Fix for MDEV-12965 and MDEV-13100:

If no configuration file and no configuration group was specified, Connector/C ddoesn't read any configurationm files.
By default the follwing groups will be read:
- client
- client-server
- client-mariadb

If no configuration file was specified, Connector/C looks up for configuration files in following locations:
- Windows:
  - System directory
  - Windows directory
  - C:\
  - Directoy from which the application was started
  - MYSQL_HOME environment variable
- Unix platforms
  - DEFAULT_SYSCONFIR (if specified)
  or
  - /etc and /etc/mysql
  - MYSQL_HOME environment variable
  - .my.cnf in home directory

Special case: If NULL or empty string will be passed for MYSQL_READ_DEFAULT_GROUP option Connector/C will read the default groups and the group which matches the application name.

CMakeLists.txt

@@ -139,6 +139,7 @@ SET(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -DDBUG_OFF")
 SET(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -DDBUG_OFF")
 
 IF(CMAKE_COMPILER_IS_GNUCC)
+  ADD_DEFINITIONS(-D_GNU_SOURCE=1)
   INCLUDE(CheckCCompilerFlag)
   SET(GCC_FLAGS -Wunused -Wno-uninitialized  -Wall -Wextra -Wformat-security -Wno-init-self -Wwrite-strings -Wshift-count-overflow -Wdeclaration-after-statement)
   FOREACH(GCC_FLAG ${GCC_FLAGS})
@@ -325,7 +326,7 @@ CONFIGURE_FILE(${CC_SOURCE_DIR}/include/mariadb_version.h.in
 INCLUDE_DIRECTORIES(${CC_BINARY_DIR}/include)
 
 IF(WIN32)
-  SET(SYSTEM_LIBS ws2_32 advapi32 kernel32)
+  SET(SYSTEM_LIBS ws2_32 advapi32 kernel32 shlwapi)
 ELSE()
   SET(SYSTEM_LIBS ${LIBPTHREAD} ${LIBDL} ${LIBM})
   IF(ICONV_EXTERNAL)

include/ma_config.h.in

@@ -278,4 +278,4 @@
 #cmakedefine HAVE_THREADS 1
 #cmakedefine SHAREDIR "@SHAREDIR@"
 #cmakedefine DEFAULT_CHARSET_HOME "@DEFAULT_CHARSET_HOME@"
-
+#cmakedefine DEFAULT_SYSCONFDIR "@DEFAULT_SYSCONFDIR@"

include/ma_global.h

@@ -420,7 +420,7 @@ typedef SOCKET_SIZE_TYPE size_socket;
 #define FN_DEVCHAR	':'
 
 #ifndef FN_LIBCHAR
-#ifdef __EMX__
+#ifdef _WIN32
 #define FN_LIBCHAR	'\\'
 #define FN_ROOTDIR	"\\"
 #else

libmariadb/ma_default.c

@@ -27,71 +27,138 @@
 
 #ifdef _WIN32
 #include <io.h>
+#include "Shlwapi.h"
+
 static const char *ini_exts[]= {"ini", "cnf", 0};
-static const char *ini_dirs[]= {"C:", ".", 0};
-static const char *ini_env_dirs[]= {"WINDOWS", "HOMEPATH", 0};
-#define ENV_HOME_DIR "HOMEPATH"
 #define R_OK 4
 #else
 #include <unistd.h>
 static const char *ini_exts[]= {"cnf", 0};
-static const char *ini_dirs[]= {"/etc", "/etc/mysql", ".", 0};
-static const char *ini_env_dirs[]= {"HOME", "SYSCONFDIR", 0};
-#define ENV_HOME_DIR "HOME"
 #endif
 
-extern my_bool _mariadb_set_conf_option(MYSQL *mysql, const char *config_option, const char *config_value);
+char **configuration_dirs= NULL;
+#define MAX_CONFIG_DIRS 6
 
