* New version 2.26

[alpine.git] / pith / detoken.c

/*
 * ========================================================================
 * Copyright 2013-2022 Eduardo Chappa
 * Copyright 2006 University of Washington
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * ========================================================================
 */

#include "../pith/headers.h"
#include "../pith/detoken.h"
#include "../pith/state.h"
#include "../pith/conf.h"
#include "../pith/status.h"
#include "../pith/pattern.h"
#include "../pith/reply.h"
#include "../pith/mailindx.h"
#include "../pith/options.h"


/*
 * Hook to read signature from local file
 */
char    *(*pith_opt_get_signature_file)(char *, int, int, int);


/*
 * Internal prototypes
 */
char    *detoken_guts(char *, int, ENVELOPE *, ACTION_S *, REDRAFT_POS_S **, int, int *);
char    *handle_if_token(char *, char *, int, ENVELOPE *, ACTION_S *, char **);
char    *get_token_arg(char *, char **);


/*
 * Detokenize signature or template files.
 *
 * If is_sig, we always use literal sigs before sigfiles if they are
 * defined. So, check for role->litsig and use it. If it doesn't exist, use
 * the global literal sig if defined. Else the role->sig file or the
 * global signature file.
 *
 * If !is_sig, use role->template.
 *
 * So we start with a literal signature or a signature or template file.
 * If that's a file, we read it first. The file could be remote.
 * Then we detokenize the literal signature or file contents and return
 * an allocated string which the caller frees.
 *
 * Args    role -- See above about what happens depending on is_sig.
 *                 relative to the pinerc dir.
 *          env -- The envelope to use for detokenizing. May be NULL.
 *  prenewlines -- How many blank lines should be included at start.
 * postnewlines -- How many blank lines should be included after.
 *       is_sig -- This is a signature (not a template file).
 *  redraft_pos -- This is a return value. If it is non-NULL coming in,
 *                 then the cursor position is returned here.
 *         impl -- This is a combination argument which is both an input
 *                 argument and a return value. If it is non-NULL and = 0,
 *                 that means that we want the cursor position returned here,
 *                 even if that position is set implicitly to the end of
 *                 the output string. If it is = 1 coming in, that means
 *                 we only want the cursor position to be set if it is set
 *                 explicitly. If it is 2, or if redraft_pos is NULL,
 *                 we don't set it at all.
 *                 If the cursor position gets set explicitly by a
 *                 _CURSORPOS_ token in the file then this is set to 2
 *                 on return. If the cursor position is set implicitly to
 *                 the end of the included file, then this is set to 1
 *                 on return.
 *
 * Returns -- An allocated string is returned.
 */
char *
detoken(ACTION_S *role, ENVELOPE *env, int prenewlines, int postnewlines,
        int is_sig, REDRAFT_POS_S **redraft_pos, int *impl)
{
    char *ret = NULL,
         *src = NULL,
         *literal_sig = NULL,
         *sigfile = NULL;

    if(is_sig){
        /*
         * If role->litsig is set, we use it;
         * Else, if VAR_LITERAL_SIG is set, we use that;
         * Else, if role->sig is set, we use that;
         * Else, if VAR_SIGNATURE_FILE is set, we use that.
         * This can be a little surprising if you set the VAR_LITERAL_SIG
         * and don't set a role->litsig but do set a role->sig. The
         * VAR_LITERAL_SIG will be used, not role->sig. The reason for this
         * is mostly that it is much easier to display the right stuff
         * in the various config screens if we do it that way. Besides,
         * people will typically use only literal sigs or only sig files,
         * there is no reason to mix them, so we don't provide support to
         * do so.
         */
        if(role && role->litsig)
          literal_sig = role->litsig;
        else if(ps_global->VAR_LITERAL_SIG)
          literal_sig = ps_global->VAR_LITERAL_SIG;
        else if(role && role->sig)
          sigfile = role->sig;
        else
          sigfile = ps_global->VAR_SIGNATURE_FILE;
    }
    else if(role && role->template)
      sigfile = role->template;

    if(literal_sig)
      src = get_signature_lit(literal_sig, prenewlines, postnewlines, is_sig,1);
    else if(sigfile && pith_opt_get_signature_file)
      src = (*pith_opt_get_signature_file)(sigfile, prenewlines, postnewlines, is_sig);
        
