Re: RFA: strip stdcall suffixes under cygwin

[Christopher Faylor <cgf@redhat.com>]

On Wed, Mar 27, 2002 at 06:35:25PM -0500, Jim Blandy wrote:
>Chris, I think I need your approval for this.

Approved.

Thanks,
cgf

>2002-03-27  Jim Blandy  <jimb@redhat.com>
>
>	* config/i386/tm-cygwin.h: #define
>	LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES.
>	* symtab.c (LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES): Provide
>	default #definition here, if tm-*.h file doesn't have one.
>	(symbol_init_mangled_name): If the above is #defined, strip off
>	the stdcall arg size, if present, from linker symbol names before
>	trying to demangle them.
>
>Index: gdb/symtab.c
>===================================================================
>RCS file: /cvs/src/src/gdb/symtab.c,v
>retrieving revision 1.59
>diff -c -r1.59 symtab.c
>*** gdb/symtab.c	2002/03/27 23:10:23	1.59
>--- gdb/symtab.c	2002/03/27 23:19:07
>***************
>*** 353,358 ****
>--- 353,362 ----
>  \f
>  /* Initialize a symbol's mangled name.  */
>  
>+ #ifndef LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES
>+ #define LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES (0)
>+ #endif
>+ 
>  /* Try to initialize the demangled name for a symbol, based on the
>     language of that symbol.  If the language is set to language_auto,
>     it will attempt to find any demangling algorithm that works and
>***************
>*** 369,381 ****
>    char *mangled = gsymbol->name;
>    char *demangled = NULL;
>  
>    if (gsymbol->language == language_unknown)
>      gsymbol->language = language_auto;
>    if (gsymbol->language == language_cplus
>        || gsymbol->language == language_auto)
>      {
>        demangled =
>!         cplus_demangle (gsymbol->name, DMGL_PARAMS | DMGL_ANSI);
>        if (demangled != NULL)
>          {
>            gsymbol->language = language_cplus;
>--- 373,418 ----
>    char *mangled = gsymbol->name;
>    char *demangled = NULL;
>  
>+   /* On Windows, some functions use the `stdcall' calling convention,
>+      in which the callee is expected to pop the arguments off the
>+      stack.  Normally, the caller takes care of this, because only the
>+      caller knows how many arguments it really passed.  To avoid
>+      confusion, the linker symbols for `stdcall' functions have names
>+      with a suffix "@N" attached to them, where "N" is the number of
>+      bytes they'll pop.  That way, if a caller thinks some `stdcall'
>+      function `foo' expects M argument bytes, but the definition of
>+      `foo' expects N argument bytes, N != M, then the call will be a
>+      reference to `foo@M', but the definition will have a linker
>+      symbol `foo@N', and you'll get a link-time `symbol not found'
>+      error, instead of a crash at run-time.
>+ 
>+      (Note how this fails to address calls through function pointers,
>+      since the byte count isn't part of the function pointer's type.
>+      Go, Microsoft!)
>+ 
>+      Whatever.  But our demangler doesn't like that '@N' suffix, so we
>+      need to strip it off.  */
>+   if (LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES)
>+     {
>+       char *arg_byte_suffix = strchr (mangled, '@');
>+       if (arg_byte_suffix)
>+         {
>+           int prefix_len = arg_byte_suffix - mangled;
>+           char *mangled_sans_suffix = alloca (prefix_len + 1);
>+           memcpy (mangled_sans_suffix, mangled, prefix_len);
>+           mangled_sans_suffix[prefix_len] = '\0';
>+ 
>+           mangled = mangled_sans_suffix;
>+         }
>+     }
>+ 
>    if (gsymbol->language == language_unknown)
>      gsymbol->language = language_auto;
>    if (gsymbol->language == language_cplus
>        || gsymbol->language == language_auto)
>      {
>        demangled =
>!         cplus_demangle (mangled, DMGL_PARAMS | DMGL_ANSI);
>        if (demangled != NULL)
>          {
>            gsymbol->language = language_cplus;
>***************
>*** 391,397 ****
>    if (gsymbol->language == language_java)
>      {
>        demangled =
>!         cplus_demangle (gsymbol->name,
>                          DMGL_PARAMS | DMGL_ANSI | DMGL_JAVA);
>        if (demangled != NULL)
>          {
>--- 428,434 ----
>    if (gsymbol->language == language_java)
>      {
>        demangled =
>!         cplus_demangle (mangled,
>                          DMGL_PARAMS | DMGL_ANSI | DMGL_JAVA);
>        if (demangled != NULL)
>          {
>Index: gdb/symtab.h
>===================================================================
>RCS file: /cvs/src/src/gdb/symtab.h,v
>retrieving revision 1.29
>diff -c -r1.29 symtab.h
>*** gdb/symtab.h	2002/03/27 23:10:24	1.29
>--- gdb/symtab.h	2002/03/27 23:19:08
>***************
>*** 159,170 ****
>        }									\
>    } while (0)
>  
>  #define SYMBOL_INIT_DEMANGLED_NAME(symbol,obstack) \
>    (symbol_init_demangled_name (&symbol->ginfo, (obstack)))
>  extern void symbol_init_demangled_name (struct general_symbol_info *symbol,
>                                          struct obstack *obstack);
>  
>-   
>  /* Macro that returns the demangled name for a symbol based on the language
>     for that symbol.  If no demangled name exists, returns NULL. */
>  
>--- 159,171 ----
>        }									\
>    } while (0)
>  
>+ 
>  #define SYMBOL_INIT_DEMANGLED_NAME(symbol,obstack) \
>    (symbol_init_demangled_name (&symbol->ginfo, (obstack)))
>  extern void symbol_init_demangled_name (struct general_symbol_info *symbol,
>                                          struct obstack *obstack);
>+ 
>  
>  /* Macro that returns the demangled name for a symbol based on the language
>     for that symbol.  If no demangled name exists, returns NULL. */
>  
>Index: gdb/config/i386/tm-cygwin.h
>===================================================================
>RCS file: /cvs/src/src/gdb/config/i386/tm-cygwin.h,v
>retrieving revision 1.11
>diff -c -r1.11 tm-cygwin.h
>*** gdb/config/i386/tm-cygwin.h	2001/11/27 05:15:58	1.11
>--- gdb/config/i386/tm-cygwin.h	2002/03/27 23:19:12
>***************
>*** 47,49 ****
>--- 47,51 ----
>  char *child_solib_loaded_library_pathname(int);
>  void child_clear_solibs (void);
>  void dll_symbol_command (char *, int);
>+ 
>+ #define LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES (1)