-char *_mariadb_get_default_file(char *filename, size_t length)
+static int add_cfg_dir(char **cfg_dirs, const char *directory)
 {
-  int dirs; int exts;
+  int i;
+
+  for (i=0; i < MAX_CONFIG_DIRS && cfg_dirs[i]; i++);
+
+  if (i < MAX_CONFIG_DIRS) {
+    cfg_dirs[i]= strdup(directory);
+    return 0;
+  }
+  return 1;
+}
+
+void release_configuration_dirs()
+{
+  if (configuration_dirs)
+  {
+    int i= 0;
+    while (configuration_dirs[i])
+      free(configuration_dirs[i++]);
+    free(configuration_dirs);
+  }
+}
+
+char **get_default_configuration_dirs()
+{
+#ifdef _WIN32
+  char dirname[FN_REFLEN];
+#endif
   char *env;
 
-  for (dirs= 0; ini_dirs[dirs]; dirs++)
+  configuration_dirs= (char **)calloc(1, (MAX_CONFIG_DIRS + 1) * sizeof(char *));
-  {
+  if (!configuration_dirs)
-    for (exts= 0; ini_exts[exts]; exts++)
+    goto end;
-    {
-      snprintf(filename, length,
-               "%s%cmy.%s", ini_dirs[dirs], FN_LIBCHAR, ini_exts[exts]);
-      if (!access(filename, R_OK))
-        return filename;
-    }
-  }
-  for (dirs= 0; ini_env_dirs[dirs]; dirs++)
-  {
-    for (exts= 0; ini_exts[exts]; exts++)
-    {
-      env= getenv(ini_env_dirs[dirs]);
-      snprintf(filename, length,
-               "%s%cmy.%s", env, FN_LIBCHAR, ini_exts[exts]);
-      if (!access(filename, R_OK))
-        return filename;
-    }
-  }
 
-  /* check for .my file in home directoy */
+#ifdef _WIN32
-  env= getenv(ENV_HOME_DIR);
+  /* On Windows operating systems configuration files are stored in
-  for (exts= 0; ini_exts[exts]; exts++)
+     1. System directory
+     2. Windows directory
+     3. C:\
+  */
+  if (!GetSystemDirectory(dirname, FN_REFLEN) ||
+      add_cfg_dir(configuration_dirs, dirname))
+    goto error;
+
+  if (!GetWindowsDirectory(dirname, FN_REFLEN) ||
+      add_cfg_dir(configuration_dirs, dirname))
+    goto error;
+
+  if (add_cfg_dir(configuration_dirs, "C:"))
+    goto error;
+
+  if (GetModuleFileName(NULL, dirname, FN_REFLEN))
   {
-    snprintf(filename, length,
+    PathRemoveFileSpec(dirname);
-             "%s%c.my.%s", env, FN_LIBCHAR, ini_exts[exts]);
+    if (add_cfg_dir(configuration_dirs, dirname))
-    if (!access(filename, R_OK))
+      goto error;
-      return filename;
   }
+#else
+  /* on *nix platforms configuration files are stored in
+     1. SYSCONFDIR (if build happens inside server package, or
+        -DDEFAULT_SYSCONFDIR was specified
+     2. /etc
+     3. /etc/mysql
+  */
+#ifdef DEFAULT_SYSCONFDIR
+  if (add_cfg_dir(configuration_dirs, DEFAULT_SYSCONFDIR))
+    goto error;
+#else
+  if (add_cfg_dir(configuration_dirs, "/etc"))
+    goto error;
+  if (add_cfg_dir(configuration_dirs, "/etc/mysql"))
+    goto error;
+#endif
+#endif
+/* This differs from https://mariadb.com/kb/en/mariadb/configuring-mariadb-with-mycnf/ where MYSQL_HOME is not specified for Windows */
+  if ((env= getenv("MYSQL_HOME")) &&
+      add_cfg_dir(configuration_dirs, env))
+    goto error;
+#ifndef _WIN32
+  if ((env= getenv("HOME")) &&
+      add_cfg_dir(configuration_dirs, env))
+    goto error;
+#endif
+end:
+  return configuration_dirs;
+error:
   return NULL;
 }
 
