Unbuffered Stdio Input

[Paul Breslaw]

I have a little program that opens a master side pty and reads from it.
I have another little program that opens the corresponding slave side
and writes to it.

If the master side is coded something like:-

    FILE *f;
    char buf[ BF ];
    int  nr;

    f = fopen( master, "a+" );
    nr = fread( buf, sizeof( char ), BF, f );

then the program hangs on the fread.

If, however, I replace the last line with

    nr = read( fileno( f ), buf, BF );

then the read succeeds. An optional 

    setbuf( f, NULL );

does not alter the situation.

I have tested the program on an HP9000/340 (HP-UX 6.5) and a 
Sun3/50 (SunOS 3.5) with not quite identical non-events :-)

Any suggestions what I've done wrong?


Paul Breslaw




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Paul Breslaw, Mecasoft SA,          |  telephone :  41 1 362 2040
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