/**
* mds — A micro-display server
* Copyright © 2014, 2015, 2016, 2017 Mattias Andrée (maandree@kth.se)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "comm.h"
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#define min(a, b) ((a) < (b) ? (a) : (b))
/**
* Initialise a connection descriptor
*
* @param this The connection descriptor
* @return Zero on success, -1 on error, `ernno`
* will have been set accordingly on error
*
* @throws EAGAIN See pthread_mutex_init(3)
* @throws ENOMEM See pthread_mutex_init(3)
* @throws EPERM See pthread_mutex_init(3)
*/
int libmds_connection_initialise(libmds_connection_t *restrict this)
{
this->socket_fd = -1;
this->message_id = UINT32_MAX;
this->client_id = NULL;
this->mutex_initialised = 0;
errno = pthread_mutex_init(&(this->mutex), NULL);
if (errno)
return -1;
this->mutex_initialised = 1;
return 0;
}
/**
* Allocate and initialise a connection descriptor
*
* @return The connection descriptor, `NULL` on error,
* `errno` will have been set accordingly on error
*
* @throws ENOMEM Out of memory, Possibly, the process hit the RLIMIT_AS or
* RLIMIT_DATA limit described in getrlimit(2).
* @throws EAGAIN See pthread_mutex_init(3)
* @throws EPERM See pthread_mutex_init(3)
*/
libmds_connection_t *
libmds_connection_create(void)
{
libmds_connection_t *rc = malloc(sizeof(libmds_connection_t));
if (!rc)
return NULL;
return libmds_connection_initialise(rc) ? NULL : rc;
}
/**
* Release all resources held by a connection descriptor
*
* @param this The connection descriptor, may be `NULL`
*/
void
libmds_connection_destroy(libmds_connection_t *restrict this)
{
if (!this)
return;
if (this->socket_fd >= 0) {
close(this->socket_fd); /* TODO Linux closes the filedescriptor on EINTR, but POSIX does not require that. */
this->socket_fd = -1;
}
free(this->client_id);
this->client_id = NULL;
if (this->mutex_initialised) {
this->mutex_initialised = 0;
pthread_mutex_destroy(&(this->mutex)); /* Can return EBUSY. */
}
}
/**
* Release all resources held by a connection descriptor,
* and release the allocation of the connection descriptor
*
* @param this The connection descriptor, may be `NULL`
*/
void
libmds_connection_free(libmds_connection_t *restrict this)
{
libmds_connection_destroy(this);
free(this);
}
/**
* Connect to the display server
*
* @param this The connection descriptor, must not be `NULL`
* @param display Pointer to `NULL` to select display be looking at
* the environment. Pointer to a string with the
* address (formatted as the environment variable
* MDS_DISPLAY) if manually specified. The pointer
* itself must not be `NULL`; it will be updated
* with the address if it points to NULL.
* @return Zero on success, -1 on error. On error, `display`
* will point to `NULL` if MDS_DISPLAY is not defiend,
* otherwise, `errno` will have been set to describe
* the error.
*
* @throws EFAULT If the display server's address is not properly
* formatted, or specifies an unsupported protocol,
* `libmds_parse_display_address` can be used to
* figure out what is wrong.
* @throws ENAMETOOLONG The filename of the target socket is too long
* @throws Any error specified for socket(2)
* @throws Any error specified for connect(2), except EINTR
*/
int
libmds_connection_establish(libmds_connection_t *restrict this, const char **restrict display)
{
libmds_display_address_t addr;
int saved_errno;
addr.address = NULL;
if (!*display)
*display = getenv("MDS_DISPLAY");
if (!*display || !strchr(*display, ':'))
goto efault;
if (libmds_parse_display_address(*display, &addr) < 0)
goto fail;
if (libmds_connection_establish_address(this, &addr) < 0)
goto fail;
free(addr.address);
return 0;
efault:
free(addr.address);
return errno = EFAULT, -1;
fail:
saved_errno = errno;
free(addr.address);
return errno = saved_errno, -1;
}
/**
* Connect to the display server
*
* @param this The connection descriptor, must not be `NULL`
* @param address The address to connect to, must not be `NULL`,
* and must be the result of a successful call to
* `libmds_parse_display_address`
* @return Zero on success, -1 on error. On error, `display`
* will point to `NULL` if MDS_DISPLAY is not defiend,
* otherwise, `errno` will have been set to describe
* the error.
