[Spice-devel] [PATCH 05/17] Use RAII to cleanup stream in case of exception or return
Jonathon Jongsma
jjongsma at redhat.com
Tue Feb 20 21:38:06 UTC 2018
On Fri, 2018-02-16 at 17:15 +0100, Christophe de Dinechin wrote:
> From: Christophe de Dinechin <dinechin at redhat.com>
>
> Get rid of C-style 'goto done' in do_capture.
> Get rid of global streamfd, pass it around (cleaned up in later
> patch)
> Fixes a race condition, make sure we only use stream after opening
>
> Signed-off-by: Christophe de Dinechin <dinechin at redhat.com>
> ---
> src/spice-streaming-agent.cpp | 79 +++++++++++++++++++++++++------
> ------------
> 1 file changed, 47 insertions(+), 32 deletions(-)
>
> diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-
> agent.cpp
> index 646d15b..9b8fd45 100644
> --- a/src/spice-streaming-agent.cpp
> +++ b/src/spice-streaming-agent.cpp
> @@ -53,14 +53,38 @@ struct SpiceStreamDataMessage
> StreamMsgData msg;
> };
>
> +struct SpiceStreamCursorMessage
> +{
> + StreamDevHeader hdr;
> + StreamMsgCursorSet msg;
> +};
> +
> +class Stream
> +{
> +public:
> + Stream(const char *name)
> + {
> + fd = open(name, O_RDWR);
> + if (fd < 0)
> + throw std::runtime_error("failed to open streaming
> device");
> + }
> + ~Stream()
> + {
> + close(fd);
> + }
> + operator int() { return fd; }
> +
> +private:
> + int fd = -1;
> +};
What about making the 'Stream' constructor take an fd so that the same
class can be used to encapsulate e.g. socket fds as well?
> +
> static bool streaming_requested = false;
> static bool quit_requested = false;
> static bool log_binary = false;
> static std::set<SpiceVideoCodecType> client_codecs;
> -static int streamfd = -1;
> static std::mutex stream_mtx;
>
> -static int have_something_to_read(int timeout)
> +static int have_something_to_read(int streamfd, int timeout)
> {
> struct pollfd pollfd = {streamfd, POLLIN, 0};
>
> @@ -76,7 +100,7 @@ static int have_something_to_read(int timeout)
> return 0;
> }
>
> -static int read_command_from_device(void)
> +static int read_command_from_device(int streamfd)
> {
> StreamDevHeader hdr;
> uint8_t msg[64];
> @@ -121,18 +145,18 @@ static int read_command_from_device(void)
> return 1;
> }
>
> -static int read_command(bool blocking)
> +static int read_command(int streamfd, bool blocking)
> {
> int timeout = blocking?-1:0;
> while (!quit_requested) {
> - if (!have_something_to_read(timeout)) {
> + if (!have_something_to_read(streamfd, timeout)) {
> if (!blocking) {
> return 0;
> }
> sleep(1);
> continue;
> }
> - return read_command_from_device();
> + return read_command_from_device(streamfd);
> }
>
> return 1;
> @@ -157,7 +181,7 @@ write_all(int fd, const void *buf, const size_t
> len)
> return written;
> }
>
> -static int spice_stream_send_format(unsigned w, unsigned h, unsigned
> c)
> +static int spice_stream_send_format(int streamfd, unsigned w,
> unsigned h, unsigned c)
> {
>
> SpiceStreamFormatMessage msg;
> @@ -178,7 +202,7 @@ static int spice_stream_send_format(unsigned w,
> unsigned h, unsigned c)
> return EXIT_SUCCESS;
> }
>
> -static int spice_stream_send_frame(const void *buf, const unsigned
> size)
> +static int spice_stream_send_frame(int streamfd, const void *buf,
> const unsigned size)
> {
> SpiceStreamDataMessage msg;
> const size_t msgsize = sizeof(msg);
> @@ -254,7 +278,7 @@ static void usage(const char *progname)
> }
>
