[libcamera-devel] [PATCH v2] v4l2: v4l2_compat: Intercept open64, openat64, and mmap64
Paul Elder
paul.elder at ideasonboard.com
Thu Jun 18 11:57:50 CEST 2020
On Wed, Jun 17, 2020 at 06:02:04PM +0300, Laurent Pinchart wrote:
> Hi Paul,
>
> Thank you for the patch.
>
> On Wed, Jun 17, 2020 at 06:05:18PM +0900, Paul Elder wrote:
> > Some applications (eg. Firefox, Google Chrome, Skype) use open64,
> > openat64, and mmap64 instead of their non-64 versions that we currently
> > intercept. Intercept these calls as well. _LARGEFILE64_SOURCE needs to
> > be set so that the 64-bit symbols are available and not synonymous to
> > the non-64-bit versions on 64-bit systems.
> >
> > Also, since we set _FILE_OFFSET_BITS to 32 to force the various open and
> > mmap symbols that we export to not be the 64-bit versions, our dlsym to
> > get the original open and mmap calls will not automatically be converted
> > to their 64-bit versions. Since we intercept both 32-bit and 64-bit
> > versions of open and mmap, we should be using the 64-bit version to
> > service both. Fetch the 64-bit versions of openat and mmap directly.
> >
> > musl defines the 64-bit symbols as macros that are equivalent to the
> > non-64-bit symbols, so we put compile guards that check if the 64-bit
> > symbols are defined.
> >
> > Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
>
> Tested-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com> # Compile with musl
>
> Did you test compilation with musl yourself ?
Yeah, I did.
> I'm afraid you'll also need __open64_2 and __openat64_2. With that
> added (which you can condition on #ifndef open64 and #ifndef openat64),
Alright.
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Thanks,
Paul
> > ---
> > Changes in v2:
> > - squash intercept 64-bit calls and use 64-bit calls into
> > this one patch
> > - use off64_t instead of __off64_t
> > - add compile guard to get musl to play nicely with the 64-bit calls
> > coexisting with the non-64-bit calls
> > ---
> > src/v4l2/meson.build | 1 +
> > src/v4l2/v4l2_camera_proxy.cpp | 2 +-
> > src/v4l2/v4l2_camera_proxy.h | 3 ++-
> > src/v4l2/v4l2_compat.cpp | 33 ++++++++++++++++++++++++++++++++
> > src/v4l2/v4l2_compat_manager.cpp | 6 +++---
> > src/v4l2/v4l2_compat_manager.h | 5 +++--
> > 6 files changed, 43 insertions(+), 7 deletions(-)
> >
> > diff --git a/src/v4l2/meson.build b/src/v4l2/meson.build
> > index 0fb941e..f2e4aaf 100644
> > --- a/src/v4l2/meson.build
> > +++ b/src/v4l2/meson.build
> > @@ -15,6 +15,7 @@ v4l2_compat_cpp_args = [
> > # file operations, disable transparent large file support.
> > '-U_FILE_OFFSET_BITS',
> > '-D_FILE_OFFSET_BITS=32',
> > + '-D_LARGEFILE64_SOURCE',
> > '-fvisibility=hidden',
> > ]
> >
> > diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
> > index d7f14e6..7425029 100644
> > --- a/src/v4l2/v4l2_camera_proxy.cpp
> > +++ b/src/v4l2/v4l2_camera_proxy.cpp
> > @@ -75,7 +75,7 @@ void V4L2CameraProxy::close()
> > }
> >
> > void *V4L2CameraProxy::mmap(void *addr, size_t length, int prot, int flags,
> > - off_t offset)
> > + off64_t offset)
> > {
> > LOG(V4L2Compat, Debug) << "Servicing mmap";
> >
> > diff --git a/src/v4l2/v4l2_camera_proxy.h b/src/v4l2/v4l2_camera_proxy.h
> > index 7c65c88..27d3e50 100644
> > --- a/src/v4l2/v4l2_camera_proxy.h
> > +++ b/src/v4l2/v4l2_camera_proxy.h
> > @@ -11,6 +11,7 @@
> > #include <linux/videodev2.h>
> > #include <map>
> > #include <memory>
> > +#include <sys/mman.h>
> > #include <sys/types.h>
> > #include <vector>
> >
> > @@ -28,7 +29,7 @@ public:
> > int open(bool nonBlocking);
> > void dup();
> > void close();
> > - void *mmap(void *addr, size_t length, int prot, int flags, off_t offset);
> > + void *mmap(void *addr, size_t length, int prot, int flags, off64_t offset);
> > int munmap(void *addr, size_t length);
> >
> > int ioctl(unsigned long request, void *arg);
> > diff --git a/src/v4l2/v4l2_compat.cpp b/src/v4l2/v4l2_compat.cpp
> > index 2a9a176..7d45ffe 100644
> > --- a/src/v4l2/v4l2_compat.cpp
> > +++ b/src/v4l2/v4l2_compat.cpp
> > @@ -38,6 +38,18 @@ LIBCAMERA_PUBLIC int open(const char *path, int oflag, ...)
