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libxcb/src/xcb_conn.c

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/* Copyright (C) 2001-2004 Bart Massey and Jamey Sharp.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the names of the authors or their
* institutions shall not be used in advertising or otherwise to promote the
* sale, use or other dealings in this Software without prior written
* authorization from the authors.
*/
/* Connection management: the core of XCB. */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <assert.h>
#if __STDC_VERSION__ >= 201112L
#include <stdalign.h>
#endif
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include "xcb.h"
#include "xcbint.h"
#if USE_POLL
#include <poll.h>
#elif !defined _WIN32
#include <sys/select.h>
#endif
#ifdef _WIN32
#include "xcb_windefs.h"
#include <io.h>
#else
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#endif /* _WIN32 */
/* SHUT_RDWR is fairly recent and is not available on all platforms */
#if !defined(SHUT_RDWR)
#define SHUT_RDWR 2
#endif
typedef struct {
uint8_t status;
uint8_t pad0[5];
uint16_t length;
} xcb_setup_generic_t;
static const xcb_setup_t xcb_error_setup = {
0, /* status: failed (but we wouldn't have a xcb_setup_t in this case) */
0, /* pad0 */
0, 0, /* protocol version, should be 11.0, but isn't */
0, /* length, invalid value */
0, /* release_number */
0, 0, /* resource_id_{base,mask} */
0, /* motion_buffer_size */
0, /* vendor_len */
0, /* maximum_request_length */
0, /* roots_len */
0, /* pixmap_formats_len */
0, /* image_byte_order */
0, /* bitmap_format_bit_order */
0, /* bitmap_format_scanline_unit */
0, /* bitmap_format_scanline_pad */
0, 0, /* {min,max}_keycode */
{ 0, 0, 0, 0 } /* pad1 */
};
/* Keep this list in sync with is_static_error_conn()! */
static const int xcb_con_error = XCB_CONN_ERROR;
static const int xcb_con_closed_mem_er = XCB_CONN_CLOSED_MEM_INSUFFICIENT;
static const int xcb_con_closed_parse_er = XCB_CONN_CLOSED_PARSE_ERR;
static const int xcb_con_closed_screen_er = XCB_CONN_CLOSED_INVALID_SCREEN;
static int is_static_error_conn(xcb_connection_t *c)
{
return c == (xcb_connection_t *) &xcb_con_error ||
c == (xcb_connection_t *) &xcb_con_closed_mem_er ||
c == (xcb_connection_t *) &xcb_con_closed_parse_er ||
c == (xcb_connection_t *) &xcb_con_closed_screen_er;
}
static int set_fd_flags(const int fd)
{
/* Win32 doesn't have file descriptors and the fcntl function. This block sets the socket in non-blocking mode */
#ifdef _WIN32
u_long iMode = 1; /* non-zero puts it in non-blocking mode, 0 in blocking mode */
int ret = 0;
ret = ioctlsocket(fd, FIONBIO, &iMode);
if(ret != 0)
return 0;
return 1;
#else
int flags = fcntl(fd, F_GETFL, 0);
if(flags == -1)
return 0;
flags |= O_NONBLOCK;
if(fcntl(fd, F_SETFL, flags) == -1)
return 0;
if(fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
return 0;
return 1;
#endif /* _WIN32 */
}
static int write_setup(xcb_connection_t *c, xcb_auth_info_t *auth_info)
{
static const char pad[3];
xcb_setup_request_t out;
struct iovec parts[6];
int count = 0;
static const uint32_t endian = 0x01020304;
int ret;
memset(&out, 0, sizeof(out));
/* B = 0x42 = MSB first, l = 0x6c = LSB first */
if(htonl(endian) == endian)
out.byte_order = 0x42;
else
out.byte_order = 0x6c;
out.protocol_major_version = X_PROTOCOL;
out.protocol_minor_version = X_PROTOCOL_REVISION;
out.authorization_protocol_name_len = 0;
out.authorization_protocol_data_len = 0;
parts[count].iov_len = sizeof(xcb_setup_request_t);
parts[count++].iov_base = &out;
parts[count].iov_len = XCB_PAD(sizeof(xcb_setup_request_t));
parts[count++].iov_base = (char *) pad;
if(auth_info)
{
parts[count].iov_len = out.authorization_protocol_name_len = auth_info->namelen;
parts[count++].iov_base = auth_info->name;
parts[count].iov_len = XCB_PAD(out.authorization_protocol_name_len);
