* [PATCH] commands: add let command which supports proper arithmetic
@ 2013-01-09 9:34 Sascha Hauer
0 siblings, 0 replies; only message in thread
From: Sascha Hauer @ 2013-01-09 9:34 UTC (permalink / raw)
To: barebox
From: Jan Luebbe <jlu@pengutronix.de>
This command works like the corresponding Unix shell command and
is used for adding, multiplying and much more.
Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
commands/Kconfig | 7 +
commands/Makefile | 1 +
commands/let.c | 93 +++++++
include/math.h | 92 +++++++
lib/Makefile | 1 +
lib/math.c | 795 +++++++++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 989 insertions(+)
create mode 100644 commands/let.c
create mode 100644 include/math.h
create mode 100644 lib/math.c
diff --git a/commands/Kconfig b/commands/Kconfig
index 75ebfb8..6501769 100644
--- a/commands/Kconfig
+++ b/commands/Kconfig
@@ -57,6 +57,13 @@ config CMD_READLINE
tristate
prompt "readline"
+config CMD_LET
+ tristate
+ prompt "let"
+ help
+ the 'let' command is used for arithmetics. It works like the corresponding
+ Unix shell command.
+
config CMD_TRUE
tristate
default y
diff --git a/commands/Makefile b/commands/Makefile
index effc91b..d9a6294 100644
--- a/commands/Makefile
+++ b/commands/Makefile
@@ -74,6 +74,7 @@ obj-$(CONFIG_CMD_GLOBAL) += global.o
obj-$(CONFIG_CMD_BASENAME) += basename.o
obj-$(CONFIG_CMD_DIRNAME) += dirname.o
obj-$(CONFIG_CMD_READLINK) += readlink.o
+obj-$(CONFIG_CMD_LET) += let.o
obj-$(CONFIG_CMD_LN) += ln.o
obj-$(CONFIG_CMD_CLK) += clk.o
obj-$(CONFIG_CMD_TFTP) += tftp.o
diff --git a/commands/let.c b/commands/let.c
new file mode 100644
index 0000000..644ede5
--- /dev/null
+++ b/commands/let.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2012 Jan Luebbe <j.luebbe@pengutronix.de>
+ *
+ * Partially based on code from BusyBox.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <common.h>
+#include <command.h>
+#include <environment.h>
+#include <errno.h>
+#include <init.h>
+#include <malloc.h>
+#include <xfuncs.h>
+#include <math.h>
+
+static void setvar(const char *name, const char *val)
+{
+ setenv(name, val); /* return value is always 0 */
+}
+
+static arith_t run_arith(const char *s)
+{
+ arith_state_t math_state;
+ arith_t result;
+
+ math_state.lookupvar = getenv;
+ math_state.setvar = setvar;
+ math_state.endofname = arith_endofname;
+
+ result = arith(&math_state, s);
+ if (math_state.errmsg)
+ printf("let: %s\n", math_state.errmsg);
+
+ return result;
+}
+
+static int do_let(int argc, char *argv[])
+{
+ arith_t i;
+
+ argv++;
+ if (!*argv) {
+ printf("let: expression expected\n");
+ return COMMAND_ERROR_USAGE;
+ }
+
+ do {
+ i = run_arith(*argv);
+ } while (*++argv);
+
+ return !i;
+}
+
+BAREBOX_CMD_HELP_START(let)
+BAREBOX_CMD_HELP_USAGE("let expr [expr ...]\n")
+BAREBOX_CMD_HELP_SHORT("evaluate arithmetic expressions\n")
+BAREBOX_CMD_HELP_TEXT ("supported operations are in order of decreasing precedence:\n")
+BAREBOX_CMD_HELP_TEXT (" X++, X--\n")
+BAREBOX_CMD_HELP_TEXT (" ++X, --X\n")
+BAREBOX_CMD_HELP_TEXT (" +X, -X\n")
+BAREBOX_CMD_HELP_TEXT (" !X, ~X\n")
+BAREBOX_CMD_HELP_TEXT (" X**Y\n")
+BAREBOX_CMD_HELP_TEXT (" X*Y, X/Y, X%Y\n")
+BAREBOX_CMD_HELP_TEXT (" X+Y, X-Y\n")
+BAREBOX_CMD_HELP_TEXT (" X<<Y, X>>Y\n")
+BAREBOX_CMD_HELP_TEXT (" X<Y, X<=Y, X>=Y, X>Y\n")
+BAREBOX_CMD_HELP_TEXT (" X==Y, X!=Y\n")
+BAREBOX_CMD_HELP_TEXT (" X&Y\n")
+BAREBOX_CMD_HELP_TEXT (" X^Y\n")
+BAREBOX_CMD_HELP_TEXT (" X|Y\n")
+BAREBOX_CMD_HELP_TEXT (" X&&Y\n")
+BAREBOX_CMD_HELP_TEXT (" X||Y\n")
+BAREBOX_CMD_HELP_TEXT (" X?Y:Z\n")
+BAREBOX_CMD_HELP_TEXT (" X*=Y, X/=Y, X%=Y\n")
+BAREBOX_CMD_HELP_TEXT (" X=Y, X&=Y, X|=Y, X^=Y, X+=Y, X-=Y, X<<=Y, X>>=Y\n")
+BAREBOX_CMD_HELP_END
+
+BAREBOX_CMD_START(let)
+ .cmd = do_let,
+ .usage = "evaluate arithmetic expressions",
+ BAREBOX_CMD_HELP(cmd_let_help)
+BAREBOX_CMD_END
diff --git a/include/math.h b/include/math.h
new file mode 100644
index 0000000..5648e3f
--- /dev/null
+++ b/include/math.h
@@ -0,0 +1,92 @@
+/* math.h - interface to shell math "library" -- this allows shells to share
+ * the implementation of arithmetic $((...)) expansions.