> static void
> -send_cursor(unsigned width, unsigned height, int hotspot_x, int
> hotspot_y,
> +send_cursor(int streamfd, unsigned width, unsigned height, int
> hotspot_x, int hotspot_y,
> std::function<void(uint32_t *)> fill_cursor)
> {
> if (width >= STREAM_MSG_CURSOR_SET_MAX_WIDTH ||
> @@ -288,7 +312,7 @@ send_cursor(unsigned width, unsigned height, int
> hotspot_x, int hotspot_y,
> write_all(streamfd, msg.get(), cursor_size);
> }
>
> -static void cursor_changes(Display *display, int event_base)
> +static void cursor_changes(int streamfd, Display *display, int
> event_base)
> {
> unsigned long last_serial = 0;
>
> @@ -310,25 +334,20 @@ static void cursor_changes(Display *display,
> int event_base)
> for (unsigned i = 0; i < cursor->width * cursor->height;
> ++i)
> pixels[i] = cursor->pixels[i];
> };
> - send_cursor(cursor->width, cursor->height, cursor->xhot,
> cursor->yhot, fill_cursor);
> + send_cursor(streamfd,
> + cursor->width, cursor->height, cursor->xhot,
> cursor->yhot, fill_cursor);
> }
> }
>
> static void
> -do_capture(const char *streamport, FILE *f_log)
> +do_capture(int streamfd, const char *streamport, FILE *f_log)
> {
> - streamfd = open(streamport, O_RDWR);
> - if (streamfd < 0)
> - throw std::runtime_error("failed to open the streaming
> device (" +
> - std::string(streamport) + "): "
> - + strerror(errno));
> -
> unsigned int frame_count = 0;
> while (!quit_requested) {
> while (!quit_requested && !streaming_requested) {
> - if (read_command(true) < 0) {
> + if (read_command(streamfd, true) < 0) {
> syslog(LOG_ERR, "FAILED to read command\n");
> - goto done;
> + return;
> }
> }
>
> @@ -370,7 +389,7 @@ do_capture(const char *streamport, FILE *f_log)
>
> syslog(LOG_DEBUG, "wXh %uX%u codec=%u\n", width,
> height, codec);
>
> - if (spice_stream_send_format(width, height, codec)
> == EXIT_FAILURE)
> + if (spice_stream_send_format(streamfd, width,
> height, codec) == EXIT_FAILURE)
> throw std::runtime_error("FAILED to send format
> message");
> }
> if (f_log) {
> @@ -382,23 +401,18 @@ do_capture(const char *streamport, FILE *f_log)
> hexdump(frame.buffer, frame.buffer_size, f_log);
> }
> }
> - if (spice_stream_send_frame(frame.buffer,
> frame.buffer_size) == EXIT_FAILURE) {
> + if (spice_stream_send_frame(streamfd,
> + frame.buffer,
> frame.buffer_size) == EXIT_FAILURE) {
> syslog(LOG_ERR, "FAILED to send a frame\n");
> break;
> }
> //usleep(1);
> - if (read_command(false) < 0) {
> + if (read_command(streamfd, false) < 0) {
> syslog(LOG_ERR, "FAILED to read command\n");
> - goto done;
> + return;
> }
> }
> }
> -
> -done:
> - if (streamfd >= 0) {
> - close(streamfd);
> - streamfd = -1;
> - }
> }
>
> #define arg_error(...) syslog(LOG_ERR, ## __VA_ARGS__);
> @@ -481,12 +495,13 @@ int main(int argc, char* argv[])
> Window rootwindow = DefaultRootWindow(display);
> XFixesSelectCursorInput(display, rootwindow,
> XFixesDisplayCursorNotifyMask);
>
> - std::thread cursor_th(cursor_changes, display, event_base);
> + Stream streamfd(streamport);
> + std::thread cursor_th(cursor_changes, (int) streamfd, display,
> event_base);
> cursor_th.detach();
>
> int ret = EXIT_SUCCESS;
> try {
> - do_capture(streamport, f_log);
> + do_capture(streamfd, streamport, f_log);
> }
> catch (std::runtime_error &err) {
> syslog(LOG_ERR, "%s\n", err.what());
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