From 346ec21c4c9007e98c84b67e4f5e4b9a67bbbce7 Mon Sep 17 00:00:00 2001 From: emersion Date: Fri, 26 Oct 2018 18:38:23 +0200 Subject: [PATCH] util: use shm_open for in-memory files shm_open is a POSIX function creating an in-memory file. Using it simplifies the code and removes the dependency on XDG_RUNTIME_DIR. The only downside is that we need to generate a random name for the shm file. --- docs/env_vars.md | 1 - include/util/os-compatibility.h | 9 -- include/util/shm.h | 7 ++ meson.build | 3 +- types/seat/wlr_seat_keyboard.c | 4 +- util/meson.build | 4 +- util/os-compatibility.c | 149 -------------------------------- util/shm.c | 67 ++++++++++++++ 8 files changed, 80 insertions(+), 164 deletions(-) delete mode 100644 include/util/os-compatibility.h create mode 100644 include/util/shm.h delete mode 100644 util/os-compatibility.c create mode 100644 util/shm.c diff --git a/docs/env_vars.md b/docs/env_vars.md index ef12e0b3..1b1a5fd6 100644 --- a/docs/env_vars.md +++ b/docs/env_vars.md @@ -30,4 +30,3 @@ generic * *WAYLAND_DISPLAY*, *_WAYLAND_DISPLAY*, *WAYLAND_SOCKET*: if set probe Wayland backend in *wlr_backend_autocreate* * *XCURSOR_PATH*: directory where xcursors are located -* *XDG_RUNTIME_DIR*: used to store non persistent temporary files diff --git a/include/util/os-compatibility.h b/include/util/os-compatibility.h deleted file mode 100644 index 2038025e..00000000 --- a/include/util/os-compatibility.h +++ /dev/null @@ -1,9 +0,0 @@ -#ifndef UTIL_OS_COMPATIBILITY_H -#define UTIL_OS_COMPATIBILITY_H - -int os_fd_set_cloexec(int fd); -int set_cloexec_or_close(int fd); -int create_tmpfile_cloexec(char *tmpname); -int os_create_anonymous_file(off_t size); - -#endif diff --git a/include/util/shm.h b/include/util/shm.h new file mode 100644 index 00000000..fb67b711 --- /dev/null +++ b/include/util/shm.h @@ -0,0 +1,7 @@ +#ifndef UTIL_SHM_H +#define UTIL_SHM_H + +int create_shm_file(void); +int allocate_shm_file(size_t size); + +#endif diff --git a/meson.build b/meson.build index 9517168a..18a5d908 100644 --- a/meson.build +++ b/meson.build @@ -56,7 +56,8 @@ udev = dependency('libudev') pixman = dependency('pixman-1') libcap = dependency('libcap', required: get_option('libcap')) logind = dependency('lib' + get_option('logind-provider'), required: get_option('logind'), version: '>=237') -math = cc.find_library('m', required: false) +math = cc.find_library('m') +rt = cc.find_library('rt') wlr_parts = [] wlr_deps = [] diff --git a/types/seat/wlr_seat_keyboard.c b/types/seat/wlr_seat_keyboard.c index 0400db14..53415f0c 100644 --- a/types/seat/wlr_seat_keyboard.c +++ b/types/seat/wlr_seat_keyboard.c @@ -12,7 +12,7 @@ #include #include "types/wlr_seat.h" #include "util/signal.h" -#include "util/os-compatibility.h" +#include "util/shm.h" static void default_keyboard_enter(struct wlr_seat_keyboard_grab *grab, struct wlr_surface *surface, uint32_t keycodes[], size_t num_keycodes, @@ -341,7 +341,7 @@ static void seat_client_send_keymap(struct wlr_seat_client *client, continue; } - int keymap_fd = os_create_anonymous_file(keyboard->keymap_size); + int keymap_fd = allocate_shm_file(keyboard->keymap_size); if (keymap_fd < 0) { wlr_log(WLR_ERROR, "creating a keymap file for %zu bytes failed", keyboard->keymap_size); continue; diff --git a/util/meson.build b/util/meson.build index f9d1997d..dca3e9a4 100644 --- a/util/meson.build +++ b/util/meson.build @@ -3,10 +3,10 @@ lib_wlr_util = static_library( files( 'array.c', 'log.c', - 'os-compatibility.c', 'region.c', + 'shm.c', 'signal.c', ), include_directories: wlr_inc, - dependencies: [wayland_server, pixman], + dependencies: [wayland_server, pixman, rt], ) diff --git a/util/os-compatibility.c b/util/os-compatibility.c deleted file mode 100644 index bd39705d..00000000 --- a/util/os-compatibility.c +++ /dev/null @@ -1,149 +0,0 @@ -/* - * Copyright © 2012 Collabora, Ltd. - * - * 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 (including the - * next