+ *
+ * This aims to be a POSIX shell math library as documented here:
+ * http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_04
+ *
+ * See math.c for internal documentation.
+ */
+
+/* The math library has just one function:
+ *
+ * arith_t arith(arith_state_t *state, const char *expr);
+ *
+ * The expr argument is the math string to parse. All normal expansions must
+ * be done already. i.e. no dollar symbols should be present.
+ *
+ * The state argument is a pointer to a struct of hooks for your shell (see below),
+ * and an error message string (NULL if no error).
+ *
+ * The function returns the answer to the expression. So if you called it
+ * with the expression:
+ * "1 + 2 + 3"
+ * you would obviously get back 6.
+ */
+
+/* To add support to a shell, you need to implement three functions:
+ *
+ * lookupvar() - look up and return the value of a variable
+ *
+ * If the shell does:
+ * foo=123
+ * Then the code:
+ * const char *val = lookupvar("foo");
+ * will result in val pointing to "123"
+ *
+ * setvar() - set a variable to some value
+ *
+ * If the arithmetic expansion does something like:
+ * $(( i = 1))
+ * then the math code will make a call like so:
+ * setvar("i", "1", 0);
+ * The storage for the first two parameters are not allocated, so your
+ * shell implementation will most likely need to strdup() them to save.
+ *
+ * endofname() - return the end of a variable name from input
+ *
+ * The arithmetic code does not know about variable naming conventions.
+ * So when it is given an experession, it knows something is not numeric,
+ * but it is up to the shell to dictate what is a valid identifiers.
+ * So when it encounters something like:
+ * $(( some_var + 123 ))
+ * It will make a call like so:
+ * end = endofname("some_var + 123");
+ * So the shell needs to scan the input string and return a pointer to the
+ * first non-identifier string. In this case, it should return the input
+ * pointer with an offset pointing to the first space. The typical
+ * implementation will return the offset of first char that does not match
+ * the regex (in C locale): ^[a-zA-Z_][a-zA-Z_0-9]*
+ */
+
+#ifndef LIB_MATH_H
+#define LIB_MATH_H 1
+
+#ifdef ENABLE_SH_MATH_SUPPORT_64
+typedef long long arith_t;
+#define ARITH_FMT "%lld"
+#define strto_arith_t simple_strtoull
+#else
+typedef long arith_t;
+#define ARITH_FMT "%ld"
+#define strto_arith_t simple_strtoul
+#endif
+
+# define is_name(c) (isalpha((unsigned char)(c)))
+# define is_in_name(c) ((c) == '_' || (c) == '.' || isalnum((unsigned char)(c)))
+const char* arith_endofname(const char *name);
+
+typedef const char* (*arith_var_lookup_t)(const char *name);
+typedef void (*arith_var_set_t)(const char *name, const char *val);
+typedef const char* (*arith_var_endofname_t)(const char *name);
+
+typedef struct arith_state_t {
+ const char *errmsg;
+ arith_var_lookup_t lookupvar;
+ arith_var_set_t setvar;
+ arith_var_endofname_t endofname;
+ void *list_of_recursed_names;
+} arith_state_t;
+
+arith_t arith(arith_state_t *state, const char *expr);
+
+#endif
diff --git a/lib/Makefile b/lib/Makefile
index 635d52e..f5d10ea 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -15,6 +15,7 @@ obj-y += libgen.o
obj-y += stringlist.o
obj-y += recursive_action.o
obj-y += make_directory.o
+obj-y += math.o
obj-$(CONFIG_BZLIB) += decompress_bunzip2.o
obj-$(CONFIG_ZLIB) += decompress_inflate.o zlib_inflate/
obj-$(CONFIG_CMDLINE_EDITING) += readline.o
diff --git a/lib/math.c b/lib/math.c
new file mode 100644
index 0000000..5a68f5e
--- /dev/null
+++ b/lib/math.c
@@ -0,0 +1,795 @@
+/*
+ * Arithmetic code ripped out of ash shell for code sharing.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Kenneth Almquist.
