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conf: add possibility to evaluate simple integer math expressions
It is useful to use the math expressions for the values in configuration. This patch adds a simple expression evaluation routines (integer only). The syntax is simplified unix shell (bash) style. Examples: $[1 + 1] $[$[2 + 2] / $var1] $[0xa0 | 0x05] As a bonus, the variable substitutions were more abstracted. The function snd_config_expand_custom() was introduced to be used for example in the topology pre-precessor. Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela
parent
32d332b786
commit
bf528b9066
5 changed files with 389 additions and 18 deletions
260
src/confeval.c
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260
src/confeval.c
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/**
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* \file confeval.c
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* \ingroup Configuration
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* \brief Configuration helper functions
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* \author Jaroslav Kysela <perex@perex.cz>
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* \date 2021
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*
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* Configuration string evaluation.
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*
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* See the \ref confarg_math page for more details.
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*/
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/*
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* Configuration string evaluation
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* Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>,
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* Jaroslav Kysela <perex@perex.cz>
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*
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <ctype.h>
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#include <limits.h>
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#include "local.h"
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typedef long long value_type_t;
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static const char *_find_end_of_expression(const char *s)
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{
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int count = 1;
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while (*s) {
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if (*s == '[') {
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count++;
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} else if (*s == ']') {
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count--;
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if (count == 0)
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return s + 1;
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}
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s++;
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}
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return NULL;
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}
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static int _parse_integer(value_type_t *val, const char **s)
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{
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long long v;
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char *end;
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errno = 0;
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v = strtoll(*s, &end, 0);
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if (errno)
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return -errno;
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*val = v;
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if (((long long)*val) != v)
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return -ERANGE;
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*s = end;
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return 0;
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}
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static int _to_integer(value_type_t *val, snd_config_t *c)
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{
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int err;
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switch(snd_config_get_type(c)) {
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case SND_CONFIG_TYPE_INTEGER:
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{
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long v;
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err = snd_config_get_integer(c, &v);
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if (err >= 0)
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*val = v;
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}
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break;
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case SND_CONFIG_TYPE_INTEGER64:
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{
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long long v;
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err = snd_config_get_integer64(c, &v);
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if (err >= 0) {
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*val = v;
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if (((long long)*val) != v)
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return -ERANGE;
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return 0;
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}
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}
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break;
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case SND_CONFIG_TYPE_STRING:
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{
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const char *s;
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long long v;
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err = snd_config_get_string(c, &s);
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if (err >= 0) {
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err = safe_strtoll(s, &v);
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if (err >= 0) {
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*val = v;
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if (((long long)*val) != v)
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return -ERANGE;
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return 0;
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}
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}
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}
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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static int _eval_string(snd_config_t **dst, const char *s,
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snd_config_expand_fcn_t fcn, void *private_data)
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{
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snd_config_t *tmp;
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const char *save, *e;
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char *m;
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value_type_t left, right;
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int err, c, op;
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enum {
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LEFT,
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OP,
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RIGHT,
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END
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} pos;
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while (*s && *s <= ' ') s++;
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save = s;
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pos = LEFT;
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op = 0;
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while (*s) {
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while (*s && *s <= ' ') s++;
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c = *s;
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if (c == '\0')
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break;
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if (pos == END) {
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SNDERR("unexpected expression tail '%s'", s);
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return -EINVAL;
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}
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if (pos == OP) {
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switch (c) {
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case '+':
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case '-':
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case '*':
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case '/':
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case '%':
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case '|':
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case '&': op = c; break;
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default:
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SNDERR("unknown operation '%c'", c);
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return -EINVAL;
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}
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pos = RIGHT;
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s++;
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continue;
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}
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if (c == '$') {
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if (s[1] == '[') {
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e = _find_end_of_expression(s + 2);
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if (e == NULL)
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return -EINVAL;
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m = malloc(e - s - 1);
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if (m == NULL)
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return -ENOMEM;
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memcpy(m, s + 2, e - s - 2);
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m[e - s - 3] = '\0';
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err = _eval_string(&tmp, m, fcn, private_data);
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free(m);
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if (err < 0)
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return err;
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s = e;
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if (*s)
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s++;
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} else {
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e = s + 1;
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while (*e) {
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if (!isalnum(*e))
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break;
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e++;
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}
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m = malloc(e - s);
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if (m == NULL)
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return -ENOMEM;
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memcpy(m, s + 1, e - s - 1);
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m[e - s - 1] = '\0';
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err = fcn(&tmp, m, private_data);
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free(m);
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if (err < 0)
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return err;
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s = e;
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}
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err = _to_integer(op == LEFT ? &left : &right, tmp);
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snd_config_delete(tmp);
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} else if (c == '-' || (c >= '0' && c <= '9')) {
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err = _parse_integer(op == LEFT ? &left : &right, &s);
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}
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if (err < 0)
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return err;
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pos = op == LEFT ? OP : END;
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}
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if (pos != OP && pos != END) {
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SNDERR("incomplete expression '%s'", save);
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return -EINVAL;
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}
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if (pos == END) {
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switch (op) {
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case '+': left = left + right; break;
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case '-': left = left - right; break;
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case '*': left = left * right; break;
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case '/': left = left / right; break;
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case '%': left = left % right; break;
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case '|': left = left | right; break;
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case '&': left = left & right; break;
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default: return -EINVAL;
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}
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}
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if (left > INT_MAX || left < INT_MIN)
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return snd_config_imake_integer64(dst, NULL, left);
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else
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return snd_config_imake_integer(dst, NULL, left);
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}
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/**
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* \brief Evaluate an math expression in the string
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* \param[out] dst The function puts the handle to the new configuration
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* node at the address specified by \a dst.
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* \param[in] s A string to evaluate
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* \param[in] fcn A function to get the variable contents
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* \param[in] private_value A private value for the variable contents function
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* \return 0 if successful, otherwise a negative error code.
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*/
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int snd_config_evaluate_string(snd_config_t **dst, const char *s,
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snd_config_expand_fcn_t fcn, void *private_data)
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{
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assert(dst && s);
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int err;
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if (*s != '$')
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return -EINVAL;
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if (s[1] == '[') {
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err = _eval_string(dst, s, fcn, private_data);
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if (err < 0)
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SNDERR("wrong expression '%s'", s);
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} else {
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err = fcn(dst, s + 1, private_data);
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}
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return err;
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}
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