diplodocus.org Git - nmh/blob - sbr/fmt_compile.c

   1
   2 /*
   3  * fmt_compile.c -- "compile" format strings for fmt_scan
   4  *
   5  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   6  * COPYRIGHT file in the root directory of the nmh distribution for
   7  * complete copyright information.
   8  *
   9  * This code compiles the format strings (documented in mh-format(5)) into
  10  * an internal form to be later processed by fmt_scan.c.
  11  *
  12  * What happens here is that the format strings are parsed and an array
  13  * of struct format structures are returned.  Each format structure is
  14  * a single operation interpreted by the the routines in fmt_scan.c.
  15  *
  16  * There is a NOT a one-to-one correspondence between format strings and
  17  * format instructions; some functions have side effects that can result
  18  * in multiple instructions being generated.  The exact list of instructions
  19  * generated by a format string can be seem with the nmh fmtdump utility.
  20  *
  21  * A list of format instructions can be found in fmt_compile.h.
  22  *
  23  * If you wish to add a new function, you will need to do the following
  24  * things:
  25  *
  26  * - Add a new instruction to the list of instructions in fmt_compile.h.
  27  *   Note that test instructions (starting with FT_IF_S_NULL) have special
  28  *   handling, so if you are NOT writing a test function then you need
  29  *   to insert it into the list before that _and_ bump all of the
  30  *   following instruction numbers.
  31  *
  32  * - Add the function name to the functable[] array below, and write any
  33  *   special code that your function may require in terms of parsing
  34  *   (it very well may not need anything).
  35  *
  36  * - Add the code in fmt_scan.c to handle your new function.
  37  *
  38  * - Document the new function in the mh-format(5) man page.
  39  *
  40  */
  41
  42 #include <h/mh.h>
  43 #include <h/addrsbr.h>
  44 #include <h/tws.h>
  45 #include <h/fmt_scan.h>
  46 #include <h/fmt_compile.h>
  47
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51 #include <time.h>
  52
  53 /*
  54  * hash table for deciding if a component is "interesting"
  55  */
  56 struct comp *wantcomp[128];
  57
  58 static struct format *formatvec;        /* array to hold formats */
  59 static struct format *next_fp;          /* next free format slot */
  60 static struct format *fp;               /* current format slot   */
  61 static struct comp *cm;                 /* most recent comp ref  */
  62 static struct ftable *ftbl;             /* most recent func ref  */
  63 static int ncomp;
  64 static int infunction;                  /* function nesting cnt  */
  65
  66 extern struct mailname fmt_mnull;
  67
  68 /* ftable->type (argument type) */
  69 #define TF_COMP    0        /* component expected                 */
  70 #define TF_NUM     1        /* number expected                    */
  71 #define TF_STR     2        /* string expected                    */
  72 #define TF_EXPR    3        /* component or func. expected        */
  73 #define TF_NONE    4        /* no argument                        */
  74 #define TF_MYBOX   5        /* special - get current user's mbox  */
  75 #define TF_NOW     6        /* special - get current unix time    */
  76 #define TF_EXPR_SV 7        /* like expr but save current str reg */
  77 #define TF_NOP     8        /* like expr but no result            */
  78
  79 /* ftable->flags */
  80 /* NB that TFL_PUTS is also used to decide whether the test
  81  * in a "%<(function)..." should be a string or numeric one.
  82  */
  83 #define TFL_PUTS   1        /* implicit putstr if top level */
  84 #define TFL_PUTN   2        /* implicit putnum if top level */
  85
  86 /*
  87  * The functable array maps between the text names of format functions and
  88  * the format instructions interpreted by the engine in fmt_scan.c.
  89  *
  90  * The elements of this structure are as follows:
  91  *
  92  * name -   The name of the function as seen in the format string.  This is
  93  *          what maps a particular function name into a format instruction.
  94  * type -   The type of argument this function expects.  Those types are
  95  *          listed above (with the TF_ prefix).  This affects what gets
  96  *          placed in the format instruction (the f_un union).