+ *
+ * Original BSD copyright notice is retained at the end of this file.
+ *
+ * Copyright (c) 1989, 1991, 1993, 1994
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
+ * was re-ported from NetBSD and debianized.
+ *
+ * rewrite arith.y to micro stack based cryptic algorithm by
+ * Copyright (c) 2001 Aaron Lehmann <aaronl@vitelus.com>
+ *
+ * Modified by Paul Mundt <lethal@linux-sh.org> (c) 2004 to support
+ * dynamic variables.
+ *
+ * Modified by Vladimir Oleynik <dzo@simtreas.ru> (c) 2001-2005 to be
+ * used in busybox and size optimizations,
+ * rewrote arith (see notes to this), added locale support,
+ * rewrote dynamic variables.
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+/* Copyright (c) 2001 Aaron Lehmann <aaronl@vitelus.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/* This is my infix parser/evaluator. It is optimized for size, intended
+ * as a replacement for yacc-based parsers. However, it may well be faster
+ * than a comparable parser written in yacc. The supported operators are
+ * listed in #defines below. Parens, order of operations, and error handling
+ * are supported. This code is thread safe. The exact expression format should
+ * be that which POSIX specifies for shells.
+ *
+ * The code uses a simple two-stack algorithm. See
+ * http://www.onthenet.com.au/~grahamis/int2008/week02/lect02.html
+ * for a detailed explanation of the infix-to-postfix algorithm on which
+ * this is based (this code differs in that it applies operators immediately
+ * to the stack instead of adding them to a queue to end up with an
+ * expression).
+ */
+
+/*
+ * Aug 24, 2001 Manuel Novoa III
+ *
+ * Reduced the generated code size by about 30% (i386) and fixed several bugs.
+ *
+ * 1) In arith_apply():
+ * a) Cached values of *numptr and &(numptr[-1]).
+ * b) Removed redundant test for zero denominator.
+ *
+ * 2) In arith():
+ * a) Eliminated redundant code for processing operator tokens by moving
+ * to a table-based implementation. Also folded handling of parens
+ * into the table.
+ * b) Combined all 3 loops which called arith_apply to reduce generated
+ * code size at the cost of speed.
+ *
+ * 3) The following expressions were treated as valid by the original code:
+ * 1() , 0! , 1 ( *3 ) .
+ * These bugs have been fixed by internally enclosing the expression in
+ * parens and then checking that all binary ops and right parens are
+ * preceded by a valid expression (NUM_TOKEN).
+ *
+ * Note: It may be desirable to replace Aaron's test for whitespace with
+ * ctype's isspace() if it is used by another busybox applet or if additional
+ * whitespace chars should be considered. Look below the "#include"s for a
+ * precompiler test.
+ */
+/*
+ * Aug 26, 2001 Manuel Novoa III
+ *
+ * Return 0 for null expressions. Pointed out by Vladimir Oleynik.
+ *
+ * Merge in Aaron's comments previously posted to the busybox list,
+ * modified slightly to take account of my changes to the code.
+ *
+ */
+/*
+ * (C) 2003 Vladimir Oleynik <dzo@simtreas.ru>
+ *
+ * - allow access to variable,
+ * use recursive value indirection: c="2*2"; a="c"; echo $((a+=2)) produce 6
+ * - implement assign syntax (VAR=expr, +=, *= etc)
+ * - implement exponentiation (** operator)
+ * - implement comma separated - expr, expr
+ * - implement ++expr --expr expr++ expr--
+ * - implement expr ? expr : expr (but second expr is always calculated)
+ * - allow hexadecimal and octal numbers
+ * - restore lost XOR operator
+ * - protect $((num num)) as true zero expr (Manuel's error)
+ * - always use special isspace(), see comment from bash ;-)
+ */
+#include <common.h>
+#include <malloc.h>
+#include <linux/ctype.h>
+#include <linux/string.h>
+#include <libbb.h>
+#include <math.h>
+
+#define lookupvar (math_state->lookupvar)
+#define setvar (math_state->setvar )
+#define endofname (math_state->endofname)
+
+typedef unsigned char operator;
+
+/* An operator's token id is a bit of a bitfield. The lower 5 bits are the
+ * precedence, and 3 high bits are an ID unique across operators of that
+ * precedence. The ID portion is so that multiple operators can have the
+ * same precedence, ensuring that the leftmost one is evaluated first.
