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helloworld how are you today?

• helloworld how are you today?

a

b

c

1. asdf
2. sdfa
3. sdfa

# 234234

# asdfjoij

- hello

- haeafs

# asdf

1. sdfadf
2. sdfasdf

In a previous lifetime, I added environment variable primitives to the VM. Well, it turns out that a better place for them is in the Factor basis vocabulary root, so this post is about moving them again.

To move a primitive out of the VM, implement its functionality in Factor code and replace usages with your word if necessary, remove it from vm/primitives.c and core/bootstrap/primitives.factor, remove the primitive code from the VM, make a new image, recompile Factor, and bootstrap. Basically, do the inverse of the previous post. What's interesting about this is how much cleaner the code is in Factor and how it can be written in a cross-platform way with the code from each patform in its own file and without spaghetti code or ifdefs.

High-level environment variable interface

Factor's high-level environment variable words let you get a single variable or all of them, set a single variable or all of them, and unset a variable. On Windows you cannot set all of the variables at once, and on Windows CE the whole concept of environment variables does not exist.

Here is the code for the main vocabulary. Notice that there are hooks on the os word, which will be a value like macosx or winnt or linux. The boilerplate at the bottom is for loading the platform-specific code.

USING: assocs combinators kernel sequences splitting system
vocabs.loader ;
IN: environment

HOOK: os-env os ( key -- value )

HOOK: set-os-env os ( value key -- )

HOOK: unset-os-env os ( key -- )

HOOK: (os-envs) os ( -- seq )

HOOK: (set-os-envs) os ( seq -- )

: os-envs ( -- assoc )
    (os-envs) [ "=" split1 ] H{ } map>assoc ;

: set-os-envs ( assoc -- )
    [ "=" swap 3append ] { } assoc>map (set-os-envs) ;

{
    { [ os unix? ] [ "environment.unix" require ] }
    { [ os winnt? ] [ "environment.winnt" require ] }
    { [ os wince? ] [ ] }
} cond

Unix environment variables, before and after

DEFINE_PRIMITIVE(os_env)
{
    char *name = unbox_char_string();
    char *value = getenv(name);
    if(value == NULL)
        dpush(F);
    else
        box_char_string(value);
}

DEFINE_PRIMITIVE(os_envs)
{
    GROWABLE_ARRAY(result);
    REGISTER_ROOT(result);
    char **env = environ;

    while(*env)
    {
        CELL string = tag_object(from_char_string(*env));
        GROWABLE_ARRAY_ADD(result,string);
        env++;
    }

    UNREGISTER_ROOT(result);
    GROWABLE_ARRAY_TRIM(result);
    dpush(result);
}

DEFINE_PRIMITIVE(set_os_env)
{
    char *key = unbox_char_string();
    REGISTER_C_STRING(key);
    char *value = unbox_char_string();
    UNREGISTER_C_STRING(key);
    setenv(key, value, 1);
}

DEFINE_PRIMITIVE(unset_os_env)
{
    char *key = unbox_char_string();
    unsetenv(key);
}

DEFINE_PRIMITIVE(set_os_envs)
{
    F_ARRAY *array = untag_array(dpop());
    CELL size = array_capacity(array);

    /* Memory leak */
    char **env = calloc(size + 1,sizeof(CELL));

    CELL i;
    for(i = 0; i < size; i++)
    {
        F_STRING *string = untag_string(array_nth(array,i));
        CELL length = to_fixnum(string->length);

        char *chars = malloc(length + 1);
        char_string_to_memory(string,chars);
        chars[length] = '\0';
        env[i] = chars;
    }

    environ = env;
}

USING: alien alien.c-types alien.strings alien.syntax kernel
layouts sequences system unix environment io.encodings.utf8
unix.utilities vocabs.loader combinators alien.accessors ;
IN: environment.unix

HOOK: environ os ( -- void* )

M: unix environ ( -- void* ) "environ" f dlsym ;

M: unix os-env ( key -- value ) getenv ;

M: unix set-os-env ( value key -- ) swap 1 setenv io-error ;

M: unix unset-os-env ( key -- ) unsetenv io-error ;

M: unix (os-envs) ( -- seq )
    environ *void* utf8 alien>strings ;

: set-void* ( value alien -- ) 0 set-alien-cell ;

M: unix (set-os-envs) ( seq -- )
    utf8 strings>alien malloc-byte-array environ set-void* ;

os {
    { macosx [ "environment.unix.macosx" require ] }
    [ drop ]
} case

MacOSX environment variables, before and after

On OSX, we have to use a function to access the environment variable.