parts[count++].iov_base = (char *) pad;
parts[count].iov_len = out.authorization_protocol_data_len = auth_info->datalen;
parts[count++].iov_base = auth_info->data;
parts[count].iov_len = XCB_PAD(out.authorization_protocol_data_len);
parts[count++].iov_base = (char *) pad;
}
assert(count <= (int) (sizeof(parts) / sizeof(*parts)));
pthread_mutex_lock(&c->iolock);
ret = _xcb_out_send(c, parts, count);
pthread_mutex_unlock(&c->iolock);
return ret;
}
static int read_setup(xcb_connection_t *c)
{
uint32_t extra_bytes, total_bytes;
const char newline = '\n';
/* Read the server response */
c->setup = malloc(sizeof(xcb_setup_generic_t));
if(!c->setup)
return 0;
if(_xcb_in_read_block(c, c->setup, sizeof(xcb_setup_generic_t)) != sizeof(xcb_setup_generic_t))
return 0;
extra_bytes = c->setup->length * UINT32_C(4);
total_bytes = extra_bytes + sizeof(xcb_setup_generic_t);
{
void *tmp = realloc(c->setup, total_bytes);
if(!tmp)
return 0;
c->setup = tmp;
}
if(_xcb_in_read_block(c, (char *) c->setup + sizeof(xcb_setup_generic_t), extra_bytes) <= 0)
return 0;
/* 0 = failed, 2 = authenticate, 1 = success */
switch(c->setup->status)
{
case 0: /* failed */
{
xcb_setup_failed_t *setup = (xcb_setup_failed_t *) c->setup;
char *msg = (char *)c->setup + sizeof(*setup);
if (setup->reason_len > extra_bytes)
setup->reason_len = (uint8_t)extra_bytes;
for (size_t i = 0; i < setup->reason_len; ++i) {
if (msg[i] < 0x20 || msg[i] > 0x7E)
msg[i] = 0x20;
}
write(STDERR_FILENO, msg, setup->reason_len);
write(STDERR_FILENO, &newline, 1);
return 0;
}
case 2: /* authenticate */
{
char *reason = (char *)c->setup + sizeof(xcb_setup_authenticate_t);
for (size_t i = 0; i < extra_bytes; ++i) {
if (reason[i] < 0x20 || reason[i] > 0x7E)
reason[i] = 0x20;
}
write(STDERR_FILENO, reason, extra_bytes);
write(STDERR_FILENO, &newline, 1);
return 0;
}
case 1: /* success */
if (total_bytes < sizeof(xcb_setup_t) + sizeof(xcb_screen_t) + sizeof(xcb_format_t))
return 0; /* not enough bytes sent, no screens, or no formats */
else
{
size_t i, j;
const uint8_t *cursor = (const uint8_t *)c->setup,
*const end = cursor + total_bytes;
xcb_setup_t *const setup = (xcb_setup_t *) c->setup;
const xcb_format_t *formats;
/*
* Padded length of the vendor string. setup->vendor_len is a
* uint16_t so overflow is impossible. Cannot exceed 65536.
*/
uint32_t const pixmap_offset = (setup->vendor_len + UINT32_C(3)) & ~UINT32_C(3);
/*
* Length of the pixmap formats. setup->pixmap_formats_len is
* uint8_t so overflow is impossible.
*/
uint32_t const pixmap_formats_len = sizeof(xcb_format_t) * setup->pixmap_formats_len;
/* Offset of the screens. Max RHS = 40 + 65536 + 8 * 255 = 67616 so no risk of overflow */
uint32_t const screen_offset = sizeof(xcb_setup_t) + pixmap_offset + pixmap_formats_len;
/* 4 zero bytes, for memcmp() */
uint32_t const zero = 0;
#if __STDC_VERSION__ >= 201112L
/* A bunch of static assertions */
static_assert(sizeof(xcb_screen_t) == 40, "bug");
static_assert(sizeof(xcb_setup_t) == 40, "bug");
static_assert(sizeof(xcb_setup_generic_t) == 8, "bug");
static_assert(sizeof(xcb_setup_authenticate_t) == 8, "bug");
static_assert(sizeof(xcb_setup_failed_t) == 8, "bug");
static_assert(sizeof(xcb_visualtype_t) == 24, "bug");
static_assert(sizeof(xcb_depth_t) == 8, "bug");
static_assert(sizeof(xcb_format_t) == 8, "bug");
static_assert(alignof(xcb_screen_t) == 4, "bug");
static_assert(alignof(xcb_visualtype_t) == 4, "bug");
static_assert(alignof(xcb_depth_t) == 2, "bug");
#endif
/* Must have at least 1 screen and 1 pixmap format */
if (setup->roots_len < 1 || setup->pixmap_formats_len < 1)
return 0;
/* First screen must fit in the data sent. */
if (total_bytes < screen_offset + sizeof(xcb_screen_t))
return 0;
/*
* xcb_setup_pixmap_formats() would be safe, but just using pointer
* arithmetic is simpler.
