[PATCH 1/3] libcamera: base: Add MemFd helper class
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Wed Jul 31 01:27:06 CEST 2024
libcamera creates memfds in two locations already, duplicating some
code. Move the code to a new MemFd helper class.
Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
include/libcamera/base/memfd.h | 34 +++++++++
include/libcamera/base/meson.build | 1 +
src/libcamera/base/memfd.cpp | 112 ++++++++++++++++++++++++++++
src/libcamera/base/meson.build | 1 +
src/libcamera/dma_buf_allocator.cpp | 46 +-----------
src/libcamera/shared_mem_object.cpp | 21 ++----
6 files changed, 157 insertions(+), 58 deletions(-)
create mode 100644 include/libcamera/base/memfd.h
create mode 100644 src/libcamera/base/memfd.cpp
diff --git a/include/libcamera/base/memfd.h b/include/libcamera/base/memfd.h
new file mode 100644
index 000000000000..b0edd2de5d83
--- /dev/null
+++ b/include/libcamera/base/memfd.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Ideas on Board Oy
+ *
+ * Anonymous file creation
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+#include <libcamera/base/flags.h>
+#include <libcamera/base/unique_fd.h>
+
+namespace libcamera {
+
+class MemFd
+{
+public:
+ enum class Seal {
+ None = 0,
+ Shrink = (1 << 0),
+ Grow = (1 << 1),
+ };
+
+ using Seals = Flags<Seal>;
+
+ static UniqueFD create(const char *name, std::size_t size,
+ Seals seals = Seal::None);
+};
+
+LIBCAMERA_FLAGS_ENABLE_OPERATORS(MemFd::Seal)
+
+} /* namespace libcamera */
diff --git a/include/libcamera/base/meson.build b/include/libcamera/base/meson.build
index bace25d56b13..2a0cee317204 100644
--- a/include/libcamera/base/meson.build
+++ b/include/libcamera/base/meson.build
@@ -21,6 +21,7 @@ libcamera_base_private_headers = files([
'event_notifier.h',
'file.h',
'log.h',
+ 'memfd.h',
'message.h',
'mutex.h',
'private.h',
diff --git a/src/libcamera/base/memfd.cpp b/src/libcamera/base/memfd.cpp
new file mode 100644
index 000000000000..0d50e2d64638
--- /dev/null
+++ b/src/libcamera/base/memfd.cpp
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Google Inc.
+ *
+ * Anonymous file creation
+ */
+
+#include <libcamera/base/memfd.h>
+
+#include <fcntl.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include <libcamera/base/log.h>
+
+/**
+ * \file base/memfd.h
+ * \brief Anonymous file creation
+ */
+
+/* uClibc doesn't provide the file sealing API. */
+#ifndef __DOXYGEN__
+#if not HAVE_FILE_SEALS
+#define F_ADD_SEALS 1033
+#define F_SEAL_SHRINK 0x0002
+#define F_SEAL_GROW 0x0004
+#endif
+#endif
+
+namespace libcamera {
+
+LOG_DECLARE_CATEGORY(File)
+
+/**
+ * \class MemFd
+ * \brief Helper class to created anonymous files
+ */
+
+/**
+ * \enum MemFd::Seal
+ * \brief Seals for the MemFd::create() function
+ * \var MemFd::Seal::None
+ * \brief No seals (used as default value)
+ * \var MemFd::Seal::Shrink
+ * \brief Prevent the memfd from shrinking
+ * \var MemFd::Seal::Grow
+ * \brief Prevent the memfd from growing
+ */
+
+/**
+ * \typedef MemFd::Seals
+ * \brief A bitwise combination of MemFd::Seal values
+ */
+
+/**
+ * \brief Create an anonymous file
+ * \param[in] name The file name (displayed in symbolic links in /proc/self/fd/)
+ * \param[in] size The file size
+ * \param[in] seals The file seals
+ * \return The descriptor of the anonymous file is creation succeeded, or an
+ *
+ * This function is a helper that wraps anonymous file (memfd) creation and
+ * sets the file size and optional seals.
