Description:
------------
The dbf included in the testscript below causes a SIGSEGV (null pointer de-reference) in php_dbase_get_record. 

On cursory debugging it appears that EOF is encountered while reading the file which leaves db_format as NULL.

It's possible that the dbase is invalid, however it opens fine in various applications, for example dbview.



Test script:
---------------
// write temp. dbase file
$data = base64_decode('A3cBEAEAAACBAB0AAAAAAAAAAAAAAAAAAAAAAAAAAABTQ0hMQUdOUgAAAE4AAAAACgAAAAAAAAAAAAAAAAAAAFRFSUxTQ0hMQUcAQwAAAAACAAAAAAAAAAAAAAAAAAAARkxJSwAAAAAAAABDAAAAABAAAAAAAAAAAAAAAAAAAAANICAgICAgMTIzNDVhIERFTldMSTA1NDYxMzI3Nzca');
$tmpFile = tmpfile();
fwrite($tmpFile, $data);
fflush($tmpFile);
$path = stream_get_meta_data($tmpFile)['uri'];

$db = dbase_open($path, 0);

$n = dbase_numrecords($db);
for ($index=1; $index<=$n; $index++) {
    // crash here
    $record = dbase_get_record_with_names($db, $index);
    print_r($record);
}
dbase_close($db);

Actual result:
--------------
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff561cb4c in php_dbase_get_record (return_value=0x7ffff5414ec0, assoc=1, execute_data=<optimized out>)
    at /tmp/pecl-database-dbase/dbase.c:456
456			if (*cur_f->db_format) {
(gdb) bt
#0  0x00007ffff561cb4c in php_dbase_get_record (return_value=0x7ffff5414ec0, assoc=1, execute_data=<optimized out>)
    at /tmp/pecl-database-dbase/dbase.c:456
#1  0x00007ffff563607d in xdebug_execute_internal (current_execute_data=0x7ffff5415020, return_value=0x7ffff5414ec0) at ./build-7.4/src/base/base.c:897
#2  0x0000555555883ebb in execute_ex ()
#3  0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff5414cd0) at ./build-7.4/src/base/base.c:779
#4  0x00005555557ee5df in zend_call_function ()
#5  0x0000555555731dff in ?? ()
#6  0x00007ffff563607d in xdebug_execute_internal (current_execute_data=0x7ffff5414c60, return_value=0x7ffff5414c50) at ./build-7.4/src/base/base.c:897
#7  0x0000555555883ebb in execute_ex ()
#8  0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff5414980) at ./build-7.4/src/base/base.c:779
#9  0x0000555555883e08 in execute_ex ()
#10 0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff54148f0) at ./build-7.4/src/base/base.c:779
#11 0x0000555555883e08 in execute_ex ()
#12 0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff5414840) at ./build-7.4/src/base/base.c:779
#13 0x0000555555883e08 in execute_ex ()
#14 0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff5414770) at ./build-7.4/src/base/base.c:779
#15 0x0000555555883e08 in execute_ex ()
#16 0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff54145c0) at ./build-7.4/src/base/base.c:779
#17 0x0000555555883e08 in execute_ex ()
#18 0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff54141b0) at ./build-7.4/src/base/base.c:779
#19 0x0000555555883e08 in execute_ex ()
#20 0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff5413350) at ./build-7.4/src/base/base.c:779
#21 0x0000555555883c8e in execute_ex ()
#22 0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff54131f0) at ./build-7.4/src/base/base.c:779
#23 0x0000555555883c8e in execute_ex ()
#24 0x00007ffff56357d2 in xdebug_execute_ex (execute_data=0x7ffff5413020) at ./build-7.4/src/base/base.c:779
#25 0x0000555555886cab in zend_execute ()
#26 0x00005555557fd1fc in zend_execute_scripts ()
#27 0x000055555579c930 in php_execute_script ()
#28 0x0000555555888dea in ?? ()
#29 0x0000555555661ec8 in ?? ()