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+ * Copyright (c) 1998-2017,2018 Free Software Foundation, Inc. *
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- * @Id: curs_getstr.3x,v 1.21 2017/02/18 16:37:18 tom Exp @
+ * @Id: curs_getstr.3x,v 1.26 2018/09/01 20:34:52 tom Exp @
+ * X/Open says also until EOf
+ * X/Open says then an EOS is added to the result
+ * X/Open doesn't mention n<0
-->
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The function <STRONG>getstr</STRONG> is equivalent to a series of calls to <STRONG>getch</STRONG>, until
a newline or carriage return is received (the terminating character is
not included in the returned string). The resulting value is placed in
- the area pointed to by the character pointer <EM>str</EM>.
+ the area pointed to by the character pointer <EM>str</EM>, followed by a NUL.
<STRONG>wgetnstr</STRONG> reads at most <EM>n</EM> characters, thus preventing a possible over-
flow of the input buffer. Any attempt to enter more characters (other
In this implementation, these functions return an error if the window
pointer is null, or if its timeout expires without having any data.
- This implementation provides an extension as well. If a SIGWINCH in-
+ This implementation provides an extension as well. If a <STRONG>SIGWINCH</STRONG> in-
terrupts the function, it will return <STRONG>KEY_RESIZE</STRONG> rather than <STRONG>OK</STRONG> or <STRONG>ERR</STRONG>.
Functions with a "mv" prefix first perform a cursor movement using
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
These functions are described in the XSI Curses standard, Issue 4.
They read single-byte characters only. The standard does not define
- any error conditions. This implementation returns ERR if the window
- pointer is null, or if the lower-level <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG> call returns an ERR.
+ any error conditions. This implementation returns <STRONG>ERR</STRONG> if the window
+ pointer is null, or if the lower-level <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG> call returns an <STRONG>ERR</STRONG>.
SVr3 and early SVr4 curses implementations did not reject function
keys; the SVr4.0 documentation claimed that "special keys" (such as
The functions <STRONG>getnstr</STRONG>, <STRONG>mvgetnstr</STRONG>, and <STRONG>mvwgetnstr</STRONG> were present but not
documented in SVr4.
+ X/Open Curses issue 5 (2007) stated that these functions "read at most
+ <EM>n</EM> bytes" but did not state whether the terminating NUL is counted in
+ that limit. X/Open Curses issue 7 (2009) changed that to say they
+ "read at most <EM>n</EM>-1 bytes" to allow for the terminating NUL. As of 2018,
+ some implementations do, some do not count it:
+
+ <STRONG>o</STRONG> ncurses 6.1 and PDCurses do not count the NUL in the given limit,
+ while
+
+ <STRONG>o</STRONG> Solaris SVr4 and NetBSD curses count the NUL as part of the limit.
+
+ <STRONG>o</STRONG> Solaris xcurses provides both: its wide-character <STRONG>wget_nstr</STRONG> re-
+ serves a NUL, but its <STRONG>wgetnstr</STRONG> does not count the NUL consistently.
+
+ In SVr4 curses, a negative value of <EM>n</EM> tells <STRONG>wgetnstr</STRONG> to assume that the
+ caller's buffer is large enough to hold the result, i.e., to act like
+ <STRONG>wgetstr</STRONG>. X/Open Curses does not mention this (or anything related to
+ negative or zero values of <EM>n</EM>), however most implementations use the
+ feature, with different limits:
+
+ <STRONG>o</STRONG> Solaris SVr4 curses and PDCurses limit the result to 255 bytes.
+ Other Unix systems than Solaris are likely to use the same limit.
+
+ <STRONG>o</STRONG> Solaris xcurses limits the result to <STRONG>LINE_MAX</STRONG> bytes.
+
+ <STRONG>o</STRONG> NetBSD 7 assumes no particular limit for the result from <STRONG>wgetstr</STRONG>.
+ However, it limits the <STRONG>wgetnstr</STRONG> parameter <EM>n</EM> to ensure that it is
+ greater than zero.
+
+ A comment in NetBSD's source code states that this is specified in
+ SUSv2.
+
+ <STRONG>o</STRONG> ncurses (before 6.2) assumes no particular limit for the result
+ from <STRONG>wgetstr</STRONG>, and treats the <EM>n</EM> parameter of <STRONG>wgetnstr</STRONG> like SVr4
+ curses.
+
+ <STRONG>o</STRONG> ncurses 6.2 uses <STRONG>LINE_MAX</STRONG>, or a larger (system-dependent) value
+ which the <STRONG>sysconf</STRONG> function may provide. If neither <STRONG>LINE_MAX</STRONG> or
+ <STRONG>sysconf</STRONG> is available, ncurses uses the POSIX value for <STRONG>LINE_MAX</STRONG> (a
+ 2048 byte limit). In either case, it reserves a byte for the ter-
+ minating NUL.
+
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>.
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