-my_bool _mariadb_read_options(MYSQL *mysql, const char *config_file,
+extern my_bool _mariadb_set_conf_option(MYSQL *mysql, const char *config_option, const char *config_value);
-    const char *group)
+
+static my_bool is_group(char *ptr, const char **groups)
 {
+  while (*groups)
+  {
+    if (!strcmp(ptr, *groups))
+      return 1;
+    groups++;
+  }
+  return 0;
+}
+
+static my_bool _mariadb_read_options_from_file(MYSQL *mysql,
+                                               const char *config_file,
+                                               const char *group)
+{
+  uint line=0;
+  my_bool read_values= 0, found_group= 0, is_escaped= 0, is_quoted= 0;
   char buff[4096],*ptr,*end,*value, *key= 0, *optval;
   MA_FILE *file= NULL;
-  char *filename;
-  uint line=0;
   my_bool rc= 1;
-  my_bool read_values= 0, found_group= 0, is_escaped= 0, is_quoted= 0;
+  const char *groups[5]= {"client",
+                          "client-server",
+                          "client-mariadb",
+                          group,
+                          NULL};
   my_bool (*set_option)(MYSQL *mysql, const char *config_option, const char *config_value);
 
+
   /* if a plugin registered a hook we will call this hook, otherwise
    * default (_mariadb_set_conf_option) will be called */
   if (mysql->options.extension && mysql->options.extension->set_option)
@@ -99,18 +166,7 @@ my_bool _mariadb_read_options(MYSQL *mysql, const char *config_file,
   else
     set_option= _mariadb_set_conf_option;
 
-  if (config_file)
+  if (!(file = ma_open(config_file, "r", NULL)))
-    filename= strdup(config_file);
-  else
-  {
-    filename= (char *)malloc(FN_REFLEN + 10);
-    if (!_mariadb_get_default_file(filename, FN_REFLEN + 10))
-    {
-      goto err;
-    }
-  }
-
-  if (!(file = ma_open(filename, "r", NULL)))
     goto err;
 
   while (ma_gets(buff,sizeof(buff)-1,file))
@@ -137,7 +193,7 @@ my_bool _mariadb_read_options(MYSQL *mysql, const char *config_file,
       }
       for ( ; isspace(end[-1]) ; end--) ;	/* Remove end space */
       end[0]=0;
-      read_values= test(strcmp(ptr, group) == 0);
+      read_values= is_group(ptr, groups);
       continue;
     }
     if (!found_group)
@@ -224,13 +280,50 @@ my_bool _mariadb_read_options(MYSQL *mysql, const char *config_file,
       key= optval= 0;
     }
   }
+  if (file)
+    ma_close(file);
   rc= 0;
 
 err:
-  free(filename);
-  if (file)
-    ma_close(file);
   return rc;
 }
 
 
+my_bool _mariadb_read_options(MYSQL *mysql,
+                              const char *config_file,
+                              const char *group)
+{
+  int i= 0,
+      exts,
+      errors= 0;
+  char filename[FN_REFLEN + 1];
+  char *env;
+
+  if (config_file)
+    return _mariadb_read_options_from_file(mysql, config_file, group);
+
+  for (i=0; i < MAX_CONFIG_DIRS && configuration_dirs[i]; i++)
+  {
+    for (exts= 0; exts < 2; exts++)
+    {
+      snprintf(filename, FN_REFLEN,
+               "%s%cmy.%s", configuration_dirs[i], FN_LIBCHAR, ini_exts[exts]);
+      if (!access(filename, R_OK))
+        errors+= _mariadb_read_options_from_file(mysql, filename, group);
+    }
+  }
+#ifndef _WIN32
+  /* special case: .my.cnf in Home directory */
+  if ((env= getenv("HOME")))
+  {
+    for (exts= 0; exts < 2; exts++)
+    {
+      snprintf(filename, FN_REFLEN,
+               "%s%c.my.%s", env, FN_LIBCHAR, ini_exts[exts]);
+      if (!access(filename, R_OK))
+        errors+= _mariadb_read_options_from_file(mysql, filename, group);
+    }
+  }
+#endif
+  return errors;
+}

libmariadb/mariadb_lib.c

@@ -68,6 +68,9 @@
 #include <ma_tls.h>
 #endif
 #include <mysql/client_plugin.h>
+#ifdef _WIN32
+#include "Shlwapi.h"
+#endif
 