  97  * f_type - The instruction corresponding to this function (from the list
  98  *          in fmt_compile.h).
  99  * extra  - Used by some functions to provide extra data to the compiler.
 100  *          Uses include:
 101  *              - Providing an alternate instruction to combine a load
 102  *                and test operation (see do_if()).
 103  *              - Passed in f_value in the format instruction to provide
 104  *                extra information for the engine (see FT_LV_DAT handling
 105  *                in fmt_scan.c).
 106  *              - Provide a hint as to preprocessing that is required for
 107  *                this instruction (see do_name()).
 108  * flags  - See the definitions for TFL_PUTS & TFL_PUTN above.
 109  */
 110
 111 struct ftable {
 112     char *name;         /* function name                  */
 113     char type;          /* argument type                  */
 114     char f_type;        /* fmt type                       */
 115     char extra;         /* arg. type dependent extra info */
 116     char flags;
 117 };
 118
 119 static struct ftable functable[] = {
 120      { "nonzero",    TF_EXPR,   FT_V_NE,        FT_IF_V_NE,     0 },
 121      { "zero",       TF_EXPR,   FT_V_EQ,        FT_IF_V_EQ,     0 },
 122      { "eq",         TF_NUM,    FT_V_EQ,        FT_IF_V_EQ,     0 },
 123      { "ne",         TF_NUM,    FT_V_NE,        FT_IF_V_NE,     0 },
 124      { "gt",         TF_NUM,    FT_V_GT,        FT_IF_V_GT,     0 },
 125      { "null",       TF_EXPR,   FT_S_NULL,      FT_IF_S_NULL,   0 },
 126      { "nonnull",    TF_EXPR,   FT_S_NONNULL,   FT_IF_S,        0 },
 127      { "match",      TF_STR,    FT_V_MATCH,     FT_IF_MATCH,    0 },
 128      { "amatch",     TF_STR,    FT_V_AMATCH,    FT_IF_AMATCH,   0 },
 129
 130      { "putstr",     TF_EXPR,   FT_STR,         0,              0 },
 131      { "putstrf",    TF_EXPR,   FT_STRF,        0,              0 },
 132      { "putnum",     TF_EXPR,   FT_NUM,         0,              0 },
 133      { "putnumf",    TF_EXPR,   FT_NUMF,        0,              0 },
 134      { "putaddr",    TF_STR,    FT_PUTADDR,     0,              0 },
 135      { "putlit",     TF_STR,    FT_STRLIT,      0,              0 },
 136      { "void",       TF_NOP,    0,              0,              0 },
 137
 138      { "comp",       TF_COMP,   FT_LS_COMP,     0,              TFL_PUTS },
 139      { "lit",        TF_STR,    FT_LS_LIT,      0,              TFL_PUTS },
 140      { "getenv",     TF_STR,    FT_LS_GETENV,   0,              TFL_PUTS },
 141      { "profile",    TF_STR,    FT_LS_CFIND,    0,              TFL_PUTS },
 142      { "decodecomp", TF_COMP,   FT_LS_DECODECOMP, 0,            TFL_PUTS },
 143      { "decode",     TF_EXPR,   FT_LS_DECODE,   0,              TFL_PUTS },
 144      { "trim",       TF_EXPR,   FT_LS_TRIM,     0,              0 },
