The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_expr.c

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    1 /*-
    2  * Mach Operating System
    3  * Copyright (c) 1991,1990 Carnegie Mellon University
    4  * All Rights Reserved.
    5  *
    6  * Permission to use, copy, modify and distribute this software and its
    7  * documentation is hereby granted, provided that both the copyright
    8  * notice and this permission notice appear in all copies of the
    9  * software, derivative works or modified versions, and any portions
   10  * thereof, and that both notices appear in supporting documentation.
   11  *
   12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
   13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   15  *
   16  * Carnegie Mellon requests users of this software to return to
   17  *
   18  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   19  *  School of Computer Science
   20  *  Carnegie Mellon University
   21  *  Pittsburgh PA 15213-3890
   22  *
   23  * any improvements or extensions that they make and grant Carnegie the
   24  * rights to redistribute these changes.
   25  */
   26 /*
   27  *      Author: David B. Golub, Carnegie Mellon University
   28  *      Date:   7/90
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __FBSDID("$FreeBSD: releng/11.1/sys/ddb/db_expr.c 308418 2016-11-07 12:10:17Z kib $");
   33 
   34 #include <sys/param.h>
   35 
   36 #include <ddb/ddb.h>
   37 #include <ddb/db_lex.h>
   38 #include <ddb/db_access.h>
   39 #include <ddb/db_command.h>
   40 
   41 static bool     db_add_expr(db_expr_t *valuep);
   42 static bool     db_mult_expr(db_expr_t *valuep);
   43 static bool     db_shift_expr(db_expr_t *valuep);
   44 static bool     db_term(db_expr_t *valuep);
   45 static bool     db_unary(db_expr_t *valuep);
   46 static bool     db_logical_or_expr(db_expr_t *valuep);
   47 static bool     db_logical_and_expr(db_expr_t *valuep);
   48 static bool     db_logical_relation_expr(db_expr_t *valuep);
   49 
   50 static bool
   51 db_term(db_expr_t *valuep)
   52 {
   53         int     t;
   54 
   55         t = db_read_token();
   56         if (t == tIDENT) {
   57             if (!db_value_of_name(db_tok_string, valuep) &&
   58                 !db_value_of_name_pcpu(db_tok_string, valuep) &&
   59                 !db_value_of_name_vnet(db_tok_string, valuep)) {
   60                 db_printf("Symbol '%s' not found\n", db_tok_string);
   61                 db_error(NULL);
   62                 /*NOTREACHED*/
   63             }
   64             return (true);
   65         }
   66         if (t == tNUMBER) {
   67             *valuep = (db_expr_t)db_tok_number;
   68             return (true);
   69         }
   70         if (t == tDOT) {
   71             *valuep = (db_expr_t)db_dot;
   72             return (true);
   73         }
   74         if (t == tDOTDOT) {
   75             *valuep = (db_expr_t)db_prev;
   76             return (true);
   77         }
   78         if (t == tPLUS) {
   79             *valuep = (db_expr_t) db_next;
   80             return (true);
   81         }
   82         if (t == tDITTO) {
   83             *valuep = (db_expr_t)db_last_addr;
   84             return (true);
   85         }
   86         if (t == tDOLLAR) {
   87             if (!db_get_variable(valuep))
   88                 return (false);
   89             return (true);
   90         }
   91         if (t == tLPAREN) {
   92             if (!db_expression(valuep)) {
   93                 db_printf("Expression syntax error after '%c'\n", '(');
   94                 db_error(NULL);
   95                 /*NOTREACHED*/
   96             }
   97             t = db_read_token();
   98             if (t != tRPAREN) {
   99                 db_printf("Expression syntax error -- expected '%c'\n", ')');
  100                 db_error(NULL);
  101                 /*NOTREACHED*/
  102             }
  103             return (true);
  104         }
  105         db_unread_token(t);
  106         return (false);
  107 }
  108 
  109 static bool
  110 db_unary(db_expr_t *valuep)
  111 {
  112         int     t;
  113 
  114         t = db_read_token();
  115         if (t == tMINUS) {
  116             if (!db_unary(valuep)) {
  117                 db_printf("Expression syntax error after '%c'\n", '-');
  118                 db_error(NULL);
