asn_read.c

ASN.1语法解析代码

/*****************************************************************************
File:     asn_read.c
Contents: Functions to parse ASN.1 as part of the ASN_GEN program.
System:   ASN development.
Created:
Author:   Charles W. Gardiner <[e-mail]>

Remarks:

COPYRIGHT 1995 BBN Systems and Technologies, A Division of Bolt Beranek and
    Newman Inc.
150 CambridgePark Drive
Cambridge, Ma. 02140
617-873-4000
*****************************************************************************/

const char asn_read_rcsid[]="$Header: /nfs/sub-rosa/u2/IOS_Project/ASN/Dev/rcs/cmd/asn_gen/asn_read.c,v 1.8 1995/08/03 18:50:41 gardiner Exp $";
char asn_read_id[] = "@(#)asn_read.c 254P";

#include "includes.h"
#include "asn_obj.h"
#include "asn_gen.h"

static void append_subclasses(uchar *),
    cvt_number(char *, char *),
    do_components(int fd, void(*func)());

int read_global(int fd)
{
/**
Function: Reads file in global state
Inputs: File descriptor
Returns: IF reaches end of file, -1
	 ELSE 0
Procedure:
1. DO
    	IF token is '::='
	    Return IN_DEFINITION
	ELSE IF token is DEFINITIONS
	    WHILE next token is not '::='
	        IF token is IMPLICIT, clear implicit flag for file
	        ELSE IF token is EXPLICIT, set explicit flag for file
		ELSE IF token is not TAGS, error
	ELSE IF haven't a classname, copy token into classname
2. WHILE have another token
   Return -1
**/
do
    {
    if (!strcmp(token, equals))
        {
        max = min = 0;
        state = IN_DEFINITION;
	return 0;
        }
    else if (!strcmp(token, definitions_w))
        {
        while (get_token(fd, token, '(') && strcmp(token, equals))
	    {
            if (!strcmp(token, implicit_w)) explicit = 0;
    	    else if (!strcmp(token, explicit_w)) explicit = 3;
            else if (strcmp(token, tags_w)) syntax(token);
	    }
        }
    else if (!*classname && *token >= 'A') strcpy(classname, token);
    }
while (get_token(fd, token, '('));
return -1;
}


int read_definition(int fd, int parent)
{
/**
Function: General function to read a definition and fill in the appropriate
	    global variables
Inputs: file descriptor for input file
Outputs: Sets flags in option and in flags.
	 Fills in tag, type, min, max, and subclass
	 Sets state as follows:
             IF definition is an upper bound, GLOBAL
             ELSE IF '{' OR '\n' is found, IN_DEFINITION
Returns: IF end of file is reached, -1
	 ELSE 0
Procedure:
1. DO
	IF token is CHOICE, set type of ASN_CHOICE
	ELSE IF token is EMPTY, do nothing
	ELSE IF token is OF, set OF bit in options and get the subclass name
	ELSE IF token is SIZE, get sizes
	ELSE IF token is TABLE, set table bit in flags and note file position
	ELSE IF token is '[', get tag
	ELSE IF token is '(', get min-max
	ELSE IF token is numeric
	    Clear any line end
            Set state to GLOBAL
	ELSE IF token is a known type name
	    IF type is ENUMERATED, set enumerated flag
	    IF no type so far, use this one
	    ELSE IF OF flag set, set subtype to this type
	    ELSE 'Or' the constructed bit into the present type
	ELSE IF (token begins with a capital letter OR *) AND
            type is not -1, set subclass & options
	IF no next token, return -1
   WHILE state is IN_DEFINITION AND token is not '{' NOR '\n'
   Return 0
**/
int tmp;
do
    {
    if (!strcmp(token, choice_w)) type = ASN_CHOICE;
    else if (!strcmp(token, empty_w));
    else if (!strcmp(token, of_w))
        {
        option |= ASN_OF_FLAG;
        if (!get_token(fd, token, '(')) syntax(of_w);
        if ((tmp = find_type(token)) != ASN_NOTYPE)
            get_expected(fd, (subtype = tmp), token);
        else if ((*token < 'A' || *token > 'Z') && *token != '*') syntax(token);
        else option |= set_name_option(subclass, token);
        }
    else if (!strcmp(token, size_w)) get_size(fd, token, &min, &max, parent);
    else if (!strcmp(token, table_w))
        {
        flags |= ASN_TABLE_FLAG;
        tablepos = lseek(fd, 0L, 1);
        }
    else if (*token == '[') tag = get_tag(fd, token);
    else if (*token == '(') get_paren(fd, token, &min, &max, parent);
    else if (*token >= '0' && *token <= '9')
	{
        while(get_token(fd, token, '(') && *token != '\n');
        state = GLOBAL;
	return 0;
	}
    else if ((tmp = find_type(token)) != ASN_NOTYPE)
        {
        get_expected(fd, tmp, token);
        if (tmp == ASN_ENUMERATED) flags |= ASN_ENUM_FLAG;
        if (type < 0) type = tmp;
        else if ((option & ASN_OF_FLAG)) subtype = tmp;
        else if (tmp > 0) type |= (tmp & ASN_CONSTRUCTED);
        }
    else if (((*token >= 'A' && *token <= 'Z') || *token == '*') &&
	type == -1) option |= set_name_option(subclass, token);
    if (!get_token(fd, token, (char)0)) return -1;
    }
while (state == IN_DEFINITION && *token != '{' && *token != '\n');
return 0;
}

