mirror of https://github.com/mpv-player/mpv
84 lines
2.0 KiB
C
84 lines
2.0 KiB
C
/*
|
|
* shmem.c - Shared memory allocation
|
|
*
|
|
* based on mpg123's xfermem.c by
|
|
* Oliver Fromme <oliver.fromme@heim3.tu-clausthal.de>
|
|
* Sun Apr 6 02:26:26 MET DST 1997
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <errno.h>
|
|
#include <sys/types.h>
|
|
#include <sys/time.h>
|
|
#include <sys/uio.h>
|
|
#include <sys/mman.h>
|
|
#include <sys/socket.h>
|
|
#include <fcntl.h>
|
|
|
|
#ifdef AIX
|
|
#include <sys/select.h>
|
|
#endif
|
|
|
|
#include <sys/ipc.h>
|
|
#include <sys/shm.h>
|
|
|
|
extern int errno;
|
|
|
|
#if defined(MAP_ANONYMOUS) && !defined(MAP_ANON)
|
|
#define MAP_ANON MAP_ANONYMOUS
|
|
#endif
|
|
|
|
static int shmem_type=0;
|
|
|
|
void* shmem_alloc(int size){
|
|
void* p;
|
|
int devzero;
|
|
while(1){
|
|
switch(shmem_type){
|
|
case 0: // ========= MAP_ANON|MAP_SHARED ==========
|
|
p=mmap(0,size,PROT_READ|PROT_WRITE,MAP_ANON|MAP_SHARED,-1,0);
|
|
if(p==MAP_FAILED) break; // failed
|
|
// printf("shmem: %d bytes allocated using mmap anon (%X)\n",size,p);
|
|
return p;
|
|
case 1: // ========= MAP_SHARED + /dev/zero ==========
|
|
if ((devzero = open("/dev/zero", O_RDWR, 0)) == -1) break;
|
|
p=mmap(0,size,PROT_READ|PROT_WRITE,MAP_SHARED,devzero,0);
|
|
if(p==MAP_FAILED) break; // failed
|
|
// printf("shmem: %d bytes allocated using mmap /dev/zero (%X)\n",size,p);
|
|
return p;
|
|
case 2: { // ========= shmget() ==========
|
|
struct shmid_ds shmemds;
|
|
int shmemid;
|
|
if ((shmemid = shmget(IPC_PRIVATE, size, IPC_CREAT | 0600)) == -1) break;
|
|
if ((int)(p = shmat(shmemid, 0, 0)) == -1){
|
|
perror ("shmat()");
|
|
shmctl (shmemid, IPC_RMID, &shmemds);
|
|
break;
|
|
}
|
|
if (shmctl(shmemid, IPC_RMID, &shmemds) == -1) {
|
|
perror ("shmctl()");
|
|
if (shmdt(p) == -1) perror ("shmdt()");
|
|
break;
|
|
}
|
|
// printf("shmem: %d bytes allocated using shmget() & shmat() (%X)\n",size,p);
|
|
return p;
|
|
}
|
|
default:
|
|
printf("FATAL: Cannot alloate %d bytes shared memory :(\n",size);
|
|
return NULL;
|
|
}
|
|
++shmem_type;
|
|
}
|
|
}
|
|
|
|
void shmem_free(void* p){
|
|
switch(shmem_type){
|
|
case 2:
|
|
if (shmdt(p) == -1) perror ("shmdt()");
|
|
break;
|
|
}
|
|
}
|