fseek man page on SmartOS

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FSEEK(3C)							     FSEEK(3C)

NAME
       fseek, fseeko - reposition a file-position indicator in a stream

SYNOPSIS
       #include <stdio.h>

       int fseek(FILE *stream, long offset, int whence);

       int fseeko(FILE *stream, off_t offset, int whence);

DESCRIPTION
       The  fseek()  function  sets the file-position indicator for the stream
       pointed to by stream. The fseeko() function  is	identical  to  fseek()
       except for the type of offset.

       The  new position, measured in bytes from the beginning of the file, is
       obtained by adding offset to the position specified  by	whence,	 whose
       values are defined in <stdio.h> as follows:

       SEEK_SET
		   Set position equal to offset bytes.

       SEEK_CUR
		   Set position to current location plus offset.

       SEEK_END
		   Set position to EOF plus offset.

       If the stream is to be used with wide character input/output functions,
       offset must either be 0 or a value  returned  by	 an  earlier  call  to
       ftell(3C) on the same stream and whence must be SEEK_SET.

       A  successful  call to fseek() clears the end-of-file indicator for the
       stream and undoes any effects of ungetc(3C) and ungetwc(3C) on the same
       stream.	 After an fseek() call, the next operation on an update stream
       may be either input or output.

       If the most recent operation, other than ftell(3C), on a	 given	stream
       is  fflush(3C), the file offset in the underlying open file description
       will be adjusted to reflect the location specified by fseek().

       The fseek() function allows  the	 file-position	indicator  to  be  set
       beyond  the  end of existing data in the file. If data is later written
       at this point, subsequent reads of data in the gap  will	 return	 bytes
       with the value 0 until data is actually written into the gap.

       The  value  of the file offset returned by fseek() on devices which are
       incapable of seeking is undefined.

       If the stream is writable and buffered data had not been written to the
       underlying file, fseek() will cause the unwritten data to be written to
       the file and mark the st_ctime and st_mtime  fields  of	the  file  for
       update.

RETURN VALUES
       The fseek() and fseeko() functions return 0 on success; otherwise, they
       returned −1 and set errno to indicate the error.

ERRORS
       The fseek() and fseeko() functions will fail if, either the  stream  is
       unbuffered or the stream's buffer needed to be flushed, and the call to
       fseek() or fseeko() causes an underlying lseek(2)  or  write(2)	to  be
       invoked:

       EAGAIN
		 The  O_NONBLOCK  flag	is set for the file descriptor and the
		 process would be delayed in the write operation.

       EBADF
		 The file descriptor underlying the stream file	 is  not  open
		 for  writing  or the stream's buffer needed to be flushed and
		 the file is not open.

       EFBIG
		 An attempt was made to write a file that exceeds the  maximum
		 file  size or the process's file size limit, or the file is a
		 regular file and an attempt was made to write	at  or	beyond
		 the offset maximum associated with the corresponding stream.

       EINTR
		 The  write  operation	was terminated due to the receipt of a
		 signal, and no data was transferred.

       EINVAL
		 The whence argument is invalid. The  resulting	 file-position
		 indicator would be set to a negative value.

       EIO
		 A physical I/O error has occurred; or the process is a member
		 of  a	background  process  group  attempting	to  perform  a
		 write(2)  operation  to  its  controlling terminal, TOSTOP is
		 set, the process is neither ignoring  nor  blocking  SIGTTOU,
		 and the process group of the process is orphaned.

       ENOSPC
		 There	was  no	 free space remaining on the device containing
		 the file.

       ENXIO
		 A request was made of a non-existent device, or  the  request
		 was outside the capabilities of the device.

       EPIPE
		 The  file  descriptor	underlying stream is associated with a
		 pipe or FIFO.

       EPIPE
		 An attempt was made to write to a pipe or FIFO	 that  is  not
		 open  for  reading by any process. A SIGPIPE signal will also
		 be sent to the calling thread.

       The fseek() function will fail if:

       EOVERFLOW
		    The resulting file offset would be a value which cannot be
		    represented correctly in an object of type long.

       The fseeko() function will fail if:

       EOVERFLOW
		    The resulting file offset would be a value which cannot be
		    represented correctly in an object of type off_t.

USAGE
       Although on the UNIX system an offset returned by ftell()  or  ftello()
       (see  ftell(3C)) is measured in bytes, and it is permissible to seek to
       positions relative to that  offset,  portability	 to  non-UNIX  systems
       requires	 that  an  offset be used by fseek() directly.	Arithmetic may
       not meaningfully be performed on such an offset, which is not necessar‐
       ily measured in bytes.

       The fseeko() function has a transitional interface for 64-bit file off‐
       sets.  See lf64(5).

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       ┌────────────────────┬─────────────────┐
       │  ATTRIBUTE TYPE    │ ATTRIBUTE VALUE │
       ├────────────────────┼─────────────────┤
       │Interface Stability │ Standard	      │
       ├────────────────────┼─────────────────┤
       │MT-Level	    │ MT-Safe	      │
       └────────────────────┴─────────────────┘

SEE ALSO
       getrlimit(2),   ulimit(2),    fopen(3UCB),    ftell(3C),	   rewind(3C),
       ungetc(3C), ungetwc(3C), attributes(5), lf64(5), standards(5)

				  Nov 1, 2003			     FSEEK(3C)
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