The fgets() function shall read bytes from stream into the array
pointed to by s, until n-1 bytes are read, or a <newline>
is read and transferred to s, or an end-of-file condition is
encountered. The string is then terminated with a null byte.
The fgets() function may mark the st_atime field of the file
associated with stream for update. The st_atime field shall be
marked for update by the first successful execution of fgetc(),
fgets(), fgetwc(), fgetws(), fread(),
fscanf(), getc(), getchar(), gets(), or
scanf() using stream that returns data not supplied by a prior
call to ungetc() or ungetwc().
Upon successful completion, fgets() shall return s. If the stream
is at end-of-file, the end-of-file indicator for the stream shall be set and
fgets() shall return a null pointer. If a read error occurs, the error
indicator for the stream shall be set, fgets() shall return a null
pointer, and shall set errno to indicate the error.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html