[libcamera-devel] [PATCH] libcamera: Open files with O_CLOEXEC

[Kieran Bingham]

Quoting Laurent Pinchart via libcamera-devel (2023-03-26 11:01:55)
> Files opened internally in libcamera without the O_CLOEXEC file will
> remain open upon a call to one of the exec(3) functions. As exec()
> doesn't destroy local or global objects, this can lead to various side
> effects. Avoid this by opening file descriptors with O_CLOEXEC for all
> internal files.

This seems more prolific than it should be.

It makes me think we should enforce it with a helper instead but I'm not
sure if that's much different to adding a checkstyle rule!?

Anyway, this seems reasonable otherwise.

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

--
Kieran

> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/ipa/vimc/vimc.cpp                            | 2 +-
>  src/libcamera/base/file.cpp                      | 5 ++++-
>  src/libcamera/media_device.cpp                   | 2 +-
>  src/libcamera/pipeline/raspberrypi/dma_heaps.cpp | 2 +-
>  4 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/src/ipa/vimc/vimc.cpp b/src/ipa/vimc/vimc.cpp
> index d5fabaf13ec6..2c255778990a 100644
> --- a/src/ipa/vimc/vimc.cpp
> +++ b/src/ipa/vimc/vimc.cpp
> @@ -168,7 +168,7 @@ void IPAVimc::initTrace()
>         if (ret)
>                 return;
>  
> -       ret = ::open(ipa::vimc::VimcIPAFIFOPath.c_str(), O_WRONLY);
> +       ret = ::open(ipa::vimc::VimcIPAFIFOPath.c_str(), O_WRONLY | O_CLOEXEC);
>         if (ret < 0) {
>                 ret = errno;
>                 LOG(IPAVimc, Error) << "Failed to open vimc IPA test FIFO: "
> diff --git a/src/libcamera/base/file.cpp b/src/libcamera/base/file.cpp
> index fb3e276d6ccd..d1ab1aa57462 100644
> --- a/src/libcamera/base/file.cpp
> +++ b/src/libcamera/base/file.cpp
> @@ -163,6 +163,9 @@ bool File::exists() const
>   * attempt to create the file with initial permissions set to 0666 (modified by
>   * the process' umask).
>   *
> + * The file is opened with the O_CLOEXEC flag, and will be closed automatically
> + * when a new binary is executed with one of the exec(3) functions.
> + *
>   * The error() status is updated.
>   *
>   * \return True on success, false otherwise
> @@ -178,7 +181,7 @@ bool File::open(File::OpenMode mode)
>         if (mode & OpenModeFlag::WriteOnly)
>                 flags |= O_CREAT;
>  
> -       fd_ = UniqueFD(::open(name_.c_str(), flags, 0666));
> +       fd_ = UniqueFD(::open(name_.c_str(), flags | O_CLOEXEC, 0666));
>         if (!fd_.isValid()) {
>                 error_ = -errno;
>                 return false;
> diff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp
> index 52c8e66e9e99..2949816b4a64 100644
> --- a/src/libcamera/media_device.cpp
> +++ b/src/libcamera/media_device.cpp
> @@ -477,7 +477,7 @@ int MediaDevice::open()
>                 return -EBUSY;
>         }
>  
> -       fd_ = UniqueFD(::open(deviceNode_.c_str(), O_RDWR));
> +       fd_ = UniqueFD(::open(deviceNode_.c_str(), O_RDWR | O_CLOEXEC));
>         if (!fd_.isValid()) {
>                 int ret = -errno;
>                 LOG(MediaDevice, Error)
> diff --git a/src/libcamera/pipeline/raspberrypi/dma_heaps.cpp b/src/libcamera/pipeline/raspberrypi/dma_heaps.cpp
> index 6b644406c90f..317b1fc17161 100644
> --- a/src/libcamera/pipeline/raspberrypi/dma_heaps.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/dma_heaps.cpp
> @@ -37,7 +37,7 @@ namespace RPi {
>  DmaHeap::DmaHeap()
>  {
>         for (const char *name : heapNames) {
> -               int ret = ::open(name, O_RDWR, 0);
> +               int ret = ::open(name, O_RDWR | O_CLOEXEC, 0);
>                 if (ret < 0) {
>                         ret = errno;
>                         LOG(RPI, Debug) << "Failed to open " << name << ": "
> -- 
> Regards,
> 
> Laurent Pinchart
>