Writing php extensions in golang
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This document discusses writing PHP extensions in Go using cgo. It explains how to build a Go package as a shared library, export functions so they can be called from C, and register the extension in PHP. Some constraints of calling C from Go like lack of function-like macros and union member access are also noted. The document provides code examples and links to a sample GitHub project for building a PHP extension in Go. It raises that segmentation faults may occasionally occur during PHP shutdown, which could indicate an issue in the Go runtime.
![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…](https://image.slidesharecdn.com/phpblt1-151124105438-lva1-app6892/85/Writing-php-extensions-in-golang-15-320.jpg)
Writing php extensions in golang
- 1. 2015/11/24 PHP BLT do_aki Writing php extensions in golang
- 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
- 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.