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May 19, 2020 01:54
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CGo and Shared Memory
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package main | |
// #include <stdlib.h> | |
// #include <string.h> | |
// #include <sys/shm.h> | |
// #include <sys/types.h> | |
// #include <stddef.h> | |
// int my_shm_open(char* filename, int open_flag){ | |
// int shm_id; | |
// key_t key; | |
// key = ftok(filename, 0x03); | |
// if(key == -1){ | |
// return -1; | |
// } | |
// if(open_flag) | |
// shm_id = shmget(key, 4096, IPC_CREAT|IPC_EXCL|0600); | |
// else | |
// shm_id = shmget(key, 0, 0); | |
// if(shm_id == -1){ | |
// return -1; | |
// } | |
// return shm_id; | |
// } | |
// int my_shm_update(int shm_id, char* content){ | |
// char* addr; | |
// addr = (char*)shmat(shm_id, NULL, 0); | |
// if(addr == (char*)-1){ | |
// return -1; | |
// } | |
// if(strlen(content) > 4095) | |
// return -1; | |
// strcpy(addr, content); | |
// shmdt(addr); | |
// return 0; | |
// } | |
// int my_shm_close(int shm_id){ | |
// shmctl(shm_id, IPC_RMID, NULL); | |
// return 0; | |
// } | |
// char* my_shm_read(char* filename){ | |
// int shm_id; | |
// char* addr; | |
// char* s; | |
// shm_id = my_shm_open(filename, 0); | |
// if(shm_id == -1) | |
// return NULL; | |
// addr = (char*)shmat(shm_id, NULL, 0); | |
// if(addr == (char*)-1){ | |
// return NULL; | |
// } | |
// s = (char*)malloc(strlen(addr) + 1); | |
// strcpy(s, addr); | |
// shmdt(addr); | |
// return s; | |
// } | |
import "C" | |
import "unsafe" | |
import "fmt" | |
func read(filename string) string { | |
f := C.CString(filename) | |
defer C.free(unsafe.Pointer(f)) | |
s := C.my_shm_read(f) | |
defer C.free(unsafe.Pointer(s)) | |
return C.GoString(s) | |
} | |
func main() { | |
fmt.Println(read("/tmp/shitballs")) | |
} |
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package main | |
// #include <stdlib.h> | |
// #include <string.h> | |
// #include <sys/shm.h> | |
// #include <sys/types.h> | |
// #include <stddef.h> | |
// int my_shm_open(char* filename, int open_flag){ | |
// int shm_id; | |
// key_t key; | |
// key = ftok(filename, 0x03); | |
// if(key == -1){ | |
// return -1; | |
// } | |
// if(open_flag) | |
// shm_id = shmget(key, 4096, IPC_CREAT|IPC_EXCL|0600); | |
// else | |
// shm_id = shmget(key, 0, 0); | |
// if(shm_id == -1){ | |
// return -1; | |
// } | |
// return shm_id; | |
// } | |
// int my_shm_update(int shm_id, char* content){ | |
// char* addr; | |
// addr = (char*)shmat(shm_id, NULL, 0); | |
// if(addr == (char*)-1){ | |
// return -1; | |
// } | |
// if(strlen(content) > 4095) | |
// return -1; | |
// strcpy(addr, content); | |
// shmdt(addr); | |
// return 0; | |
// } | |
// int my_shm_close(int shm_id){ | |
// shmctl(shm_id, IPC_RMID, NULL); | |
// return 0; | |
// } | |
// char* my_shm_read(char* filename){ | |
// int shm_id; | |
// char* addr; | |
// char* s; | |
// shm_id = my_shm_open(filename, 0); | |
// if(shm_id == -1) | |
// return NULL; | |
// addr = (char*)shmat(shm_id, NULL, 0); | |
// if(addr == (char*)-1){ | |
// return NULL; | |
// } | |
// s = (char*)malloc(strlen(addr) + 1); | |
// strcpy(s, addr); | |
// shmdt(addr); | |
// return s; | |
// } | |
import "C" | |
import "unsafe" | |
import ( | |
"log" | |
"time" | |
) | |
type errorString struct { | |
s string | |
} | |
func (e *errorString) Error() string { | |
return e.s | |
} | |
func open(file string) (int, error) { | |
f := C.CString(file) | |
defer C.free(unsafe.Pointer(f)) | |
r := int(C.my_shm_open(f, C.int(1))) | |
if r == -1 { | |
return 0, &errorString{"error"} | |
} | |
return r, nil | |
} | |
func update(shm_id int, content string) error { | |
c := C.CString(content) | |
defer C.free(unsafe.Pointer(c)) | |
r := int(C.my_shm_update(C.int(shm_id), c)) | |
if r == -1 { | |
return &errorString{"update error"} | |
} | |
return nil | |
} | |
func close(shm_id int) error { | |
C.my_shm_close(C.int(shm_id)) | |
return nil | |
} | |
func main() { | |
id, err := open("/tmp/shitballs") | |
if err != nil { | |
log.Fatalln("Aww", err) | |
} | |
defer close(id) | |
err = update(id, "hello world") | |
if err != nil { | |
log.Fatal(err) | |
} | |
time.Sleep(1e9 * 100) | |
} |
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