 #define ASYNC_CONTEXT_DEFAULT_STACK_SIZE (4096*15)
 #define MA_RPL_VERSION_HACK "5.5.5-"
@@ -80,6 +83,8 @@ extern ulong net_buffer_length;  /* net.c */
 static MYSQL_PARAMETERS mariadb_internal_parameters= {&max_allowed_packet, &net_buffer_length, 0};
 static my_bool mysql_client_init=0;
 static void mysql_close_options(MYSQL *mysql);
+extern void release_configuration_dirs();
+extern char **get_default_configuration_dirs();
 extern my_bool  ma_init_done;
 extern my_bool  mysql_ps_subsystem_initialized;
 extern my_bool mysql_handle_local_infile(MYSQL *mysql, const char *filename);
@@ -1309,7 +1314,7 @@ MYSQL *mthd_my_real_connect(MYSQL *mysql, const char *host, const char *user,
   {
     char *hdr = mysql->options.extension->proxy_header;
     size_t len = mysql->options.extension->proxy_header_len;
-    if (ma_pvio_write(pvio, hdr, len) <= 0)
+    if (ma_pvio_write(pvio, (unsigned char *)hdr, len) <= 0)
     {
       ma_pvio_close(pvio);
       goto error;
@@ -2655,6 +2660,26 @@ mysql_optionsv(MYSQL *mysql,enum mysql_option option, ...)
     OPT_SET_VALUE_STR(&mysql->options, my_cnf_file, (char *)arg1);
     break;
   case MYSQL_READ_DEFAULT_GROUP:
+    if (!arg1 || !((char *)arg1)[0])
+    {
+#if defined(__APPLE__) || defined(__FreeBSD__)
+      const char * appname = getprogname();
+#elif defined(_GNU_SOURCE)
+      const char * appname = program_invocation_short_name;
+#elif defined(WIN32)
+      char appname[FN_REFLEN]= "";
+
+      if (GetModuleFileName(NULL, appname, FN_REFLEN))
+      {
+        PathStripPath(appname);
+        PathRemoveExtension(appname);
+      }
+#else
+      const char * appname = "";
+#endif
+      OPT_SET_VALUE_STR(&mysql->options, my_cnf_group, appname);
+      break;
+    }
     OPT_SET_VALUE_STR(&mysql->options, my_cnf_group, (char *)arg1);
     break;
   case MYSQL_SET_CHARSET_DIR:
@@ -3452,6 +3477,7 @@ static void mysql_once_init()
 {
   ma_init();					/* Will init threads */
   init_client_errs();
+  get_default_configuration_dirs();
   if (mysql_client_plugin_init())
   {
 #ifdef _WIN32
@@ -3485,6 +3511,9 @@ static void mysql_once_init()
   }
   if (!mysql_ps_subsystem_initialized)
     mysql_init_ps_subsystem();
+#ifdef HAVE_TLS
+  ma_tls_start(0, 0);
+#endif
   ignore_sigpipe();
   mysql_client_init = 1;
 #ifdef _WIN32
@@ -3522,6 +3551,7 @@ void STDCALL mysql_server_end(void)
   if (!mysql_client_init)
     return;
 
+  release_configuration_dirs();
   mysql_client_plugin_deinit();
 
   list_free(pvio_callback, 0);