+ *
+ * invalid UniqueFD otherwise
+ */
+UniqueFD MemFd::create(const char *name, std::size_t size, Seals seals)
+{
+#if HAVE_MEMFD_CREATE
+ int ret = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
+#else
+ int ret = syscall(SYS_memfd_create, name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
+#endif
+ if (ret < 0) {
+ ret = errno;
+ LOG(File, Error)
+ << "Failed to allocate memfd storage for " << name
+ << ": " << strerror(ret);
+ return {};
+ }
+
+ UniqueFD memfd(ret);
+
+ ret = ftruncate(memfd.get(), size);
+ if (ret < 0) {
+ ret = errno;
+ LOG(File, Error)
+ << "Failed to set memfd size for " << name
+ << ": " << strerror(ret);
+ return {};
+ }
+
+ if (seals) {
+ int fileSeals = (seals & Seal::Shrink ? F_SEAL_SHRINK : 0)
+ | (seals & Seal::Grow ? F_SEAL_GROW : 0);
+
+ ret = fcntl(memfd.get(), F_ADD_SEALS, fileSeals);
+ if (ret < 0) {
+ ret = errno;
+ LOG(File, Error)
+ << "Failed to seal the memfd for " << name
+ << ": " << strerror(ret);
+ return {};
+ }
+ }
+
+ return memfd;
+}
+
+} /* namespace libcamera */
diff --git a/src/libcamera/base/meson.build b/src/libcamera/base/meson.build
index 7a7fd7e4ca87..4a228d335ba4 100644
--- a/src/libcamera/base/meson.build
+++ b/src/libcamera/base/meson.build
@@ -10,6 +10,7 @@ libcamera_base_sources = files([
'file.cpp',
'flags.cpp',
'log.cpp',
+ 'memfd.cpp',
'message.cpp',
'mutex.cpp',
'object.cpp',
diff --git a/src/libcamera/dma_buf_allocator.cpp b/src/libcamera/dma_buf_allocator.cpp
index c06eca7d04ec..be6efb89fbb7 100644
--- a/src/libcamera/dma_buf_allocator.cpp
+++ b/src/libcamera/dma_buf_allocator.cpp
@@ -13,7 +13,6 @@
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
-#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
@@ -22,6 +21,7 @@
#include <linux/udmabuf.h>
#include <libcamera/base/log.h>
+#include <libcamera/base/memfd.h>
/**
* \file dma_buf_allocator.cpp
@@ -126,54 +126,16 @@ DmaBufAllocator::~DmaBufAllocator() = default;
* \brief Check if the DmaBufAllocator instance is valid
* \return True if the DmaBufAllocator is valid, false otherwise
*/
-
-/* uClibc doesn't provide the file sealing API. */
-#ifndef __DOXYGEN__
-#if not HAVE_FILE_SEALS
-#define F_ADD_SEALS 1033
-#define F_SEAL_SHRINK 0x0002
-#endif
-#endif
-
UniqueFD DmaBufAllocator::allocFromUDmaBuf(const char *name, std::size_t size)
{
/* Size must be a multiple of the page size. Round it up. */
std::size_t pageMask = sysconf(_SC_PAGESIZE) - 1;
size = (size + pageMask) & ~pageMask;
-#if HAVE_MEMFD_CREATE
- int ret = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
-#else
- int ret = syscall(SYS_memfd_create, name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
-#endif
- if (ret < 0) {
- ret = errno;
- LOG(DmaBufAllocator, Error)
- << "Failed to allocate memfd storage for " << name
- << ": " << strerror(ret);
- return {};
- }
-
- UniqueFD memfd(ret);
-
- ret = ftruncate(memfd.get(), size);
- if (ret < 0) {
- ret = errno;
- LOG(DmaBufAllocator, Error)
- << "Failed to set memfd size for " << name
- << ": " << strerror(ret);
- return {};
- }
-
/* udmabuf dma-buffers *must* have the F_SEAL_SHRINK seal. */
- ret = fcntl(memfd.get(), F_ADD_SEALS, F_SEAL_SHRINK);
- if (ret < 0) {
- ret = errno;
- LOG(DmaBufAllocator, Error)
- << "Failed to seal the memfd for " << name
- << ": " << strerror(ret);
+ UniqueFD memfd = MemFd::create(name, size, MemFd::Seal::Shrink);
+ if (!memfd.isValid())
return {};
- }
struct udmabuf_create create;
@@ -182,7 +144,7 @@ UniqueFD DmaBufAllocator::allocFromUDmaBuf(const char *name, std::size_t size)
create.offset = 0;
create.size = size;
- ret = ::ioctl(providerHandle_.get(), UDMABUF_CREATE, &create);
+ int ret = ::ioctl(providerHandle_.get(), UDMABUF_CREATE, &create);
if (ret < 0) {
ret = errno;
LOG(DmaBufAllocator, Error)
diff --git a/src/libcamera/shared_mem_object.cpp b/src/libcamera/shared_mem_object.cpp
index 809fbdaf95de..022645e71a35 100644
--- a/src/libcamera/shared_mem_object.cpp
+++ b/src/libcamera/shared_mem_object.cpp
@@ -13,9 +13,9 @@
#include <stddef.h>
#include <stdint.h>
#include <sys/mman.h>
-#include <sys/syscall.h>
#include <sys/types.h>
-#include <unistd.h>
+
+#include <libcamera/base/memfd.h>
/**
* \file shared_mem_object.cpp
@@ -58,22 +58,11 @@ SharedMem::SharedMem() = default;
*/
SharedMem::SharedMem(const std::string &name, std::size_t size)
{
-#if HAVE_MEMFD_CREATE
- int fd = memfd_create(name.c_str(), MFD_CLOEXEC);
-#else
- int fd = syscall(SYS_memfd_create, name.c_str(), MFD_CLOEXEC);
-#endif
- if (fd < 0)
+ UniqueFD memfd = MemFd::create(name.c_str(), size);
+ if (!memfd.isValid())
return;
- fd_ = SharedFD(std::move(fd));
- if (!fd_.isValid())
- return;
-
- if (ftruncate(fd_.get(), size) < 0) {
- fd_ = SharedFD();
- return;
- }
+ fd_ = SharedFD(std::move(memfd));
void *mem = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED,
fd_.get(), 0);
--
Regards,
Laurent Pinchart
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