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Use shm_open instead of mkstemp

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shm_open is more reliable because it does not require
a writeable filesystem folder, unlike mkstemp.
This commit is contained in:
Manuel Stoeckl 2022-11-24 17:40:55 -05:00 committed by Simon Ser
parent 226244e93c
commit cbdafb031a
1 changed files with 29 additions and 47 deletions
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78
pool-buffer.c
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@ -1,60 +1,40 @@
#define _POSIX_C_SOURCE 200809L
#include <assert.h>
#include <cairo/cairo.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <time.h>
#include <unistd.h>
#include <wayland-client.h>
#include "pool-buffer.h"
static bool set_cloexec(int fd) {
long flags = fcntl(fd, F_GETFD);
if (flags == -1) {
return false;
}
static int anonymous_shm_open(void) {
int retries = 100;
if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1) {
return false;
}
return true;
}
static int create_pool_file(size_t size, char **name) {
static const char template[] = "sway-client-XXXXXX";
const char *path = getenv("XDG_RUNTIME_DIR");
if (path == NULL) {
fprintf(stderr, "XDG_RUNTIME_DIR is not set\n");
return -1;
}
size_t name_size = strlen(template) + 1 + strlen(path) + 1;
*name = malloc(name_size);
if (*name == NULL) {
fprintf(stderr, "allocation failed\n");
return -1;
}
snprintf(*name, name_size, "%s/%s", path, template);
int fd = mkstemp(*name);
if (fd < 0) {
return -1;
}
if (!set_cloexec(fd)) {
close(fd);
return -1;
}
if (ftruncate(fd, size) < 0) {
close(fd);
return -1;
}
do {
// try a probably-unique name
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
pid_t pid = getpid();
char name[50];
snprintf(name, sizeof(name), "/swaylock-%x-%x",
(unsigned int)pid, (unsigned int)ts.tv_nsec);
// shm_open guarantees that O_CLOEXEC is set
int fd = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
if (fd >= 0) {
shm_unlink(name);
return fd;
}
--retries;
} while (retries > 0 && errno == EEXIST);
return -1;
}
static void buffer_release(void *data, struct wl_buffer *wl_buffer) {
@ -74,9 +54,14 @@ static struct pool_buffer *create_buffer(struct wl_shm *shm,
void *data = NULL;
if (size > 0) {
char *name;
int fd = create_pool_file(size, &name);
assert(fd != -1);
int fd = anonymous_shm_open();
if (fd == -1) {
return NULL;
}
if (ftruncate(fd, size) < 0) {
close(fd);
return NULL;
}
data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
struct wl_shm_pool *pool = wl_shm_create_pool(shm, fd, size);
buf->buffer = wl_shm_pool_create_buffer(pool, 0,
@ -84,9 +69,6 @@ static struct pool_buffer *create_buffer(struct wl_shm *shm,
wl_buffer_add_listener(buf->buffer, &buffer_listener, buf);
wl_shm_pool_destroy(pool);
close(fd);
unlink(name);
free(name);
fd = -1;
}
buf->size = size;