unittest/libmariadb/connection.c

@@ -1105,7 +1105,152 @@ static int test_auth256(MYSQL *my)
   return OK;
 }
 
+static int test_mdev13100(MYSQL *my __attribute__((unused)))
+{
+  MYSQL *mysql= mysql_init(NULL);
+  int rc;
+  FILE *fp;
+
+  if (!(fp= fopen("./mdev13100.cnf", "w")))
+    return FAIL;
+
+   /* [client] group only */
+  fprintf(fp, "[client]\n");
+  fprintf(fp, "default-character-set=latin2\n");
+
+  fclose(fp);
+
+  rc= mysql_options(mysql, MYSQL_READ_DEFAULT_FILE, "./mdev13100.cnf");
+  check_mysql_rc(rc, mysql);
+
+  if (!my_test_connect(mysql, hostname, username,
+                             password, schema, port, socketname, 0))
+  {
+    diag("Error: %s", mysql_error(mysql));
+    return FAIL;
+  }
+  FAIL_IF(strcmp("latin2", mysql_character_set_name(mysql)), "Expected charset latin2");
+  mysql_close(mysql);
+
+  /* value from client-mariadb group */
+  mysql= mysql_init(NULL);
+  if (!(fp= fopen("./mdev13100.cnf", "w")))
+    return FAIL;
+
+  fprintf(fp, "[client]\n");
+  fprintf(fp, "default-character-set=latin1\n");
+  fprintf(fp, "[client-server]\n");
+  fprintf(fp, "default-character-set=latin2\n");
+
+  fclose(fp);
+
+  rc= mysql_options(mysql, MYSQL_READ_DEFAULT_FILE, "./mdev13100.cnf");
+  check_mysql_rc(rc, mysql);
+
+  if (!my_test_connect(mysql, hostname, username,
+                             password, schema, port, socketname, 0))
+  {
+    diag("Error: %s", mysql_error(mysql));
+    return FAIL;
+  }
+  FAIL_IF(strcmp("latin2", mysql_character_set_name(mysql)), "Expected charset latin2");
+  mysql_close(mysql);
+
+/* values from client-mariadb group */
+  mysql= mysql_init(NULL);
+
+if (!(fp= fopen("./mdev13100.cnf", "w")))
+    return FAIL;
+
+  fprintf(fp, "[client]\n");
+  fprintf(fp, "default-character-set=latin1\n");
+  fprintf(fp, "[client-server]\n");
+  fprintf(fp, "default-character-set=utf8\n");
+  fprintf(fp, "[client-mariadb]\n");
+  fprintf(fp, "default-character-set=latin2\n");
+
+  fclose(fp);
+
+  rc= mysql_options(mysql, MYSQL_READ_DEFAULT_FILE, "./mdev13100.cnf");
+  check_mysql_rc(rc, mysql);
+
+  if (!my_test_connect(mysql, hostname, username,
+                             password, schema, port, socketname, 0))
+  {
+    diag("Error: %s", mysql_error(mysql));
+    return FAIL;
+  }
+  FAIL_IF(strcmp("latin2", mysql_character_set_name(mysql)), "Expected charset latin2");
+  mysql_close(mysql);
+
+/* values from mdev-13100 group */
+  mysql= mysql_init(NULL);
+  if (!(fp= fopen("./mdev13100.cnf", "w")))
+    return FAIL;
+
+  fprintf(fp, "[client]\n");
+  fprintf(fp, "default-character-set=latin1\n");
+  fprintf(fp, "[client-server]\n");
+  fprintf(fp, "default-character-set=latin1\n");
+  fprintf(fp, "[client-mariadb]\n");
+  fprintf(fp, "default-character-set=utf8\n");
+  fprintf(fp, "[mdev13100]\n");
+  fprintf(fp, "default-character-set=latin2\n");
+
+  fclose(fp);
+
+  rc= mysql_options(mysql, MYSQL_READ_DEFAULT_FILE, "./mdev13100.cnf");
+  check_mysql_rc(rc, mysql);
+  rc= mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "mdev13100");
+  check_mysql_rc(rc, mysql);
+
+  if (!my_test_connect(mysql, hostname, username,
+                             password, schema, port, socketname, 0))
+  {
+    diag("Error: %s", mysql_error(mysql));
+    return FAIL;
+  }
+  FAIL_IF(strcmp("latin2", mysql_character_set_name(mysql)), "Expected charset latin2");
+  mysql_close(mysql);
+
+/* values from [programname] group */
+  mysql= mysql_init(NULL);
+  if (!(fp= fopen("./mdev13100.cnf", "w")))
+    return FAIL;
+
+  fprintf(fp, "[client]\n");
+  fprintf(fp, "default-character-set=latin1\n");
+  fprintf(fp, "[client-server]\n");
+  fprintf(fp, "default-character-set=latin1\n");
+  fprintf(fp, "[client-mariadb]\n");
+  fprintf(fp, "default-character-set=utf8\n");
+  fprintf(fp, "[connection]\n");
+  fprintf(fp, "default-character-set=latin2\n");
+
+  fclose(fp);
+
+  rc= mysql_options(mysql, MYSQL_READ_DEFAULT_FILE, "./mdev13100.cnf");
+  check_mysql_rc(rc, mysql);
+  rc= mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "");
+  check_mysql_rc(rc, mysql);
+
+  if (!my_test_connect(mysql, hostname, username,
+                             password, schema, port, socketname, 0))
+  {
+    diag("Error: %s", mysql_error(mysql));
+    return FAIL;
+  }
+  FAIL_IF(strcmp("latin2", mysql_character_set_name(mysql)), "Expected charset latin2");
+  mysql_close(mysql);
+
+  remove("./mdev13100.cnf");
+
+  return OK; 
+}
+
+
 struct my_tests_st my_tests[] = {
+  {"test_mdev13100", test_mdev13100, TEST_CONNECTION_DEFAULT, 0, NULL,  NULL},
   {"test_auth256", test_auth256, TEST_CONNECTION_DEFAULT, 0, NULL,  NULL},
   {"test_reset", test_reset, TEST_CONNECTION_DEFAULT, 0, NULL,  NULL},
   {"test_unix_socket_close", test_unix_socket_close, TEST_CONNECTION_NONE, 0, NULL,  NULL},

