NAME
read - read from file
SYNOPSIS
(read = 3.)
(file descriptor in r0)
sys read; buffer; nbytes
read(fildes, buffer, nbytes)
char *buffer;
DESCRIPTION
A file descriptor is a word returned from a successful open,
creat, dup, or pipe call. Buffer is the location of nbytes
contiguous bytes into which the input will be placed. It is
not guaranteed that all nbytes bytes will be read; for exam-
ple if the file refers to a typewriter at most one line will
be returned. In any event the number of characters read is
returned (in r0).
If the returned value is 0, then end-of-file has been
reached.
SEE ALSO
open (II), creat (II), dup (II), pipe (II)
DIAGNOSTICS
As mentioned, 0 is returned when the end of the file has
been reached. If the read was otherwise unsuccessful the
error bit (c-bit) is set. Many conditions can generate an
error: physical I/O errors, bad buffer address, preposterous
nbytes, file descriptor not that of an input file. From C,
a -1 return indicates the error.
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