] != '_' && strlen(name) < (sizeof(buf) - 1))
        {
            buf[0] = '_';
            strcpy(buf + 1, name);
            address = lookup(dll, buf);
        }
        if (!address)
        {
            dlmessage = dll == DL_NEXT ? e_cover : e_undefined;
            return 0;
        }
        return (void*)address;
    }

    extern char* dlerror(void)
    {
        char*   msg;

        msg = (char*)dlmessage;
        dlmessage = 0;
        return msg;
    }

#else
    /*
     * punt
     */

    static int  err;

    extern void* dlopen(const char* path, int mode)
    {
        err = 1;
        return 0;
    }

    extern int dlclose(void* dll)
    {
        err = 1;
        return 0;
    }

    extern void* dlsym(void* handle, const char* name)
    {
        err = 1;
        return 0;
    }

    extern char* dlerror(void)
    {
        if (!err)
            return 0;
        err = 0;
        return "dynamic linking not supported";
    }

#endif
#endif
#endif
#endif
#endif