 145      { "compval",    TF_COMP,   FT_LV_COMP,     0,              TFL_PUTN },
 146      { "compflag",   TF_COMP,   FT_LV_COMPFLAG, 0,              TFL_PUTN },
 147      { "num",        TF_NUM,    FT_LV_LIT,      0,              TFL_PUTN },
 148      { "msg",        TF_NONE,   FT_LV_DAT,      0,              TFL_PUTN },
 149      { "cur",        TF_NONE,   FT_LV_DAT,      1,              TFL_PUTN },
 150      { "size",       TF_NONE,   FT_LV_DAT,      2,              TFL_PUTN },
 151      { "width",      TF_NONE,   FT_LV_DAT,      3,              TFL_PUTN },
 152      { "unseen",     TF_NONE,   FT_LV_DAT,      4,              TFL_PUTN },
 153      { "dat",        TF_NUM,    FT_LV_DAT,      0,              TFL_PUTN },
 154      { "strlen",     TF_NONE,   FT_LV_STRLEN,   0,              TFL_PUTN },
 155      { "me",         TF_MYBOX,  FT_LS_LIT,      0,              TFL_PUTS },
 156      { "plus",       TF_NUM,    FT_LV_PLUS_L,   0,              TFL_PUTN },
 157      { "minus",      TF_NUM,    FT_LV_MINUS_L,  0,              TFL_PUTN },
 158      { "divide",     TF_NUM,    FT_LV_DIVIDE_L, 0,              TFL_PUTN },
 159      { "modulo",     TF_NUM,    FT_LV_MODULO_L, 0,              TFL_PUTN },
 160      { "charleft",   TF_NONE,   FT_LV_CHAR_LEFT, 0,             TFL_PUTN },
 161      { "timenow",    TF_NOW,    FT_LV_LIT,      0,              TFL_PUTN },
 162
 163      { "month",      TF_COMP,   FT_LS_MONTH,    FT_PARSEDATE,   TFL_PUTS },
 164      { "lmonth",     TF_COMP,   FT_LS_LMONTH,   FT_PARSEDATE,   TFL_PUTS },
 165      { "tzone",      TF_COMP,   FT_LS_ZONE,     FT_PARSEDATE,   TFL_PUTS },
 166      { "day",        TF_COMP,   FT_LS_DAY,      FT_PARSEDATE,   TFL_PUTS },
 167      { "weekday",    TF_COMP,   FT_LS_WEEKDAY,  FT_PARSEDATE,   TFL_PUTS },
 168      { "tws",        TF_COMP,   FT_LS_822DATE,  FT_PARSEDATE,   TFL_PUTS },
 169      { "sec",        TF_COMP,   FT_LV_SEC,      FT_PARSEDATE,   TFL_PUTN },
 170      { "min",        TF_COMP,   FT_LV_MIN,      FT_PARSEDATE,   TFL_PUTN },
 171      { "hour",       TF_COMP,   FT_LV_HOUR,     FT_PARSEDATE,   TFL_PUTN },
 172      { "mday",       TF_COMP,   FT_LV_MDAY,     FT_PARSEDATE,   TFL_PUTN },
 173      { "mon",        TF_COMP,   FT_LV_MON,      FT_PARSEDATE,   TFL_PUTN },
 174      { "year",       TF_COMP,   FT_LV_YEAR,     FT_PARSEDATE,   TFL_PUTN },
 175      { "yday",       TF_COMP,   FT_LV_YDAY,     FT_PARSEDATE,   TFL_PUTN },
 176      { "wday",       TF_COMP,   FT_LV_WDAY,     FT_PARSEDATE,   TFL_PUTN },
 177      { "zone",       TF_COMP,   FT_LV_ZONE,     FT_PARSEDATE,   TFL_PUTN },
 178      { "clock",      TF_COMP,   FT_LV_CLOCK,    FT_PARSEDATE,   TFL_PUTN },
 179      { "rclock",     TF_COMP,   FT_LV_RCLOCK,   FT_PARSEDATE,   TFL_PUTN },
 180      { "sday",       TF_COMP,   FT_LV_DAYF,     FT_PARSEDATE,   TFL_PUTN },
 181      { "szone",      TF_COMP,   FT_LV_ZONEF,    FT_PARSEDATE,   TFL_PUTN },
