conky/src/algebra.cc

/*
 *
 * Conky, a system monitor, based on torsmo
 *
 * Any original torsmo code is licensed under the BSD license
 *
 * All code written since the fork of torsmo is licensed under the GPL
 *
 * Please see COPYING for details
 *
 * Copyright (c) 2004, Hannu Saransaari and Lauri Hakkarainen
 * Copyright (c) 2005-2018 Brenden Matthews, Philip Kovacs, et. al.
 *	(see AUTHORS)
 * All rights reserved.
 *
 * 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 3 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.
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
#include "algebra.h"
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <memory>
#include "config.h"
#include "conky.h"
#include "logging.h"

/* find the operand in the given expression
 * returns the index of the first op character or -1 on error
 */
int find_match_op(const char *expr) {
  unsigned int idx;

  for (idx = 0; idx < strlen(expr); idx++) {
    switch (expr[idx]) {
      case '=':
      case '!':
        if (expr[idx + 1] != '=') return -1;
        /* fall through */
      case '<':
      case '>':
        return idx;
        break;
    }
  }
  return -1;
}

int get_match_type(const char *expr) {
  int idx;
  const char *str;

  if ((idx = find_match_op(expr)) == -1) return -1;
  str = expr + idx;

  if (*str == '=' && *(str + 1) == '=')
    return OP_EQ;
  else if (*str == '!' && *(str + 1) == '=')
    return OP_NEQ;
  else if (*str == '>') {
    if (*(str + 1) == '=') return OP_GEQ;
    return OP_GT;
  } else if (*str == '<') {
    if (*(str + 1) == '=') return OP_LEQ;
    return OP_LT;
  }
  return -1;
}

/* generic compare function
 *
 * v is actually the difference of the compared values. For strings
 * this is equal to the output of str(n)cmp(). Use a macro here, as
 * it's type-independent.
 */
#define COMPARE(v, t)  \
  switch (t) {         \
    case OP_GT:        \
      return (v > 0);  \
    case OP_LT:        \
      return (v < 0);  \
    case OP_EQ:        \
      return (v == 0); \
    case OP_GEQ:       \
      return (v >= 0); \
    case OP_LEQ:       \
      return (v <= 0); \
    case OP_NEQ:       \
      return (v != 0); \
  }                    \
  return 0

int lcompare(long a, enum match_type mtype, long b) {
  DBGP2("comparing longs '%ld' and '%ld'", a, b);
  COMPARE((a - b), mtype);
}
int dcompare(double a, enum match_type mtype, double b) {
  DBGP2("comparing doubles '%.lf' and '%.lf'", a, b);
  COMPARE((a - b), mtype);
}

int scompare(const char *a, enum match_type mtype, const char *b) {
  DBGP2("comparing strings '%s' and '%s'", a, b);
  COMPARE(strcmp(a, b), mtype);
}

enum arg_type get_arg_type(const char *arg) {
  const char *p, *e;

  p = arg;
  e = arg + strlen(arg) - 1;

  while (p != e && *e && *e == ' ') e--;
  while (p != e && *p == ' ') p++;

  if (*p == '"' && *e == '"') return ARG_STRING;

  if (*p == '-')  // allow negative values
    p++;
  while (p <= e) {
    if (!isdigit(*p)) break;
    p++;
  }
  if (p == e + 1) return ARG_LONG;
  if (*p == '.') {
    p++;
    while (p <= e) {
      if (!isdigit(*p)) return ARG_BAD;
      p++;
    }
    return ARG_DOUBLE;
  }
  return ARG_BAD;
}

char *arg_to_string(const char *arg) {
  const char *start;
  int len;

  start = arg;
  len = 0;
  while (*start && *start == ' ') start++;
  if (!(*(start++) == '"')) return NULL;
  while (start[len] != '"') len++;
  return strndup(start, len);
}
double arg_to_double(const char *arg) {
  double d;
  if (sscanf(arg, "%lf", &d) != 1) {
    NORM_ERR("converting '%s' to double failed", arg);
    return 0.0;
  }
  return d;
}
long arg_to_long(const char *arg) {
  long l;
  if (sscanf(arg, "%ld", &l) != 1) {
    NORM_ERR("converting '%s' to long failed", arg);
    return 0;
  }
  return l;
}
int compare(const char *expr) {
  char *expr_dup;
  int idx, mtype;
  enum arg_type type1, type2;
  long lng_a, lng_b;
  double dbl_a, dbl_b;

  idx = find_match_op(expr);
  mtype = get_match_type(expr);

  if (!idx || mtype == -1) {
    NORM_ERR("failed to parse compare string '%s'", expr);
    return -2;
  }

  expr_dup = strdup(expr);
  expr_dup[idx] = '\0';
  if (expr_dup[idx + 1] == '=') expr_dup[++idx] = '\0';

  type1 = get_arg_type(expr_dup);
  type2 = get_arg_type(expr_dup + idx + 1);
  if (type1 == ARG_BAD || type2 == ARG_BAD) {
    NORM_ERR("Bad arguments: '%s' and '%s'", expr_dup, (expr_dup + idx + 1));
    free(expr_dup);
    return -2;
  }
  if (type1 == ARG_LONG && type2 == ARG_DOUBLE) type1 = ARG_DOUBLE;
  if (type1 == ARG_DOUBLE && type2 == ARG_LONG) type2 = ARG_DOUBLE;
  if (type1 != type2) {
    NORM_ERR("trying to compare args '%s' and '%s' of different type", expr_dup,
             (expr_dup + idx + 1));
    free(expr_dup);
    return -2;
  }
  switch (type1) {
    case ARG_STRING: {
      char *a, *b;
      a = arg_to_string(expr_dup);
      b = arg_to_string(expr_dup + idx + 1);
      idx = scompare(a, (enum match_type)mtype, b);
      free(a);
      free(b);
      free(expr_dup);
      return idx;
    }
    case ARG_LONG:
      lng_a = arg_to_long(expr_dup);
      lng_b = arg_to_long(expr_dup + idx + 1);
      free(expr_dup);
      return lcompare(lng_a, (enum match_type)mtype, lng_b);
    case ARG_DOUBLE:
      dbl_a = arg_to_double(expr_dup);
      dbl_b = arg_to_double(expr_dup + idx + 1);
      free(expr_dup);
      return dcompare(dbl_a, (enum match_type)mtype, dbl_b);
    case ARG_BAD: /* make_gcc_happy() */;
  }
  /* not reached */
  free(expr_dup);
  return -2;
}

int check_if_match(struct text_object *obj) {
  std::unique_ptr<char[]> expression(new char[max_user_text.get(*state)]);
  int val;
  int result = 1;

  generate_text_internal(expression.get(), max_user_text.get(*state),
                         *obj->sub);
  DBGP("parsed arg into '%s'", expression.get());

  val = compare(expression.get());
  if (val == -2) {
    NORM_ERR("compare failed for expression '%s'", expression.get());
  } else if (!val) {
    result = 0;
  }
  return result;
}