int read_item(int fd, int parent, void(*func)())
{
/**
Function: General function to read an item and fill in appropriate global
variables
Input: File descriptor for input
Outputs: Sets option flags
	 Fills in tag, type, min, max, itemname, subclass, subtype,
	    defaultname and numstring
Procedure:
1. WHILE token is neither ',' NOR '}'
	IF token is CHOICE, set constructed bit in type
	ELSE IF token is COMPONENTS, do components stuff
        ELSE IF token is DEFAULT, make defaultname and set default flag
	ELSE IF token is DEFINED
	    IF next token isn't BY OR token after that isn't lower case
		Syntax error
	    Make a name in defined_by
	ELSE IF token is EMPTY, do nothing
	ELSE IF token is EXPLICIT, set temporary explicit flag
	ELSE IF token is FUNCTION
	    Set type
            Get all tokens up to ')'
	    Append ';'
	ELSE IF token is IMPLICIT, clear temporary explicit flag
	ELSE IF token is OF, error
	ELSE IF token is OPTIONAL, set OPTIONAL flag in options
	ELSE IF token is SIZE, get min-max
	ELSE IF token is TABLE
            Get table name to skip it
	    Set table variable
	ELSE IF token is TAGS, do nothing
	ELSE IF token is '[', get tag
	ELSE IF token is '('
	    IF enumerated flag set, get material for tag
	    ELSE Get min-max
	ELSE IF token is a defined type
	    IF this is a table AND (there's a type OR a subclass already)
		append token to alt_subclasses
	    ELSE IF have a subclass already, syntax error
	    ELSE IF have no type yet, use that
	    ELSE IF explicit tagging, set subtype
	    ELSE
		'Or' the constructed bit into type
        	Get expected sequel to token, if any
	ELSE IF token begins with a number
	    IF TABLE bit is set, convert number
	    ELSE IF enumerated flag is set
		Put token into itemname prefixed with e
		Set enumerated flag
	ELSE IF name begins with a capital letter
	    IF this is a table item AND (there is already a subclass OR a type)
		Append this to the alt_subclasses
	    ELSE IF there is already a subclass OR a type, syntax error
	    ELSE set the subclass and option from the token
	ELSE IF name begins with a lower-case letter
            IF no itemname so far, set token in itemname with options
	IF no next token, return -1
   Return 0
**/
char *c;
int tmp;
struct name_table *ntbp;
struct id_table *idp = (struct id_table *)0;
while (*token != ',' && *token != '}')
    {
    if (!strcmp(token, choice_w))
        {
        if (tag >= 0) tag |= ASN_CONSTRUCTED;
        else if (type >= 0) type |= ASN_CONSTRUCTED;
        else type = ASN_CONSTRUCTED;
        }
    else if (!strcmp(token, components_w)) do_components(fd, func);
    else if (!strcmp(token, default_w))
        {
        option |= (ASN_OPTIONAL_FLAG | ASN_DEFAULT_FLAG);
        get_token(fd, token, '(');
        c = defaultname;
        if (*token >= '0' && *token <= '9') *c++ = 'e';
        else if (!strcmp(token, empty_w) || !strcmp(token, null_w) ||
            (*token == '"' && token[1] == '"')) cat(token, "{");
        strcpy(c, token);
        }
    else if (!strcmp(token, defined_w))
        {
        if (!get_token(fd, token, '(') || strcmp(token, "BY") ||
	    !get_token(fd, definer, '(') || (*definer < 'a' && *definer > 'z'))
	    syntax(defined_w);
        mk_in_name(defined_by, itemname, classname);
	if (type > 0) tag = type;
        type = -1;      /* cancel ANY or other universal primitive */
	*inclass = 0;
        }
    else if (!strcmp(token, empty_w));
    else if (!strcmp(token, explicit_w)) explicit |= 1;
    else if (!strcmp(token, function_w))
	{
	type = ASN_FUNCTION;
	if (!get_token(fd, token, (char)0)) fatal(19, (char *)0);
	c = cat(itemname, token);
	for (tmp = 4; tmp-- && get_token(fd, token, (char)0) && *token != '('; )
	    {
	    *c++ = ' ';
	    c = cat(c, token);