Convert track names and input lines to NFC. This is a database format

[disorder] / doc / disorder_protocol.5.in

diff --git a/doc/disorder_protocol.5.in b/doc/disorder_protocol.5.in
index d20edcf..bf293e9 100644 (file)
--- a/doc/disorder_protocol.5.in
+++ b/doc/disorder_protocol.5.in
@@ -26,10 +26,12 @@ in this man page.
 The protocol is liable to change without notice.  You are recommended to check
 the implementation before believing this document.
 .SH "GENERAL SYNTAX"
 The protocol is liable to change without notice.  You are recommended to check
 the implementation before believing this document.
 .SH "GENERAL SYNTAX"

-Everything is encoded using UTF-8.
+Everything is encoded using UTF-8.  See
+.B "CHARACTER ENCODING"
+below for more detail on character encoding issues.

 .PP
 .PP

-Commands and responses consist of a line followed (depending on the
-command or response) by a message.
+Commands and responses consist of a line perhaps followed (depending on the
+command or response) by a body.

 .PP
 The line syntax is the same as described in \fBdisorder_config\fR(5) except
 that comments are prohibited.
 .PP
 The line syntax is the same as described in \fBdisorder_config\fR(5) except
 that comments are prohibited.


@@ -455,6 +457,63 @@ The volume changed.
 is as defined in
 .B "TRACK INFORMATION"
 above.
 is as defined in
 .B "TRACK INFORMATION"
 above.

+.SH "CHARACTER ENCODING"
+All data sent by both server and client is encoded using UTF-8.  Moreover it
+must be valid UTF-8, i.e. non-minimal sequences are not permitted, nor are
+surrogates, nor are code points outside the Unicode code space.
+.PP
+There are no particular normalization requirements on either side of the
+protocol.  The server currently converts internally to NFC, the client must
+normalize the responses returned if it needs some normalized form for further
+processing.
+.PP
+The various characters which divide up lines may not be followed by combining
+characters.  For instance all of the following are prohibited:
+.TP
+.B o
+LINE FEED followed by a combining character.  For example the sequence
+LINE FEED, COMBINING GRAVE ACCENT is never permitted.
+.TP
+.B o
+APOSTROPHE or QUOTATION MARK followed by a combining character when used to
+delimit fields.  For instance a line starting APOSTROPHE, COMBINING CEDILLA
+is prohibited.
+.IP
+Note that such sequences are not prohibited when the quote character cannot be
+interpreted as a field delimiter.  For instance APOSTROPHE, REVERSE SOLIDUS,
+APOSTROPHE, COMBINING CEDILLA, APOSTROPHE would be permitted.
+.TP
+.B o
+REVERSE SOLIDUS (BACKSLASH) followed by a combining character in a quoted
+string when it is the first character of an escape sequence.  For instance a
+line starting APOSTROPHE, REVERSE SOLIDUS, COMBINING TILDE is prohibited.
+.IP
+As above such sequences are not prohibited when the character is not being used
+to start an escape sequence.  For instance APOSTROPHE, REVERSE SOLIDUS,
+REVERSE SOLIDS, COMBINING TILDER, APOSTROPHE is permitted.
+.TP
+.B o
+Any of the field-splitting whitespace characters followed by a combining
+character when not part of a quoted field.  For instance a line starting COLON,
+SPACE, COMBINING CANDRABINDU is prohibited.
+.IP
+As above non-delimiter uses are fine.
+.TP
+.B o
+The FULL STOP characters used to quote or delimit a body.
+.PP
+Furthermore none of these characters are permitted to appear in the context of
+a canonical decomposition (i.e. they must still be present when converted to
+NFC).  In practice however this is not an issue in Unicode 5.0.
+.PP
+These rules are consistent with the observation that the split() function is
+essentially a naive ASCII parser.  The implication is not that these sequences
+never actually appear in the protocol, merely that the server is not required
+to honor them in any useful way nor be consistent between versions: in current
+versions the result will be lines and fields that start with combining
+characters and are not necessarily split where you expect, but future versions
+may remove them, reject them or ignore some or all of the delimiters that have
+following combining characters, and no notice will be given of any change.

 .SH "SEE ALSO"
 \fBdisorder\fR(1),
 \fBtime\fR(2),
 .SH "SEE ALSO"
 \fBdisorder\fR(1),
 \fBtime\fR(2),