 182      { "dst",        TF_COMP,   FT_LV_DST,      FT_PARSEDATE,   TFL_PUTN },
 183      { "pretty",     TF_COMP,   FT_LS_PRETTY,   FT_PARSEDATE,   TFL_PUTS },
 184      { "nodate",     TF_COMP,   FT_LV_COMPFLAG, FT_PARSEDATE,   TFL_PUTN },
 185      { "date2local", TF_COMP,   FT_LOCALDATE,   FT_PARSEDATE,   0 },
 186      { "date2gmt",   TF_COMP,   FT_GMTDATE,     FT_PARSEDATE,   0 },
 187
 188      { "pers",       TF_COMP,   FT_LS_PERS,     FT_PARSEADDR,   TFL_PUTS },
 189      { "mbox",       TF_COMP,   FT_LS_MBOX,     FT_PARSEADDR,   TFL_PUTS },
 190      { "host",       TF_COMP,   FT_LS_HOST,     FT_PARSEADDR,   TFL_PUTS },
 191      { "path",       TF_COMP,   FT_LS_PATH,     FT_PARSEADDR,   TFL_PUTS },
 192      { "gname",      TF_COMP,   FT_LS_GNAME,    FT_PARSEADDR,   TFL_PUTS },
 193      { "note",       TF_COMP,   FT_LS_NOTE,     FT_PARSEADDR,   TFL_PUTS },
 194      { "addr",       TF_COMP,   FT_LS_ADDR,     FT_PARSEADDR,   TFL_PUTS },
 195      { "proper",     TF_COMP,   FT_LS_822ADDR,  FT_PARSEADDR,   TFL_PUTS },
 196      { "type",       TF_COMP,   FT_LV_HOSTTYPE, FT_PARSEADDR,   TFL_PUTN },
 197      { "ingrp",      TF_COMP,   FT_LV_INGRPF,   FT_PARSEADDR,   TFL_PUTN },
 198      { "nohost",     TF_COMP,   FT_LV_NOHOSTF,  FT_PARSEADDR,   TFL_PUTN },
 199      { "formataddr", TF_EXPR_SV,FT_FORMATADDR,  FT_FORMATADDR,  0 },
 200      { "concataddr", TF_EXPR_SV,FT_CONCATADDR,  FT_FORMATADDR,  0 },
 201      { "friendly",   TF_COMP,   FT_LS_FRIENDLY, FT_PARSEADDR,   TFL_PUTS },
 202
 203      { "mymbox",     TF_COMP,   FT_LV_COMPFLAG, FT_MYMBOX,      TFL_PUTN },
 204      { "addtoseq",   TF_STR,    FT_ADDTOSEQ,    0,              0 },
 205
 206      { "unquote",   TF_EXPR,    FT_LS_UNQUOTE,  0,              TFL_PUTS},
 207
 208      { NULL,         0,         0,              0,              0 }
 209 };
 210
 211 /* Add new component to the hash table */
 212 #define NEWCOMP(cm,name) do { \
 213         cm = ((struct comp *) calloc(1, sizeof (struct comp)));\
 214         cm->c_name = name;\
 215         ncomp++;\
 216         i = CHASH(name);\
 217         cm->c_next = wantcomp[i];\
 218         wantcomp[i] = cm; \
 219         } while (0)
 220
 221 #define NEWFMT (next_fp++)
 222 #define NEW(type,fill,wid) do {\
 223         fp=NEWFMT; fp->f_type=(type); fp->f_fill=(fill); fp->f_width=(wid); \
 224         } while (0)
 225
 226 /* Add (possibly new) component to the hash table */
 227 #define ADDC(name) do { \
 228         FINDCOMP(cm, name);\
 229         if (!cm) {\
 230             NEWCOMP(cm,name);\
 231         }\
 232         fp->f_comp = cm; \
 233         } while (0)
 234
 235 #define LV(type, value)         do { NEW(type,0,0); fp->f_value = (value); } while (0)
 236 #define LS(type, str)           do { NEW(type,0,0); fp->f_text = (str); } while (0)
 237
