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Message-ID: <0a9301c17269$075c5a30$0200a8c0@lifelesswks>
From: "Robert Collins" <robert DOT collins AT itdomain DOT com DOT au>
To: "Danny Smith" <danny_r_smith_2001 AT yahoo DOT co DOT nz>,
   "cygwin-apps" <cygwin-apps AT cygwin DOT com>,
   "mingw-dvlpr" <mingw-dvlpr AT lists DOT sourceforge DOT net>
References: <20011121084158 DOT 22945 DOT qmail AT web14501 DOT mail DOT yahoo DOT com>
Subject: Re: ld  ---export--all --exclude-libs,?
Date: Wed, 21 Nov 2001 19:46:35 +1100
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IIRC the reason the auto-export feature didn't automatically prevent
forwarded exports was we didn't know how. I had a quick look at doing
that when I tweaked Paul's work to also exlude the cygwin common
symbols.

If you've found how to detect forward exports coming from other
libraries, then _please_ make excluding those the default. In fact IMO
such symbols should require explicit source code decoration -say via the
.def file- to create as AFAIK there is no ELF equivalent to a forwarded
symbol.

Rob

===
----- Original Message -----
From: "Danny Smith" <danny_r_smith_2001 AT yahoo DOT co DOT nz>
To: "cygwin-apps" <cygwin-apps AT cygwin DOT com>; "mingw-dvlpr"
<mingw-dvlpr AT lists DOT sourceforge DOT net>
Sent: Wednesday, November 21, 2001 7:41 PM
Subject: ld ---export--all --exclude-libs,?


