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cfg.c

/* $Id: cfg.c,v 1.47 2005/05/08 04:32:43 reinelt Exp $^
 *
 * config file stuff
 *
 * Copyright (C) 1999, 2000 Michael Reinelt <reinelt@eunet.at>
 * Copyright (C) 2004 The LCD4Linux Team <lcd4linux-devel@users.sourceforge.net>
 *
 * This file is part of LCD4Linux.
 *
 * LCD4Linux 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, or (at your option)
 * any later version.
 *
 * LCD4Linux 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, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 * $Log: cfg.c,v $
 * Revision 1.47  2005/05/08 04:32:43  reinelt
 * CodingStyle added and applied
 *
 * Revision 1.46  2005/05/02 05:15:46  reinelt
 * make busy-flag checking configurable for LCD-Linux driver
 *
 * Revision 1.45  2005/01/18 06:30:21  reinelt
 * added (C) to all copyright statements
 *
 * Revision 1.44  2005/01/17 06:29:24  reinelt
 * added software-controlled backlight support to HD44780
 *
 * Revision 1.43  2004/11/29 04:42:06  reinelt
 * removed the 99999 msec limit on widget update time (thanks to Petri Damsten)
 *
 * Revision 1.42  2004/06/26 12:04:59  reinelt
 *
 * uh-oh... the last CVS log message messed up things a lot...
 *
 * Revision 1.41  2004/06/26 09:27:20  reinelt
 *
 * added '-W' to CFLAGS
 * changed all C++ comments to C ones
 * cleaned up a lot of signed/unsigned mistakes
 *
 * Revision 1.40  2004/06/20 10:09:52  reinelt
 *
 * 'const'ified the whole source
 *
 * Revision 1.39  2004/03/11 06:39:58  reinelt
 * big patch from Martin:
 * - reuse filehandles
 * - memory leaks fixed
 * - earlier busy-flag checking with HD44780
 * - reuse memory for strings in RESULT and hash
 * - netdev_fast to wavid time-consuming regex
 *
 * Revision 1.38  2004/03/08 16:26:26  reinelt
 * re-introduced \nnn (octal) characters in strings
 * text widgets can have a 'update' speed of 0 which means 'never'
 * (may be used for static content)
 *
 * Revision 1.37  2004/03/06 20:31:16  reinelt
 * Complete rewrite of the evaluator to get rid of the code
 * from mark Morley (because of license issues).
 * The new Evaluator does a pre-compile of expressions, and
 * stores them in trees. Therefore it should be reasonable faster...
 *
 * Revision 1.36  2004/03/03 03:47:04  reinelt
 * big patch from Martin Hejl:
 * - use qprintf() where appropriate
 * - save CPU cycles on gettimeofday()
 * - add quit() functions to free allocated memory
 * - fixed lots of memory leaks
 *
 * Revision 1.35  2004/03/01 04:29:51  reinelt
 * cfg_number() returns -1 on error, 0 if value not found (but default val used),
 *  and 1 if value was used from the configuration.
 * HD44780 driver adopted to new cfg_number()
 * Crystalfontz 631 driver nearly finished
 *
 * Revision 1.34  2004/02/18 06:39:20  reinelt
 * T6963 driver for graphic displays finished
 *
 * Revision 1.33  2004/02/01 18:08:50  reinelt
 * removed strtok() from layout processing (took me hours to find this bug)
 * further strtok() removind should be done!
 *
 * Revision 1.32  2004/01/30 20:57:55  reinelt
 * HD44780 patch from Martin Hejl
 * dmalloc integrated
 *
 * Revision 1.31  2004/01/29 04:40:02  reinelt
 * every .c file includes "config.h" now
 *
 * Revision 1.30  2004/01/22 07:57:45  reinelt
 * several bugs fixed where segfaulting on layout>display
 * Crystalfontz driver optimized, 632 display already works
 *
 * Revision 1.29  2004/01/18 06:54:08  reinelt
 * bug in expr.c fixed (thanks to Xavier)
 * some progress with /proc/stat parsing
 *
 * Revision 1.28  2004/01/16 05:04:53  reinelt
 * started plugin proc_stat which should parse /proc/stat
 * which again is a paint in the a**
 * thinking over implementation methods of delta functions
 * (CPU load, ...)
 *
 * Revision 1.27  2004/01/14 11:33:00  reinelt
 * new plugin 'uname' which does what it's called
 * text widget nearly finished
 * first results displayed on MatrixOrbital
 *
 * Revision 1.26  2004/01/11 18:26:02  reinelt
 * further widget and layout processing
 *
 * Revision 1.25  2004/01/11 09:26:15  reinelt
 * layout starts to exist...
 *
 * Revision 1.24  2004/01/10 20:22:33  reinelt
 * added new function 'cfg_list()' (not finished yet)
 * added layout.c (will replace processor.c someday)
 * added widget_text.c (will be the first and most important widget)
 * modified lcd4linux.c so that old-style configs should work, too
 *
 * Revision 1.23  2004/01/09 04:16:06  reinelt
 * added 'section' argument to cfg_get(), but NULLed it on all calls by now.
 *
 * Revision 1.22  2004/01/08 06:00:28  reinelt
 * allowed '.' in key names
 * allowed empty section keys (not only "section anything {", but "anything {")
 *
 * Revision 1.21  2004/01/08 05:28:12  reinelt
 * Luk Claes added to AUTHORS
 * cfg: section handling ('{}') added
 *
 * Revision 1.20  2004/01/07 10:15:41  reinelt
 * small glitch in evaluator fixed
 * made config table sorted and access with bsearch(),
 * which should be much faster
 *
 * Revision 1.19  2003/12/19 05:35:14  reinelt
 * renamed 'client' to 'plugin'
 *
 * Revision 1.18  2003/10/11 06:01:52  reinelt
 *
 * renamed expression.{c,h} to client.{c,h}
 * added config file client
 * new functions 'AddNumericVariable()' and 'AddStringVariable()'
 * new parameter '-i' for interactive mode
 *
 * Revision 1.17  2003/10/05 17:58:50  reinelt
 * libtool junk; copyright messages cleaned up
 *
 * Revision 1.16  2003/09/09 06:54:43  reinelt
 * new function 'cfg_number()'
 *
 * Revision 1.15  2003/08/24 05:17:58  reinelt
 * liblcd4linux patch from Patrick Schemitz
 *
 * Revision 1.14  2003/08/14 03:47:40  reinelt
 * remove PID file if driver initialisation fails
 *
 * Revision 1.13  2003/02/22 07:53:10  reinelt
 * cfg_get(key,defval)
 *
 * Revision 1.12  2001/03/09 12:14:24  reinelt
 *
 * minor cleanups
 *
 * Revision 1.11  2001/03/08 15:25:38  ltoetsch
 * improved exec
 *
 * Revision 1.10  2001/03/07 18:10:21  ltoetsch
 * added e(x)ec commands
 *
 * Revision 1.9  2000/08/10 09:44:09  reinelt
 *
 * new debugging scheme: error(), info(), debug()
 * uses syslog if in daemon mode
 *
 * Revision 1.8  2000/07/31 06:46:35  reinelt
 *
 * eliminated some compiler warnings with glibc
 *
 * Revision 1.7  2000/04/15 11:13:54  reinelt
 *
 * added '-d' (debugging) switch
 * added several debugging messages
 * removed config entry 'Delay' for HD44780 driver
 * delay loop for HD44780 will be calibrated automatically
 *
 * Revision 1.6  2000/04/03 04:46:38  reinelt
 *
 * added '-c key=val' option
 *
 * Revision 1.5  2000/03/28 07:22:15  reinelt
 *
 * version 0.95 released
 * X11 driver up and running
 * minor bugs fixed
 *
 * Revision 1.4  2000/03/26 20:00:44  reinelt
 *
 * README.Raster added
 *
 * Revision 1.3  2000/03/26 19:03:52  reinelt
 *
 * more Pixmap renaming
 * quoting of '#' in config file
 *
 * Revision 1.2  2000/03/10 17:36:02  reinelt
 *
 * first unstable but running release
 *
 * Revision 1.1  2000/03/10 11:40:47  reinelt
 * *** empty log message ***
 *
 * Revision 1.3  2000/03/07 11:01:34  reinelt
 *
 * system.c cleanup
 *
 * Revision 1.2  2000/03/06 06:04:06  reinelt
 *
 * minor cleanups
 *
 */

