mariadb/extra/my_print_defaults.c
Davi Arnaut bb036c93b4 Bug#42733: Type-punning warnings when compiling MySQL --
strict aliasing violations.

Essentially, the problem is that large parts of the server were
developed in simpler times (last decades, pre C99 standard) when
strict aliasing and compilers supporting such optimizations were
rare to non-existent. Thus, when compiling the server with a modern
compiler that uses strict aliasing rules to perform optimizations,
there are several places in the code that might trigger undefined
behavior.

As evinced by some recent bugs, GCC does a somewhat good of job
misoptimizing such code, but on the other hand also gives warnings
about suspicious code. One problem is that the warnings aren't
always accurate, yet we can't afford to just shut them off as we
might miss real cases. False-positive cases are aggravated mostly
by casts that are likely to trigger undefined behavior.

The solution is to start a cleanup process focused on fixing and
reducing the amount of strict-aliasing related warnings produced
by GCC and others compilers. A good deal of noise reduction can
be achieved by just removing useless casts that are product of
historical cruft and are likely to trigger undefined behavior if
dereferenced.
2010-06-10 17:16:43 -03:00

205 lines
6.5 KiB
C

/* Copyright (C) 2000 MySQL AB
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; version 2 of the License.
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, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
** print_default.c:
** Print all parameters in a default file that will be given to some program.
**
** Written by Monty
*/
#include <my_global.h>
#include <my_sys.h>
#include <m_string.h>
#include <my_getopt.h>
const char *config_file="my"; /* Default config file */
uint verbose= 0, opt_defaults_file_used= 0;
const char *default_dbug_option="d:t:o,/tmp/my_print_defaults.trace";
static struct my_option my_long_options[] =
{
/*
NB: --config-file is troublesome, because get_defaults_options() doesn't
know about it, but we pretend --config-file is like --defaults-file. In
fact they behave differently: see the comments at the top of
mysys/default.c for how --defaults-file should behave.
This --config-file option behaves as:
- If it has a directory name part (absolute or relative), then only this
file is read; no error is given if the file doesn't exist
- If the file has no directory name part, the standard locations are
searched for a file of this name (and standard filename extensions are
added if the file has no extension)
*/
{"config-file", 'c', "Deprecated, please use --defaults-file instead. "
"Name of config file to read; if no extension is given, default "
"extension (e.g., .ini or .cnf) will be added",
&config_file, &config_file, 0, GET_STR, REQUIRED_ARG,
0, 0, 0, 0, 0, 0},
#ifdef DBUG_OFF
{"debug", '#', "This is a non-debug version. Catch this and exit",
0,0, 0, GET_DISABLED, OPT_ARG, 0, 0, 0, 0, 0, 0},
#else
{"debug", '#', "Output debug log", &default_dbug_option,
&default_dbug_option, 0, GET_STR, OPT_ARG, 0, 0, 0, 0, 0, 0},
#endif
{"defaults-file", 'c', "Like --config-file, except: if first option, "
"then read this file only, do not read global or per-user config "
"files; should be the first option",
&config_file, &config_file, 0, GET_STR, REQUIRED_ARG,
0, 0, 0, 0, 0, 0},
{"defaults-extra-file", 'e',
"Read this file after the global config file and before the config "
"file in the users home directory; should be the first option",
&my_defaults_extra_file, &my_defaults_extra_file, 0,
GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"defaults-group-suffix", 'g',
"In addition to the given groups, read also groups with this suffix",
&my_defaults_group_suffix, &my_defaults_group_suffix,
0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"extra-file", 'e',
"Deprecated. Synonym for --defaults-extra-file.",
&my_defaults_extra_file,
&my_defaults_extra_file, 0, GET_STR,
REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"no-defaults", 'n', "Return an empty string (useful for scripts).",
0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
{"help", '?', "Display this help message and exit.",
0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
{"verbose", 'v', "Increase the output level",
0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
{"version", 'V', "Output version information and exit.",
0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0}
};
#include <help_start.h>
static void usage(my_bool version)
{
printf("%s Ver 1.6 for %s at %s\n",my_progname,SYSTEM_TYPE,
MACHINE_TYPE);
if (version)
return;
puts("This software comes with ABSOLUTELY NO WARRANTY. This is free software,\nand you are welcome to modify and redistribute it under the GPL license\n");
puts("Prints all arguments that is give to some program using the default files");
printf("Usage: %s [OPTIONS] groups\n", my_progname);
my_print_help(my_long_options);
my_print_default_files(config_file);
my_print_variables(my_long_options);
printf("\nExample usage:\n%s --defaults-file=example.cnf client mysql\n", my_progname);
}
#include <help_end.h>
static my_bool
get_one_option(int optid, const struct my_option *opt __attribute__((unused)),
char *argument __attribute__((unused)))
{
switch (optid) {
case 'c':
opt_defaults_file_used= 1;
break;
case 'n':
exit(0);
case 'I':
case '?':
usage(0);
exit(0);
case 'v':
verbose++;
break;
case 'V':
usage(1);
exit(0);
case '#':
DBUG_PUSH(argument ? argument : default_dbug_option);
break;
}
return 0;
}
static int get_options(int *argc,char ***argv)
{
int ho_error;
if ((ho_error=handle_options(argc, argv, my_long_options, get_one_option)))
exit(ho_error);
if (*argc < 1)
{
usage(0);
return 1;
}
return 0;
}
int main(int argc, char **argv)
{
int count, error, args_used;
char **load_default_groups, *tmp_arguments[6];
char **argument, **arguments, **org_argv;
char *defaults, *extra_defaults, *group_suffix;
MY_INIT(argv[0]);
org_argv= argv;
args_used= get_defaults_options(argc, argv, &defaults, &extra_defaults,
&group_suffix);
/* Copy defaults-xxx arguments & program name */
count=args_used+1;
arguments= tmp_arguments;
memcpy((char*) arguments, (char*) org_argv, count * sizeof(*org_argv));
arguments[count]= 0;
/* Check out the args */
if (!(load_default_groups=(char**) my_malloc((argc+1)*sizeof(char*),
MYF(MY_WME))))
exit(1);
if (get_options(&argc,&argv))
exit(1);
memcpy((char*) load_default_groups, (char*) argv, (argc + 1) * sizeof(*argv));
if ((error= load_defaults(config_file, (const char **) load_default_groups,
&count, &arguments)))
{
if (verbose && opt_defaults_file_used)
{
if (error == 1)
fprintf(stderr, "WARNING: Defaults file '%s' not found!\n",
config_file);
/* This error is not available now. For the future */
if (error == 2)
fprintf(stderr, "WARNING: Defaults file '%s' is not a regular file!\n",
config_file);
}
error= 2;
}
for (argument= arguments+1 ; *argument ; argument++)
puts(*argument);
my_free((char*) load_default_groups,MYF(0));
free_defaults(arguments);
exit(error);
}