  119                 /*NOTREACHED*/
  120             }
  121             *valuep = -*valuep;
  122             return (true);
  123         }
  124         if (t == tEXCL) {
  125             if(!db_unary(valuep)) {
  126                 db_printf("Expression syntax error after '%c'\n", '!');
  127                 db_error(NULL);
  128                 /* NOTREACHED  */
  129             }
  130             *valuep = (!(*valuep));
  131             return (true);
  132         }
  133         if (t == tBIT_NOT) {
  134             if(!db_unary(valuep)) {
  135                 db_printf("Expression syntax error after '%c'\n", '~');
  136                 db_error(NULL);
  137                 /* NOTREACHED */
  138             }
  139             *valuep = (~(*valuep));
  140             return (true);
  141         }
  142         if (t == tSTAR) {
  143             /* indirection */
  144             if (!db_unary(valuep)) {
  145                 db_printf("Expression syntax error after '%c'\n", '*');
  146                 db_error(NULL);
  147                 /*NOTREACHED*/
  148             }
  149             *valuep = db_get_value((db_addr_t)*valuep, sizeof(void *),
  150                 false);
  151             return (true);
  152         }
  153         db_unread_token(t);
  154         return (db_term(valuep));
  155 }
  156 
  157 static bool
  158 db_mult_expr(db_expr_t *valuep)
  159 {
  160         db_expr_t       lhs, rhs;
  161         int             t;
  162 
  163         if (!db_unary(&lhs))
  164             return (false);
  165 
  166         t = db_read_token();
  167         while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH ||
  168             t == tBIT_AND ) {
  169             if (!db_term(&rhs)) {
  170                 db_printf("Expression syntax error after '%c'\n",
  171                     t == tSTAR ? '*' : t == tSLASH ? '/' : t == tPCT ? '%' :
  172                     t == tHASH ? '#' : '&');
  173                 db_error(NULL);
  174                 /*NOTREACHED*/
  175             }
  176             switch(t)  {
  177                 case tSTAR:
  178                     lhs *= rhs;
  179                     break;
  180                 case tBIT_AND:
  181                     lhs &= rhs;
  182                     break;
  183                 default:
  184                     if (rhs == 0) {
  185                         db_error("Division by 0\n");
  186                         /*NOTREACHED*/
  187                     }
  188                     if (t == tSLASH)
  189                         lhs /= rhs;
  190                     else if (t == tPCT)
  191                         lhs %= rhs;
  192                     else
  193                         lhs = roundup(lhs, rhs);
  194             }
  195             t = db_read_token();
  196         }
  197         db_unread_token(t);
  198         *valuep = lhs;
  199         return (true);
  200 }
  201 
  202 static bool
  203 db_add_expr(db_expr_t *valuep)
  204 {
  205         db_expr_t       lhs, rhs;
  206         int             t;
  207 
  208         if (!db_mult_expr(&lhs))
  209             return (false);
  210 
  211         t = db_read_token();
  212         while (t == tPLUS || t == tMINUS || t == tBIT_OR) {
  213             if (!db_mult_expr(&rhs)) {
  214                 db_printf("Expression syntax error after '%c'\n",
  215                     t == tPLUS ? '+' : t == tMINUS ? '-' : '|');
  216                 db_error(NULL);
  217                 /*NOTREACHED*/
  218             }
  219             switch (t) {
  220             case tPLUS:
  221                 lhs += rhs;
  222                 break;
  223             case tMINUS:
  224                 lhs -= rhs;
  225                 break;
  226             case tBIT_OR:
  227                 lhs |= rhs;
  228                 break;
  229             default:
  230                 __unreachable();
  231             }
  232             t = db_read_token();
  233         }
  234         db_unread_token(t);
  235         *valuep = lhs;
  236         return (true);
  237 }
  238 
  239 static bool
  240 db_shift_expr(db_expr_t *valuep)
  241 {
  242         db_expr_t       lhs, rhs;
  243         int             t;
  244 
  245         if (!db_add_expr(&lhs))
  246                 return (false);
  247         t = db_read_token();
  248         while (t == tSHIFT_L || t == tSHIFT_R) {