 238 #define PUTCOMP(comp)           do { NEW(FT_COMP,0,0); ADDC(comp); } while (0)
 239 #define PUTLIT(str)             do { NEW(FT_LIT,0,0); fp->f_text = (str); } while (0)
 240 #define PUTC(c)                 do { NEW(FT_CHAR,0,0); fp->f_char = (c); } while (0)
 241
 242 static char *format_string;
 243 static unsigned char *usr_fstring;      /* for CERROR */
 244
 245 #define CERROR(str) compile_error (str, cp)
 246
 247 /*
 248  * external prototypes
 249  */
 250 extern char *getusername(void);
 251
 252 /*
 253  * static prototypes
 254  */
 255 static struct ftable *lookup(char *);
 256 static void compile_error(char *, char *);
 257 static char *compile (char *);
 258 static char *do_spec(char *);
 259 static char *do_name(char *, int);
 260 static char *do_func(char *);
 261 static char *do_expr (char *, int);
 262 static char *do_loop(char *);
 263 static char *do_if(char *);
 264
 265
 266 /*
 267  * Lookup a function name in the functable
 268  */
 269 static struct ftable *
 270 lookup(char *name)
 271 {
 272     register struct ftable *t = functable;
 273     register char *nm;
 274     register char c = *name;
 275
 276     while ((nm = t->name)) {
 277         if (*nm == c && strcmp (nm, name) == 0)
 278             return (ftbl = t);
 279
 280         t++;
 281     }
 282     return (struct ftable *) 0;
 283 }
 284
 285
 286 static void
 287 compile_error(char *str, char *cp)
 288 {
 289     int i, errpos, errctx;
 290
 291     errpos = cp - format_string;
 292     errctx = errpos > 20 ? 20 : errpos;
 293     usr_fstring[errpos] = '\0';
 294
 295     for (i = errpos-errctx; i < errpos; i++) {
 296 #ifdef LOCALE
 297         if (iscntrl(usr_fstring[i]))
 298 #else
 299         if (usr_fstring[i] < 32)
 300 #endif
 301             usr_fstring[i] = '_';
 302     }
 303
 304     advise(NULL, "\"%s\": format compile error - %s",
 305            &usr_fstring[errpos-errctx], str);
 306     adios (NULL, "%*s", errctx+1, "^");
 307 }
 308
 309 /*
 310  * Compile format string "fstring" into format list "fmt".
 311  * Return the number of header components found in the format
 312  * string.
 313  */
 314
 315 int
 316 fmt_compile(char *fstring, struct format **fmt)
 317 {
 318     register char *cp;
 319     size_t i;
 320
 321     if (format_string)
 322         free (format_string);
 323     format_string = getcpy (fstring);
 324     usr_fstring = fstring;
 325
 326     /* init the component hash table. */
 327     for (i = 0; i < sizeof(wantcomp)/sizeof(wantcomp[0]); i++)
 328         wantcomp[i] = 0;
 329
 330     memset((char *) &fmt_mnull, 0, sizeof(fmt_mnull));
 331
 332     /* it takes at least 4 char to generate one format so we
 333      * allocate a worst-case format array using 1/4 the length
 334      * of the format string.  We actually need twice this much
 335      * to handle both pre-processing (e.g., address parsing) and
 336      * normal processing.
