[{"id":5274,"web_url":"https://patchwork.libcamera.org/comment/5274/","msgid":"<20200618103119.GC5959@pendragon.ideasonboard.com>","date":"2020-06-18T10:31:19","subject":"Re: [libcamera-devel] [PATCH v3] v4l2: v4l2_compat: Intercept\n\topen64, openat64, and mmap64","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Paul,\n\nThank you for the patch.\n\nOn Thu, Jun 18, 2020 at 07:08:11PM +0900, Paul Elder wrote:\n> Some applications (eg. Firefox, Google Chrome, Skype) use open64,\n> openat64, and mmap64 instead of their non-64 versions that we currently\n> intercept. Intercept these calls as well. _LARGEFILE64_SOURCE needs to\n> be set so that the 64-bit symbols are available and not synonymous to\n> the non-64-bit versions on 64-bit systems.\n> \n> Also, since we set _FILE_OFFSET_BITS to 32 to force the various open and\n> mmap symbols that we export to not be the 64-bit versions, our dlsym to\n> get the original open and mmap calls will not automatically be converted\n> to their 64-bit versions. Since we intercept both 32-bit and 64-bit\n> versions of open and mmap, we should be using the 64-bit version to\n> service both. Fetch the 64-bit versions of openat and mmap directly.\n> \n> musl defines the 64-bit symbols as macros that are equivalent to the\n> non-64-bit symbols, so we put compile guards that check if the 64-bit\n> symbols are defined.\n> \n> Signed-off-by: Paul Elder \n> Reviewed-by: Niklas Söderlund \n> Tested-by: Laurent Pinchart # Compile with musl\n> Reviewed-by: Laurent Pinchart \n> \n> ---\n> Changes in v3:\n> - add __open64_2 and __openat64_2\n> \n> Changes in v2:\n> - squash intercept 64-bit calls and use 64-bit calls into\n> this one patch\n> - use off64_t instead of __off64_t\n> - add compile guard to get musl to play nicely with the 64-bit calls\n> coexisting with the non-64-bit calls\n> ---\n> src/v4l2/meson.build | 1 +\n> src/v4l2/v4l2_camera_proxy.cpp | 2 +-\n> src/v4l2/v4l2_camera_proxy.h | 3 +-\n> src/v4l2/v4l2_compat.cpp | 47 ++++++++++++++++++++++++++++++++\n> src/v4l2/v4l2_compat_manager.cpp | 6 ++--\n> src/v4l2/v4l2_compat_manager.h | 5 ++--\n> 6 files changed, 57 insertions(+), 7 deletions(-)\n> \n> diff --git a/src/v4l2/meson.build b/src/v4l2/meson.build\n> index 0fb941e..f2e4aaf 100644\n> --- a/src/v4l2/meson.build\n> +++ b/src/v4l2/meson.build\n> @@ -15,6 +15,7 @@ v4l2_compat_cpp_args = [\n> # file operations, disable transparent large file support.\n> '-U_FILE_OFFSET_BITS',\n> '-D_FILE_OFFSET_BITS=32',\n> + '-D_LARGEFILE64_SOURCE',\n> '-fvisibility=hidden',\n> ]\n> \n> diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp\n> index d7f14e6..7425029 100644\n> --- a/src/v4l2/v4l2_camera_proxy.cpp\n> +++ b/src/v4l2/v4l2_camera_proxy.cpp\n> @@ -75,7 +75,7 @@ void V4L2CameraProxy::close()\n> }\n> \n> void *V4L2CameraProxy::mmap(void *addr, size_t length, int prot, int flags,\n> -\t\t\t off_t offset)\n> +\t\t\t off64_t offset)\n> {\n> \tLOG(V4L2Compat, Debug) << \"Servicing mmap\";\n> \n> diff --git a/src/v4l2/v4l2_camera_proxy.h b/src/v4l2/v4l2_camera_proxy.h\n> index 7c65c88..27d3e50 100644\n> --- a/src/v4l2/v4l2_camera_proxy.h\n> +++ b/src/v4l2/v4l2_camera_proxy.h\n> @@ -11,6 +11,7 @@\n> #include \n> #include \n> #include \n> +#include \n> #include \n> #include \n> \n> @@ -28,7 +29,7 @@ public:\n> \tint open(bool nonBlocking);\n> \tvoid dup();\n> \tvoid close();\n> -\tvoid *mmap(void *addr, size_t length, int prot, int flags, off_t offset);\n> +\tvoid *mmap(void *addr, size_t length, int prot, int flags, off64_t offset);\n> \tint munmap(void *addr, size_t length);\n> \n> \tint ioctl(unsigned long request, void *arg);\n> diff --git a/src/v4l2/v4l2_compat.cpp b/src/v4l2/v4l2_compat.cpp\n> index 2a9a176..2e80de5 100644\n> --- a/src/v4l2/v4l2_compat.cpp\n> +++ b/src/v4l2/v4l2_compat.cpp\n> @@ -38,12 +38,31 @@ LIBCAMERA_PUBLIC int open(const char *path, int oflag, ...)\n> \t\t\t\t\t\t oflag, mode);\n> }\n> \n> +#ifndef open64\n> +LIBCAMERA_PUBLIC int open64(const char *path, int oflag, ...)\n> +{\n> +\tmode_t mode = 0;\n> +\tif (oflag & O_CREAT || oflag & O_TMPFILE)\n> +\t\textract_va_arg(mode_t, mode, oflag);\n> +\n> +\treturn V4L2CompatManager::instance()->openat(AT_FDCWD, path,\n> +\t\t\t\t\t\t oflag | O_LARGEFILE, mode);\n> +}\n> +#endif\n> +\n> /* _FORTIFY_SOURCE redirects open to __open_2 */\n> LIBCAMERA_PUBLIC int __open_2(const char *path, int oflag)\n> {\n> \treturn open(path, oflag);\n> }\n> \n> +#ifndef __open64_2\n\nI think this should be open64, not __open64_2. open64 is defined as a\nmacro in musl, which doesn't support FORTIFY_SOURCE, and thus doesn't\ndefine __open64_2. #ifndef __open64_2 will always be true, so we would\nexpose an unneeded symbol when compiled against musl.\n\nI would also move the open64 function below __open_2, so you can group\nopen64 and __open64_2 in a single conditional block.\n\nSame for openat64.\n\n> +LIBCAMERA_PUBLIC int __open64_2(const char *path, int oflag)\n> +{\n> +\treturn open(path, oflag);\n> +}\n> +#endif\n> +\n> LIBCAMERA_PUBLIC int openat(int dirfd, const char *path, int oflag, ...)\n> {\n> \tmode_t mode = 0;\n> @@ -53,11 +72,30 @@ LIBCAMERA_PUBLIC int openat(int dirfd, const char *path, int oflag, ...)\n> \treturn V4L2CompatManager::instance()->openat(dirfd, path, oflag, mode);\n> }\n> \n> +#ifndef openat64\n> +LIBCAMERA_PUBLIC int openat64(int dirfd, const char *path, int oflag, ...)\n> +{\n> +\tmode_t mode = 0;\n> +\tif (oflag & O_CREAT || oflag & O_TMPFILE)\n> +\t\textract_va_arg(mode_t, mode, oflag);\n> +\n> +\treturn V4L2CompatManager::instance()->openat(dirfd, path,\n> +\t\t\t\t\t\t oflag | O_LARGEFILE, mode);\n> +}\n> +#endif\n> +\n> LIBCAMERA_PUBLIC int __openat_2(int dirfd, const char *path, int oflag)\n> {\n> \treturn openat(dirfd, path, oflag);\n> }\n> \n> +#ifndef __openat64_2\n> +LIBCAMERA_PUBLIC int __openat64_2(int dirfd, const char *path, int oflag)\n> +{\n> +\treturn openat(dirfd, path, oflag);\n> +}\n> +#endif\n> +\n> LIBCAMERA_PUBLIC int dup(int oldfd)\n> {\n> \treturn V4L2CompatManager::instance()->dup(oldfd);\n> @@ -75,6 +113,15 @@ LIBCAMERA_PUBLIC void *mmap(void *addr, size_t length, int prot, int flags,\n> \t\t\t\t\t\t fd, offset);\n> }\n> \n> +#ifndef mmap64\n> +LIBCAMERA_PUBLIC void *mmap64(void *addr, size_t length, int prot, int flags,\n> +\t\t\t int fd, off64_t offset)\n> +{\n> +\treturn V4L2CompatManager::instance()->mmap(addr, length, prot, flags,\n> +\t\t\t\t\t\t fd, offset);\n> +}\n> +#endif\n> +\n> LIBCAMERA_PUBLIC int munmap(void *addr, size_t length)\n> {\n> \treturn V4L2CompatManager::instance()->munmap(addr, length);\n> diff --git a/src/v4l2/v4l2_compat_manager.cpp b/src/v4l2/v4l2_compat_manager.cpp\n> index 56533c4..8da3316 100644\n> --- a/src/v4l2/v4l2_compat_manager.cpp\n> +++ b/src/v4l2/v4l2_compat_manager.cpp\n> @@ -39,11 +39,11 @@ void get_symbol(T &func, const char *name)\n> V4L2CompatManager::V4L2CompatManager()\n> \t: cm_(nullptr)\n> {\n> -\tget_symbol(fops_.openat, \"openat\");\n> +\tget_symbol(fops_.openat, \"openat64\");\n> \tget_symbol(fops_.dup, \"dup\");\n> \tget_symbol(fops_.close, \"close\");\n> \tget_symbol(fops_.ioctl, \"ioctl\");\n> -\tget_symbol(fops_.mmap, \"mmap\");\n> +\tget_symbol(fops_.mmap, \"mmap64\");\n> \tget_symbol(fops_.munmap, \"munmap\");\n> }\n> \n> @@ -200,7 +200,7 @@ int V4L2CompatManager::close(int fd)\n> }\n> \n> void *V4L2CompatManager::mmap(void *addr, size_t length, int prot, int flags,\n> -\t\t\t int fd, off_t offset)\n> +\t\t\t int fd, off64_t offset)\n> {\n> \tV4L2CameraProxy *proxy = getProxy(fd);\n> \tif (!proxy)\n> diff --git a/src/v4l2/v4l2_compat_manager.h b/src/v4l2/v4l2_compat_manager.h\n> index 14338a5..3d4e512 100644\n> --- a/src/v4l2/v4l2_compat_manager.h\n> +++ b/src/v4l2/v4l2_compat_manager.h\n> @@ -11,6 +11,7 @@\n> #include \n> #include \n> #include \n> +#include \n> #include \n> #include \n> \n> @@ -30,7 +31,7 @@ public:\n> \t\tusing close_func_t = int (*)(int fd);\n> \t\tusing ioctl_func_t = int (*)(int fd, unsigned long request, ...);\n> \t\tusing mmap_func_t = void *(*)(void *addr, size_t length, int prot,\n> -\t\t\t\t\t int flags, int fd, off_t offset);\n> +\t\t\t\t\t int flags, int fd, off64_t offset);\n> \t\tusing munmap_func_t = int (*)(void *addr, size_t length);\n> \n> \t\topenat_func_t openat;\n> @@ -51,7 +52,7 @@ public:\n> \tint dup(int oldfd);\n> \tint close(int fd);\n> \tvoid *mmap(void *addr, size_t length, int prot, int flags,\n> -\t\t int fd, off_t offset);\n> +\t\t int fd, off64_t offset);\n> \tint munmap(void *addr, size_t length);\n> \tint ioctl(int fd, unsigned long request, void *arg);\n> \n> -- \n> 2.27.0\n>","headers":{"Return-Path":"","Received":["from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 05B7A603C1\n\tfor ;\n\tThu, 18 Jun 2020 12:31:43 +0200 (CEST)","from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi\n\t[81.175.216.236])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 6C809F9;\n\tThu, 18 Jun 2020 12:31:42 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"vWeCwW6/\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1592476302;\n\tbh=qhgtrUIkV+qoHEtezeKcOfzYGERS67IYgh1ZrXn+284=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=vWeCwW6/ZUuikF6grmE5NBj2japME2sZoIeJl9FdUC+HTOJW5cbMNWNOjpow9S9Zq\n\tFdZIZn3qM162XFRDN3TF8jkHfpEeZ+iL34RXpVR3C2b4kEKTqoLc1xM8Trt7Shawpy\n\t1u6J/bXvix9CqfRsRJs7SFyORW6pEThAQ5ZQIWR4=","Date":"Thu, 18 Jun 2020 13:31:19 +0300","From":"Laurent Pinchart ","To":"Paul Elder ","Cc":"libcamera-devel@lists.libcamera.org, Niklas =?utf-8?q?S=C3=B6derlund?=\n\t","Message-ID":"<20200618103119.GC5959@pendragon.ideasonboard.com>","References":"<20200618100811.22111-1-paul.elder@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; 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