    if(src){
        if(*src)
          ret = detoken_src(src, FOR_TEMPLATE, env, role, redraft_pos, impl);

        fs_give((void **)&src);
    }

    return(ret);
}


/*
 * Filter the source string from the template file and return an allocated
 * copy of the result with text replacements for the tokens.
 * Fill in offset in redraft_pos.
 *
 * This is really inefficient but who cares? It's just cpu time.
 */
char *
detoken_src(char *src, int for_what, ENVELOPE *env, ACTION_S *role,
            REDRAFT_POS_S **redraft_pos, int *impl)
{
    int   loopcnt = 25;         /* just in case, avoid infinite loop */
    char *ret = NULL, *str1, *str2;
    int   done = 0;

    if(!src)
      return(src);
    
    /*
     * We keep running it through until it stops changing so user can
     * nest calls to token stuff.
     */
    str1 = src;
    do {
        /* short-circuit if no chance it will change */
        if(strindex(str1, '_'))
          str2 = detoken_guts(str1, for_what, env, role, NULL, 0, NULL);
        else
          str2 = str1;

        if(str1 && str2 && (str1 == str2 || !strcmp(str1, str2))){
            done++;                             /* It stopped changing */
            if(str1 && str1 != src && str1 != str2)
              fs_give((void **)&str1);
        }
        else{                                   /* Still changing */
            if(str1 && str1 != src && str1 != str2)
              fs_give((void **)&str1);
            
            str1 = str2;
        }

    } while(str2 && !done && loopcnt-- > 0);

    /*
     * Have to run it through once more to get the redraft_pos and
     * to remove any backslash escape for a token.
     */
    if((str2 && strindex(str2, '_')) ||
       (impl && *impl == 0 && redraft_pos && !*redraft_pos)){
        ret = detoken_guts(str2, for_what, env, role, redraft_pos, 1, impl);
        if(str2 != src)
          fs_give((void **)&str2);
    }
    else if(str2){
        if(str2 == src)
          ret = cpystr(str2);
        else
          ret = str2;
    }

    return(ret);
}


/*
 * The guts of the detokenizing routines. Filter the src string looking for
 * tokens and replace them with the appropriate text. In the case of the
 * cursor_pos token we set redraft_pos instead.
 *
 * Args        src --  The source string
 *        for_what --  
 *             env --  Envelope to look in for token replacements.
 *     redraft_pos --  Return the redraft offset here, if non-zero.
 *       last_pass --  This is a flag to tell detoken_guts whether or not to do
 *                     the replacement for _CURSORPOS_. Leave it as is until
 *                     the last pass. We need this because we want to defer
 *                     cursor placement until the very last call to detoken,
 *                     otherwise we'd have to keep track of the cursor
 *                     position as subsequent text replacements (nested)
 *                     take place.
 *                     This same flag is also used to decide when to eliminate
 *                     backslash escapes from in front of tokens. The only
 *                     use of backslash escapes is to escape an entire token.
 *                     That is, \_DATE_ is a literal _DATE_, but any other
 *                     backslash is a literal backslash. That way, nobody
 *                     but wackos will have to worry about backslashes.
 *         impl -- This is a combination argument which is both an input
 *                 argument and a return value. If it is non-NULL and 0
 *                 coming in, that means that we should set redraft_pos,
 *                 even if that position is set implicitly to the end of
 *                 the output string. If it is 1 coming in, that means
 *                 we only want the cursor position to be set if it is set
 *                 explicitly. If it is 2 coming in (or if
 *                 redraft_pos is NULL) then we don't set it at all.
 *                 If the cursor position gets set explicitly by a
 *                 _CURSORPOS_ token in the file then this is set to 2
 *                 on return. If the cursor position is set implicitly to
 *                 the end of the included file, then this is set to 1
 *                 on return.
 *
 * Returns   pointer to alloced result
 */
char *
detoken_guts(char *src, int for_what, ENVELOPE *env, ACTION_S *role,
             REDRAFT_POS_S **redraft_pos, int last_pass, int *impl)
{
#define MAXSUB 500
    char          *p, *q = NULL, *dst = NULL;
    char           subbuf[MAXSUB+1], *repl;
    INDEX_PARSE_T *pt;
    long           l, cnt = 0L;
    int            sizing_pass = 1, suppress_tokens = 0;

    if(!src)
      return(NULL);

top:

