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/* Copyright (C) 2005 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#include "my_global.h"
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#include "mysys_priv.h"
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#define BUFF_SIZE 1024
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#define RESERVE 1024 /* Extend buffer with this extent */
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static char *add_option(char *dst, const char *option_value,
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const char *option, int remove_option);
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Add/remove option to the option file section.
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modify_defaults_file()
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file_location The location of configuration file to edit
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option The name of the option to look for (can be NULL)
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option value The value of the option we would like to set (can be NULL)
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section_name The name of the section (must be NOT NULL)
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remove_option This defines what we want to remove:
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- MY_REMOVE_NONE -- nothing to remove;
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- MY_REMOVE_OPTION -- remove the specified option;
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- MY_REMOVE_SECTION -- remove the specified section;
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We open the option file first, then read the file line-by-line,
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looking for the section we need. At the same time we put these lines
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into a buffer. Then we look for the option within this section and
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change/remove it. In the end we get a buffer with modified version of the
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file. Then we write it to the file, truncate it if needed and close it.
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Note that there is a small time gap, when the file is incomplete,
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and this theoretically might introduce a problem.
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1 - some error has occured. Probably due to the lack of resourses
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2 - cannot open the file
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int modify_defaults_file(const char *file_location, const char *option,
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const char *option_value,
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const char *section_name, int remove_option)
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char linebuff[BUFF_SIZE], *src_ptr, *dst_ptr, *file_buffer;
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size_t opt_len= 0, optval_len= 0, sect_len;
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uint nr_newlines= 0, buffer_size;
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my_bool in_section= FALSE, opt_applied= 0;
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uint reserve_extended;
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int reserve_occupied= 0;
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DBUG_ENTER("modify_defaults_file");
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if (!(cnf_file= my_fopen(file_location, O_RDWR | O_BINARY, MYF(0))))
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/* my_fstat doesn't use the flag parameter */
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if (my_fstat(fileno(cnf_file), &file_stat, MYF(0)))
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if (option && option_value)
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opt_len= strlen(option);
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optval_len= strlen(option_value);
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new_opt_len= opt_len + 1 + optval_len + NEWLINE_LEN;
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/* calculate the size of the buffer we need */
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reserve_extended= (opt_len +
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1 + /* For '=' char */
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optval_len + /* Option value len */
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NEWLINE_LEN + /* Space for newline */
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RESERVE); /* Some additional space */
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buffer_size= (file_stat.st_size +
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1); /* The ending zero */
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Reserve space to read the contents of the file and some more
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for the option we want to add.
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if (!(file_buffer= (char*) my_malloc(buffer_size + reserve_extended,
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sect_len= strlen(section_name);
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for (dst_ptr= file_buffer; fgets(linebuff, BUFF_SIZE, cnf_file); )
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/* Skip over whitespaces */
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for (src_ptr= linebuff; my_isspace(&my_charset_latin1, *src_ptr);
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if (!*src_ptr) /* Empty line */
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/* correct the option (if requested) */
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if (option && in_section && !strncmp(src_ptr, option, opt_len) &&
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(*(src_ptr + opt_len) == '=' ||
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my_isspace(&my_charset_latin1, *(src_ptr + opt_len)) ||
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*(src_ptr + opt_len) == '\0'))
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char *old_src_ptr= src_ptr;
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src_ptr= strend(src_ptr+ opt_len); /* Find the end of the line */
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/* could be negative */
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reserve_occupied+= (int) new_opt_len - (int) (src_ptr - old_src_ptr);
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if (reserve_occupied >= (int) reserve_extended)
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reserve_extended= (uint) reserve_occupied + RESERVE;
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if (!(file_buffer= (char*) my_realloc(file_buffer, buffer_size +
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MYF(MY_WME|MY_FREE_ON_ERROR))))
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dst_ptr= add_option(dst_ptr, option_value, option, remove_option);
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If we are going to the new group and have an option to apply, do
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it now. If we are removing a single option or the whole section
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this will only trigger opt_applied flag.
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if (in_section && !opt_applied && *src_ptr == '[')
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dst_ptr= add_option(dst_ptr, option_value, option, remove_option);
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opt_applied= 1; /* set the flag to do write() later */
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reserve_occupied= new_opt_len+ opt_len + 1 + NEWLINE_LEN;
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for (; nr_newlines; nr_newlines--)
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dst_ptr= strmov(dst_ptr, NEWLINE);
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/* Skip the section if MY_REMOVE_SECTION was given */
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if (!in_section || remove_option != MY_REMOVE_SECTION)
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dst_ptr= strmov(dst_ptr, linebuff);
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/* Look for a section */
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/* Copy the line to the buffer */
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if (!strncmp(++src_ptr, section_name, sect_len))
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/* Skip over whitespaces. They are allowed after section name */
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for (; my_isspace(&my_charset_latin1, *src_ptr); src_ptr++)
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continue; /* Missing closing parenthesis. Assume this was no group */
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if (remove_option == MY_REMOVE_SECTION)
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dst_ptr= dst_ptr - strlen(linebuff);
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in_section= FALSE; /* mark that this section is of no interest to us */
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File ended. Apply an option or set opt_applied flag (in case of
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MY_REMOVE_SECTION) so that the changes are saved. Do not do anything
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if we are removing non-existent option.
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if (!opt_applied && in_section && (remove_option != MY_REMOVE_OPTION))
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/* New option still remains to apply at the end */
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if (!remove_option && *(dst_ptr - 1) != '\n')
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dst_ptr= strmov(dst_ptr, NEWLINE);
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dst_ptr= add_option(dst_ptr, option_value, option, remove_option);
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for (; nr_newlines; nr_newlines--)
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dst_ptr= strmov(dst_ptr, NEWLINE);
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/* Don't write the file if there are no changes to be made */
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if (my_chsize(fileno(cnf_file), (my_off_t) (dst_ptr - file_buffer), 0,
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my_fseek(cnf_file, 0, MY_SEEK_SET, MYF(0)) ||
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my_fwrite(cnf_file, (uchar*) file_buffer, (size_t) (dst_ptr - file_buffer),
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if (my_fclose(cnf_file, MYF(MY_WME)))
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my_free(file_buffer, MYF(0));
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my_free(file_buffer, MYF(0));
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my_fclose(cnf_file, MYF(0));
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DBUG_RETURN(1); /* out of resources */
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static char *add_option(char *dst, const char *option_value,
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const char *option, int remove_option)
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dst= strmov(dst, option);
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dst= strmov(dst, option_value);
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dst= strmov(dst, NEWLINE);
added
removed
mysys/default_modify.c