*/
formats = (const xcb_format_t *)(cursor + pixmap_offset);
/* Validate the pixmap formats. Bounds have been checked already. */
for (i = 0; i < setup->pixmap_formats_len; ++i) {
/* Depth must not be zero. */
if (formats[i].depth == 0)
return 0;
/* Bits per pixel must not be zero and must be a multiple of 8. */
if ((formats[i].bits_per_pixel < 8) ||
(formats[i].bits_per_pixel % 8) != 0)
return 0;
}
/*
* Alignment is guaranteed because screen_offset is a multiple of 4
* and c->setup was allocated by malloc(). cursor is kept 4-byte
* aligned at all times.
*/
cursor = (const uint8_t *)setup + screen_offset;
/* Validate each screen. */
for (i = 0; i < setup->roots_len; ++i) {
const struct xcb_screen_t *screen;
const struct xcb_depth_t *depth;
const struct xcb_visualtype_t *visuals;
/*
* Screen must fit in the buffer with room for a depth and a
* visual type.
*/
if ((end - cursor) <
(sizeof(*screen) + sizeof(*depth) + sizeof(*visuals)))
return 0;
screen = (const struct xcb_screen_t *)cursor;
cursor += sizeof(*screen);
/* Screens must have at least one depth */
if (screen->allowed_depths_len < 1)
return 0;
for (j = 0; j < screen->allowed_depths_len; ++j) {
uint32_t visuals_size, k;
/* Depth must fit in the buffer with room for a visual type. */
if ((end - cursor) < (sizeof(*depth) + sizeof(*visuals)))
return 0;
/*
* Alignment is guaranteed because xcb_screen_t has greater
* alignment (4) than xcb_depth_t (2). sizeof(xcb_depth_t)
* is a multiple of 4 so alignment will be maintained.
*/
depth = (const struct xcb_depth_t *)cursor;
cursor += sizeof(*depth);
/* Padding must be zero */
if ((depth->pad0 != 0) ||
(memcmp(depth->pad1, &zero, sizeof(zero)) != 0))
return 0;
/* Depths must have at least one visual type */
if (depth->visuals_len < 1)
return 0;
/* depth->visuals_len is uint16_t so overflow is impossible. */
visuals_size = (uint32_t)depth->visuals_len * sizeof(*visuals);
/* Visuals must fit in the buffer. */
if ((size_t)(end - cursor) < visuals_size)
return 0;
/* Cursor is 4-byte aligned, which is sufficient. */
visuals = (const xcb_visualtype_t *)cursor;
for (k = 0; k < depth->visuals_len; ++k) {
/* Padding must be zero. */
if (memcmp(visuals[k].pad0, &zero, 4))
return 0;
/* Bits per RGB value must not be zero. */
if (visuals[k].bits_per_rgb_value < 1)
return 0;
}
cursor += visuals_size;
}
}
if (end != cursor)
return 0; /* trailing junk */
}
return 1;
default:
return 0;
}
}
/* precondition: there must be something for us to write. */
static int write_vec(xcb_connection_t *c, struct iovec **vector, int *count)
{
#ifndef _WIN32
int n;
#endif
assert(!c->out.queue_len);
#ifdef _WIN32
/* Could use the WSASend win32 function for scatter/gather i/o but setting up the WSABUF struct from
an iovec would require more work and I'm not sure of the benefit....works for now */
while (*count)
{
struct iovec *vec = *vector;
if (vec->iov_len)
{
int ret = send(c->fd, vec->iov_base, vec->iov_len, 0);
if (ret == SOCKET_ERROR)
{
int err = WSAGetLastError();
if (err == WSAEWOULDBLOCK)
{
return 1;
}
}
if (ret <= 0)
{
_xcb_conn_shutdown(c, XCB_CONN_ERROR);
return 0;
}
c->out.total_written += ret;
vec->iov_len -= ret;