 337      */
 338     i = strlen(fstring)/2 + 1;
 339                 if (i==1) i++;
 340     next_fp = formatvec = (struct format *)calloc ((size_t) i,
 341                                                    sizeof(struct format));
 342     if (next_fp == NULL)
 343         adios (NULL, "unable to allocate format storage");
 344
 345     ncomp = 0;
 346     infunction = 0;
 347
 348     cp = compile(format_string);
 349     if (*cp) {
 350         CERROR("extra '%>', '%|' or '%?'");
 351     }
 352     LV(FT_DONE, 0);             /* really done */
 353     *fmt = formatvec;
 354
 355     return (ncomp);
 356 }
 357
 358 static char *
 359 compile (char *sp)
 360 {
 361     register char *cp = sp;
 362     register int  c;
 363
 364     for (;;) {
 365         sp = cp;
 366         while ((c = *cp) && c != '%')
 367             cp++;
 368         *cp = 0;
 369         switch (cp-sp) {
 370         case 0:
 371             break;
 372         case 1:
 373             PUTC(*sp);
 374             break;
 375         default:
 376             PUTLIT(sp);
 377             break;
 378         }
 379         if (c == 0)
 380             return (cp);
 381
 382         switch (c = *++cp) {
 383         case '%':
 384             PUTC (*cp);
 385             cp++;
 386             break;
 387
 388         case '|':
 389         case '>':
 390         case '?':
 391         case ']':
 392             return (cp);
 393
 394         case '<':
 395             cp = do_if(++cp);
 396             break;
 397
 398         case '[':       /* ] */
 399             cp = do_loop(++cp);
 400             break;
 401
 402         case ';':       /* comment line */
 403             cp++;
 404             while ((c = *cp++) && c != '\n')
 405                 continue;
 406             break;
 407
 408         default:
 409             cp = do_spec(cp);
 410             break;
 411         }
 412     }
 413 }
 414
 415
 416 /*
 417  * Process functions & components (handle field width here as well
 418  */
 419 static char *
 420 do_spec(char *sp)
 421 {
 422     register char *cp = sp;
 423     register int c;
 424 #ifndef lint
 425     register int ljust = 0;
 426 #endif  /* not lint */
 427     register int wid = 0;
 428     register char fill = ' ';
 429
 430     c = *cp++;
 431     if (c == '-') {
 432         ljust++;
 433         c = *cp++;
 434     }
 435     if (c == '0') {
 436         fill = c;
 437         c = *cp++;
 438     }
 439     while (isdigit(c)) {
 440         wid = wid*10 + (c - '0');
 441         c = *cp++;
 442     }
 443     if (c == '{') {
 444         cp = do_name(cp, 0);
 445         if (! infunction)
 446             fp->f_type = wid? FT_COMPF : FT_COMP;
 447     }
 448     else if (c == '(') {
 449         cp = do_func(cp);
 450         if (! infunction) {
 451             if (ftbl->flags & TFL_PUTS) {
 452                 LV( wid? FT_STRF : FT_STR, ftbl->extra);
 453             }
 454             else if (ftbl->flags & TFL_PUTN) {
 455                 LV( wid? FT_NUMF : FT_NUM, ftbl->extra);
 456             }
 457         }
 458     }
 459     else {
 460         CERROR("component or function name expected");
 461     }
 462     if (ljust)
 463         wid = -wid;
 464     fp->f_width = wid;
 465     fp->f_fill = fill;
 466
 467     return (cp);
 468 }
 469
 470 /*
 471  * Process a component name.  Normally this involves generating an FT_COMP
 472  * instruction for the specified component.  If preprocess is set, then we
 473  * do some extra processing.
 474  */
 475 static char *
 476 do_name(char *sp, int preprocess)
 477 {
 478     register char *cp = sp;
 479     register int c;
 480     register int i;
 481     static int primed = 0;
 482
 483     while (isalnum(c = *cp++) || c == '-' || c == '_')
 484         ;
 485     if (c != '}') {
 486         CERROR("'}' expected");
 487     }
 488     cp[-1] = '\0';
 489     PUTCOMP(sp);
 490     switch (preprocess) {
 491
 492     case FT_PARSEDATE:
 493         if (cm->c_type & CT_ADDR) {
 494             CERROR("component used as both date and address");
 495         }
 496         cm->c_tws = (struct tws *)
 497             calloc((size_t) 1, sizeof(*cm->c_tws));
 498         fp->f_type = preprocess;
 499         PUTCOMP(sp);
 500         cm->c_type |= CT_DATE;
 501         break;
 502
 503     case FT_MYMBOX:
 504         if (!primed) {
 505             ismymbox ((struct mailname *) 0);
 506             primed++;
 507         }
 508         /* fall through */
 509     case FT_PARSEADDR:
 510         if (cm->c_type & CT_DATE) {
 511             CERROR("component used as both date and address");
 512         }
 513         cm->c_mn = &fmt_mnull;
 514         fp->f_type = preprocess;
 515         PUTCOMP(sp);
 516         cm->c_type |= CT_ADDR;
 517         break;
 518
 519     case FT_FORMATADDR:
 520         if (cm->c_type & CT_DATE) {
 521             CERROR("component used as both date and address");
 522         }
 523         cm->c_type |= CT_ADDR;
 524         break;
 525     }
 526     return (cp);
 527 }
 528
 529 /*
 530  * Generate one or more instructions corresponding to the named function.
