conky/src/template.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) 2005-2019 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 <cctype>
#include <cstdlib>
#include <string>
#include "conky.h"
#include "logging.h"

namespace {
conky::simple_config_setting<std::string> _template[10] = {
    {"template0", std::string(), true}, {"template1", std::string(), true},
    {"template2", std::string(), true}, {"template3", std::string(), true},
    {"template4", std::string(), true}, {"template5", std::string(), true},
    {"template6", std::string(), true}, {"template7", std::string(), true},
    {"template8", std::string(), true}, {"template9", std::string(), true}};
}  // namespace

/* backslash_escape - do the actual substitution task for template objects
 *
 * The field templates is used for substituting the \N occurences. Set it to
 * nullptr to leave them as they are.
 */
static char *backslash_escape(const char *src, char **templates,
                              unsigned int template_count) {
  char *src_dup;
  const char *p;
  unsigned int dup_idx = 0, dup_len;

  dup_len = strlen(src) + 1;
  src_dup = static_cast<char *>(malloc(dup_len * sizeof(char)));

  p = src;
  while (*p != 0) {
    switch (*p) {
      case '\\':
        if (*(p + 1) == 0) { break; }
        if (*(p + 1) == '\\') {
          src_dup[dup_idx++] = '\\';
          p++;
        } else if (*(p + 1) == ' ') {
          src_dup[dup_idx++] = ' ';
          p++;
        } else if (*(p + 1) == 'n') {
          src_dup[dup_idx++] = '\n';
          p++;
        } else if (templates != nullptr) {
          unsigned int tmpl_num;
          int digits;
          if ((sscanf(p + 1, "%u%n", &tmpl_num, &digits) <= 0) ||
              (tmpl_num > template_count)) {
            break;
          }
          if (tmpl_num == 0)
            CRIT_ERR(
                nullptr, nullptr,
                "invalid template argument \\0; arguments must start at \\1");
          dup_len += strlen(templates[tmpl_num - 1]);
          src_dup =
              static_cast<char *>(realloc(src_dup, dup_len * sizeof(char)));
          sprintf(src_dup + dup_idx, "%s", templates[tmpl_num - 1]);
          dup_idx += strlen(templates[tmpl_num - 1]);
          p += digits;
        }
        break;
      default:
        src_dup[dup_idx++] = *p;
        break;
    }
    p++;
  }
  src_dup[dup_idx++] = '\0';
  src_dup = static_cast<char *>(realloc(src_dup, dup_idx * sizeof(char)));
  return src_dup;
}

/* handle_template_object - core logic of the template object
 *
 * use config variables like this:
 * template1 = "$\1\2"
 * template2 = "\1: ${fs_bar 4,100 \2} ${fs_used \2} / ${fs_size \2}"
 *
 * and use them like this:
 * ${template1 node name}
 * ${template2 root /}
 * ${template2 cdrom /mnt/cdrom}
 */
static char *handle_template(const char *tmpl, const char *args) {
  char *args_dup = nullptr;
  char *p, *p_old;
  char **argsp = nullptr;
  unsigned int argcnt = 0, template_idx, i;
  char *eval_text;

  if ((sscanf(tmpl, "template%u", &template_idx) != 1) ||
      (template_idx >= MAX_TEMPLATES)) {
    return nullptr;
  }

  if (args != nullptr) {
    args_dup = strdup(args);
    p = args_dup;
    while (*p != 0) {
      while ((*p != 0) && (*p == ' ' && (p == args_dup || *(p - 1) != '\\'))) {
        p++;
      }
      if (p > args_dup && *(p - 1) == '\\') { p--; }
      p_old = p;
      while ((*p != 0) && (*p != ' ' || (p > args_dup && *(p - 1) == '\\'))) {
        p++;
      }
      if (*p != 0) {
        (*p) = '\0';
        p++;
      }
      argsp = static_cast<char **>(realloc(argsp, ++argcnt * sizeof(char *)));
      argsp[argcnt - 1] = p_old;
    }
    for (i = 0; i < argcnt; i++) {
      char *tmp;
      tmp = backslash_escape(argsp[i], nullptr, 0);
      DBGP2("%s: substituted arg '%s' to '%s'", tmpl, argsp[i], tmp);
      argsp[i] = tmp;
    }
  }

  eval_text = backslash_escape(_template[template_idx].get(*state).c_str(),
                               argsp, argcnt);
  DBGP("substituted %s, output is '%s'", tmpl, eval_text);
  free(args_dup);
  for (i = 0; i < argcnt; i++) { free(argsp[i]); }
  free(argsp);
  return eval_text;
}

/* Search inbuf and replace all found template object references
 * with the substituted value. */
char *find_and_replace_templates(const char *inbuf) {
  char *outbuf, *indup, *p, *o, *templ, *args, *tmpl_out;
  int stack, outlen;

  outlen = strlen(inbuf) + 1;
  o = outbuf = static_cast<char *>(calloc(outlen, sizeof(char)));
  memset(outbuf, 0, outlen * sizeof(char));

  p = indup = strdup(inbuf);
  while (*p != 0) {
    while ((*p != 0) && *p != '$') { *(o++) = *(p++); }

    if ((*p) == 0) { break; }

    if ((static_cast<int>(strncmp(p, "$template", strlen("$template")) != 0) !=
         0) &&
        (strncmp(p, "${template", strlen("${template")) != 0)) {
      *(o++) = *(p++);
      continue;
    }

    if (*(p + 1) == '{') {
      p += 2;
      templ = p;
      while ((*p != 0) && (isspace((unsigned char)*p) == 0) && *p != '{' &&
             *p != '}') {
        p++;
      }
      if (*p == '}') {
        args = nullptr;
      } else {
        args = p;
      }

      stack = 1;
      while ((*p != 0) && stack > 0) {
        if (*p == '{') {
          stack++;
        } else if (*p == '}') {
          stack--;
        }
        p++;
      }
      if (stack == 0) {
        // stack is empty. that means the previous char was }, so we zero it
        *(p - 1) = '\0';
      } else {
        // we ran into the end of string without finding a closing }, bark
        CRIT_ERR(nullptr, nullptr,
                 "cannot find a closing '}' in template expansion");
      }
    } else {
      templ = p + 1;
      p += strlen("$template");
      while ((*p != 0) && (isdigit((unsigned char)*p) != 0)) { p++; }
      args = nullptr;
    }
    tmpl_out = handle_template(templ, args);
    if (tmpl_out != nullptr) {
      int len = strlen(tmpl_out);
      outlen += len;
      *o = '\0';
      outbuf = static_cast<char *>(realloc(outbuf, outlen * sizeof(char)));
      strncat(outbuf, tmpl_out, len);
      free(tmpl_out);
      o = outbuf + strlen(outbuf);
    } else {
      NORM_ERR("failed to handle template '%s' with args '%s'", templ, args);
    }
  }
  *o = '\0';
  outbuf =
      static_cast<char *>(realloc(outbuf, (strlen(outbuf) + 1) * sizeof(char)));
  free(indup);
  return outbuf;
}

/* check text for any template object references */
int text_contains_templates(const char *text) {
  if (strcasestr(text, "${template") != nullptr) { return 1; }
  if (strcasestr(text, "$template") != nullptr) { return 1; }
  return 0;
}