+ * Consider * and /
+ */
+#define tok_decl(prec,id) (((id)<<5) | (prec))
+#define PREC(op) ((op) & 0x1F)
+
+#define TOK_LPAREN tok_decl(0,0)
+
+#define TOK_COMMA tok_decl(1,0)
+
+/* All assignments are right associative and have the same precedence,
+ * but there are 11 of them, which doesn't fit into 3 bits for unique id.
+ * Abusing another precedence level:
+ */
+#define TOK_ASSIGN tok_decl(2,0)
+#define TOK_AND_ASSIGN tok_decl(2,1)
+#define TOK_OR_ASSIGN tok_decl(2,2)
+#define TOK_XOR_ASSIGN tok_decl(2,3)
+#define TOK_PLUS_ASSIGN tok_decl(2,4)
+#define TOK_MINUS_ASSIGN tok_decl(2,5)
+#define TOK_LSHIFT_ASSIGN tok_decl(2,6)
+#define TOK_RSHIFT_ASSIGN tok_decl(2,7)
+
+#define TOK_MUL_ASSIGN tok_decl(3,0)
+#define TOK_DIV_ASSIGN tok_decl(3,1)
+#define TOK_REM_ASSIGN tok_decl(3,2)
+
+#define fix_assignment_prec(prec) do { if (prec == 3) prec = 2; } while (0)
+
+/* Ternary conditional operator is right associative too */
+#define TOK_CONDITIONAL tok_decl(4,0)
+#define TOK_CONDITIONAL_SEP tok_decl(4,1)
+
+#define TOK_OR tok_decl(5,0)
+
+#define TOK_AND tok_decl(6,0)
+
+#define TOK_BOR tok_decl(7,0)
+
+#define TOK_BXOR tok_decl(8,0)
+
+#define TOK_BAND tok_decl(9,0)
+
+#define TOK_EQ tok_decl(10,0)
+#define TOK_NE tok_decl(10,1)
+
+#define TOK_LT tok_decl(11,0)
+#define TOK_GT tok_decl(11,1)
+#define TOK_GE tok_decl(11,2)
+#define TOK_LE tok_decl(11,3)
+
+#define TOK_LSHIFT tok_decl(12,0)
+#define TOK_RSHIFT tok_decl(12,1)
+
+#define TOK_ADD tok_decl(13,0)
+#define TOK_SUB tok_decl(13,1)
+
+#define TOK_MUL tok_decl(14,0)
+#define TOK_DIV tok_decl(14,1)
+#define TOK_REM tok_decl(14,2)
+
+/* Exponent is right associative */
+#define TOK_EXPONENT tok_decl(15,1)
+
+/* Unary operators */
+#define UNARYPREC 16
+#define TOK_BNOT tok_decl(UNARYPREC,0)
+#define TOK_NOT tok_decl(UNARYPREC,1)
+
+#define TOK_UMINUS tok_decl(UNARYPREC+1,0)
+#define TOK_UPLUS tok_decl(UNARYPREC+1,1)
+
+#define PREC_PRE (UNARYPREC+2)
+
+#define TOK_PRE_INC tok_decl(PREC_PRE, 0)
+#define TOK_PRE_DEC tok_decl(PREC_PRE, 1)
+
+#define PREC_POST (UNARYPREC+3)
+
+#define TOK_POST_INC tok_decl(PREC_POST, 0)
+#define TOK_POST_DEC tok_decl(PREC_POST, 1)
+
+#define SPEC_PREC (UNARYPREC+4)
+
+#define TOK_NUM tok_decl(SPEC_PREC, 0)
+#define TOK_RPAREN tok_decl(SPEC_PREC, 1)
+
+/* from busybox's libbb/skip_whitespace.c */
+static char *skip_whitespace(const char *s)
+{
+ /* In POSIX/C locale (the only locale we care about: do we REALLY want
+ * to allow Unicode whitespace in, say, .conf files? nuts!)
+ * isspace is only these chars: "\t\n\v\f\r" and space.
+ * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
+ * Use that.