 531  * The different type of function arguments are handled here.
 532  */
 533 static char *
 534 do_func(char *sp)
 535 {
 536     register char *cp = sp;
 537     register int c;
 538     register struct ftable *t;
 539     register int n;
 540     int mflag;          /* minus sign in NUM */
 541
 542     infunction++;
 543
 544     while (isalnum(c = *cp++))
 545         ;
 546     if (c != '(' && c != '{' && c != ' ' && c != ')') {
 547         CERROR("'(', '{', ' ' or ')' expected");
 548     }
 549     cp[-1] = '\0';
 550     if ((t = lookup (sp)) == 0) {
 551         CERROR("unknown function");
 552     }
 553     if (isspace(c))
 554         c = *cp++;
 555
 556     switch (t->type) {
 557
 558     case TF_COMP:
 559         if (c != '{') {
 560             CERROR("component name expected");
 561         }
 562         cp = do_name(cp, t->extra);
 563         fp->f_type = t->f_type;
 564         c = *cp++;
 565         break;
 566
 567     case TF_NUM:
 568         if ((mflag = (c == '-')))
 569             c = *cp++;
 570         n = 0;
 571         while (isdigit(c)) {
 572             n = n*10 + (c - '0');
 573             c = *cp++;
 574         }
 575         if (mflag)
 576             n = (-n);
 577         LV(t->f_type,n);
 578         break;
 579
 580     case TF_STR:
 581         sp = cp - 1;
 582         while (c && c != ')')
 583             c = *cp++;
 584         cp[-1] = '\0';
 585         LS(t->f_type,sp);
 586         break;
 587
 588     case TF_NONE:
 589         LV(t->f_type,t->extra);
 590         break;
 591
 592     case TF_MYBOX:
 593         LS(t->f_type, getusername());
 594         break;
 595
 596     case TF_NOW:
 597         LV(t->f_type, time((time_t *) 0));
 598         break;
 599
 600     case TF_EXPR_SV:
 601         LV(FT_SAVESTR, 0);
 602         /* fall through */
 603     case TF_EXPR:
 604         *--cp = c;
 605         cp = do_expr(cp, t->extra);
 606         LV(t->f_type, 0);
 607         c = *cp++;
 608         ftbl = t;
 609         break;
 610
 611     case TF_NOP:
 612         *--cp = c;
 613         cp = do_expr(cp, t->extra);
 614         c = *cp++;
 615         ftbl = t;
 616         break;
 617     }
 618     if (c != ')') {
 619         CERROR("')' expected");
 620     }
 621     --infunction;
 622     return (cp);
 623 }
 624
 625 /*
 626  * Handle an expression as an argument.  Basically we call one of do_name(),
 627  * do_func(), or do_if()
 628  */
 629 static char *
 630 do_expr (char *sp, int preprocess)
 631 {
 632     register char *cp = sp;
 633     register int  c;
 634
 635     if ((c = *cp++) == '{') {
 636         cp = do_name (cp, preprocess);
 637         fp->f_type = FT_LS_COMP;
 638     } else if (c == '(') {
 639         cp = do_func (cp);
 640     } else if (c == ')') {
 641         return (--cp);
 642     } else if (c == '%' && *cp == '<') {
 643         cp = do_if (cp+1);
 644     } else {
 645         CERROR ("'(', '{', '%<' or ')' expected");
 646     }
 647     return (cp);
 648 }
 649
 650 /*
 651  * I am guessing this was for some kind of loop statement, which would have
 652  * looked like %[ .... %].  It looks like the way this would have worked
 653  * is that the format engine would have seen that FT_DONE had a 1 in the
 654  * f_un.f_un_value and then decided whether or not to continue the loop.
