Subject: Bug when running transcode from httpd
Date: Thursday 16th February 2006 03:59:45 UTC (over 10 years ago)
Ok, this is a little involved, so hang with me. I'm pretty sure I've found a problem in 1.0.2 and current CVS HEAD. The root of the problem is the file descriptor abstraction in libxio, mixed with the usage of fdopen. In tcprobe.c, when probe_path returns TC_PROBE_PATH_FILE, xio_open() is called to open the input file. In this case, this is the first file to be opened by tcprobe so 3 is used for the abstracted descriptor (ret_fd) inside libxio.c xio_open(). When the unix io fallback is used, _handles->data is set to the file descriptor open() returns. This works fine IF AND ONLY IF open returns the same value as ret_fd (3 in this case) -- see below. In my case, when transcode is run from a script spawned by httpd, open() returns 15. So the file is open on file descriptor 15 and xio_open returns 3 to ipipe.fd_in @ tcprobe.c:251 Next &ipipe is passed to tcprobe_thread(), which calls probe_pes(). At scan_pes.c:530, ipipe->fd_in is used in a call to fdopen to get a FILE* -- but ipipe->fd_in is 3 (the abstracted file descriptor returned by xio_open) -- not the REAL file descriptor, that's 15. The subsequent calls to fread all fail, causing all sorts of bad things to happen. Is my logic wrong? I'll work on a patch. David.