+ */
+ while (*s == ' ' || (unsigned char)(*s - 9) <= (13 - 9))
+ s++;
+
+ return (char *) s;
+}
+
+static int is_assign_op(operator op)
+{
+ operator prec = PREC(op);
+ fix_assignment_prec(prec);
+
+ return prec == PREC(TOK_ASSIGN)
+ || prec == PREC_PRE
+ || prec == PREC_POST;
+}
+
+static int is_right_associative(operator prec)
+{
+ return prec == PREC(TOK_ASSIGN)
+ || prec == PREC(TOK_EXPONENT)
+ || prec == PREC(TOK_CONDITIONAL);
+}
+
+typedef struct {
+ arith_t val;
+ /* We acquire second_val only when "expr1 : expr2" part
+ * of ternary ?: op is evaluated.
+ * We treat ?: as two binary ops: (expr ? (expr1 : expr2)).
+ * ':' produces a new value which has two parts, val and second_val;
+ * then '?' selects one of them based on its left side.
+ */
+ arith_t second_val;
+ char second_val_present;
+ /* If NULL then it's just a number, else it's a named variable */
+ char *var;
+} var_or_num_t;
+
+typedef struct remembered_name {
+ struct remembered_name *next;
+ const char *var;
+} remembered_name;
+
+
+static arith_t evaluate_string(arith_state_t *math_state, const char *expr);
+
+static const char *arith_lookup_val(arith_state_t *math_state, var_or_num_t *t)
+{
+ if (t->var) {
+ const char *p = lookupvar(t->var);
+ if (p) {
+ remembered_name *cur;
+ remembered_name cur_save;
+
+ /* did we already see this name?
+ * testcase: a=b; b=a; echo $((a))
+ */
+ for (cur = math_state->list_of_recursed_names; cur; cur = cur->next) {
+ if (strcmp(cur->var, t->var) == 0) {
+ /* Yes */
+ return "expression recursion loop detected";
+ }
+ }
+
+ /* push current var name */
+ cur = math_state->list_of_recursed_names;
+ cur_save.var = t->var;
+ cur_save.next = cur;
+ math_state->list_of_recursed_names = &cur_save;
+
+ /* recursively evaluate p as expression */
+ t->val = evaluate_string(math_state, p);
+
+ /* pop current var name */
+ math_state->list_of_recursed_names = cur;
+
+ return math_state->errmsg;
+ }
+ /* treat undefined var as 0 */
+ t->val = 0;
+ }
+ return 0;
+}
+
+/* "Applying" a token means performing it on the top elements on the integer
+ * stack. For an unary operator it will only change the top element, but a
+ * binary operator will pop two arguments and push the result */
+static const char* noinline arith_apply(arith_state_t *math_state, operator op,
+ var_or_num_t *numstack, var_or_num_t **numstackptr)
+{
+#define NUMPTR (*numstackptr)
+
+ var_or_num_t *top_of_stack;
+ arith_t rez;
+ const char *err;
+
+ /* There is no operator that can work without arguments */
+ if (NUMPTR == numstack)
+ goto err;
+
+ top_of_stack = NUMPTR - 1;
+
+ /* Resolve name to value, if needed */
+ err = arith_lookup_val(math_state, top_of_stack);
+ if (err)
+ return err;
+
+ rez = top_of_stack->val;
+ if (op == TOK_UMINUS)
+ rez = -rez;
+ else if (op == TOK_NOT)
+ rez = !rez;
+ else if (op == TOK_BNOT)
+ rez = ~rez;
+ else if (op == TOK_POST_INC || op == TOK_PRE_INC)
+ rez++;
+ else if (op == TOK_POST_DEC || op == TOK_PRE_DEC)
+ rez--;
+ else if (op != TOK_UPLUS) {
+ /* Binary operators */
+ arith_t right_side_val;
+ char bad_second_val;
+
+ /* Binary operators need two arguments */
+ if (top_of_stack == numstack)
+ goto err;
+ /* ...and they pop one */
+ NUMPTR = top_of_stack; /* this decrements NUMPTR */
+
+ bad_second_val = top_of_stack->second_val_present;
+ if (op == TOK_CONDITIONAL) { /* ? operation */
+ /* Make next if (...) protect against
+ * $((expr1 ? expr2)) - that is, missing ": expr" */
+ bad_second_val = !bad_second_val;
+ }
