151 lines
5.7 KiB
HTML
151 lines
5.7 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of SD_BUS_PATH_ENCODE</TITLE>
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</HEAD><BODY>
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<H1>SD_BUS_PATH_ENCODE</H1>
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Section: sd_bus_path_encode (3)<BR>Updated: <BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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sd_bus_path_encode, sd_bus_path_encode_many, sd_bus_path_decode, sd_bus_path_decode_many - Convert an external identifier into an object path and back
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<P>
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<B>
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</B><PRE>
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#include <<A HREF="file:///usr/include/systemd/sd-bus.h">systemd/sd-bus.h</A>>
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</PRE>
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<DL COMPACT>
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<DT id="1">
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<B>int sd_bus_path_encode(const char *</B><I>prefix</I><B>, const char *</B><I>external_id</I><B>, char **</B><I>ret_path</I><B>);</B>
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<DT id="2">
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<B>int sd_bus_path_encode_many(char **</B><I>out</I><B>, const char *</B><I>path_template</I><B>, ...);</B>
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<DT id="3">
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<B>int sd_bus_path_decode(const char *</B><I>path</I><B>, const char *</B><I>prefix</I><B>, char **</B><I>ret_external_id</I><B>);</B>
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<DT id="4">
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<B>int sd_bus_path_decode_many(const char *</B><I>path</I><B>, const char *</B><I>path_template</I><B>, ...);</B>
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</DL>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<P>
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<B>sd_bus_path_encode()</B>
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<DD>and
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<B>sd_bus_path_decode()</B>
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convert external identifier strings into object paths and back. These functions are useful to map application-specific string identifiers of any kind into bus object paths in a simple, reversible and safe way.
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<P>
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<B>sd_bus_path_encode()</B>
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takes a bus path prefix and an external identifier string as arguments, plus a place to store the returned bus path string. The bus path prefix must be a valid bus path, starting with a slash
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"/", and not ending in one. The external identifier string may be in any format, may be the empty string, and has no restrictions on the charset --- however, it must always be
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<B>NUL</B>-terminated. The returned string will be the concatenation of the bus path prefix plus an escaped version of the external identifier string. This operation may be reversed with
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<B>sd_bus_path_decode()</B>. It is recommended to only use external identifiers that generally require little escaping to be turned into valid bus path identifiers (for example, by sticking to a 7-bit ASCII character set), in order to ensure the resulting bus path is still short and easily processed.
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<P>
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<B>sd_bus_path_decode()</B>
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reverses the operation of
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<B>sd_bus_path_encode()</B>
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and thus regenerates an external identifier string from a bus path. It takes a bus path and a prefix string, plus a place to store the returned external identifier string. If the bus path does not start with the specified prefix, 0 is returned and the returned string is set to
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<B>NULL</B>. Otherwise, the string following the prefix is unescaped and returned in the external identifier string.
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<P>
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The escaping used will replace all characters which are invalid in a bus object path by
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"_", followed by a hexadecimal value. As a special case, the empty string will be replaced by a lone
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"_".
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<P>
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<B>sd_bus_path_encode_many()</B>
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works like its counterpart
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<B>sd_bus_path_encode()</B>, but takes a path template as argument and encodes multiple labels according to its embedded directives. For each
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"%"
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character found in the template, the caller must provide a string via varargs, which will be encoded and embedded at the position of the
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"%"
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character. Any other character in the template is copied verbatim into the encoded path.
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<P>
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<B>sd_bus_path_decode_many()</B>
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does the reverse of
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<B>sd_bus_path_encode_many()</B>. It decodes the passed object path according to the given path template. For each
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"%"
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character in the template, the caller must provide an output storage ("char **") via varargs. The decoded label will be stored there. Each
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"%"
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character will only match the current label. It will never match across labels. Furthermore, only a single directive is allowed per label. If
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"NULL"
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is passed as output storage, the label is verified but not returned to the caller.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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<P>
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On success,
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<B>sd_bus_path_encode()</B>
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returns positive or 0, and a valid bus path in the return argument. On success,
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<B>sd_bus_path_decode()</B>
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returns a positive value if the prefixed matched, or 0 if it did not. If the prefix matched, the external identifier is returned in the return parameter. If it did not match, NULL is returned in the return parameter. On failure, a negative errno-style error number is returned by either function. The returned strings must be
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<B><A HREF="/cgi-bin/man/man2html?3+free">free</A></B>(3)'d by the caller.
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<A NAME="lbAF"> </A>
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<H2>NOTES</H2>
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<P>
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These APIs are implemented as a shared library, which can be compiled and linked to with the
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<B>libsystemd</B> <B><A HREF="/cgi-bin/man/man2html?1+pkg-config">pkg-config</A></B>(1)
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file.
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<P>
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<B><A HREF="/cgi-bin/man/man2html?1+systemd">systemd</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?3+sd-bus">sd-bus</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+free">free</A></B>(3)
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="5"><A HREF="#lbAB">NAME</A><DD>
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<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="8"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="9"><A HREF="#lbAF">NOTES</A><DD>
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<DT id="10"><A HREF="#lbAG">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:55 GMT, March 31, 2021
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