> > oflag, mode);
> > }
> >
> > +#ifndef open64
> > +LIBCAMERA_PUBLIC int open64(const char *path, int oflag, ...)
> > +{
> > + mode_t mode = 0;
> > + if (oflag & O_CREAT || oflag & O_TMPFILE)
> > + extract_va_arg(mode_t, mode, oflag);
> > +
> > + return V4L2CompatManager::instance()->openat(AT_FDCWD, path,
> > + oflag | O_LARGEFILE, mode);
> > +}
> > +#endif
> > +
> > /* _FORTIFY_SOURCE redirects open to __open_2 */
> > LIBCAMERA_PUBLIC int __open_2(const char *path, int oflag)
> > {
> > @@ -53,6 +65,18 @@ LIBCAMERA_PUBLIC int openat(int dirfd, const char *path, int oflag, ...)
> > return V4L2CompatManager::instance()->openat(dirfd, path, oflag, mode);
> > }
> >
> > +#ifndef openat64
> > +LIBCAMERA_PUBLIC int openat64(int dirfd, const char *path, int oflag, ...)
> > +{
> > + mode_t mode = 0;
> > + if (oflag & O_CREAT || oflag & O_TMPFILE)
> > + extract_va_arg(mode_t, mode, oflag);
> > +
> > + return V4L2CompatManager::instance()->openat(dirfd, path,
> > + oflag | O_LARGEFILE, mode);
> > +}
> > +#endif
> > +
> > LIBCAMERA_PUBLIC int __openat_2(int dirfd, const char *path, int oflag)
> > {
> > return openat(dirfd, path, oflag);
> > @@ -75,6 +99,15 @@ LIBCAMERA_PUBLIC void *mmap(void *addr, size_t length, int prot, int flags,
> > fd, offset);
> > }
> >
> > +#ifndef mmap64
> > +LIBCAMERA_PUBLIC void *mmap64(void *addr, size_t length, int prot, int flags,
> > + int fd, off64_t offset)
> > +{
> > + return V4L2CompatManager::instance()->mmap(addr, length, prot, flags,
> > + fd, offset);
> > +}
> > +#endif
> > +
> > LIBCAMERA_PUBLIC int munmap(void *addr, size_t length)
> > {
> > return V4L2CompatManager::instance()->munmap(addr, length);
> > diff --git a/src/v4l2/v4l2_compat_manager.cpp b/src/v4l2/v4l2_compat_manager.cpp
> > index 56533c4..8da3316 100644
> > --- a/src/v4l2/v4l2_compat_manager.cpp
> > +++ b/src/v4l2/v4l2_compat_manager.cpp
> > @@ -39,11 +39,11 @@ void get_symbol(T &func, const char *name)
> > V4L2CompatManager::V4L2CompatManager()
> > : cm_(nullptr)
> > {
> > - get_symbol(fops_.openat, "openat");
> > + get_symbol(fops_.openat, "openat64");
> > get_symbol(fops_.dup, "dup");
> > get_symbol(fops_.close, "close");
> > get_symbol(fops_.ioctl, "ioctl");
> > - get_symbol(fops_.mmap, "mmap");
> > + get_symbol(fops_.mmap, "mmap64");
> > get_symbol(fops_.munmap, "munmap");
> > }
> >
> > @@ -200,7 +200,7 @@ int V4L2CompatManager::close(int fd)
> > }
> >
> > void *V4L2CompatManager::mmap(void *addr, size_t length, int prot, int flags,
> > - int fd, off_t offset)
> > + int fd, off64_t offset)
> > {
> > V4L2CameraProxy *proxy = getProxy(fd);
> > if (!proxy)
> > diff --git a/src/v4l2/v4l2_compat_manager.h b/src/v4l2/v4l2_compat_manager.h
> > index 14338a5..3d4e512 100644
> > --- a/src/v4l2/v4l2_compat_manager.h
> > +++ b/src/v4l2/v4l2_compat_manager.h
> > @@ -11,6 +11,7 @@
> > #include <fcntl.h>
> > #include <map>
> > #include <memory>
> > +#include <sys/mman.h>
> > #include <sys/types.h>
> > #include <vector>
> >
> > @@ -30,7 +31,7 @@ public:
> > using close_func_t = int (*)(int fd);
> > using ioctl_func_t = int (*)(int fd, unsigned long request, ...);
> > using mmap_func_t = void *(*)(void *addr, size_t length, int prot,
> > - int flags, int fd, off_t offset);
> > + int flags, int fd, off64_t offset);
> > using munmap_func_t = int (*)(void *addr, size_t length);
> >
> > openat_func_t openat;
> > @@ -51,7 +52,7 @@ public:
> > int dup(int oldfd);
> > int close(int fd);
> > void *mmap(void *addr, size_t length, int prot, int flags,
> > - int fd, off_t offset);
> > + int fd, off64_t offset);
> > int munmap(void *addr, size_t length);
> > int ioctl(int fd, unsigned long request, void *arg);
> >
>
> --
> Regards,
>
> Laurent Pinchart
More information about the libcamera-devel
mailing list