  249             if (!db_add_expr(&rhs)) {
  250                 db_printf("Expression syntax error after '%s'\n",
  251                     t == tSHIFT_L ? "<<" : ">>");
  252                 db_error(NULL);
  253                 /*NOTREACHED*/
  254             }
  255             if (rhs < 0) {
  256                 db_printf("Negative shift amount %jd\n", (intmax_t)rhs);
  257                 db_error(NULL);
  258                 /*NOTREACHED*/
  259             }
  260             if (t == tSHIFT_L)
  261                 lhs <<= rhs;
  262             else {
  263                 /* Shift right is unsigned */
  264                 lhs = (unsigned) lhs >> rhs;
  265             }
  266             t = db_read_token();
  267         }
  268         db_unread_token(t);
  269         *valuep = lhs;
  270         return (true);
  271 }
  272 
  273 static bool
  274 db_logical_relation_expr(
  275         db_expr_t *valuep)
  276 {
  277         db_expr_t       lhs, rhs;
  278         int             t;
  279 
  280         if (!db_shift_expr(&lhs))
  281             return (false);
  282 
  283         t = db_read_token();
  284         while (t == tLOG_EQ || t == tLOG_NOT_EQ || t == tGREATER ||
  285             t == tGREATER_EQ || t == tLESS || t == tLESS_EQ) {
  286             if (!db_shift_expr(&rhs)) {
  287                 db_printf("Expression syntax error after '%s'\n",
  288                     t == tLOG_EQ ? "==" : t == tLOG_NOT_EQ ? "!=" :
  289                     t == tGREATER ? ">" : t == tGREATER_EQ ? ">=" :
  290                     t == tLESS ? "<" : "<=");
  291                 db_error(NULL);
  292                 /*NOTREACHED*/
  293             }
  294             switch(t) {
  295                 case tLOG_EQ:
  296                     lhs = (lhs == rhs);
  297                     break;
  298                 case tLOG_NOT_EQ:
  299                     lhs = (lhs != rhs);
  300                     break;
  301                 case tGREATER:
  302                     lhs = (lhs > rhs);
  303                     break;
  304                 case tGREATER_EQ:
  305                     lhs = (lhs >= rhs);
  306                     break;
  307                 case tLESS:
  308                     lhs = (lhs < rhs);
  309                     break;
  310                 case tLESS_EQ:
  311                     lhs = (lhs <= rhs);
  312                     break;
  313                 default:
  314                     __unreachable();
  315             }
  316             t = db_read_token();
  317         }
  318         db_unread_token(t);
  319         *valuep = lhs;
  320         return (true);
  321 }
  322 
  323 static bool
  324 db_logical_and_expr(
  325         db_expr_t *valuep)
  326 {
  327         db_expr_t       lhs, rhs;
  328         int             t;
  329 
  330         if (!db_logical_relation_expr(&lhs))
  331             return (false);
  332 
  333         t = db_read_token();
  334         while (t == tLOG_AND) {
  335             if (!db_logical_relation_expr(&rhs)) {
  336                 db_printf("Expression syntax error after '%s'\n", "&&");
  337                 db_error(NULL);
  338                 /*NOTREACHED*/
  339             }
  340             lhs = (lhs && rhs);
  341             t = db_read_token();
  342         }
  343         db_unread_token(t);
  344         *valuep = lhs;
  345         return (true);
  346 }
  347 
  348 static bool
  349 db_logical_or_expr(
  350         db_expr_t *valuep)
  351 {
  352         db_expr_t       lhs, rhs;
  353         int             t;
  354 
  355         if (!db_logical_and_expr(&lhs))
  356                 return(false);
  357 
  358         t = db_read_token();
  359         while (t == tLOG_OR) {
  360                 if (!db_logical_and_expr(&rhs)) {
  361                         db_printf("Expression syntax error after '%s'\n", "||");
  362                         db_error(NULL);
  363                         /*NOTREACHED*/
  364                 }
  365                 lhs = (lhs || rhs);
  366                 t = db_read_token();
  367         }
  368         db_unread_token(t);
  369         *valuep = lhs;
  370         return (true);
  371 }
  372 
  373 int
  374 db_expression(db_expr_t *valuep)
  375 {
  376         return (db_logical_or_expr(valuep));
  377 }

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