vec->iov_base = (char *)vec->iov_base + ret;
}
if (vec->iov_len == 0) {
(*vector)++;
(*count)--;
}
}
if (!*count)
*vector = 0;
#else
n = *count;
if (n > IOV_MAX)
n = IOV_MAX;
#if HAVE_SENDMSG
if (c->out.out_fd.nfd) {
union {
struct cmsghdr cmsghdr;
char buf[CMSG_SPACE(XCB_MAX_PASS_FD * sizeof(int))];
} cmsgbuf;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_iov = *vector,
.msg_iovlen = n,
.msg_control = cmsgbuf.buf,
.msg_controllen = CMSG_LEN(c->out.out_fd.nfd * sizeof (int)),
};
int i;
struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg);
hdr->cmsg_len = msg.msg_controllen;
hdr->cmsg_level = SOL_SOCKET;
hdr->cmsg_type = SCM_RIGHTS;
memcpy(CMSG_DATA(hdr), c->out.out_fd.fd, c->out.out_fd.nfd * sizeof (int));
n = sendmsg(c->fd, &msg, 0);
if(n < 0 && errno == EAGAIN)
return 1;
for (i = 0; i < c->out.out_fd.nfd; i++)
close(c->out.out_fd.fd[i]);
c->out.out_fd.nfd = 0;
} else
#endif
{
n = writev(c->fd, *vector, n);
if(n < 0 && errno == EAGAIN)
return 1;
}
if(n <= 0)
{
_xcb_conn_shutdown(c, XCB_CONN_ERROR);
return 0;
}
c->out.total_written += n;
for(; *count; --*count, ++*vector)
{
int cur = (*vector)->iov_len;
if(cur > n)
cur = n;
if(cur) {
(*vector)->iov_len -= cur;
(*vector)->iov_base = (char *) (*vector)->iov_base + cur;
n -= cur;
}
if((*vector)->iov_len)
break;
}
if(!*count)
*vector = 0;
assert(n == 0);
#endif /* _WIN32 */
return 1;
}
/* Public interface */
const xcb_setup_t *xcb_get_setup(xcb_connection_t *c)
{
if(is_static_error_conn(c))
return &xcb_error_setup;
/* doesn't need locking because it's never written to. */
return c->setup;
}
int xcb_get_file_descriptor(xcb_connection_t *c)
{
if(is_static_error_conn(c))
return -1;
/* doesn't need locking because it's never written to. */
return c->fd;
}
int xcb_connection_has_error(xcb_connection_t *c)
{
/* doesn't need locking because it's read and written atomically. */
return c->has_error;
}
xcb_connection_t *xcb_connect_to_fd(int fd, xcb_auth_info_t *auth_info)
{
xcb_connection_t* c;
#ifndef _WIN32
#ifndef USE_POLL
if(fd >= FD_SETSIZE) /* would overflow in FD_SET */
{
close(fd);
return _xcb_conn_ret_error(XCB_CONN_ERROR);
}
#endif
#endif /* !_WIN32*/
c = calloc(1, sizeof(xcb_connection_t));
if(!c) {
#ifdef _WIN32
closesocket(fd);
#else
close(fd);
#endif
return _xcb_conn_ret_error(XCB_CONN_CLOSED_MEM_INSUFFICIENT) ;
}
c->fd = fd;
if(!(
set_fd_flags(fd) &&
pthread_mutex_init(&c->iolock, 0) == 0 &&
_xcb_in_init(&c->in) &&
_xcb_out_init(&c->out) &&
write_setup(c, auth_info) &&
read_setup(c) &&
_xcb_ext_init(c) &&
_xcb_xid_init(c)
))
{
xcb_disconnect(c);
return _xcb_conn_ret_error(XCB_CONN_ERROR);
}
return c;
}
void xcb_disconnect(xcb_connection_t *c)
{
if(c == NULL || is_static_error_conn(c))
return;
free(c->setup);
/* disallow further sends and receives */
shutdown(c->fd, SHUT_RDWR);
#ifdef _WIN32
closesocket(c->fd);
#else
close(c->fd);
#endif
pthread_mutex_destroy(&c->iolock);
_xcb_in_destroy(&c->in);
_xcb_out_destroy(&c->out);
_xcb_ext_destroy(c);
_xcb_xid_destroy(c);
free(c);
#ifdef _WIN32
WSACleanup();
#endif
}
/* Private interface */
void _xcb_conn_shutdown(xcb_connection_t *c, int err)
{
c->has_error = err;
}
/* Return connection error state.
