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diff packages/net/tcpip/current/doc/read.html @ 97:ced4577552cd ecos-sw-2000-06-06

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Merge from eCos master repository on 2000-06-06-08:44:00-BST
author jlarmour
date Tue, 06 Jun 2000 08:39:36 +0000
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+<html>
+<body>
+<pre>
+NAME
+       read - read from a file descriptor
+
+SYNOPSIS
+       ssize_t read(int fd, void *buf, size_t count);
+
+DESCRIPTION
+       read()  attempts  to  read  up  to  count  bytes from file
+       descriptor fd into the buffer starting at buf.
+
+       If count is zero, read() returns zero  and  has  no  other
+       results.
+
+
+RETURN VALUE
+       On success, the number of bytes  read  is  returned  (zero
+       indicates  end of file), and the file position is advanced
+       by this number.  It is not an  error  if  this  number  is
+       smaller  than the number of bytes requested; this may hap-
+       pen for example because fewer bytes are actually available
+       right  now (maybe because we were close to end-of-file, or
+       because we are reading from a pipe, or from  a  terminal),
+       or  because read() was interrupted by a signal.  On error,
+       -1 is returned, and errno is set  appropriately.  In  this
+       case  it is left unspecified whether the file position (if
+       any) changes.
+
+ERRORS
+       EINTR   The call was interrupted by a  signal  before  any
+               data was read.
+
+       EAGAIN  Non-blocking  I/O  has  been selected using O_NON-
+               BLOCK and no data was  immediately  available  for
+               reading.
+
+       EIO     I/O  error.  This will happen for example when the
+               process is in a background process group, tries to
+               read  from  its  controlling tty, and either it is
+               ignoring or blocking SIGTTIN or its process  group
+               is  orphaned.   It  may also occur when there is a
+               low-level I/O error while reading from a  disk  or
+               tape.
+
+       EISDIR  fd refers to a directory.
+
+       EBADF   fd  is  not a valid file descriptor or is not open
+               for reading.
+
+       EINVAL  fd is attached to an object  which  is  unsuitable
+               for reading.
+
+       Other  errors may occur, depending on the object connected
+       to fd.  POSIX allows a  read  that  is  interrupted  after
+       reading  some  data to return -1 (with errno set to EINTR)
+       or to return the number of bytes already read.
+</pre>
+</body>
+</html>