Improved subprocess error handling.

- Added --errorlog argument to log subprocess errors.
- Check if rtmpdump has --jtv argument when needed.

2 files changed, 39 insertions, 6 deletions

diff --git a/src/livestreamer/cli.py b/src/livestreamer/cli.py
index f610101..cf96a29 100644
--- a/src/livestreamer/cli.py
+++ b/src/livestreamer/cli.py
@@ -13,6 +13,7 @@ parser.add_argument("-o", "--output", metavar="filename", help="Write stream to
 parser.add_argument("-f", "--force", action="store_true", help="Always write to file even if it already exists")
 parser.add_argument("-O", "--stdout", action="store_true", help="Write stream to stdout instead of playing it")
 parser.add_argument("-c", "--cmdline", action="store_true", help="Print command-line used internally to play stream, this may not be available on all streams")
+parser.add_argument("-e", "--errorlog", action="store_true", help="Log possible errors from internal command-line to a temporary file, use when debugging")
 parser.add_argument("-l", "--plugins", action="store_true", help="Print all currently installed plugins")
 
 RCFILE = os.path.expanduser("~/.livestreamerrc")
@@ -75,7 +76,7 @@ def output_stream(stream, args):
     out = None
 
     try:
-        fd = stream.open()
+        fd = stream.open(errorlog=args.errorlog)
     except livestreamer.StreamError as err:
         exit(("Could not open stream - {0}").format(err))
 
diff --git a/src/livestreamer/stream.py b/src/livestreamer/stream.py
index 03949f2..8dd4115 100644
--- a/src/livestreamer/stream.py
+++ b/src/livestreamer/stream.py
@@ -2,24 +2,43 @@ from livestreamer.utils import urlopen
 
 import os
 import pbs
+import time
+import tempfile
 
 class StreamError(Exception):
     pass
 
 class Stream(object):
-    def open(self):
+    def open(self, **args):
        raise NotImplementedError
 
 class StreamProcess(Stream):
     def __init__(self, params):
         self.params = params or {}
+        self.params["_bg"] = True
+        self.params["_err"] = open(os.devnull, "w")
 
     def cmdline(self):
         return str(self.cmd.bake(**self.params))
 
-    def open(self):
+    def open(self, errorlog=False):
+        if errorlog:
+            tmpfile = tempfile.NamedTemporaryFile(prefix="livestreamer",
+                                                  suffix=".err", delete=False)
+            self.params["_err"] = tmpfile
+
         stream = self.cmd(**self.params)
 
+        # Wait 0.5 seconds to see if program exited prematurely
+        time.sleep(0.5)
+        stream.process.poll()
+
+        if stream.process.returncode is not None:
+            if errorlog:
+                raise StreamError(("Error while executing subprocess, error output logged to: {0}").format(tmpfile.name))
+            else:
+                raise StreamError("Error while executing subprocess")
+
         return stream.process.stdout
 
 class RTMPStream(StreamProcess):
@@ -27,18 +46,31 @@ class RTMPStream(StreamProcess):
         StreamProcess.__init__(self, params)
 
         self.params["flv"] = "-"
-        self.params["_bg"] = True
-        self.params["_err"] = open(os.devnull, "w")
 
         try:
             self.cmd = pbs.rtmpdump
         except pbs.CommandNotFound:
             raise StreamError("Unable to find 'rtmpdump' command")
 
+    def open(self, **args):
+        if "jtv" in self.params and not self._has_jtv_support():
+            raise StreamError("Installed rtmpdump does not support --jtv argument")
+
+        return StreamProcess.open(self, **args)
+
+    def _has_jtv_support(self):
+        help = self.cmd(help=True, _err_to_out=True)
+
+        for line in help.split("\n"):
+            if line[:5] == "--jtv":
+                return True
+
+        return False
+
 class HTTPStream(Stream):
     def __init__(self, url):
         self.url = url
 
-    def open(self):
+    def open(self, **args):
         return urlopen(self.url)