*
* @throws EFAULT `libmds_display_address_t` contains unset parameters.
* @throws Any error specified for socket(2)
* @throws Any error specified for connect(2), except EINTR
*/
int
libmds_connection_establish_address(libmds_connection_t *restrict this,
const libmds_display_address_t *restrict address)
{
if (address->domain < 0) goto efault;
if (address->type < 0) goto efault;
if (address->protocol < 0) goto efault;
if (!address->address) goto efault;
this->socket_fd = socket(address->domain, address->type, address->protocol);
if (this->socket_fd < 0)
goto fail;
while (connect(this->socket_fd, address->address, address->address_len))
if (errno != EINTR)
goto fail;
return 0;
efault:
errno = EFAULT;
fail:
return -1;
}
/**
* Wrapper for `libmds_connection_send_unlocked` that locks
* the mutex of the connection
*
* @param this The connection descriptor, must not be `NULL`
* @param message The message to send, must not be `NULL`
* @param length The length of the message, should be positive
* @return The number of sent bytes. Less than `length` on error,
* `ernno` will have been set accordingly on error
*
* @throws EACCES See send(2)
* @throws EWOULDBLOCK See send(2), only if the socket has been modified to nonblocking
* @throws EBADF See send(2)
* @throws ECONNRESET If connection was lost
* @throws EDESTADDRREQ See send(2)
* @throws EFAULT See send(2)
* @throws EINVAL See send(2)
* @throws ENOBUFS See send(2)
* @throws ENOMEM See send(2)
* @throws ENOTCONN See send(2)
* @throws ENOTSOCK See send(2)
* @throws See pthread_mutex_lock(3)
*/
size_t
libmds_connection_send(libmds_connection_t *restrict this, const char *restrict message, size_t length)
{
int saved_errno;
size_t r;
if (libmds_connection_lock(this))
return 0;
r = libmds_connection_send_unlocked(this, message, length, 1);
saved_errno = errno;
(void) libmds_connection_unlock(this);
return errno = saved_errno, r;
}
/**
* Send a message to the display server, without locking the
* mutex of the conncetion
*
* @param this The connection descriptor, must not be `NULL`
* @param message The message to send, must not be `NULL`
* @param length The length of the message, should be positive
* @param continue_on_interrupt Whether to continue sending if interrupted by a signal
* @return The number of sent bytes. Less than `length` on error,
* `ernno` will have been set accordingly on error
*
* @throws EACCES See send(2)
* @throws EWOULDBLOCK See send(2), only if the socket has been modified to nonblocking
* @throws EBADF See send(2)
* @throws ECONNRESET If connection was lost
* @throws EDESTADDRREQ See send(2)
* @throws EFAULT See send(2)
* @throws EINTR If interrupted by a signal, only if `continue_on_interrupt' is zero
* @throws EINVAL See send(2)
* @throws ENOBUFS See send(2)
* @throws ENOMEM See send(2)
* @throws ENOTCONN See send(2)
* @throws ENOTSOCK See send(2)
*/
size_t
libmds_connection_send_unlocked(libmds_connection_t *restrict this, const char *restrict message,
size_t length, int continue_on_interrupt)
{
size_t block_size = length;
size_t sent = 0;
ssize_t just_sent;
errno = 0;
while (length > 0) {
if ((just_sent = send(this->socket_fd, message + sent, min(block_size, length), MSG_NOSIGNAL)) < 0) {
if (errno == EPIPE)
errno = ECONNRESET;
if (errno == EMSGSIZE) {
block_size >>= 1;
if (!block_size)
return sent;
} else if (errno == EINTR && continue_on_interrupt) {
continue;
} else {
return sent;
}
} else {
sent += (size_t)just_sent;
length -= (size_t)just_sent;
}
}
return sent;
}
