Let's factor it out so we can reuse it.
Signed-off-by: David Hildenbrand <da...@redhat.com>
Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
Reviewed-by: Peter Xu <pet...@redhat.com>
---
backends/hostmem-shm.c | 45 ++++---------------------------------------
include/qemu/osdep.h | 1 +
meson.build | 8 ++++++--
util/oslib-posix.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++
util/oslib-win32.c | 6 ++++++
5 files changed, 69 insertions(+), 43 deletions(-)
diff --git a/backends/hostmem-shm.c b/backends/hostmem-shm.c
index 5551ba7..fabee41 100644
--- a/backends/hostmem-shm.c
+++ b/backends/hostmem-shm.c
@@ -25,11 +25,9 @@ struct HostMemoryBackendShm {
static bool
shm_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
{
- g_autoptr(GString) shm_name = g_string_new(NULL);
g_autofree char *backend_name = NULL;
uint32_t ram_flags;
- int fd, oflag;
- mode_t mode;
+ int fd;
if (!backend->size) {
error_setg(errp, "can't create shm backend with size 0");
@@ -41,48 +39,13 @@ shm_backend_memory_alloc(HostMemoryBackend *backend, Error
**errp)
return false;
}
- /*
- * Let's use `mode = 0` because we don't want other processes to open our
- * memory unless we share the file descriptor with them.
- */
- mode = 0;
- oflag = O_RDWR | O_CREAT | O_EXCL;
- backend_name = host_memory_backend_get_name(backend);
-
- /*
- * Some operating systems allow creating anonymous POSIX shared memory
- * objects (e.g. FreeBSD provides the SHM_ANON constant), but this is not
- * defined by POSIX, so let's create a unique name.
- *
- * From Linux's shm_open(3) man-page:
- * For portable use, a shared memory object should be identified
- * by a name of the form /somename;"
- */
- g_string_printf(shm_name, "/qemu-" FMT_pid "-shm-%s", getpid(),
- backend_name);
-
- fd = shm_open(shm_name->str, oflag, mode);
+ fd = qemu_shm_alloc(backend->size, errp);
if (fd < 0) {
- error_setg_errno(errp, errno,
- "failed to create POSIX shared memory");
- return false;
- }
-
- /*
- * We have the file descriptor, so we no longer need to expose the
- * POSIX shared memory object. However it will remain allocated as long as
- * there are file descriptors pointing to it.
- */
- shm_unlink(shm_name->str);
-
- if (ftruncate(fd, backend->size) == -1) {
- error_setg_errno(errp, errno,
- "failed to resize POSIX shared memory to %" PRIu64,
- backend->size);
- close(fd);
return false;
}
+ /* Let's do the same as memory-backend-ram,share=on would do. */
+ backend_name = host_memory_backend_get_name(backend);
ram_flags = RAM_SHARED;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index b94fb5f..112ebdf 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -509,6 +509,7 @@ int qemu_daemon(int nochdir, int noclose);
void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared,
bool noreserve);
void qemu_anon_ram_free(void *ptr, size_t size);
+int qemu_shm_alloc(size_t size, Error **errp);
#ifdef _WIN32
#define HAVE_CHARDEV_SERIAL 1
diff --git a/meson.build b/meson.build
index b715ea7..2e709c9 100644
--- a/meson.build
+++ b/meson.build
@@ -3706,9 +3706,13 @@ libqemuutil = static_library('qemuutil',
build_by_default: false,
sources: util_ss.sources() + stub_ss.sources() +
genh,
dependencies: [util_ss.dependencies(), libm,
threads, glib, socket, malloc])
+qemuutil_deps = [event_loop_base]
+if host_os != 'windows'
+ qemuutil_deps += [rt]
+endif
qemuutil = declare_dependency(link_with: libqemuutil,
sources: genh + version_res,
- dependencies: [event_loop_base])
+ dependencies: qemuutil_deps)
if have_system or have_user
decodetree = generator(find_program('scripts/decodetree.py'),
@@ -4362,7 +4366,7 @@ if have_tools
subdir('contrib/elf2dmp')
executable('qemu-edid', files('qemu-edid.c', 'hw/display/edid-generate.c'),
- dependencies: qemuutil,
+ dependencies: [qemuutil, rt],
install: true)
if have_vhost_user
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 7a542cb..2bb34da 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -931,3 +931,55 @@ void qemu_close_all_open_fd(const int *skip, unsigned int
nskip)
qemu_close_all_open_fd_fallback(skip, nskip, open_max);
}
}
+
+int qemu_shm_alloc(size_t size, Error **errp)
+{
+ g_autoptr(GString) shm_name = g_string_new(NULL);
+ int fd, oflag, cur_sequence;
+ static int sequence;
+ mode_t mode;
+
+ cur_sequence = qatomic_fetch_inc(&sequence);
+
+ /*
+ * Let's use `mode = 0` because we don't want other processes to open our
+ * memory unless we share the file descriptor with them.
+ */
+ mode = 0;
+ oflag = O_RDWR | O_CREAT | O_EXCL;
+
+ /*
+ * Some operating systems allow creating anonymous POSIX shared memory
+ * objects (e.g. FreeBSD provides the SHM_ANON constant), but this is not
+ * defined by POSIX, so let's create a unique name.
+ *
+ * From Linux's shm_open(3) man-page:
+ * For portable use, a shared memory object should be identified
+ * by a name of the form /somename;"
+ */
+ g_string_printf(shm_name, "/qemu-" FMT_pid "-shm-%d", getpid(),
+ cur_sequence);
+
+ fd = shm_open(shm_name->str, oflag, mode);
+ if (fd < 0) {
+ error_setg_errno(errp, errno,
+ "failed to create POSIX shared memory");
+ return -1;
+ }
+
+ /*
+ * We have the file descriptor, so we no longer need to expose the
+ * POSIX shared memory object. However it will remain allocated as long as
+ * there are file descriptors pointing to it.
+ */
+ shm_unlink(shm_name->str);
+
+ if (ftruncate(fd, size) == -1) {
+ error_setg_errno(errp, errno,
+ "failed to resize POSIX shared memory to %zu", size);
+ close(fd);
+ return -1;
+ }
+
+ return fd;
+}
diff --git a/util/oslib-win32.c b/util/oslib-win32.c
index b623830..b735163 100644
--- a/util/oslib-win32.c
+++ b/util/oslib-win32.c
@@ -877,3 +877,9 @@ void qemu_win32_map_free(void *ptr, HANDLE h, Error **errp)
}
CloseHandle(h);
}
+
+int qemu_shm_alloc(size_t size, Error **errp)
+{
+ error_setg(errp, "Shared memory is not supported.");
+ return -1;
+}
--
1.8.3.1