> Hello, I'm after some criticism, before submitting this to binutils.
>
> IMO, the auto-export feature of ld needs (at least) an option to
exclude
> whole libs from export. The following patch does that. It also adds a
few
> more default lib excludes and scans for backward compat implib symbols
> (__imp_)
>
> I think this patch doesn't do enough.
>
> My preference would be to exclude *all* libs by default, with a
command
> line option to explicity *include* named libs.  Why? It is too easy
for
> licensed library code to sneak into dll's using --export-all. This
affects
> distributability (sic) of the dll and apps dependent on the dll.
> The user may be unaware of this infection because its automatic.
> At least make the user think about what she/he is exporting.
>
> I will gladly throw away the following to work on a patch to exclude
all
> libs by default if given encouragement.
>
> Any comments.
>
>
> 2001-11-21  Danny Smith  <dannysmith AT users DOT sourceforge DOT net>
>
> * ld/emultempl/pe.em (OPTION_EXCLUDE_LIBS): Add new define.
> (longopts): Add new option --exclude-libs.
> (gld_${EMULATION_NAME}_list_options): Document it.
> (gld_${EMULATION_NAME}_parse_args): Use it.
> * ld/pe-dll.h (pe_dll_add_excludes): Add second param to prototype.
> * ld/pe-dll.c (autofilter_liblist): Add more default libs.
> (exclude_list_struct): Add field type to distinguish
> symbols from whole archives.
> (pe_dll_add_excludes): Set excludes->type.
> (auto_export): Scan for old __imp_ prefix as well as _imp__
> when filtering symbols. Add new variable libname and set to
>   archive basename if abfd. Use it when filtering default and
> user-specified libarary excludes. Use excludes->type when
> scanning user-specified excludes.
>
> Index: src/ld/pe-dll.c
> ===================================================================
> RCS file: /cvs/src/src/ld/pe-dll.c,v
> retrieving revision 1.37
> diff -u -p -r1.37 pe-dll.c
> --- pe-dll.c 2001/10/19 14:25:51 1.37
> +++ pe-dll.c 2001/11/21 08:20:19
> @@ -231,6 +231,9 @@ static autofilter_entry_type autofilter_
>    { "libgcc.", 7 },
>    { "libstdc++.", 10 },
>    { "libmingw32.", 11 },
> +  { "libg2c.", 7 },
> +  { "libsupc++.", 10 },  /* g++ 3.x  */
> +  { "libobjc.", 8 },
>    { NULL, 0 }
>  };
>
> @@ -368,14 +371,16 @@ typedef struct exclude_list_struct
>    {
>      char *string;
>      struct exclude_list_struct *next;
> +    int type;
>    }
>  exclude_list_struct;
>
>  static struct exclude_list_struct *excludes = 0;
>
>  void
> -pe_dll_add_excludes (new_excludes)
> +pe_dll_add_excludes (new_excludes, type)
>       const char *new_excludes;
> +     const int type;
>  {
>    char *local_copy;
>    char *exclude_string;
> @@ -391,6 +396,7 @@ pe_dll_add_excludes (new_excludes)
>        xmalloc (sizeof (struct exclude_list_struct)));
>        new_exclude->string = (char *) xmalloc (strlen (exclude_string)
+
> 1);
>        strcpy (new_exclude->string, exclude_string);
> +      new_exclude->type = type;
>        new_exclude->next = excludes;
>        excludes = new_exclude;
>      }
> @@ -398,6 +404,7 @@ pe_dll_add_excludes (new_excludes)
>    free (local_copy);
>  }
>
> +
>  /* abfd is a bfd containing n (or NULL)
>     It can be used for contextual checks.  */
>
> @@ -410,9 +417,13 @@ auto_export (abfd, d, n)
>    int i;
>    struct exclude_list_struct *ex;
>    autofilter_entry_type *afptr;
> +  const char * libname = 0;
> +  if (abfd && abfd->my_archive)
> +    libname = lbasename (abfd->my_archive->filename);
>
>    /* We should not re-export imported stuff.  */
> -  if (strncmp (n, "_imp__", 6) == 0)
> +  if ((strncmp (n, "_imp__", 6) == 0)
> +      || (strncmp (n, "__imp_", 6) == 0))
>      return 0;
>
>    for (i = 0; i < d->num_exports; i++)
> @@ -429,14 +440,14 @@ auto_export (abfd, d, n)
>   n, abfd, abfd->my_archive);
>
>        /* First of all, make context checks:
> -         Don't export anything from libgcc.  */
> -      if (abfd && abfd->my_archive)
> +         Don't export anything from standard libs.  */
> +      if (libname)
>   {
>     afptr = autofilter_liblist;
>
>     while (afptr->name)
>       {
> -       if (strstr (abfd->my_archive->filename, afptr->name))
> +       if (strncmp (libname, afptr->name, afptr->len) == 0 )
>   return 0;
>         afptr++;
>       }
> @@ -495,8 +506,15 @@ auto_export (abfd, d, n)
>      }
>
>    for (ex = excludes; ex; ex = ex->next)
> -    if (strcmp (n, ex->string) == 0)
> -      return 0;
> +    {
> +      if (ex->type == 1)
> + {
> +   if (libname && (strcmp (libname, ex->string) == 0))
> +            return 0;
> + }
> +      else if (strcmp (n, ex->string) == 0)
> +        return 0;
> +    }
>
>    return 1;
>  }
> Index: src/ld/pe-dll.h
> ===================================================================
> RCS file: /cvs/src/src/ld/pe-dll.h,v
> retrieving revision 1.5
> diff -u -p -r1.5 pe-dll.h
> --- pe-dll.h 2001/09/12 15:58:10 1.5
> +++ pe-dll.h 2001/11/21 08:20:19
> @@ -36,7 +36,7 @@ extern int pe_dll_compat_implib;
>  extern int pe_dll_extra_pe_debug;
>
>  extern void pe_dll_id_target PARAMS ((const char *));
> -extern void pe_dll_add_excludes PARAMS ((const char *));
> +extern void pe_dll_add_excludes PARAMS ((const char *, const int));
>  extern void pe_dll_generate_def_file PARAMS ((const char *));
>  extern void pe_dll_generate_implib PARAMS ((def_file *, const char
*));
>  extern void pe_process_import_defs PARAMS ((bfd *, struct
bfd_link_info
> *));
> Index: src/ld/emultempl/pe.em
> ===================================================================
> RCS file: /cvs/src/src/ld/emultempl/pe.em,v
> retrieving revision 1.54
> diff -u -p -r1.54 pe.em
> --- pe.em 2001/09/24 18:21:24 1.54
> +++ pe.em 2001/11/21 08:20:30
> @@ -221,7 +221,9 @@ gld_${EMULATION_NAME}_before_parse()
>  #define OPTION_DLL_ENABLE_AUTO_IMPORT (OPTION_NO_DEFAULT_EXCLUDES +
1)
>  #define OPTION_DLL_DISABLE_AUTO_IMPORT (OPTION_DLL_ENABLE_AUTO_IMPORT
+ 1)
>  #define OPTION_ENABLE_EXTRA_PE_DEBUG (OPTION_DLL_DISABLE_AUTO_IMPORT
+ 1)
> +#define OPTION_EXCLUDE_LIBS (OPTION_ENABLE_EXTRA_PE_DEBUG + 1)
>
> +
>  static struct option longopts[] = {
>    /* PE options */
>    {"base-file", required_argument, NULL, OPTION_BASE_FILE},
> @@ -247,6 +249,7 @@ static struct option longopts[] = {
>    {"output-def", required_argument, NULL, OPTION_OUT_DEF},
>    {"export-all-symbols", no_argument, NULL, OPTION_EXPORT_ALL},
>    {"exclude-symbols", required_argument, NULL,
OPTION_EXCLUDE_SYMBOLS},
> +  {"exclude-libs", required_argument, NULL, OPTION_EXCLUDE_LIBS},
>    {"kill-at", no_argument, NULL, OPTION_KILL_ATS},
>    {"add-stdcall-alias", no_argument, NULL, OPTION_STDCALL_ALIASES},
>    {"enable-stdcall-fixup", no_argument, NULL,
> OPTION_ENABLE_STDCALL_FIXUP},
> @@ -333,6 +336,7 @@ gld_${EMULATION_NAME}_list_options (file
>    fprintf (file, _("  --disable-stdcall-fixup            Don't link
_sym
> to _sym AT nn\n"));
>    fprintf (file, _("  --enable-stdcall-fixup             Link _sym to
> _sym AT nn without warnings\n"));
>    fprintf (file, _("  --exclude-symbols sym,sym,...      Exclude
symbols
> from automatic export\n"));
> +  fprintf (file, _("  --exclude-libs lib,lib,...         Exclude
libraries
> from automatic export\n"));
>    fprintf (file, _("  --export-all-symbols
Automatically
> export all globals to DLL\n"));
>    fprintf (file, _("  --kill-at                          Remove @nn
from
> exported symbols\n"));
>    fprintf (file, _("  --out-implib <file>                Generate
import
> library\n"));
> @@ -586,7 +590,10 @@ gld_${EMULATION_NAME}_parse_args(argc, a
>        pe_dll_export_everything = 1;
>        break;
>      case OPTION_EXCLUDE_SYMBOLS:
> -      pe_dll_add_excludes (optarg);
> +      pe_dll_add_excludes (optarg, 0);
> +      break;
> +    case OPTION_EXCLUDE_LIBS:
> +      pe_dll_add_excludes (optarg, 1);
>        break;
>      case OPTION_KILL_ATS:
>        pe_dll_kill_ats = 1;
>
>
>
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