mariadb/mysys/default_modify.c

/*
  Add/remove option to the option file section.

  SYNOPSYS
    modify_defaults_file()
    file_location     The location of configuration file to edit
    option            option to look for
    option value      The value of the option we would like to set
    section_name      the name of the section
    remove_option     This is true if we want to remove the option.
                      False otherwise.
  IMPLEMENTATION
    We open the option file first, then read the file line-by-line,
    looking for the section we need. At the same time we put these lines
    into a buffer. Then we look for the option within this section and
    change/remove it. In the end we get a buffer with modified version of the
    file. Then we write it to the file, truncate it if needed and close it.

  RETURN
    0 - ok
    1 - some error has occured. Probably due to the lack of resourses
    2 - cannot open the file
*/

#include "my_global.h"
#include "mysys_priv.h"
#include "m_string.h"
#include <my_dir.h>

#define BUFF_SIZE 1024

#ifdef __WIN__
#define NEWLINE "\r\n"
#define NEWLINE_LEN 2
#else
#define NEWLINE "\n"
#define NEWLINE_LEN 1
#endif

int modify_defaults_file(const char *file_location, const char *option,
                         const char *option_value,
                         const char *section_name, int remove_option)
{
  FILE *cnf_file;
  struct stat file_stat;
  char linebuff[BUFF_SIZE], tmp[BUFF_SIZE], *tmp_ptr, *src_ptr, *dst_ptr,
       *file_buffer;
  uint optlen, optval_len, sect_len;
  my_bool in_section= FALSE;
  DBUG_ENTER("modify_defaults_file");

  optlen= strlen(option);
  optval_len= strlen(option_value);
  sect_len= strlen(section_name);

  if (!(cnf_file= my_fopen(file_location, O_RDWR | O_BINARY, MYF(0))))
    DBUG_RETURN(2);

  /* my_fstat doesn't use the flag parameter */
  if (my_fstat(fileno(cnf_file), &file_stat, MYF(0)))
    goto err;

  /*
    Reserve space to read the contents of the file and some more
    for the option we want to add.
  */
  if (!(file_buffer= (char*) my_malloc(sizeof(char)*
				       (file_stat.st_size +
					/* option name len */
					optlen +
					/* reserve space for newline */
					NEWLINE_LEN +
					/* reserve for '=' char */
					1 +           
					/* option value len */
					optval_len), MYF(MY_WME))))
    goto malloc_err;

  for (dst_ptr= file_buffer, tmp_ptr= 0;
       fgets(linebuff, BUFF_SIZE, cnf_file); )
  {
    /* Skip over whitespaces */
    for (src_ptr= linebuff; my_isspace(&my_charset_latin1, *src_ptr);
	 src_ptr++)
    {}

    if (in_section && !strncmp(src_ptr, option, optlen) &&
	(*(src_ptr + optlen) == '=' ||
	 my_isspace(&my_charset_latin1, *(src_ptr + optlen)) ||
	 *(src_ptr + optlen) == '\0'))
    {
      /* The option under modifying was found in this section. Apply new. */
      if (!remove_option)
	dst_ptr= strmov(dst_ptr, tmp);
      tmp_ptr= 0; /* To mark that we have already applied this */
    }
    else
    {
      /* If going to new group and we have option to apply, do it now */
      if (tmp_ptr && *src_ptr == '[')
      {
	dst_ptr= strmov(dst_ptr, tmp);
	tmp_ptr= 0;
      }
      dst_ptr= strmov(dst_ptr, linebuff);
    }
    /* Look for a section */
    if (*src_ptr == '[')
    {
      /* Copy the line to the buffer */
      if (!strncmp(++src_ptr, section_name, sect_len))
      {
	src_ptr+= sect_len;
	/* Skip over whitespaces. They are allowed after section name */
	for (; my_isspace(&my_charset_latin1, *src_ptr); src_ptr++)
	{}

	if (*src_ptr != ']')
	  continue; /* Missing closing parenthesis. Assume this was no group */
	
        in_section= TRUE;
        /* add option */
        if (!remove_option)
        {
          tmp_ptr= strmov(tmp, option);
          if (*option_value)
          {
	    *tmp_ptr++= '=';
            tmp_ptr= strmov(tmp_ptr, option_value);
          }
          /* add a newline */
	  strmov(tmp_ptr, NEWLINE);
        }
      }
      else
        in_section= FALSE; /* mark that this section is of no interest to us */
    }
  }
  /* File ended. New option still remains to apply at the end */
  if (tmp_ptr)
  {
    if (*(dst_ptr - 1) != '\n')
      *dst_ptr++= '\n';
    dst_ptr= strmov(dst_ptr, tmp);    
  }

  if (my_chsize(fileno(cnf_file), (my_off_t) (dst_ptr - file_buffer), 0,
		MYF(MY_WME)) ||
      my_fseek(cnf_file, 0, MY_SEEK_SET, MYF(0)) ||
      my_fwrite(cnf_file, file_buffer, (uint) (dst_ptr - file_buffer),
		MYF(MY_NABP)) ||
      my_fclose(cnf_file, MYF(MY_WME)))
     goto err;

  my_free(file_buffer, MYF(0));

  DBUG_RETURN(0);

err:
  my_free(file_buffer, MYF(0));
malloc_err:
  my_fclose(cnf_file, MYF(0));
  DBUG_RETURN(1); /* out of resources */
}