Re: relocwrapper interaction with replacement functions

[Bruno Haible]

Hi Ben,

> To demonstrate what I meant, I spent a bit of time working on
> modules/relocatable-prog-wrapper, coming up with this:
> 
>     Makefile.am:
>     if !RELOCATABLE_VIA_LD
>     noinst_PROGRAMS += reloc-wrapper
>     reloc_wrapper_CPPFLAGS = \
>             -I$(builddir) -I$(srcdir) -I$(RELOCATABLE_CONFIG_H_DIR) \
>             -DHAVE_CONFIG_H -DIN_RELOCWRAPPER -DNO_XMALLOC \
>             -DINSTALLPREFIX=\"$(prefix)\" -DINSTALLDIR=\"...\" \
>             -DLIBPATHVAR=\"$(shlibpathvar)\" -DLIBDIRS=$(libdirs) \
>             -DEXEEXT=\"$(EXEEXT)\"
>     reloc_wrapper_SOURCES = \
>             relocwrapper.c progname.c progreloc.c areadlink.c readlink.c \
>             canonicalize-lgpl.c malloca.c relocatable.c setenv.c strerror.c \
>             c-ctype.c
>     endif
> 
> before I realized that there was no way to fill in the ... in
> the -DINSTALLDIR=\"...\" part, since it can vary from one binary
> to another.  So I see what you mean now.

And that's not all. You also need some magic which causes a program 'foo'
to be installed as $(bindir)/foo.bin or $(libexecdir)/foo.bin, rather
than $(bindir)/foo or $(libexecdir)/foo...

> > What is the complete required symbol list (nm ...o | grep ' U ') of the set
> > of modules compiled for the relocwrapper on your system?
> 
> Here it is:
> 
>          U abort
>          U access
>          U canonicalize_file_name
>          U compute_curr_prefix
>          U __errno
>          U execv
>          U exit
>          U fprintf
>          U free
>          U freea
>          U fwrite
>          U getcwd
>          U getenv
>          U get_full_program_name
>          U __guard
>          U lstat
>          U malloc
>          U memcpy
>          U memmove
>          U mmalloca
>          U program_name
>          U readlink
>          U realloc
>          U relocate
>          U rpl_readlink
>          U rpl_strerror
>          U setenv
>          U set_program_name
>          U set_program_name_and_installdir
>          U set_relocation_prefix
>          U __sF
>          U sprintf
>          U __stack_smash_handler
>          U strchr
>          U strcmp
>          U strcpy
>          U strerror
>          U strncmp
>          U strrchr

Thanks. Among these functions, only the following are replaced by gnulib:

  canonicalize_file_name
  fprintf
  free
  fwrite
  getcwd
  lstat
  malloc
  memcpy
  memmove
  readlink
  realloc
  setenv
  sprintf
  strerror

Eliminating those which are replaced among this file set:

  relocwrapper.c progname.c progreloc.c areadlink.c readlink.c \
  canonicalize-lgpl.c malloca.c relocatable.c setenv.c strerror.c \
  c-ctype.c

The following remain:

  fprintf
  free
  fwrite
  getcwd
  lstat
  malloc
  memcpy
  memmove
  realloc
  sprintf

Eliminating those where the replacing module is obsolete:

  fprintf
  fwrite
  getcwd
  lstat
  malloc
  realloc
  sprintf

Detailed analysis:
  - fprintf is only used in relocwrapper.c, with %s directives => no gnulib
    replacement needed.
  - fwrite is emitted by gcc, when we call fputs in progname.c. There is no
    risk that it might accidentally call rpl_fwrite. => nothing to do.
  - getcwd: used by canonicalize-lgpl.c. Here it could be useful to use the
    gnulib replacement.
  - lstat: used by canonicalize-lgpl.c. I don't understand why this doesn't
    give link errors on mingw??
  - malloc: used by relocwrapper.c, progreloc.c, areadlink.c,
    canonicalize-lgpl.c, malloca.c, relocatable.c, setenv.c. No gnulib
    replacement needed, except in areadlink.c.
  - realloc: used by areadlink.c, canonicalize-lgpl.c, setenv.c. No gnulib
    replacement needed.
  - sprintf: used by progreloc.c, strerror.c. No gnulib replacement needed.

This leads to a series of 4 patches:
  [1/4] setenv
  [2/4] misc. relocwrapper link errors
  [3/4] areadlink, relocwrapper link errors
  [4/4] getcwd, relocwrapper link errors

Bruno