[PATCH spice-streaming-agent] Use RAII to cleanup stream in case of exception or return

[Christophe de Dinechin <christophe@xxxxxxxxxxxx>]

From: Christophe de Dinechin <dinechin@xxxxxxxxxx>

This lets us get rid of C-style 'goto done' in do_capture.

Signed-off-by: Christophe de Dinechin <dinechin@xxxxxxxxxx>
---
 src/spice-streaming-agent.cpp | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
index ed7ddb9..e2719fa 100644
--- a/src/spice-streaming-agent.cpp
+++ b/src/spice-streaming-agent.cpp
@@ -348,17 +348,30 @@ do_capture(const char *streamport, FILE *f_log)
     if (!capture)
         throw std::runtime_error("cannot find a suitable capture system");
 
-    streamfd = open(streamport, O_RDWR);
-    if (streamfd < 0)
-        // TODO was syslog(LOG_ERR, "Failed to open %s: %s\n", streamport, strerror(errno));
-        throw std::runtime_error("failed to open streaming device");
+    struct Stream
+    {
+        Stream(const char *name, int &fd): fd(fd)
+        {
+            fd = open(name, O_RDWR);
+            if (fd < 0)
+                throw std::runtime_error("failed to open streaming device");
+        }
+        ~Stream()
+        {
+            if (fd >= 0)
+                close(fd);
+            fd = -1;
+        }
+        int &fd;
+    }
+    stream(streamport, streamfd);
 
     unsigned int frame_count = 0;
     while (! quit) {
         while (!quit && !streaming_requested) {
             if (read_command(1) < 0) {
                 syslog(LOG_ERR, "FAILED to read command\n");
-                goto done;
+                return;
             }
         }
 
@@ -409,19 +422,13 @@ do_capture(const char *streamport, FILE *f_log)
             //usleep(1);
             if (read_command(0) < 0) {
                 syslog(LOG_ERR, "FAILED to read command\n");
-                goto done;
+                return;
             }
             if (!streaming_requested) {
                 capture->Reset();
             }
         }
     }
-
-done:
-    if (streamfd >= 0) {
-        close(streamfd);
-        streamfd = -1;
-    }
 }
 
 #define arg_error(...) syslog(LOG_ERR, ## __VA_ARGS__);
@@ -441,7 +448,7 @@ int main(int argc, char* argv[])
     if (isatty(fileno(stderr)) && isatty(fileno(stdin))) {
         stdin_ok = true;
     }
-    
+
     openlog("spice-streaming-agent", stdin_ok? (LOG_PERROR|LOG_PID) : LOG_PID, LOG_USER);
     setlogmask(logmask);
 
@@ -526,4 +533,3 @@ int main(int argc, char* argv[])
     closelog();
     return ret;
 }
-
-- 
2.13.5 (Apple Git-94)

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