#ifndef environ
    extern char ***_NSGetEnviron(void);
    #define environ (*_NSGetEnviron())
#endif

USING: alien.syntax system environment.unix ;
IN: environment.unix.macosx

FUNCTION: void* _NSGetEnviron ( ) ;

M: macosx environ _NSGetEnviron ;

Windows NT environment variables, before and after

Draw your own conclusions.

DEFINE_PRIMITIVE(os_env) 
{ 
    F_CHAR *key = unbox_u16_string(); 
    F_CHAR *value = safe_malloc(MAX_UNICODE_PATH * 2); 
    int ret; 
    ret = GetEnvironmentVariable(key, value, MAX_UNICODE_PATH * 2); 
    if(ret == 0) 
        dpush(F); 
    else 
        dpush(tag_object(from_u16_string(value))); 
    free(value); 
}

DEFINE_PRIMITIVE(os_envs)
{
    GROWABLE_ARRAY(result);
    REGISTER_ROOT(result);

    TCHAR *env = GetEnvironmentStrings();
    TCHAR *finger = env;

    for(;;)
    {
        TCHAR *scan = finger;
        while(*scan != '\0')
            scan++;
        if(scan == finger)
            break;

        CELL string = tag_object(from_u16_string(finger));
        GROWABLE_ARRAY_ADD(result,string);

        finger = scan + 1;
    }

    FreeEnvironmentStrings(env);

    UNREGISTER_ROOT(result);
    GROWABLE_ARRAY_TRIM(result);
    dpush(result);
}
 
DEFINE_PRIMITIVE(set_os_env) 
{ 
    F_CHAR *key = unbox_u16_string(); 
    REGISTER_C_STRING(key); 
    F_CHAR *value = unbox_u16_string(); 
    UNREGISTER_C_STRING(key); 
    if(!SetEnvironmentVariable(key, value)) 
        general_error(ERROR_IO, tag_object(get_error_message()), F, NULL); 
} 
 
DEFINE_PRIMITIVE(unset_os_env) 
{ 
    if(!SetEnvironmentVariable(unbox_u16_string(), NULL) 
        && GetLastError() != ERROR_ENVVAR_NOT_FOUND) 
        general_error(ERROR_IO, tag_object(get_error_message()), F, NULL); 
} 
 
DEFINE_PRIMITIVE(set_os_envs) 
{ 
    not_implemented_error(); 
}

USING: alien.strings fry io.encodings.utf16 kernel
splitting windows windows.kernel32 ;
IN: environment.winnt

M: winnt os-env ( key -- value )
    MAX_UNICODE_PATH "TCHAR" <c-array>
    [ dup length GetEnvironmentVariable ] keep over 0 = [
        2drop f
    ] [
        nip utf16n alien>string
    ] if ;

M: winnt set-os-env ( value key -- )
    swap SetEnvironmentVariable win32-error=0/f ;

M: winnt unset-os-env ( key -- )
    f SetEnvironmentVariable 0 = [
        GetLastError ERROR_ENVVAR_NOT_FOUND =
        [ win32-error ] unless
    ] when ;

M: winnt (os-envs) ( -- seq )
    GetEnvironmentStrings [
        <memory-stream> [
            utf16n decode-input
            [ "\0" read-until drop dup empty? not ]
            [ ] [ drop ] produce
        ] with-input-stream*
    ] [ FreeEnvironmentStrings win32-error=0/f ] bi ;