[m-rev.] for review: implement C version of mmc

[Julien Fischer]

On Thu, 20 Oct 2005, Ian MacLarty wrote:

> > > 	MinGW, so it is independent of Cygwin.
> > >
> > > configure.in:
> > > 	Add options to enable the standalone version of mmc and to give
> > > 	relative paths for the C compiler and the linker commands that generate
> > > 	an executable and a shared library.
> >
> > What's the relationship between the C compiler used to build the Mercury
> > compiler and the one used by the standalone version?
> >
>
> There is no relationship.
>
We discussed this in person this morning.

> > > ===================================================================
> > > RCS file: README.Standalone
> > > diff -N README.Standalone
> > > --- /dev/null	1 Jan 1970 00:00:00 -0000
> > > +++ README.Standalone	1 Oct 2005 08:27:44 -0000
> > > @@ -0,0 +1,94 @@
> > > +-----------------------------------------------------------------------------
> > > +
> > > +INTRODUCTION
> > > +
> > > +This file describes how to build a version of the Mercury compiler that has
> > > +a C compiler and linker packaged with it and so doesn't depend on any external
> > > +programs.
> >
> > Doesn't it still need the sort utility in order to use fact tables?
> >
>
> -programs.  The directory containing the Mercury and C compilers can be moved
> +programs (Mercury will still require the `sort' program to compile
> +programs that make use of :- pragma fact_table).
> +
>
The appropriate README file (Standalone or Windows?) should mention that
fact table's won't (yet) work then.

> diff -u util/path_util.c util/path_util.c
> --- util/path_util.c	1 Oct 2005 08:43:52 -0000
> +++ util/path_util.c	19 Oct 2005 13:31:19 -0000
> @@ -12,7 +12,12 @@
>  ** Author: Ian MacLarty.
>  **
>  ** This file implements some utility functions for manipulating paths and
> -** working out were an executable is being executed from.
> +** working out were an executable is being run from.
> +** The functions in this file are used by mmc.c when it is in standalone
> +** mode to work out where it is being run from, so that it can pass the
> +** absolute paths to the configuration and library directories and the
> +** absolute paths of the C compiler and linker to mercury_compile.
> +** It also contains a few string manipulation functions used by mmc.
>  */
>
>
> @@ -22,6 +27,7 @@
>  #include <string.h>
>
>  #include "mercury_conf.h"
> +#include "mercury_conf_param.h"
>
>  #include "path_util.h"
>
> @@ -31,16 +37,16 @@
>
>  #define MAX_PATH_SIZE   8128
>
> -static  void    split_path_into_dir_and_file(char *path, char **dir,
> +static  void    split_path_into_dir_and_file(const char *path, char **dir,
>                      char **filename);
> -static  int     file_exists_and_is_executable(char* path);
> -static  char    *search_path(char *path, const char *path_separator,
> -                    char *filename);
> -static  char*   copy_substring(char* str, int start, int end);
> +static  int     file_exists_and_is_executable(const char *path);
> +static  char    *search_path(const char *path, const char *path_separator,
> +                    const char *filename);
> +static  char*   copy_substring(const char *str, int start, int end);
>  static  void    delete_quotes(char* str);
>
>  char*
> -find_exec_dir(char* cmd)
> +find_exec_dir(const char *cmd)
>  {
>      char    *filename;
>      char    *cmd_dir;
>          free(filename);

...

> -copy_substring(char* str, int start, int end)
> +copy_substring(const char *str, int start, int end)
>  {
>      char*   new_str;
>
> @@ -371,6 +415,11 @@
>          new_str = malloc(end - start + 2);
>          strncpy(new_str, &str[start], end - start + 1);
>          new_str[end - start + 1] = '\0';
> +        if (new_str == NULL) {
> +            fprintf(stderr, "Error: Could not allocate %i bytes of memory\n",
> +                strlen(str) + 1);
> +            exit(EXIT_FAILURE);
> +        }

That looks wrong.  The check for malloc returning NULL should occur before
you attempt to use the memory it allocates.

...

> +#ifdef MR_HAVE_UNISTD_H
> +    /*
> +    ** We have execv, so set up the argument vector and call execv.
> +    */
> +    {
> +        char            **mercury_compiler_args;
> +        int             num_args;
> +        int             current_arg;
> +        int             current_orig_arg;
> +
> +        num_args = 0;
> +        if (strcmp(link_exec_cmd_absolute_path, "") != 0) {
> +            num_args += 2;
> +        }
> +        if (strcmp(link_shared_lib_cmd_absolute_path, "") != 0) {
> +            num_args += 2;
> +        }
> +        num_args += argc;
> +        mercury_compiler_args = (char **)
> +            calloc(num_args + 1, sizeof(char **));

You need to make sure that calloc doesn't return NULL here.

Once this has boostrapped you should modify tools/test_mercury so
that the nightly tests on one of the machines (not the rotd host for
now) use the C version of mmc.

Julien.
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