shm.cpp
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/*
* shm.cpp
*
* Created on: 15 gru 2018
* Author: mariuszo
*/
#include <sys/mman.h>
#include <sys/stat.h>
#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include "shm.h"
/*
#include <memory.h>
#include <stdlib.h>
*/
std::map<std::string, shm::shmInUse> shm::inProcessMapping;
std::recursive_mutex shm::inProcessMappingLock;
shmRing::shmRing(const std::string& name, int flags, mode_t mode):shm(name, flags, mode), m_placeholder(NULL), m_placeholderSize(0), m_data2(NULL) {
}
bool shmRing::alloc(const size_t& size) {
int fd=-1;
int prot=PROT_READ;
const size_t pageSize=(size_t)sysconf(_SC_PAGESIZE);
inProcessMappingLock.lock();
if (inProcessMapping.find(m_name)!=inProcessMapping.end()){
perror("ERROR: SHM object already created");
inProcessMappingLock.unlock();
return false;
}
if (size%pageSize != 0)
m_size=((size)/pageSize+1)*pageSize;
m_placeholderSize=2*m_size+2*pageSize;
shm_unlink(m_name.c_str());
while (1) {
fd=shm_open(("/"+m_name).c_str(), m_flags | O_CREAT | O_EXCL, m_mode);
if (fd == -1){
perror(strerror(errno));
break;
}
if (ftruncate(fd, m_size) == -1){
perror(strerror(errno));
break;
}
if (m_flags|O_RDWR)
prot|=PROT_WRITE;
m_placeholder=mmap(NULL,m_placeholderSize, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (m_placeholder == MAP_FAILED){
perror(strerror(errno));
break;
}
m_data=mmap((uint8_t*)m_placeholder+pageSize, m_size, prot, MAP_SHARED|MAP_FIXED, fd, 0);
if (m_data == MAP_FAILED){
perror(strerror(errno));
break;
}
m_data2=mmap((uint8_t*)m_data+m_size,m_size, prot, MAP_SHARED|MAP_FIXED, fd, 0);
if (m_data2 == MAP_FAILED){
perror(strerror(errno));
break;
}
close(fd);
memset(m_data2,0,m_size);
inProcessMapping[m_name].obj=this;
++inProcessMapping[m_name].count;
inProcessMapping[m_name].unlink=true;
inProcessMappingLock.unlock();
return true;
}
if (fd !=-1) {
close(fd);
fd=-1;
shm_unlink(("/"+m_name).c_str());
}
if (m_data2)
munmap(m_data2,m_size);
if (m_data)
munmap(m_data,m_size);
if (m_placeholder)
munmap(m_placeholder,m_placeholderSize);
m_size=0;
m_data=NULL;
m_data2=NULL;
m_placeholder=NULL;
inProcessMappingLock.unlock();
return false;
}
bool shmRing::attach() {
if (m_size!=0 || m_data!=NULL) {
perror("ERROR: SHM object already initialized");
return false;
}
inProcessMappingLock.lock();
if (inProcessMapping.find(m_name)!=inProcessMapping.end()) {
m_size = ((shmRing*)(inProcessMapping[m_name].obj))->m_size;
m_data = ((shmRing*)(inProcessMapping[m_name].obj))->m_data;
m_data2 = ((shmRing*)(inProcessMapping[m_name].obj))->m_data2;
++inProcessMapping[m_name].count;
inProcessMappingLock.unlock();
return true;
}
int fd = -1;
int prot = PROT_READ;
const size_t pageSize = (size_t)sysconf(_SC_PAGESIZE);
struct stat buf;
while (1) {
fd = shm_open(("/"+m_name).c_str(), m_flags, 0);
if (fd==-1) {
perror(strerror(errno));
break;
}
if (fstat(fd, &buf)==-1) {
perror(strerror(errno));
break;
}
if (m_flags|O_RDWR)
prot |= PROT_WRITE;
m_size = buf.st_size;
m_placeholderSize=2*m_size+2*pageSize;
m_placeholder = mmap(NULL, m_placeholderSize, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (m_placeholder==MAP_FAILED) {
perror(strerror(errno));
break;
}
m_data = mmap((uint8_t*)m_placeholder+pageSize, m_size, prot, MAP_SHARED|MAP_FIXED, fd, 0);
if (m_data==MAP_FAILED) {
perror(strerror(errno));
break;
}
m_data2 = mmap((uint8_t*)m_data+m_size, m_size, prot, MAP_SHARED|MAP_FIXED, fd, 0);
if (m_data2==MAP_FAILED) {
perror(strerror(errno));