/* 
 * exported functions:
 *
 * cfg_init (source)
 *   read configuration from source
 *   returns  0 if successful
 *   returns -1 in case of an error
 * 
 * cfg_source (void)
 *   returns the file the configuration was read from
 * 
 * cfg_cmd (arg)
 *   allows us to overwrite entries in the 
 *   config-file from the command line.
 *   arg is 'key=value'
 *   cfg_cmd can be called _before_ cfg_read()
 *   returns 0 if ok, -1 if arg cannot be parsed
 *
 * cfg_list (section)
 *   returns a list of all keys in the specified section
 *   This list was allocated be cfg_list() and must be 
 *   freed by the caller!
 *
 * cfg_get_raw (section, key, defval) 
 *   return the a value for a given key in a given section 
 *   or <defval> if key does not exist. Does NOT evaluate
 *   the expression. Therefore used to get the expression 
 *   itself!
 *
 * cfg_get (section, key, defval) 
 *   return the a value for a given key in a given section 
 *   or <defval> if key does not exist. The specified
 *   value in the config is treated as a expression and 
 *   is evaluated!
 *
 * cfg_number (section, key, defval, min, int max, *value) 
 *   return the a value for a given key in a given section 
 *   convert it into a number with syntax checking
 *   check if its in a given range. As it uses cfg_get()
 *   internally, the evaluator is used here, too.
 * 
 */