+ if (bad_second_val) {
+ /* Protect against $((expr <not_?_op> expr1 : expr2)) */
+ return "malformed ?: operator";
+ }
+
+ top_of_stack--; /* now points to left side */
+
+ if (op != TOK_ASSIGN) {
+ /* Resolve left side value (unless the op is '=') */
+ err = arith_lookup_val(math_state, top_of_stack);
+ if (err)
+ return err;
+ }
+
+ right_side_val = rez;
+ rez = top_of_stack->val;
+ if (op == TOK_CONDITIONAL) /* ? operation */
+ rez = (rez ? right_side_val : top_of_stack[1].second_val);
+ else if (op == TOK_CONDITIONAL_SEP) { /* : operation */
+ if (top_of_stack == numstack) {
+ /* Protect against $((expr : expr)) */
+ return "malformed ?: operator";
+ }
+ top_of_stack->second_val_present = op;
+ top_of_stack->second_val = right_side_val;
+ }
+ else if (op == TOK_BOR || op == TOK_OR_ASSIGN)
+ rez |= right_side_val;
+ else if (op == TOK_OR)
+ rez = right_side_val || rez;
+ else if (op == TOK_BAND || op == TOK_AND_ASSIGN)
+ rez &= right_side_val;
+ else if (op == TOK_BXOR || op == TOK_XOR_ASSIGN)
+ rez ^= right_side_val;
+ else if (op == TOK_AND)
+ rez = rez && right_side_val;
+ else if (op == TOK_EQ)
+ rez = (rez == right_side_val);
+ else if (op == TOK_NE)
+ rez = (rez != right_side_val);
+ else if (op == TOK_GE)
+ rez = (rez >= right_side_val);
+ else if (op == TOK_RSHIFT || op == TOK_RSHIFT_ASSIGN)
+ rez >>= right_side_val;
+ else if (op == TOK_LSHIFT || op == TOK_LSHIFT_ASSIGN)
+ rez <<= right_side_val;
+ else if (op == TOK_GT)
+ rez = (rez > right_side_val);
+ else if (op == TOK_LT)
+ rez = (rez < right_side_val);
+ else if (op == TOK_LE)
+ rez = (rez <= right_side_val);
+ else if (op == TOK_MUL || op == TOK_MUL_ASSIGN)
+ rez *= right_side_val;
+ else if (op == TOK_ADD || op == TOK_PLUS_ASSIGN)
+ rez += right_side_val;
+ else if (op == TOK_SUB || op == TOK_MINUS_ASSIGN)
+ rez -= right_side_val;
+ else if (op == TOK_ASSIGN || op == TOK_COMMA)
+ rez = right_side_val;
+ else if (op == TOK_EXPONENT) {
+ arith_t c;
+ if (right_side_val < 0)
+ return "exponent less than 0";
+ c = 1;
+ while (--right_side_val >= 0)
+ c *= rez;
+ rez = c;
+ }
+ else if (right_side_val == 0)
+ return "divide by zero";
+ else if (op == TOK_DIV || op == TOK_DIV_ASSIGN)
+ rez /= right_side_val;
+ else if (op == TOK_REM || op == TOK_REM_ASSIGN)
+ rez %= right_side_val;
+ }
+
+ if (is_assign_op(op)) {
+ char buf[sizeof(arith_t)*3 + 2];
+
+ if (top_of_stack->var == NULL) {
+ /* Hmm, 1=2 ? */
+
+ /*
+ * TODO: actually, bash allows ++7 but for some
+ * reason it evals to 7, not 8
+ */
+ goto err;
+ }
+ /* Save to shell variable */
+ sprintf(buf, ARITH_FMT, rez);
+ setvar(top_of_stack->var, buf);
+ /* After saving, make previous value for v++ or v-- */
+ if (op == TOK_POST_INC)
+ rez--;
+ else if (op == TOK_POST_DEC)
+ rez++;
+ }
+
+ top_of_stack->val = rez;
+ /* Erase var name, it is just a number now */
+ free(top_of_stack->var);
+ top_of_stack->var = NULL;
+ return NULL;
+ err:
+ return "arithmetic syntax error";
+#undef NUMPTR
+}
+
+/* longest must be first */
+static const char op_tokens[] __attribute__((aligned(1))) = {
+ '<','<','=',0, TOK_LSHIFT_ASSIGN,
+ '>','>','=',0, TOK_RSHIFT_ASSIGN,
+ '<','<', 0, TOK_LSHIFT,
+ '>','>', 0, TOK_RSHIFT,
+ '|','|', 0, TOK_OR,
+ '&','&', 0, TOK_AND,
+ '!','=', 0, TOK_NE,
+ '<','=', 0, TOK_LE,
+ '>','=', 0, TOK_GE,
+ '=','=', 0, TOK_EQ,
+ '|','=', 0, TOK_OR_ASSIGN,
+ '&','=', 0, TOK_AND_ASSIGN,
+ '*','=', 0, TOK_MUL_ASSIGN,
+ '/','=', 0, TOK_DIV_ASSIGN,
+ '%','=', 0, TOK_REM_ASSIGN,
+ '+','=', 0, TOK_PLUS_ASSIGN,