break;
}
close(fd);
fd = -1;
inProcessMapping[m_name].obj = this;
++inProcessMapping[m_name].count;
inProcessMapping[m_name].unlink = false;
inProcessMappingLock.unlock();
return true;
}
if (m_data2)
munmap(m_data2, m_size);
if (m_data)
munmap(m_data, m_size);
if (m_placeholder)
munmap(m_placeholder, m_placeholderSize);
m_size = 0;
m_data = NULL;
m_data2 = NULL;
m_placeholder = NULL;
inProcessMappingLock.unlock();
return false;
}
bool shmRing::mlock() {
return (::mlock(m_data, m_size*2) != -1);
}
void shmRing::munlock() {
if (::munlock(m_data, m_size*2) == -1)
throw; //TODO
}
void shmRing::free() {
inProcessMappingLock.lock();
if (m_data)
munmap(m_data, m_size);
if (m_data)
munmap(m_data,m_size);
if (m_placeholder)
munmap(m_placeholder,m_placeholderSize);
m_size=0;
m_data=NULL;
m_data2=NULL;
m_placeholder=NULL;
inProcessMappingLock.unlock();
}
shm::shm(const std::string& name, int flags, mode_t mode):m_name(name), m_flags(flags), m_mode(mode), m_data(NULL), m_size(0) {
if (m_name.length()>NAME_MAX-16)
throw std::logic_error("SHM name too long");
}
void shm::free() {
inProcessMappingLock.lock();
if ((--inProcessMapping[m_name].count)==0) {
if (m_data)
munmap(m_data, m_size);
if (m_name!="" && inProcessMapping[m_name].unlink)
shm_unlink(m_name.c_str());
inProcessMapping.erase(m_name);
}
inProcessMappingLock.unlock();
}
void shm::unlink() {
shm_unlink(m_name.c_str());
}
bool shm::alloc(const size_t& size) {
int fd=-1;
int prot=PROT_READ;
inProcessMappingLock.lock();
if (inProcessMapping.find(m_name)!=inProcessMapping.end()){
perror("ERROR: SHM object already created");
inProcessMappingLock.unlock();
return false;
}
m_size=size;
shm_unlink(m_name.c_str());
while (1) {
fd=shm_open(("/"+m_name).c_str(), m_flags | O_CREAT | O_EXCL, m_mode);
if (fd == -1)
break;
if (ftruncate(fd, size) == -1)
break;
if (m_flags|O_RDWR)
prot|=PROT_WRITE;
m_data=mmap(NULL,m_size, prot, MAP_SHARED, fd, 0);
if (m_data == MAP_FAILED)
break;
close(fd);
memset(m_data,0,m_size);
inProcessMapping[m_name].obj=this;
++inProcessMapping[m_name].count;
inProcessMapping[m_name].unlink=true;
inProcessMappingLock.unlock();
return true;
}
if (fd !=-1) {
close(fd);
fd=-1;
shm_unlink(("/"+m_name).c_str());
}
m_size=0;
m_data=NULL;
inProcessMappingLock.unlock();
return false;
}
bool shm::attach(){
if (m_size != 0 || m_data != NULL) {
perror("ERROR: SHM object already initialized");
return false;
}
inProcessMappingLock.lock();
if (inProcessMapping.find(m_name)==inProcessMapping.end()){
int fd=-1;
int prot=PROT_READ;
struct stat buf;
fd=shm_open(("/"+m_name).c_str(), m_flags, 0);
if (fd == -1) {
perror(strerror(errno));
inProcessMappingLock.unlock();
return false;;
}
if (fstat(fd, &buf) == -1) {
close(fd);
fd=-1;
perror(strerror(errno));
inProcessMappingLock.unlock();
return false;;
}
if (m_flags|O_RDWR)
prot|=PROT_WRITE;
m_size=buf.st_size;
m_data=mmap(NULL,m_size, prot, MAP_SHARED, fd, 0);
if (m_data == MAP_FAILED){
m_data=NULL;
close(fd);
fd=-1;
perror(strerror(errno));
inProcessMappingLock.unlock();
return false;;
}
close(fd);
fd=-1;
inProcessMapping[m_name].obj=this;
++inProcessMapping[m_name].count;
inProcessMapping[m_name].unlink=false;
} else {
m_size=inProcessMapping[m_name].obj->m_size;
m_data=inProcessMapping[m_name].obj->m_data;
++inProcessMapping[m_name].count;
}
inProcessMappingLock.unlock();
return true;
}
bool shm::mlock() {
return (::mlock(m_data, m_size) != -1);
}
void shm::munlock() {
if (::munlock(m_data, m_size) == -1)
throw; //TODO
}