release/src/router/mysql/mysys/default_modify.c

   1 /* Copyright (c) 2005-2007 MySQL AB
   2
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; version 2 of the License.
   6
   7    This program is distributed in the hope that it will be useful,
   8    but WITHOUT ANY WARRANTY; without even the implied warranty of
   9    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10    GNU General Public License for more details.
  11
  12    You should have received a copy of the GNU General Public License
  13    along with this program; if not, write to the Free Software
  14    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  15
  16 #include "my_global.h"
  17 #include "mysys_priv.h"
  18 #include "m_string.h"
  19 #include <my_dir.h>
  20
  21 #define BUFF_SIZE 1024
  22 #define RESERVE 1024                   /* Extend buffer with this extent */
  23
  24 #ifdef __WIN__
  25 #define NEWLINE "\r\n"
  26 #define NEWLINE_LEN 2
  27 #else
  28 #define NEWLINE "\n"
  29 #define NEWLINE_LEN 1
  30 #endif
  31
  32 static char *add_option(char *dst, const char *option_value,
  33                         const char *option, int remove_option);
  34
  35
  36 /*
  37   Add/remove option to the option file section.
  38
  39   SYNOPSYS
  40     modify_defaults_file()
  41     file_location     The location of configuration file to edit
  42     option            The name of the option to look for (can be NULL)
  43     option value      The value of the option we would like to set (can be NULL)
  44     section_name      The name of the section (must be NOT NULL)
  45     remove_option     This defines what we want to remove:
  46                         - MY_REMOVE_NONE -- nothing to remove;
  47                         - MY_REMOVE_OPTION -- remove the specified option;
  48                         - MY_REMOVE_SECTION -- remove the specified section;
  49   IMPLEMENTATION
  50     We open the option file first, then read the file line-by-line,
  51     looking for the section we need. At the same time we put these lines
  52     into a buffer. Then we look for the option within this section and
  53     change/remove it. In the end we get a buffer with modified version of the
  54     file. Then we write it to the file, truncate it if needed and close it.
  55     Note that there is a small time gap, when the file is incomplete,
  56     and this theoretically might introduce a problem.
  57
  58   RETURN
  59     0 - ok
  60     1 - some error has occured. Probably due to the lack of resourses
  61     2 - cannot open the file
  62 */
  63
  64 int modify_defaults_file(const char *file_location, const char *option,
  65                          const char *option_value,
  66                          const char *section_name, int remove_option)
  67 {
  68   FILE *cnf_file;
  69   MY_STAT file_stat;
  70   char linebuff[BUFF_SIZE], *src_ptr, *dst_ptr, *file_buffer;
  71   size_t opt_len= 0, optval_len= 0, sect_len, new_opt_len, reserve_extended;
  72   uint nr_newlines= 0, buffer_size;
  73   my_bool in_section= FALSE, opt_applied= 0;
  74   int reserve_occupied= 0;
  75   DBUG_ENTER("modify_defaults_file");
  76
  77   if (!(cnf_file= my_fopen(file_location, O_RDWR | O_BINARY, MYF(0))))
  78     DBUG_RETURN(2);
  79
  80   /* my_fstat doesn't use the flag parameter */
  81   if (my_fstat(fileno(cnf_file), &file_stat, MYF(0)))
  82     goto malloc_err;
  83
  84   if (option && option_value)
  85   {
  86     opt_len= strlen(option);
  87     optval_len= strlen(option_value);
  88   }
  89
  90   new_opt_len= opt_len + 1 + optval_len + NEWLINE_LEN;
  91
  92   /* calculate the size of the buffer we need */
  93   reserve_extended= (opt_len +
  94                      1 +                        /* For '=' char */
  95                      optval_len +               /* Option value len */
  96                      NEWLINE_LEN +              /* Space for newline */
  97                      RESERVE);                  /* Some additional space */
  98
  99   buffer_size= (file_stat.st_size +
 100                 1);                             /* The ending zero */
 101
 102   /*
 103     Reserve space to read the contents of the file and some more
 104     for the option we want to add.