+ '-','=', 0, TOK_MINUS_ASSIGN,
+ '-','-', 0, TOK_POST_DEC,
+ '^','=', 0, TOK_XOR_ASSIGN,
+ '+','+', 0, TOK_POST_INC,
+ '*','*', 0, TOK_EXPONENT,
+ '!', 0, TOK_NOT,
+ '<', 0, TOK_LT,
+ '>', 0, TOK_GT,
+ '=', 0, TOK_ASSIGN,
+ '|', 0, TOK_BOR,
+ '&', 0, TOK_BAND,
+ '*', 0, TOK_MUL,
+ '/', 0, TOK_DIV,
+ '%', 0, TOK_REM,
+ '+', 0, TOK_ADD,
+ '-', 0, TOK_SUB,
+ '^', 0, TOK_BXOR,
+ /* uniq */
+ '~', 0, TOK_BNOT,
+ ',', 0, TOK_COMMA,
+ '?', 0, TOK_CONDITIONAL,
+ ':', 0, TOK_CONDITIONAL_SEP,
+ ')', 0, TOK_RPAREN,
+ '(', 0, TOK_LPAREN,
+ 0
+};
+#define ptr_to_rparen (&op_tokens[sizeof(op_tokens)-7])
+
+const char *arith_endofname(const char *name)
+{
+ if (!is_name(*name))
+ return name;
+ while (*++name) {
+ if (!is_in_name(*name))
+ break;
+ }
+ return name;
+}
+
+static arith_t evaluate_string(arith_state_t *math_state, const char *expr)
+{
+ operator lasttok;
+ const char *errmsg;
+ const char *start_expr = expr = skip_whitespace(expr);
+ unsigned expr_len = strlen(expr) + 2;
+ /* Stack of integers */
+ /*
+ * The proof that there can be no more than strlen(startbuf)/2+1
+ * integers in any given correct or incorrect expression
+ * is left as an exercise to the reader.
+ */
+ var_or_num_t *const numstack = xzalloc((expr_len / 2) * sizeof(numstack[0]));
+ var_or_num_t *numstackptr = numstack;
+ /* Stack of operator tokens */
+ operator *const stack = xzalloc(expr_len * sizeof(stack[0]));
+ operator *stackptr = stack;
+ arith_t result;
+
+ if (numstack == NULL || stack == NULL) {
+ errmsg = "out of memory";
+ goto err_with_custom_msg;
+ }
+
+ /* Start with a left paren */
+ *stackptr++ = lasttok = TOK_LPAREN;
+ errmsg = NULL;
+
+ while (1) {
+ const char *p;
+ operator op;
+ operator prec;
+ char arithval;
+
+ expr = skip_whitespace(expr);
+ arithval = *expr;
+ if (arithval == '\0') {
+ if (expr == start_expr) {
+ /* Null expression */
+ numstack->val = 0;
+ goto ret;
+ }
+
+ /*
+ * This is only reached after all tokens have been extracted from the
+ * input stream. If there are still tokens on the operator stack, they
+ * are to be applied in order. At the end, there should be a final
+ * result on the integer stack
+ */
+
+ if (expr != ptr_to_rparen + 1) {
+ /*
+ * If we haven't done so already,
+ * append a closing right paren
+ * and let the loop process it
+ */
+ expr = ptr_to_rparen;
+ continue;
+ }
+ /* At this point, we're done with the expression */
+ if (numstackptr != numstack + 1) {
+ /* ...but if there isn't, it's bad */
+ goto err;
+ }
+ if (numstack->var) {
+ /* expression is $((var)) only, lookup now */
+ errmsg = arith_lookup_val(math_state, numstack);
+ free(numstack->var);
+ numstack->var = NULL;
+ }
+ goto ret;
+ }
+
+ p = endofname(expr);
+ if (p != expr) {
+ /* Name */
+ size_t var_name_size = (p-expr) + 1; /* +1 for NUL */
+ free(numstackptr->var);
+ numstackptr->var = xzalloc(var_name_size);
+ safe_strncpy(numstackptr->var, expr, var_name_size);
+ expr = p;
+ num:
+ numstackptr->second_val_present = 0;
+ numstackptr++;
+ lasttok = TOK_NUM;
+ continue;
+ }
+
+ if (isdigit(arithval)) {
+ /* Number */
+ free(numstackptr->var);
+ numstackptr->var = NULL;
+ errno = 0;
+ numstackptr->val = strto_arith_t(expr, (char**) &expr, 0);
+ if (errno)
+ numstackptr->val = 0; /* bash compat */
+ goto num;
+ }
+
+ /* Should be an operator */
+ p = op_tokens;
+ while (1) {
+ /*
+ * TODO: bash allows 7+++v, treats it as 7 + ++v
+ * we treat it as 7++ + v and reject
+ */
+ /* Compare expr to current op_tokens[] element */
+ const char *e = expr;