    /*
     * The tokens we look for begin with _. The only escaping mechanism
     * is a backslash in front of a token. This will give you the literal
     * token. So \_DATE_ is a literal _DATE_.
     * Tokens like _word_ are replaced with the appropriate text if
     * word is recognized. If _word_ is followed immediately by a left paren
     * it is an if-else thingie. _word_(match_this,if_text,else_text) means to
     * replace that with either the if_text or else_text depending on whether
     * what _word_ (without the paren) would produce matches match_this or not.
     */
    p = src;
    while(*p){
        switch(*p){
          case '_':             /* possible start of token */
            if(!suppress_tokens &&
               (pt = itoktype(p+1, for_what | DELIM_USCORE)) != NULL){
                char *free_this = NULL;

                p += (strlen(pt->name) + 2);    /* skip over token */

                repl = subbuf;
                subbuf[0] = '\0';

                if(pt->ctype == iCursorPos){
                    if(!last_pass){     /* put it back */
                        subbuf[0] = '_';
                        strncpy(subbuf+1, pt->name, sizeof(subbuf)-2);
                        subbuf[sizeof(subbuf)-1] = '\0';
                        strncat(subbuf, "_", sizeof(subbuf)-strlen(subbuf)-1);
                        subbuf[sizeof(subbuf)-1] = '\0';
                    }

                    if(!sizing_pass){
                        if(q-dst < cnt+1)
                          *q = '\0';

                        l = strlen(dst);
                        if(redraft_pos && impl && *impl != 2){
                            if(!*redraft_pos){
                                *redraft_pos =
                                 (REDRAFT_POS_S *)fs_get(sizeof(**redraft_pos));
                                memset((void *)*redraft_pos, 0,
                                       sizeof(**redraft_pos));
                                (*redraft_pos)->hdrname = cpystr(":");
                            }

                            (*redraft_pos)->offset  = l;
                            *impl = 2;  /* set explicitly */
                        }
                    }
                }
                else if(pt->what_for & FOR_REPLY_INTRO)
                  repl = get_reply_data(env, role, pt->ctype,
                                        subbuf, sizeof(subbuf)-1);

                if(*p == LPAREN){               /* if-else construct */
                    char *skip_ahead;

                    repl = free_this = handle_if_token(repl, p, for_what,
                                                       env, role,
                                                       &skip_ahead);
                    p = skip_ahead;
                }

                if(repl && repl[0]){
                    if(sizing_pass)
                      cnt += (long)strlen(repl);
                    else{
                        strncpy(q, repl, cnt-(q-dst));
                        dst[cnt] = '\0';
                        q += strlen(repl);
                    }
                }

                if(free_this)
                  fs_give((void **)&free_this);
            }
            else{       /* unrecognized token, treat it just like text */
                suppress_tokens = 0;
                if(sizing_pass)
                  cnt++;
                else if(q-dst < cnt+1)
                  *q++ = *p;

                p++;
            }

            break;

          case BSLASH:
            /*
             * If a real token follows the backslash, then the backslash
             * is here to escape the token. Otherwise, it's just a
             * regular character.
             */
            if(*(p+1) == '_' &&
               ((pt = itoktype(p+2, for_what | DELIM_USCORE)) != NULL)){
                /*
                 * Backslash is escape for literal token.
                 * If we're on the last pass we want to eliminate the
                 * backslash, otherwise we keep it.
                 * In either case, suppress_tokens will cause the token
                 * lookup to be skipped above so that the token will
                 * be treated as literal text.
                 */
                suppress_tokens++;
                if(last_pass){
                    p++;
                    break;
                }
                /* else, fall through and keep backslash */
            }
            /* this is a literal backslash, fall through */
        
          default:
            if(sizing_pass)
              cnt++;
            else if(q-dst < cnt+1)
              *q++ = *p;        /* copy the character */

            p++;
            break;
        }
    }

    if(!sizing_pass && q-dst < cnt+1)
      *q = '\0';

    if(sizing_pass){
        sizing_pass = 0;
        /*
         * Now we're done figuring out how big the answer will be. We
         * allocate space for it and go back through filling it in.
         */
        cnt = MAX(cnt, 0L);
        q = dst = (char *)fs_get((cnt + 1) * sizeof(char));
        goto top;
    }