#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>

#include <unistd.h>
#include <sys/stat.h>

#include "debug.h"
#include "evaluator.h"
#include "cfg.h"

#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif

typedef struct {
    char *key;
    char *val;
    int lock;
} ENTRY;


static char *Config_File = NULL;
static ENTRY *Config = NULL;
static int nConfig = 0;


/* bsearch compare function for config entries */
static int c_lookup(const void *a, const void *b)
{
    char *key = (char *) a;
    ENTRY *entry = (ENTRY *) b;

    return strcasecmp(key, entry->key);
}


/* qsort compare function for variables */
static int c_sort(const void *a, const void *b)
{
    ENTRY *ea = (ENTRY *) a;
    ENTRY *eb = (ENTRY *) b;

    return strcasecmp(ea->key, eb->key);
}


/* remove leading and trailing whitespace */
static char *strip(char *s, const int strip_comments)
{
    char *p;

    while (isblank(*s))
      s++;
    for (p = s; *p; p++) {
      if (*p == '"')
          do
            p++;
          while (*p && *p != '\n' && *p != '"');
      if (*p == '\'')
          do
            p++;
          while (*p && *p != '\n' && *p != '\'');
      if (*p == '\n' || (strip_comments && *p == '#' && (p == s || *(p - 1) != '\\'))) {
          *p = '\0';
          break;
      }
    }
    for (p--; p > s && isblank(*p); p--)
      *p = '\0';
    return s;
}


/* unquote a string */
static char *dequote(char *string)
{
    int quote = 0;
    char *s = string;
    char *p = string;

    do {
      if (*s == '\'') {
          quote = !quote;
          *p++ = *s;
      } else if (quote && *s == '\\') {
          s++;
          if (*s >= '0' && *s <= '7') {
            int n;
            unsigned int c = 0;
            sscanf(s, "%3o%n", &c, &n);
            if (c == 0 || c > 255) {
                error("WARNING: illegal '\\' in <%s>", string);
            } else {
                *p++ = c;
                s += n - 1;
            }
          } else {
            *p++ = *s;
          }
      } else {
          *p++ = *s;
      }
    } while (*s++);

    return string;
}


/* which if a string contains only valid chars */
/* i.e. start with a char and contains chars and nums */
static int validchars(const char *string)
{
    const char *c;

    for (c = string; *c; c++) {
      /* first and following chars */
      if ((*c >= 'A' && *c <= 'Z') || (*c >= 'a' && *c <= 'z') || (*c == '_'))
          continue;
      /* only following chars */
      if ((c > string) && ((*c >= '0' && *c <= '9') || (*c == '.') || (*c == '-')))
          continue;
      return 0;
    }
    return 1;
}


static void cfg_add(const char *section, const char *key, const char *val, const int lock)
{
    char *buffer;
    ENTRY *entry;

    /* allocate buffer  */
    buffer = malloc(strlen(section) + strlen(key) + 2);
    *buffer = '\0';

    /* prepare section.key */
    if (section != NULL && *section != '\0') {
      strcpy(buffer, section);
      strcat(buffer, ".");
    }
    strcat(buffer, key);

    /* does the key already exist? */
    entry = bsearch(buffer, Config, nConfig, sizeof(ENTRY), c_lookup);

    if (entry != NULL) {
      if (entry->lock > lock)
          return;
      debug("Warning: key <%s>: value <%s> overwritten with <%s>", buffer, entry->val, val);
      free(buffer);
      if (entry->val)
          free(entry->val);
      entry->val = dequote(strdup(val));
      return;
    }

    nConfig++;
    Config = realloc(Config, nConfig * sizeof(ENTRY));
    Config[nConfig - 1].key = buffer;
    Config[nConfig - 1].val = dequote(strdup(val));
    Config[nConfig - 1].lock = lock;

    qsort(Config, nConfig, sizeof(ENTRY), c_sort);