+ while (1) {
+ if (*p == '\0') {
+ /* Match: operator is found */
+ expr = e;
+ goto tok_found;
+ }
+ if (*p != *e)
+ break;
+ p++;
+ e++;
+ }
+ /* No match, go to next element of op_tokens[] */
+ while (*p)
+ p++;
+ p += 2; /* skip NUL and TOK_foo bytes */
+ if (*p == '\0') {
+ /* No next element, operator not found */
+ //math_state->syntax_error_at = expr;
+ goto err;
+ }
+ }
+ tok_found:
+ op = p[1]; /* fetch TOK_foo value */
+ /* NB: expr now points past the operator */
+
+ /* post grammar: a++ reduce to num */
+ if (lasttok == TOK_POST_INC || lasttok == TOK_POST_DEC)
+ lasttok = TOK_NUM;
+
+ /*
+ * Plus and minus are binary (not unary) _only_ if the last
+ * token was a number, or a right paren (which pretends to be
+ * a number, since it evaluates to one). Think about it.
+ * It makes sense.
+ */
+ if (lasttok != TOK_NUM) {
+ switch (op) {
+ case TOK_ADD:
+ op = TOK_UPLUS;
+ break;
+ case TOK_SUB:
+ op = TOK_UMINUS;
+ break;
+ case TOK_POST_INC:
+ op = TOK_PRE_INC;
+ break;
+ case TOK_POST_DEC:
+ op = TOK_PRE_DEC;
+ break;
+ }
+ }
+ /*
+ * We don't want an unary operator to cause recursive descent on the
+ * stack, because there can be many in a row and it could cause an
+ * operator to be evaluated before its argument is pushed onto the
+ * integer stack.
+ * But for binary operators, "apply" everything on the operator
+ * stack until we find an operator with a lesser priority than the
+ * one we have just extracted. If op is right-associative,
+ * then stop "applying" on the equal priority too.
+ * Left paren is given the lowest priority so it will never be
+ * "applied" in this way.
+ */
+ prec = PREC(op);
+ if ((prec > 0 && prec < UNARYPREC) || prec == SPEC_PREC) {
+ /* not left paren or unary */
+ if (lasttok != TOK_NUM) {
+ /* binary op must be preceded by a num */
+ goto err;
+ }
+ while (stackptr != stack) {
+ operator prev_op = *--stackptr;
+ if (op == TOK_RPAREN) {
+ /*
+ * The algorithm employed here is simple: while we don't
+ * hit an open paren nor the bottom of the stack, pop
+ * tokens and apply them
+ */
+ if (prev_op == TOK_LPAREN) {
+ /*
+ * Any operator directly after a
+ * close paren should consider itself binary
+ */
+ lasttok = TOK_NUM;
+ goto next;
+ }
+ } else {
+ operator prev_prec = PREC(prev_op);
+ fix_assignment_prec(prec);
+ fix_assignment_prec(prev_prec);
+ if (prev_prec < prec
+ || (prev_prec == prec && is_right_associative(prec))
+ ) {
+ stackptr++;
+ break;
+ }
+ }
+ errmsg = arith_apply(math_state, prev_op, numstack, &numstackptr);
+ if (errmsg)
+ goto err_with_custom_msg;
+ }
+ if (op == TOK_RPAREN)
+ goto err;
+ }
+
+ /* Push this operator to the stack and remember it */
+ *stackptr++ = lasttok = op;
+next: ;
+ } /* while (1) */
+
+err:
+ errmsg = "arithmetic syntax error";
+err_with_custom_msg:
+ result = -1;
+ret:
+ result = numstack->val;
+ free(stack);
+ free(numstack);
+ math_state->errmsg = errmsg;
+ return result;
+}
+
+arith_t arith(arith_state_t *math_state, const char *expr)
+{
+ math_state->errmsg = NULL;
+ math_state->list_of_recursed_names = NULL;
+ return evaluate_string(math_state, expr);
+}
+
+/*
+ * Copyright (c) 1989, 1991, 1993, 1994
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Kenneth Almquist.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
--
1.7.10.4
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2013-01-09 9:34 [PATCH] commands: add let command which supports proper arithmetic Sascha Hauer
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