On Feb 26 22:05, Ken Brown wrote: > I'm not sure exactly where the bug is, but here's what happens (STC at the > end): > > 1. I use freopen to open a file "foo" and associate it with stdin. > > 2. I use fread to read a byte from foo. > > 3. I call popen, expecting the child process to have foo as its stdin, with > the file-position indicator pointing to the second byte. But instead the > child sees an empty stdin. > > If I omit step 2, the child process does indeed have foo as its stdin. Are > my expectations wrong, or is this a bug?
Wrong expectations. Keep in mind that the default read mode using stdio functions is buffered. So your fread fills the buffer in f. The buffer is typically something like 1K or 4K. If the file is shorter than that, the file pointer will be set to EOF when calling popen. Try this before calling fread: setvbuf(f, NULL, _IONBF, 0); Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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