[CRIU] [PATCH 3/3] lib: add criu_check() to libcriu

[Pavel Emelyanov]

On 11/22/2013 12:41 PM, Andrew Vagin wrote:
> On Fri, Nov 22, 2013 at 05:20:37AM +0400, Ruslan Kuprieiev wrote:
>>
>> Signed-off-by: Ruslan Kuprieiev <kupruser at gmail.com>
>> ---
>>  lib/criu.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 128 insertions(+)
>>
>> diff --git a/lib/criu.c b/lib/criu.c
>> index 2bd224e..f154a88 100644
>> --- a/lib/criu.c
>> +++ b/lib/criu.c
>> @@ -1,3 +1,131 @@
>>  #include "version.h"
>> +#include <sys/socket.h>
>> +#include <sys/un.h>
>> +#include <limits.h>
>> +#include <stdio.h>
>> +#include <unistd.h>
>> +#include <stdlib.h>
>> +
>> +#include "rpc.pb-c.h"
>> +
>> +#define MAX_MSG_SIZE 1024
>> +#define CR_DEFAULT_SERVICE_ADDRESS "/var/run/criu_service.socket"
>>  
>>  const char *criu_lib_version = CRIU_VERSION;
>> +
>> +static char *service_address = CR_DEFAULT_SERVICE_ADDRESS;
>> +
>> +void criu_set_service_address(char *path)
>> +{
>> +	if (path)
>> +		service_address = path;
>> +	else
>> +		service_address = CR_DEFAULT_SERVICE_ADDRESS;
>> +}
>> +
>> +static CriuResp *recv_resp(int socket_fd)
>> +{
>> +	unsigned char buf[MAX_MSG_SIZE];
>> +	int len;
>> +	CriuResp *msg = 0;
>> +
>> +	len = read(socket_fd, buf, MAX_MSG_SIZE);
>> +	if (len == -1) {
>> +		perror("Can't read response");
>> +		return NULL;
>> +	}
>> +
>> +	msg = criu_resp__unpack(NULL, len, buf);
>> +	if (!msg) {
>> +		perror("Failed unpacking response");
>> +		return NULL;
>> +	}
>> +
>> +	return msg;
>> +}
>> +
>> +static int send_req(int socket_fd, CriuReq *req)
>> +{
>> +	unsigned char buf[MAX_MSG_SIZE];
>> +	int len;
>> +
>> +	len = criu_req__get_packed_size(req);
>> +
>> +	if (criu_req__pack(req, buf) != len) {
>> +		perror("Failed packing request");
>> +		return -1;
>> +	}
>> +
>> +	if (write(socket_fd, buf, len)  == -1) {
>> +		perror("Can't send request");
>> +		return -1;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int criu_connect(void)
>> +{
>> +	int fd, ret;
>> +	struct sockaddr_un addr;
>> +	socklen_t addr_len;
>> +
>> +	fd = socket(AF_LOCAL, SOCK_SEQPACKET, 0);
>> +	if (fd < 0) {
>> +		perror("Can't create socket");
>> +		return -1;
>> +	}
>> +
>> +	memset(&addr, 0, sizeof(addr));
>> +	addr.sun_family = AF_LOCAL;
>> +
>> +	strcpy(addr.sun_path, service_address);
>> +
>> +	addr_len = strlen(addr.sun_path) + sizeof(addr.sun_family);
>> +
>> +	ret = connect(fd, (struct sockaddr *) &addr, addr_len);
>> +	if (ret < 0) {
>> +		perror("Can't connect to socket");
>> +		close(fd);
>> +	}
>> +
>> +	return fd;
>> +}
>> +
>> +int criu_check(void)
> 
> I'm not sure that a stateless approach is good here. First of all you
> will need to connect and disconnect each time.

Why is it bad?

> Can we create interface similar with dynamic linking loader (man
> dlopen).
> 
> struct criu_handle *h;
> 
> h = criu_open()
> criu_check(h);
> ...
> criu_smth(h);
> ...
> criu_close(h);

We can. What are the benefits of state-full approach?