}


int cfg_cmd(const char *arg)
{
    char *key, *val;
    char buffer[256];

    strncpy(buffer, arg, sizeof(buffer));
    key = strip(buffer, 0);
    for (val = key; *val; val++) {
      if (*val == '=') {
          *val++ = '\0';
          break;
      }
    }
    if (*key == '\0' || *val == '\0')
      return -1;
    if (!validchars(key))
      return -1;
    cfg_add("", key, val, 1);
    return 0;
}


char *cfg_list(const char *section)
{
    int i, len;
    char *key, *list;

    /* calculate key length */
    len = strlen(section) + 1;

    /* prepare search key */
    key = malloc(len + 1);
    strcpy(key, section);
    strcat(key, ".");

    /* start with empty string */
    list = malloc(1);
    *list = '\0';

    /* search matching entries */
    for (i = 0; i < nConfig; i++) {
      if (strncasecmp(Config[i].key, key, len) == 0) {
          list = realloc(list, strlen(list) + strlen(Config[i].key) - len + 2);
          if (*list != '\0')
            strcat(list, "|");
          strcat(list, Config[i].key + len);
      }
    }

    free(key);
    return list;
}


static char *cfg_lookup(const char *section, const char *key)
{
    int len;
    char *buffer;
    ENTRY *entry;

    /* calculate key length */
    len = strlen(key) + 1;
    if (section != NULL)
      len += strlen(section) + 1;

    /* allocate buffer  */
    buffer = malloc(len);
    *buffer = '\0';

    /* prepare section:key */
    if (section != NULL && *section != '\0') {
      strcpy(buffer, section);
      strcat(buffer, ".");
    }
    strcat(buffer, key);

    /* search entry */
    entry = bsearch(buffer, Config, nConfig, sizeof(ENTRY), c_lookup);

    /* free buffer again */
    free(buffer);

    if (entry != NULL)
      return entry->val;

    return NULL;
}


char *cfg_get_raw(const char *section, const char *key, const char *defval)
{
    char *val = cfg_lookup(section, key);

    if (val != NULL)
      return val;
    return (char *) defval;
}


char *cfg_get(const char *section, const char *key, const char *defval)
{
    char *expression;
    char *retval;
    void *tree = NULL;
    RESULT result = { 0, 0, 0, NULL };

    expression = cfg_lookup(section, key);

    if (expression != NULL) {
      if (*expression == '\0')
          return "";
      if (Compile(expression, &tree) == 0 && Eval(tree, &result) == 0) {
          retval = strdup(R2S(&result));
          DelTree(tree);
          DelResult(&result);
          return (retval);
      }
      DelTree(tree);
      DelResult(&result);
    }
    if (defval)
      return strdup(defval);
    return NULL;
}


int cfg_number(const char *section, const char *key, const int defval, const int min, const int max, int *value)
{
    char *expression;
    void *tree = NULL;
    RESULT result = { 0, 0, 0, NULL };

    /* start with default value */
    /* in case of an (uncatched) error, you have the */
    /* default value set, which may be handy... */
    *value = defval;

    expression = cfg_get_raw(section, key, NULL);
    if (expression == NULL || *expression == '\0') {
      return 0;
    }

    if (Compile(expression, &tree) != 0) {
      DelTree(tree);
      return -1;
    }
    if (Eval(tree, &result) != 0) {
      DelTree(tree);
      DelResult(&result);
      return -1;
    }
    *value = R2N(&result);
    DelTree(tree);
    DelResult(&result);

    if (*value < min) {
      error("bad '%s' value '%d' in %s, minimum is %d", key, *value, cfg_source(), min);
      *value = min;
      return -1;
    }

    if (max > min && max != -1 && *value > max) {
      error("bad '%s' value '%d' in %s, maximum is %d", key, *value, cfg_source(), max);
      *value = max;
      return -1;
    }

    return 1;
}


static int cfg_check_source(const char *file)
{
    /* as passwords and commands are stored in the config file,
     * we will check that:
     * - file is a normal file (or /dev/null)
     * - file owner is owner of program
     * - file is not accessible by group
     * - file is not accessible by other
     */

    struct stat stbuf;
    uid_t uid, gid;
    int error;

    uid = geteuid();
    gid = getegid();

    if (stat(file, &stbuf) == -1) {
      error("stat(%s) failed: %s", file, strerror(errno));
      return -1;
    }
    if (S_ISCHR(stbuf.st_mode) && strcmp(file, "/dev/null") == 0)
      return 0;

