[PATCH, libgfortran] PR 60324 Unbounded stack allocations in libgfortran

[Janne Blomqvist <blomqvist dot janne at gmail dot com>]

Hi,

in the spirit of PR 60324 and 61035, here's a patch that gets rid of
the remaining potentially unbounded stack allocations in libgfortran.
All uses of __builtin_alloca() and VLA's are replaced either straight
with heap allocated memory, or with a fixed size stack buffer,
potentially switching to heap storage for large sizes in places where
performance might matter. In order to avoid reintroducing these kinds
of issues, I also added -Werror=vla to AM_CFLAGS.

This might also help limited targets like nvptx that lack VLA's.

Regtested on x86_64-unknown-linux-gnu, Ok for trunk?

2014-11-13  Janne Blomqvist  <jb@gcc.gnu.org>

    PR libfortran/60324
    * configure: Regenerated.
    * configure.ac (AM_CFLAGS): Add Werror=vla.
    * libgfortran.h (gfc_alloca): Remove macro.
    (fc_strdup_notrim): New prototype.
    * intrinsics/access.c (access_func): Use fc_strdup rather than
    stack allocation.
    * intrinsics/chdir.c (chdir_i4_sub): Likewise.
    (chdir_i8_sub): Likewise.
    * intrinsics/chmod.c (chmod_internal): New function, move logic
    here.
    (chmod_func): Call chmod_internal.
    * intrinsics/env.c (getenv): Use fc_strdup rather than stack
    allocation.
    (get_environment_variable_i4): Likewise.
    * intrinsics/execute_command_line.c (execute_command_line):
    Likewise.
    * intrinsics/hostnm.c (hostnm_0): New function, use static buffer
    rather than VLA.
    (hostnm_i4_sub): Call hostnm_0.
    (hostnm_i8_sub): Likewise.
    (hostnm): Likewise.
    * intrinsics/link.c (link_internal): New function, use fc_strdup
    rather than stack allocation.
    (link_i4_sub): Call link_internal.
    (link_i8_sub): Likewise.
    (link_i4): Likewise.
    (link_i8): Likewise.
    * intrinsics/perror.c (perror_sub): Use fc_strdup rather than
    stack allocation.
    * intrinsics/random.c (random_seed_i4): Use static buffer rather
    than VLA, use _Static_assert to make sure it's big enough.
    * intrinsics/rename.c (rename_internal): New function, use
    fc_strdup rather than stack allocation.
    (rename_i4_sub): Call rename_internal.
    (rename_i8_sub): Likewise.
    (rename_i4): Likewise.
    (rename_i8): Likewise.
    * intrinsics/stat.c (stat_i4_sub_0): Use fc_strdup rather than
    stack allocation.
    (stat_i8_sub_0): Likewise.
    * intrinsics/symlink.c (symlnk_internal): New function, use
    fc_strdup rather than stack allocation.
    (symlnk_i4_sub): Call symlnk_internal.
    (symlnk_i8_sub): Likewise.
    (symlnk_i4): Likewise.
    (symlnk_i8): Likewise.
    * intrinsics/system.c (system_sub): Use fc_strdup rather than
    stack allocation.
    * intrinsics/unlink.c (unlink_i4_sub): Likewise.
    * io/file_pos.c (READ_CHUNK): Make it a macro rather than variable.
    * io/list_read.c (nml_get_obj_data): Use fixed stack buffer, fall
    back to xmalloc/free for large sizes.
    * io/read.c (read_f): Likewise.
    * io/transfer.c (MAX_READ): Make it a macro rather than variable.
    (WRITE_CHUNK): Likewise.
    * io/write_float.def (write_float): Use fixed stack buffer, fall
    back to xmalloc/free for large sizes.
    * runtime/string.c (fc_strdup_notrim): New function.


-- 
Janne Blomqvist

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