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race-condition safe implementation of test_if_data_home_dir()

don't realpath() twice
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vuvova committed Feb 20, 2017
1 parent 93cb024 commit 955f2f036d6252b90e2bffcec521dd4a7db0a30a
Showing with 34 additions and 15 deletions.
  1. +1 −1 sql/mysqld.cc
  2. +31 −13 sql/sql_parse.cc
  3. +2 −1 sql/sql_parse.h
@@ -7267,7 +7267,7 @@ static int mysql_init_variables(void)
mysql_home[0]= pidfile_name[0]= log_error_file[0]= 0;
#if defined(HAVE_REALPATH) && !defined(HAVE_valgrind) && !defined(HAVE_BROKEN_REALPATH)
/* We can only test for sub paths if my_symlink.c is using realpath */
mysys_test_invalid_symlink= test_if_data_home_dir;
mysys_test_invalid_symlink= path_starts_from_data_home_dir;
#endif
opt_log= opt_slow_log= 0;
opt_bin_log= opt_bin_log_used= 0;
@@ -7697,26 +7697,20 @@ bool check_ident_length(LEX_STRING *ident)
Check if path does not contain mysql data home directory
SYNOPSIS
test_if_data_home_dir()
dir directory
path_starts_from_data_home_dir()
dir directory, with all symlinks resolved
RETURN VALUES
0 ok
1 error ; Given path contains data directory
*/
C_MODE_START
extern "C" {

int test_if_data_home_dir(const char *dir)
int path_starts_from_data_home_dir(const char *path)
{
char path[FN_REFLEN];
int dir_len;
DBUG_ENTER("test_if_data_home_dir");
int dir_len= strlen(path);
DBUG_ENTER("path_starts_from_data_home_dir");

if (!dir)
DBUG_RETURN(0);

(void) fn_format(path, dir, "", "", MY_RETURN_REAL_PATH);
dir_len= strlen(path);
if (mysql_unpacked_real_data_home_len<= dir_len)
{
if (dir_len > mysql_unpacked_real_data_home_len &&
@@ -7744,7 +7738,31 @@ int test_if_data_home_dir(const char *dir)
DBUG_RETURN(0);
}

C_MODE_END
}

/*
Check if path does not contain mysql data home directory
SYNOPSIS
test_if_data_home_dir()
dir directory
RETURN VALUES
0 ok
1 error ; Given path contains data directory
*/

int test_if_data_home_dir(const char *dir)
{
char path[FN_REFLEN];
DBUG_ENTER("test_if_data_home_dir");

if (!dir)
DBUG_RETURN(0);

(void) fn_format(path, dir, "", "", MY_RETURN_REAL_PATH);
DBUG_RETURN(path_starts_from_data_home_dir(path));
}


/**
@@ -33,7 +33,8 @@ enum enum_mysql_completiontype {
COMMIT_RELEASE=-1, COMMIT=0, COMMIT_AND_CHAIN=6
};

extern "C" int test_if_data_home_dir(const char *dir);
extern "C" int path_starts_from_data_home_dir(const char *dir);
int test_if_data_home_dir(const char *dir);

bool multi_update_precheck(THD *thd, TABLE_LIST *tables);
bool multi_delete_precheck(THD *thd, TABLE_LIST *tables);

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