    error = 0;
    if (!S_ISREG(stbuf.st_mode)) {
      error("security error: '%s' is not a regular file", file);
      error = -1;
    }
    if (stbuf.st_uid != uid || stbuf.st_gid != gid) {
      error("security error: owner and/or group of '%s' don't match", file);
      error = -1;
    }
    if (stbuf.st_mode & S_IRWXG || stbuf.st_mode & S_IRWXO) {
      error("security error: group or other have access to '%s'", file);
      error = -1;
    }
    return error;
}


static int cfg_read(const char *file)
{
    FILE *stream;
    char buffer[256];
    char section[256];
    char *line, *key, *val, *end;
    int section_open, section_close;
    int error, lineno;

    stream = fopen(file, "r");
    if (stream == NULL) {
      error("open(%s) failed: %s", file, strerror(errno));
      return -1;
    }

    /* start with empty section */
    strcpy(section, "");

    error = 0;
    lineno = 0;
    while ((line = fgets(buffer, 256, stream)) != NULL) {

      /* increment line number */
      lineno++;

      /* skip empty lines */
      if (*(line = strip(line, 1)) == '\0')
          continue;

      /* reset section flags */
      section_open = 0;
      section_close = 0;

      /* key is first word */
      key = line;

      /* search first blank between key and value */
      for (val = line; *val; val++) {
          if (isblank(*val)) {
            *val++ = '\0';
            break;
          }
      }

      /* strip value */
      val = strip(val, 1);

      /* search end of value */
      if (*val)
          for (end = val; *(end + 1); end++);
      else
          end = val;

      /* if last char is '{', a section has been opened */
      if (*end == '{') {
          section_open = 1;
          *end = '\0';
          val = strip(val, 0);
      }

      /* provess "value" in double-quotes */
      if (*val == '"' && *end == '"') {
          *end = '\0';
          val++;
      }

      /* if key is '}', a section has been closed */
      if (strcmp(key, "}") == 0) {
          section_close = 1;
          *key = '\0';
      }

      /* sanity check: '}' should be the only char in a line */
      if (section_close && (section_open || *val != '\0')) {
          error("error in config file '%s' line %d: garbage after '}'", file, lineno);
          error = 1;
          break;
      }

      /* check key for valid chars */
      if (!validchars(key)) {
          error("error in config file '%s' line %d: key '%s' is invalid", file, lineno, key);
          error = 1;
          break;
      }

      /* on section-open, check value for valid chars */
      if (section_open && !validchars(val)) {
          error("error in config file '%s' line %d: section '%s' is invalid", file, lineno, val);
          error = 1;
          break;
      }

      /* on section-open, append new section name */
      if (section_open) {
          /* is the section[] array big enough? */
          if (strlen(section) + strlen(key) + 3 > sizeof(section)) {
            error("error in config file '%s' line %d: section buffer overflow", file, lineno);
            error = 1;
            break;
          }
          if (*section != '\0')
            strcat(section, ".");
          strcat(section, key);
          if (*val != '\0') {
            strcat(section, ":");
            strcat(section, val);
          }
          continue;
      }

      /* on section-close, remove last section name */
      if (section_close) {
          /* sanity check: section already empty? */
          if (*section == '\0') {
            error("error in config file '%s' line %d: unmatched closing brace", file, lineno);
            error = 1;
            break;
          }

          end = strrchr(section, '.');
          if (end == NULL)
            *section = '\0';
          else
            *end = '\0';
          continue;
      }

      /* finally: add key */
      cfg_add(section, key, val, 0);

    }

    /* sanity check: are the braces balanced? */
    if (!error && *section != '\0') {
      error("error in config file '%s' line %d: unbalanced braces", file, lineno);
      error = 1;
    }

    fclose(stream);

    return -error;
}


int cfg_init(const char *file)
{
    if (cfg_check_source(file) == -1) {
      return -1;
    }

    if (cfg_read(file) < 0)
      return -1;

    if (Config_File)
      free(Config_File);
    Config_File = strdup(file);

    return 0;
}


char *cfg_source(void)
{
    if (Config_File)
      return Config_File;
    else
      return "";
}


int cfg_exit(void)
{
    int i;
    for (i = 0; i < nConfig; i++) {
      if (Config[i].key)
          free(Config[i].key);
      if (Config[i].val)
          free(Config[i].val);
    }

    if (Config) {
      free(Config);
      Config = NULL;
    }

    if (Config_File) {
      free(Config_File);
      Config_File = NULL;
    }

    return 0;
}

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