 105   */
 106   if (!(file_buffer= (char*) my_malloc(buffer_size + reserve_extended,
 107                                        MYF(MY_WME))))
 108     goto malloc_err;
 109
 110   sect_len= strlen(section_name);
 111
 112   for (dst_ptr= file_buffer; fgets(linebuff, BUFF_SIZE, cnf_file); )
 113   {
 114     /* Skip over whitespaces */
 115     for (src_ptr= linebuff; my_isspace(&my_charset_latin1, *src_ptr);
 116          src_ptr++)
 117     {}
 118
 119     if (!*src_ptr) /* Empty line */
 120     {
 121       nr_newlines++;
 122       continue;
 123     }
 124
 125     /* correct the option (if requested) */
 126     if (option && in_section && !strncmp(src_ptr, option, opt_len) &&
 127         (*(src_ptr + opt_len) == '=' ||
 128          my_isspace(&my_charset_latin1, *(src_ptr + opt_len)) ||
 129          *(src_ptr + opt_len) == '\0'))
 130     {
 131       char *old_src_ptr= src_ptr;
 132       src_ptr= strend(src_ptr+ opt_len);        /* Find the end of the line */
 133
 134       /* could be negative */
 135       reserve_occupied+= (int) new_opt_len - (int) (src_ptr - old_src_ptr);
 136       if (reserve_occupied >= (int) reserve_extended)
 137       {
 138         reserve_extended= (uint) reserve_occupied + RESERVE;
 139         if (!(file_buffer= (char*) my_realloc(file_buffer, buffer_size +
 140                                               reserve_extended,
 141                                               MYF(MY_WME|MY_FREE_ON_ERROR))))
 142           goto malloc_err;
 143       }
 144       opt_applied= 1;
 145       dst_ptr= add_option(dst_ptr, option_value, option, remove_option);
 146     }
 147     else
 148     {
 149       /*
 150         If we are going to the new group and have an option to apply, do
 151         it now. If we are removing a single option or the whole section
 152         this will only trigger opt_applied flag.
 153       */
 154
 155       if (in_section && !opt_applied && *src_ptr == '[')
 156       {
 157         dst_ptr= add_option(dst_ptr, option_value, option, remove_option);
 158         opt_applied= 1;           /* set the flag to do write() later */
 159         reserve_occupied= new_opt_len+ opt_len + 1 + NEWLINE_LEN;
 160       }
 161
 162       for (; nr_newlines; nr_newlines--)
 163         dst_ptr= strmov(dst_ptr, NEWLINE);
 164
 165       /* Skip the section if MY_REMOVE_SECTION was given */
 166       if (!in_section || remove_option != MY_REMOVE_SECTION)
 167         dst_ptr= strmov(dst_ptr, linebuff);
 168     }
 169     /* Look for a section */
 170     if (*src_ptr == '[')
 171     {
 172       /* Copy the line to the buffer */
 173       if (!strncmp(++src_ptr, section_name, sect_len))
 174       {
 175         src_ptr+= sect_len;
 176         /* Skip over whitespaces. They are allowed after section name */
 177         for (; my_isspace(&my_charset_latin1, *src_ptr); src_ptr++)
 178         {}
 179
 180         if (*src_ptr != ']')
 181         {
 182           in_section= FALSE;
 183           continue; /* Missing closing parenthesis. Assume this was no group */
 184         }
 185
 186         if (remove_option == MY_REMOVE_SECTION)
 187           dst_ptr= dst_ptr - strlen(linebuff);
 188
 189         in_section= TRUE;
 190       }
 191       else
 192         in_section= FALSE; /* mark that this section is of no interest to us */
 193     }
 194   }
 195
 196   /*
 197     File ended. Apply an option or set opt_applied flag (in case of
 198     MY_REMOVE_SECTION) so that the changes are saved. Do not do anything
 199     if we are removing non-existent option.
 200   */
 201
 202   if (!opt_applied && in_section && (remove_option != MY_REMOVE_OPTION))
 203   {
 204     /* New option still remains to apply at the end */
 205     if (!remove_option && *(dst_ptr - 1) != '\n')
 206       dst_ptr= strmov(dst_ptr, NEWLINE);
 207     dst_ptr= add_option(dst_ptr, option_value, option, remove_option);
 208     opt_applied= 1;
 209   }
 210   for (; nr_newlines; nr_newlines--)
 211     dst_ptr= strmov(dst_ptr, NEWLINE);
 212
 213   if (opt_applied)
 214   {
 215     /* Don't write the file if there are no changes to be made */
 216     if (my_chsize(fileno(cnf_file), (my_off_t) (dst_ptr - file_buffer), 0,
 217                   MYF(MY_WME)) ||
 218         my_fseek(cnf_file, 0, MY_SEEK_SET, MYF(0)) ||
 219         my_fwrite(cnf_file, (uchar*) file_buffer, (size_t) (dst_ptr - file_buffer),
 220                   MYF(MY_NABP)))
 221       goto err;
 222   }
 223   if (my_fclose(cnf_file, MYF(MY_WME)))
 224     DBUG_RETURN(1);
 225
 226   my_free(file_buffer, MYF(0));
 227   DBUG_RETURN(0);
 228
 229 err:
 230   my_free(file_buffer, MYF(0));
 231 malloc_err:
 232   my_fclose(cnf_file, MYF(0));
 233   DBUG_RETURN(1); /* out of resources */
 234 }
 235
 236
 237 static char *add_option(char *dst, const char *option_value,
 238                         const char *option, int remove_option)
 239 {
 240   if (!remove_option)
 241   {
 242     dst= strmov(dst, option);
 243     if (*option_value)
 244     {
 245       *dst++= '=';
 246       dst= strmov(dst, option_value);
 247     }
 248     /* add a newline */
 249     dst= strmov(dst, NEWLINE);
 250   }
 251   return dst;
 252 }