[MDEV-14978] Client programs to use $MYSQL_HOST consistently

Only `mysql` client program was using $MYSQL_HOST as the default host.
Add the same feature in most other client programs.

All new code of the whole pull request, including one or several files that are
either new files or modified ones, are contributed under the BSD-new license. I
am contributing on behalf of my employer Amazon Web Services, Inc.

client/mysqladmin.cc

@@ -245,7 +245,7 @@ static const char *load_default_groups[]=
 my_bool
 get_one_option(const struct my_option *opt, const char *argument, const char *filename)
 {
-
+ 
  /* Track when protocol is set via CLI to not force overrides */
  static my_bool ignore_protocol_override = FALSE;
 
@@ -373,6 +373,11 @@ int main(int argc,char *argv[])
  int error= 0, temp_argc;
  MYSQL mysql;
  char **commands, **save_argv, **temp_argv;
+ char *tmp;
+
+ tmp= (char *) getenv("MYSQL_HOST");
+ if (tmp && !host)
+ host= my_strdup(PSI_NOT_INSTRUMENTED, tmp, MYF(MY_WME));
 
  MY_INIT(argv[0]);
  sf_leaking_memory=1; /* don't report memory leaks on early exits */

client/mysqlbinlog.cc

@@ -2286,6 +2286,11 @@ get_one_option(const struct my_option *opt, const char *argument, const char *fi
 static int parse_args(int *argc, char*** argv)
 {
  int ho_error;
+ char *tmp;
+
+ tmp= (char *) getenv("MYSQL_HOST");
+ if (tmp && !host)
+ host= my_strdup(PSI_NOT_INSTRUMENTED, tmp, MYF(MY_WME));
 
  if ((ho_error=handle_options(argc, argv, my_options, get_one_option)))
  {

client/mysqlcheck.c

@@ -434,9 +434,14 @@ get_one_option(const struct my_option *opt,
 
 static int get_options(int *argc, char ***argv)
 {
+ char *tmp;
  int ho_error;
  DBUG_ENTER("get_options");
 
+ tmp= (char *) getenv("MYSQL_HOST");
+ if (tmp && !current_host)
+ current_host= my_strdup(PSI_NOT_INSTRUMENTED, tmp, MYF(MY_WME));
+
  if (*argc == 1)
  {
  usage();

client/mysqldump.c

@@ -1121,9 +1121,15 @@ get_one_option(const struct my_option *opt,
 
 static int get_options(int *argc, char ***argv)
 {
+ char *tmp;
  int ho_error;
+
  MYSQL_PARAMETERS *mysql_params= mysql_get_parameters();
 
+ tmp= (char *) getenv("MYSQL_HOST");
+ if (tmp && !current_host)
+ current_host= my_strdup(PSI_NOT_INSTRUMENTED, tmp, MYF(MY_WME));
+
  opt_max_allowed_packet= *mysql_params->p_max_allowed_packet;
  opt_net_buffer_length= *mysql_params->p_net_buffer_length;
 

client/mysqlimport.c

@@ -324,8 +324,13 @@ get_one_option(const struct my_option *opt, const char *argument,
 
 static int get_options(int *argc, char ***argv)
 {
+ char *tmp;
  int ho_error;
 
+ tmp= (char *) getenv("MYSQL_HOST");
+ if (tmp && !current_host)
+ current_host= my_strdup(PSI_NOT_INSTRUMENTED, tmp, MYF(MY_WME));
+
  if ((ho_error=handle_options(argc, argv, my_long_options, get_one_option)))
  exit(ho_error);
  if (debug_info_flag)

client/mysqlshow.c

@@ -410,8 +410,13 @@ get_one_option(const struct my_option *opt, const char *argument,
 static void
 get_options(int *argc,char ***argv)
 {
+ char *tmp;
  int ho_error;
 
+ tmp= (char *) getenv("MYSQL_HOST");
+ if (tmp && !host)
+ host= my_strdup(PSI_NOT_INSTRUMENTED, tmp, MYF(MY_WME));
+
  if ((ho_error=handle_options(argc, argv, my_long_options, get_one_option)))
  exit(ho_error);
 

client/mysqlslap.c

@@ -1228,10 +1228,15 @@ build_select_string(my_bool key)
 static int
 get_options(int *argc,char ***argv)
 {
+ char *tmp;
  int ho_error;
  char *tmp_string;
  MY_STAT sbuf; /* Stat information for the data file */
 