paragraph) 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 OR COPYRIGHT HOLDERS - * 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. - */ - -#define _POSIX_C_SOURCE 200809L -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include "util/os-compatibility.h" - -int os_fd_set_cloexec(int fd) { - if (fd == -1) { - return -1; - } - - long flags = fcntl(fd, F_GETFD); - if (flags == -1) { - return -1; - } - - if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1) { - return -1; - } - - return 0; -} - -int set_cloexec_or_close(int fd) { - if (os_fd_set_cloexec(fd) != 0) { - close(fd); - return -1; - } - return fd; -} - -int create_tmpfile_cloexec(char *tmpname) { - int fd; - mode_t prev_umask = umask(0066); -#ifdef HAVE_MKOSTEMP - fd = mkostemp(tmpname, O_CLOEXEC); - if (fd >= 0) { - unlink(tmpname); - } -#else - fd = mkstemp(tmpname); - if (fd >= 0) { - fd = set_cloexec_or_close(fd); - unlink(tmpname); - } -#endif - umask(prev_umask); - - return fd; -} - -/* - * Create a new, unique, anonymous file of the given size, and - * return the file descriptor for it. The file descriptor is set - * CLOEXEC. The file is immediately suitable for mmap()'ing - * the given size at offset zero. - * - * The file should not have a permanent backing store like a disk, - * but may have if XDG_RUNTIME_DIR is not properly implemented in OS. - * - * The file name is deleted from the file system. - * - * The file is suitable for buffer sharing between processes by - * transmitting the file descriptor over Unix sockets using the - * SCM_RIGHTS methods. - * - * If the C library implements posix_fallocate(), it is used to - * guarantee that disk space is available for the file at the - * given size. If disk space is insufficient, errno is set to ENOSPC. - * If posix_fallocate() is not supported, program may receive - * SIGBUS on accessing mmap()'ed file contents instead. - */ -int os_create_anonymous_file(off_t size) { - static const char template[] = "/wlroots-shared-XXXXXX"; - - const char *path = getenv("XDG_RUNTIME_DIR"); - if (!path) { - errno = ENOENT; - return -1; - } - - char *name = malloc(strlen(path) + sizeof(template)); - if (!name) { - return -1; - } - - strcpy(name, path); - strcat(name, template); - - int fd = create_tmpfile_cloexec(name); - free(name); - if (fd < 0) { - return -1; - } - -#ifdef WLR_HAS_POSIX_FALLOCATE - int ret; - do { - ret = posix_fallocate(fd, 0, size); - } while (ret == EINTR); - if (ret != 0) { - close(fd); - errno = ret; - return -1; - } -#else - int ret; - do { - ret = ftruncate(fd, size); - } while (ret < 0 && errno == EINTR); - if (ret < 0) { - close(fd); - return -1; - } -#endif - - return fd; -} diff --git a/util/shm.c b/util/shm.c new file mode 100644 index 00000000..3783e473 --- /dev/null +++ b/util/shm.c @@ -0,0 +1,67 @@ +#define _POSIX_C_SOURCE 200112L +#include +#include +#include +#include +#include +#include +#include +#include "util/shm.h" + +static void randname(char *buf) { + struct timespec ts; + clock_gettime(CLOCK_REALTIME, &ts); + long r = ts.tv_nsec; + for (int i = 0; i < 6; ++i) { + buf[i] = 'A'+(r&15)+(r&16)*2; + r >>= 5; + } +} + +int create_shm_file(void) { + int retries = 100; + do { + char name[] = "/wlroots-XXXXXX"; + randname(name + strlen(name) - 6); + + --retries; + // CLOEXEC is guaranteed to be set by shm_open + int fd = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0600); + if (fd >= 0) { + shm_unlink(name); + return fd; + } + } while (retries > 0 && errno == EEXIST); + + return -1; +} + +int allocate_shm_file(size_t size) { + int fd = create_shm_file(); + if (fd < 0) { + return -1; + } + +#ifdef WLR_HAS_POSIX_FALLOCATE + int ret; + do { + ret = posix_fallocate(fd, 0, size); + } while (ret == EINTR); + if (ret != 0) { + close(fd); + errno = ret; + return -1; + } +#else + int ret; + do { + ret = ftruncate(fd, size); + } while (ret < 0 && errno == EINTR); + if (ret < 0) { + close(fd); + return -1; + } +#endif + + return fd; +}