    /*
     * Set redraft_pos to character following the template, unless
     * it has already been set.
     */
    if(dst && impl && *impl == 0 && redraft_pos && !*redraft_pos){
        *redraft_pos = (REDRAFT_POS_S *)fs_get(sizeof(**redraft_pos));
        memset((void *)*redraft_pos, 0, sizeof(**redraft_pos));
        (*redraft_pos)->offset  = strlen(dst);
        (*redraft_pos)->hdrname = cpystr(":");
        *impl = 1;
    }

    if(dst && cnt >= 0)
      dst[cnt] = '\0';

    return(dst);
}


/*
 * Do the if-else part of the detokenization for one case of if-else.
 * The input src should like (match_this, if_matched, else)...
 * 
 * Args expands_to -- This is what the token to the left of the paren
 *                    expanded to, and this is the thing we're going to
 *                    compare with the match_this part.
 *             src -- The source string beginning with the left paren.
 *        for_what -- 
 *             env -- 
 *      skip_ahead -- Tells caller how long the (...) part was so caller can
 *                    skip over that part of the source.
 *
 * Returns -- an allocated string which is the answer, or NULL if nothing.
 */
char *
handle_if_token(char *expands_to, char *src, int for_what, ENVELOPE *env,
                ACTION_S *role, char **skip_ahead)
{
    char *ret = NULL;
    char *skip_to;
    char *match_this, *if_matched, *else_part;

    if(skip_ahead)
      *skip_ahead = src;

    if(!src || *src != LPAREN){
        dprint((1,"botch calling handle_if_token, missing paren\n"));
        return(ret);
    }

    if(!*++src){
        q_status_message(SM_ORDER, 3, 3,
            "Unexpected end of token string in Reply-LeadIn, Sig, or template");
        return(ret);
    }

    match_this = get_token_arg(src, &skip_to);
    
    /*
     * If the match_this argument is a token, detokenize it first.
     */
    if(match_this && *match_this == '_'){
        char *exp_match_this;

        exp_match_this = detoken_src(match_this, for_what, env,
                                     role, NULL, NULL);
        fs_give((void **)&match_this);
        match_this = exp_match_this;
    }

    if(!match_this)
      match_this = cpystr("");

    if(!expands_to)
      expands_to = "";

    src = skip_to;
    while(src && *src && (isspace((unsigned char)*src) || *src == ','))
      src++;

    if_matched = get_token_arg(src, &skip_to);
    src = skip_to;
    while(src && *src && (isspace((unsigned char)*src) || *src == ','))
      src++;

    else_part = get_token_arg(src, &skip_to);
    src = skip_to;
    while(src && *src && *src != RPAREN)
      src++;

    if(src && *src == RPAREN)
      src++;

    if(skip_ahead)
      *skip_ahead = src;

    if(!strcmp(match_this, expands_to)){
        ret = if_matched;
        if(else_part)
          fs_give((void **)&else_part);
    }
    else{
        ret = else_part;
        if(if_matched)
          fs_give((void **)&if_matched);
    }

    fs_give((void **)&match_this);

    return(ret);
}


char *
get_token_arg(char *src, char **skip_to)
{
    int   quotes = 0, done = 0;
    char *ret = NULL, *p;

    while(*src && isspace((unsigned char)*src)) /* skip space before string */
      src++;

    if(*src == RPAREN){
        if(skip_to)
          *skip_to = src;

        return(ret);
    }

    p = ret = (char *)fs_get((strlen(src) + 1) * sizeof(char));
    while(!done){
        switch(*src){
          case QUOTE:
            if(++quotes == 2)
              done++;

            src++;
            break;

          case BSLASH:  /* don't count \" as a quote, just copy */
            if(*(src+1) == BSLASH || *(src+1) == QUOTE){
                src++;  /* skip backslash */
                *p++ = *src++;
            }
            else
              src++;

            break;
        
          case SPACE:
          case TAB:
          case RPAREN:
          case COMMA:
            if(quotes)
              *p++ = *src++;
            else
              done++;
            
            break;

          case '\0':
            done++;
            break;

          default:
            *p++ = *src++;
            break;
        }
    }

    *p = '\0';
    if(skip_to)
      *skip_to = src;
    
    return(ret);
}