+ tmp= (char *) getenv("MYSQL_HOST");
+ if (tmp && !host)
+ host= my_strdup(PSI_NOT_INSTRUMENTED, tmp, MYF(MY_WME));
+
  DBUG_ENTER("get_options");
  if ((ho_error= handle_options(argc, argv, my_long_options, get_one_option)))
  exit(ho_error);

mysql-test/suite/client/client-env-variable.result

@@ -0,0 +1,24 @@
+CREATE DATABASE env_variable;
+USE env_variable;
+CREATE TABLE pet (name VARCHAR(20));
+show binary logs;
+Log_name File_size
+master-bin.000001 635
++----+------+-----------+--------------+---------+------+----------+------------------+----------+
+| Id | User | Host | db | Command | Time | State | Info | Progress |
++----+------+-----------+--------------+---------+------+----------+------------------+----------+
+| 5 | root | localhost | env_variable | Sleep | 0 | | | 0.000 |
+| 6 | root | localhost | | Query | 0 | starting | show processlist | 0.000 |
++----+------+-----------+--------------+---------+------+----------+------------------+----------+
+env_variable.pet OK
+env_variable.pet: Records: 2 Deleted: 0 Skipped: 0 Warnings: 0
+Database: env_variable
++--------+
+| Tables |
++--------+
+| pet |
++--------+
+****************
+# Setting MYSQL_HOST environment variable 
+Done
+DROP DATABASE env_variable;

mysql-test/suite/client/client-env-variable.test

@@ -0,0 +1,65 @@
+-- source include/have_log_bin.inc
+
+# Set up environment varibles for client programs
+--let MYSQLADMIN = $MYSQL_BINDIR/client//mariadb-admin
+--let MYSQLBINLOG = $MYSQL_BINDIR/client//mariadb-binlog
+--let MYSQLCHECK = $MYSQL_BINDIR/client//mariadb-check
+--let MYSQLDUMP = $MYSQL_BINDIR/client//mariadb-dump
+--let MYSQLIMPORT = $MYSQL_BINDIR/client//mariadb-import
+--let MYSQLSHOW = $MYSQL_BINDIR/client//mariadb-show
+--let MYSQLSLAP = $MYSQL_BINDIR/client//mariadb-slap
+
+# Creating a database for the client programs
+CREATE DATABASE env_variable;
+USE env_variable;
+CREATE TABLE pet (name VARCHAR(20));
+show binary logs;
+
+# Creating a data file for mysqlimport
+write_file $MYSQL_TMP_DIR/pet;
+buster 
+bob
+EOF
+
+# Options for client program
+--let $options = --user=root --port=16000 --socket=$MYSQL_TMP_DIR/mysqld.1.sock
+
+# Run client programs using the default `localhost`
+--exec $MYSQLADMIN $options processlist
+--exec $MYSQLBINLOG $options --read-from-remote-server master-bin.000001 > /dev/null 2>&1
+--exec $MYSQLCHECK $options -c --databases env_variable
+--exec $MYSQLDUMP $options env_variable > $MYSQL_TMP_DIR/tmp.sql
+--exec $MYSQLIMPORT $options env_variable --local $MYSQL_TMP_DIR/pet
+--exec $MYSQLSHOW $options env_variable
+--exec $MYSQLSLAP $options > /dev/null 2>&1
+
+--echo ****************
+--echo # Setting MYSQL_HOST environment variable 
+--let MYSQL_HOST=nonexistent-sever
+
+# Now run the same command as before with MYSQL_HOST environment variable
+# Client programs are expected to fail since the server does not exist
+# Some client program fails with error 1 and some fails wtih error 2
+
+--error 1
+--exec $MYSQLADMIN $options processlist
+
+--error 1
+--exec $MYSQLBINLOG $options --read-from-remote-server master-bin.000001 > /dev/null 2>&1
+
+--error 2
+--exec $MYSQLCHECK $options -c --databases env_variable
+
+--error 2
+--exec $MYSQLDUMP $options env_variable > $MYSQL_TMP_DIR/tmp.sql
+
+--error 1
+--exec $MYSQLIMPORT $options env_variable $MYSQL_TMP_DIR/pet
+
+--error 1
+--exec $MYSQLSLAP $options > /dev/null 2>&1
+
+# Clean up
+--echo Done
+DROP DATABASE env_variable;
+