unittest/libmariadb/misc.c

@@ -30,6 +30,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 /*
   Bug#28075 "COM_DEBUG crashes mysqld"
 */
+#ifdef _WIN32
+#define R_OK 4
+#endif
 
 static int test_bug28075(MYSQL *mysql)
 {
@@ -1051,6 +1054,49 @@ static int test_remote2(MYSQL *my)
 }
 #endif
 
+#ifndef _WIN32
+static int test_mdev12965(MYSQL *unused __attribute__((unused)))
+{
+  MYSQL *mysql;
+  my_bool reconnect = 0;
+  FILE *fp= NULL;
+	char *env= getenv("HOME");
+  char cnf_file1[FN_REFLEN + 1],
+       cnf_file2[FN_REFLEN + 1];
+
+  snprintf(cnf_file1, FN_REFLEN, "%s%c.my.cnf", env, FN_LIBCHAR);
+  snprintf(cnf_file2, FN_REFLEN, "%s%cmy.cnf", env, FN_LIBCHAR);
+
+  if (!access(cnf_file1, R_OK) || !access(cnf_file2, R_OK))
+  {
+    diag("Skip this test, it would overwrite configuration files in your home directory");
+    return SKIP;
+  }
+
+  mysql= mysql_init(NULL);
+  fp= fopen(cnf_file1, "w");
+  fprintf(fp, "[test]\ndefault-character-set=latin2");
+  fclose(fp);
+
+  fp= fopen(cnf_file2, "w");
+  fprintf(fp, "[test]\nreconnect=1");
+  fclose(fp);
+
+  mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "test");
+  my_test_connect(mysql, hostname, username, password, schema,
+                         0, socketname, 0), mysql_error(mysql);
+
+  remove(cnf_file1);
+  remove(cnf_file2);
+
+  FAIL_IF(strcmp(mysql_character_set_name(mysql), "latin2"), "expected charset latin2");
+  mysql_get_optionv(mysql, MYSQL_OPT_RECONNECT, &reconnect);
+  FAIL_IF(reconnect != 1, "expected reconnect=1");
+  mysql_close(mysql);
+  return OK;
+}
+#endif
+
 static int test_get_info(MYSQL *mysql)
 {
   size_t sval;
@@ -1267,6 +1313,9 @@ static int test_wl6797(MYSQL *mysql)
 }
 
 struct my_tests_st my_tests[] = {
+#ifndef _WIN32
+  {"test_mdev12965", test_mdev12965, TEST_CONNECTION_DEFAULT, 0, NULL, NULL},
+#endif
   {"test_wl6797", test_wl6797, TEST_CONNECTION_DEFAULT, 0, NULL, NULL},
   {"test_server_status", test_server_status, TEST_CONNECTION_DEFAULT, 0, NULL, NULL},
   {"test_read_timeout", test_read_timeout, TEST_CONNECTION_DEFAULT, 0, NULL, NULL},