* To make thread-safe, I need a seperate static
* variable for every possible error.
* has_error is the first field in xcb_connection_t, so just
* return a casted int here; checking has_error (and only
* has_error) will be safe.
*/
xcb_connection_t *_xcb_conn_ret_error(int err)
{
switch(err)
{
case XCB_CONN_CLOSED_MEM_INSUFFICIENT:
{
return (xcb_connection_t *) &xcb_con_closed_mem_er;
}
case XCB_CONN_CLOSED_PARSE_ERR:
{
return (xcb_connection_t *) &xcb_con_closed_parse_er;
}
case XCB_CONN_CLOSED_INVALID_SCREEN:
{
return (xcb_connection_t *) &xcb_con_closed_screen_er;
}
case XCB_CONN_ERROR:
default:
{
return (xcb_connection_t *) &xcb_con_error;
}
}
}
int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vector, int *count)
{
int ret;
#if USE_POLL
struct pollfd fd;
#else
fd_set rfds, wfds;
#endif
/* If the thing I should be doing is already being done, wait for it. */
if(count ? c->out.writing : c->in.reading)
{
pthread_cond_wait(cond, &c->iolock);
return 1;
}
#if USE_POLL
memset(&fd, 0, sizeof(fd));
fd.fd = c->fd;
fd.events = POLLIN;
#else
FD_ZERO(&rfds);
FD_SET(c->fd, &rfds);
#endif
++c->in.reading;
#if USE_POLL
if(count)
{
fd.events |= POLLOUT;
++c->out.writing;
}
#else
FD_ZERO(&wfds);
if(count)
{
FD_SET(c->fd, &wfds);
++c->out.writing;
}
#endif
pthread_mutex_unlock(&c->iolock);
do {
#if USE_POLL
ret = poll(&fd, 1, -1);
/* If poll() returns an event we didn't expect, such as POLLNVAL, treat
* it as if it failed. */
if(ret >= 0 && (fd.revents & ~fd.events))
{
ret = -1;
break;
}
#else
ret = select(c->fd + 1, &rfds, &wfds, 0, 0);
#endif
} while (ret == -1 && errno == EINTR);
if(ret < 0)
{
_xcb_conn_shutdown(c, XCB_CONN_ERROR);
ret = 0;
}
pthread_mutex_lock(&c->iolock);
if(ret)
{
/* The code allows two threads to call select()/poll() at the same time.
* First thread just wants to read, a second thread wants to write, too.
* We have to make sure that we don't steal the reading thread's reply
* and let it get stuck in select()/poll().
* So a thread may read if either:
* - There is no other thread that wants to read (the above situation
* did not occur).
* - It is the reading thread (above situation occurred).
*/
int may_read = c->in.reading == 1 || !count;
#if USE_POLL
if(may_read && (fd.revents & POLLIN) != 0)
#else
if(may_read && FD_ISSET(c->fd, &rfds))
#endif
ret = ret && _xcb_in_read(c);
#if USE_POLL
if((fd.revents & POLLOUT) != 0)
#else
if(FD_ISSET(c->fd, &wfds))
#endif
ret = ret && write_vec(c, vector, count);
}
if(count)
--c->out.writing;
--c->in.reading;
return ret;
}
uint64_t xcb_total_read(xcb_connection_t *c)
{
uint64_t n;
if (xcb_connection_has_error(c))
return 0;
pthread_mutex_lock(&c->iolock);
n = c->in.total_read;
pthread_mutex_unlock(&c->iolock);
return n;
}
uint64_t xcb_total_written(xcb_connection_t *c)
{
uint64_t n;
if (xcb_connection_has_error(c))
return 0;
pthread_mutex_lock(&c->iolock);
n = c->out.total_written;
pthread_mutex_unlock(&c->iolock);
return n;
}
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