Bug#20145 perror segfault when call it with error nr

  - Add test case(execute perror)
  - Check if strerror has returned NULL and set msg to "Unknown Error" in that case
  - Thanks to Steven Xie for pointing out how to fix. 


extra/perror.c:
  strerror might return NULL on Solaris 2.8
mysql-test/mysql-test-run.pl:
  Add possibility to execute perror from test case
mysql-test/r/have_perror.require:
  New BitKeeper file ``mysql-test/r/have_perror.require''
mysql-test/r/perror.result:
  New BitKeeper file ``mysql-test/r/perror.result''
mysql-test/t/perror.test:
  New BitKeeper file ``mysql-test/t/perror.test''

extra/perror.c

@@ -218,8 +218,11 @@ int main(int argc,char *argv[])
       On some system, like NETWARE, strerror(unknown_error) returns a
       string 'Unknown Error'.  To avoid printing it we try to find the
       error string by asking for an impossible big error message.
+
+      On Solaris 2.8 it might return NULL
     */
-    msg= strerror(10000);
+    if ((msg= strerror(10000)) == NULL)
+      msg= "Unknown Error";
 
     /*
       Allocate a buffer for unknown_error since strerror always returns

mysql-test/mysql-test-run.pl

@@ -187,6 +187,7 @@ our $exe_mysqltest;
 our $exe_slave_mysqld;
 our $exe_im;
 our $exe_my_print_defaults;
+our $exe_perror;
 our $lib_udf_example;
 our $exe_libtool;
 
@@ -1048,6 +1049,8 @@ sub executable_setup () {
       $path_charsetsdir=   mtr_path_exists("$glob_basedir/share/charsets");
       $exe_my_print_defaults=
 	mtr_exe_exists("$path_client_bindir/my_print_defaults");
+      $exe_perror=
+	mtr_exe_exists("$path_client_bindir/perror");
     }
     else
     {
@@ -1060,6 +1063,8 @@ sub executable_setup () {
         "$glob_basedir/server-tools/instance-manager/mysqlmanager");
       $exe_my_print_defaults=
 	mtr_exe_exists("$glob_basedir/extra/my_print_defaults");
+      $exe_perror=
+	mtr_exe_exists("$glob_basedir/extra/perror");
     }
 
     if ( $glob_use_embedded_server )
@@ -1107,6 +1112,8 @@ sub executable_setup () {
 			"$glob_basedir/scripts/mysql_fix_privilege_tables");
     $exe_my_print_defaults=
       mtr_exe_exists("$path_client_bindir/my_print_defaults");
+    $exe_perror=
+      mtr_exe_exists("$path_client_bindir/perror");
 
     $path_language=      mtr_path_exists("$glob_basedir/share/mysql/english/",
                                          "$glob_basedir/share/english/");
@@ -3103,6 +3110,7 @@ sub run_mysqltest ($) {
   $ENV{'MYSQL_MY_PRINT_DEFAULTS'}=  $exe_my_print_defaults;
   $ENV{'UDF_EXAMPLE_LIB'}=
     ($lib_udf_example ? basename($lib_udf_example) : "");
+  $ENV{'MY_PERROR'}=                 $exe_perror;
 
   $ENV{'NDB_MGM'}=                  $exe_ndb_mgm;
   $ENV{'NDB_BACKUP_DIR'}=           $path_ndb_data_dir;

mysql-test/r/have_perror.require

+have_perror
+1

mysql-test/r/perror.result

+MySQL error code 150: Foreign key constraint is incorrectly formed
+Is a named type file
+Didn't find key on read or update

mysql-test/t/perror.test

+#
+# Check if the variable MY_PERROR is set
+#
+--require r/have_perror.require
+disable_query_log;
+eval select LENGTH("$MY_PERROR") > 0 as "have_perror";
+enable_query_log;
+
+--exec $MY_PERROR 150
+--exec $MY_PERROR --silent 120
+