PHP BLT #1

1. 2015/11/24 PHP BLT
do_aki
Writing
php extensions
in golang

2. @do_aki
＠do_aki
http://do-aki.net/

4. https://speakerdeck.com/naruse/writing-extension-libraries-in-go

5. In case of PHP……?

6. golang buildmode
• -buildmode=c-shared
• build the main package (main
function is dummy)
• export symbol by “//export”
https://golang.org/s/execmodes

7. cgo(call C function)
package main
/*
#include <stdlib.h>
*/
import “C”
func Random() int {
return int(C.random())
}

8. cgo(export)
package main
import “C”
//export go_func
func go_func() int {
return 1
}

9. php extension loading process
1. load shared library (.so / .dll)
2. fetch “get_module” or
“_get_module” symbol
3. call fetched function and get
pointer to zend_module_entry
structure
4. register module using the
zend_module_entry
ref:php_load_extension in ext/standard/dl.c

10. export get_module
package main
/*
#include “php.h”
*/
import “C”
var gophp_module_entry C.zend_module_entry
//export get_module
func get_module() *C.zend_module_entry {
gophp_module_entry.name = C.Cstring(“gophp”)
gophp_module_entry.functions = …
// fill member in gophp_module_entry
return gophp_module_entry;
}

11. export get_module
package main
/*
#include “php.h”
*/
import “C”
var gophp_module_entry C.zend_module_entry
//export get_module
func get_module() *C.zend_module_entry {
gophp_module_entry.name = C.Cstring(“gophp”)
gophp_module_entry.functions = …
// fill member in gophp_module_entry
return gophp_module_entry;
}

12. constraints of c in go
function
-like
macro
Access
union
member

13. separate export function and
function definition
• err: multiple definition of ` xxx'
• write definition in non_export.go
(not include //export)
• write declarations in export.go
(include //export)
• go build non_export.go export.go

14. github.com/do-aki/gophp_sample

15. but,but,but
• segmentation fault in shutdown
process sometimes……
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffee4c2700 (LWP 8943)]
0x00007ffff04d6821 in ?? ()
(gdb) backtrace
#0 0x00007ffff04d6821 in ?? ()
#1 0x00007ffff04a6213 in ?? ()
#2 0x000000c82002ce90 in ?? ()
#3 0x0000000000000000 in ?? ()
in go runtime? Umm…

16. fin.