 655  * There is no support for this in the format engine, so right now if
 656  * you try using it you will reach the FT_DONE and simply stop.  I'm leaving
 657  * this here in case someone wants to continue the work.
 658  */
 659 static char *
 660 do_loop(char *sp)
 661 {
 662     register char *cp = sp;
 663     struct format *floop;
 664
 665     floop = next_fp;
 666     cp = compile (cp);
 667     if (*cp++ != ']')
 668         CERROR ("']' expected");
 669
 670     LV(FT_DONE, 1);             /* not yet done */
 671     LV(FT_GOTO, 0);
 672     fp->f_skip = floop - fp;    /* skip backwards */
 673
 674     return cp;
 675 }
 676
 677 /*
 678  * Handle an if-elsif-endif statement.  Note here that the branching
 679  * is handled by the f_skip member of the struct format (which is really
 680  * just f_width overloaded).  This number controls how far to move forward
 681  * (or back) in the format instruction array.
 682  */
 683 static char *
 684 do_if(char *sp)
 685 {
 686     register char *cp = sp;
 687     register struct format *fexpr,
 688                            *fif = (struct format *)NULL;
 689     register int c = '<';
 690
 691     for (;;) {
 692         if (c == '<') {                 /* doing an IF */
 693             if ((c = *cp++) == '{') /*}*/{
 694                 cp = do_name(cp, 0);
 695                 fp->f_type = FT_LS_COMP;
 696                 LV (FT_IF_S, 0);
 697             }
 698             else if (c == '(') {
 699                 cp = do_func(cp);
 700                 /* see if we can merge the load and the "if" */
 701                 if (ftbl->f_type >= IF_FUNCS)
 702                     fp->f_type = ftbl->extra;
 703                 else {
 704                     /* Put out a string test or a value test depending
 705                      * on what this function's return type is.
 706                      */
 707                     if (ftbl->flags & TFL_PUTS) {
 708                         LV (FT_IF_S, 0);
 709                     } else {
 710                         LV (FT_IF_V_NE, 0);
 711                     }
 712                 }
 713             }
 714             else {
 715                 CERROR("'(' or '{' expected");  /*}*/
 716             }
 717         }
 718
 719         fexpr = fp;                     /* loc of [ELS]IF */
 720         cp = compile (cp);              /* compile IF TRUE stmts */
 721         if (fif)
 722             fif->f_skip = next_fp - fif;
 723
 724         if ((c = *cp++) == '|') {       /* the last ELSE */
 725             LV(FT_GOTO, 0);
 726             fif = fp;                   /* loc of GOTO */
 727             fexpr->f_skip = next_fp - fexpr;
 728
 729             fexpr = (struct format *)NULL;/* no extra ENDIF */
 730
 731             cp = compile (cp);          /* compile ELSE stmts */
 732             fif->f_skip = next_fp - fif;
 733             c = *cp++;
 734         }
 735         else if (c == '?') {            /* another ELSIF */
 736             LV(FT_GOTO, 0);
 737             fif = fp;                   /* loc of GOTO */
 738             fexpr->f_skip = next_fp - fexpr;
 739
 740             c = '<';                    /* impersonate an IF */
 741             continue;
 742         }
 743         break;
 744     }
 745
 746     if (c != '>') {
 747         CERROR("'>' expected.");
 748     }
 749
 750     if (fexpr)                          /* IF ... [ELSIF ...] ENDIF */
 751         fexpr->f_skip = next_fp - fexpr;
 752
 753     return (cp);
 754 }