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authorLennart Poettering <lennart@poettering.net>2015-10-04 17:36:19 +0200
committerLennart Poettering <lennart@poettering.net>2015-10-06 11:52:48 +0200
commit8dd4c05b5495c7ffe0f12ace87e71abe17bd0a0e (patch)
tree30a788ca911facca15b4f1fa8641e78753caa574 /man
parent79c7626d1f239e02152ad698298a1b5d0e9fbacf (diff)
core: add support for naming file descriptors passed using socket activation
This adds support for naming file descriptors passed using socket activation. The names are passed in a new $LISTEN_FDNAMES= environment variable, that matches the existign $LISTEN_FDS= one and contains a colon-separated list of names. This also adds support for naming fds submitted to the per-service fd store using FDNAME= in the sd_notify() message. This also adds a new FileDescriptorName= setting for socket unit files to set the name for fds created by socket units. This also adds a new call sd_listen_fds_with_names(), that is similar to sd_listen_fds(), but also returns the names of the fds. systemd-activate gained the new --fdname= switch to specify a name for testing socket activation. This is based on #1247 by Maciej Wereski. Fixes #1247.
Diffstat (limited to 'man')
-rw-r--r--man/sd_listen_fds.xml133
-rw-r--r--man/sd_notify.xml31
-rw-r--r--man/systemd-activate.xml13
-rw-r--r--man/systemd.socket.xml23
-rw-r--r--man/systemd.xml1
5 files changed, 168 insertions, 33 deletions
diff --git a/man/sd_listen_fds.xml b/man/sd_listen_fds.xml
index 9b9705eb2e..ea55671e4f 100644
--- a/man/sd_listen_fds.xml
+++ b/man/sd_listen_fds.xml
@@ -1,4 +1,4 @@
-<?xml version='1.0'?> <!--*-nxml-*-->
+<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
@@ -45,6 +45,7 @@
<refnamediv>
<refname>sd_listen_fds</refname>
+ <refname>sd_listen_fds_with_names</refname>
<refname>SD_LISTEN_FDS_START</refname>
<refpurpose>Check for file descriptors passed by the system manager</refpurpose>
</refnamediv>
@@ -59,23 +60,26 @@
<funcdef>int <function>sd_listen_fds</function></funcdef>
<paramdef>int <parameter>unset_environment</parameter></paramdef>
</funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_listen_fds_with_names</function></funcdef>
+ <paramdef>int <parameter>unset_environment</parameter></paramdef>
+ <paramdef>char*** <parameter>names</parameter></paramdef>
+ </funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
- <para><function>sd_listen_fds()</function> shall be called by a
- daemon to check for file descriptors passed by the init system as
- part of the socket-based activation logic.</para>
-
- <para>If the <parameter>unset_environment</parameter> parameter is
- non-zero, <function>sd_listen_fds()</function> will unset the
- <varname>$LISTEN_FDS</varname> and <varname>$LISTEN_PID</varname>
- environment variables before returning (regardless of whether the
- function call itself succeeded or not). Further calls to
- <function>sd_listen_fds()</function> will then fail, but the
- variables are no longer inherited by child processes.</para>
+ <para><function>sd_listen_fds()</function> may be invoked by a
+ daemon to check for file descriptors passed by the service manager as
+ part of the socket-based activation logic. It returns the number
+ of received file descriptors. If no file descriptors have been
+ received zero is returned. The first file descriptor may be found
+ at file descriptor number 3
+ (i.e. <constant>SD_LISTEN_FDS_START</constant>), the remaining
+ descriptors follow at 4, 5, 6, ..., if any.</para>
<para>If a daemon receives more than one file descriptor, they
will be passed in the same order as configured in the systemd
@@ -108,12 +112,86 @@
<literal>FDSTORE=1</literal> messages, these file descriptors are
passed last, in arbitrary order, and with duplicates
removed.</para>
+
+ <para>If the <parameter>unset_environment</parameter> parameter is
+ non-zero, <function>sd_listen_fds()</function> will unset the
+ <varname>$LISTEN_FDS</varname>, <varname>$LISTEN_PID</varname> and
+ <varname>$LISTEN_FDNAMES</varname> environment variables before
+ returning (regardless of whether the function call itself
+ succeeded or not). Further calls to
+ <function>sd_listen_fds()</function> will then return zero, but the
+ variables are no longer inherited by child processes.</para>
+
+ <para><function>sd_listen_fds_with_names()</function> is like
+ <function>sd_listen_fds()</function> but optionally also returns
+ an array of strings with identification names for the passed file
+ descriptors, if that is available, and the
+ <parameter>names</parameter> parameter is non-NULL. This
+ information is read from the <varname>$LISTEN_FDNAMES</varname>
+ variable, which may contain a colon-separated list of names. For
+ socket-activated services, these names may be configured with the
+ <varname>FileDescriptorName=</varname> setting in socket unit
+ files, see
+ <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details. For file descriptors pushed into the file descriptor
+ store (see above) the name is set via the
+ <varname>FDNAME=</varname> field transmitted via
+ <function>sd_pid_notify_with_fds()</function>. The primary usecase
+ for these names are services which accept a variety of file
+ descriptors which are not recognizable with functions like
+ <function>sd_is_socket()</function> alone, and thus require
+ identification via a name. It is recommended to rely on named file
+ descriptors only if identification via
+ <function>sd_is_socket()</function> and related calls is not
+ sufficient. Note that the names used are not unique in any
+ way. The returned array of strings has as many entries as file
+ descriptors has been received, plus a final NULL pointer
+ terminating the array. The caller needs to free the array itself
+ and each of its elements with libc's <varname>free()</varname>
+ call after use. If the <parameter>names</parameter> parameter is
+ NULL the call is entirely equivalent to
+ <function>sd_listen_fds()</function>.</para>
+
+ <para>Under specific conditions the following automatic file
+ descriptor names are returned:
+
+ <table>
+ <title>
+ <command>Special names</command>
+ </title>
+
+ <tgroup cols='2'>
+ <thead>
+ <row>
+ <entry>Name</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><literal>unknown</literal></entry>
+ <entry>The process received no name for the specific file descriptor from the service manager.</entry>
+ </row>
+
+ <row>
+ <entry><literal>stored</literal></entry>
+ <entry>The file descriptor originates in the service manager's per-service file descriptor store, and the <varname>FDNAME=</varname> field was absent when the file descriptor was submitted to the service manager.</entry>
+ </row>
+
+ <row>
+ <entry><literal>connection</literal></entry>
+ <entry>The service was activated in per-connection style using <varname>Accept=yes</varname> in the socket unit file, and the file descriptor is the connection socket.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </para>
</refsect1>
<refsect1>
<title>Return Value</title>
- <para>On failure, this call returns a negative errno-style error
+ <para>On failure, these calls returns a negative errno-style error
code. If
<varname>$LISTEN_FDS</varname>/<varname>$LISTEN_PID</varname> was
not set or was not correctly set for this daemon and hence no file
@@ -128,13 +206,16 @@
<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
- <para>Internally, this function checks whether the
- <varname>$LISTEN_PID</varname> environment variable equals the
- daemon PID. If not, it returns immediately. Otherwise, it parses
- the number passed in the <varname>$LISTEN_FDS</varname>
+ <para>Internally, <function>sd_listen_fds()</function> checks
+ whether the <varname>$LISTEN_PID</varname> environment variable
+ equals the daemon PID. If not, it returns immediately. Otherwise,
+ it parses the number passed in the <varname>$LISTEN_FDS</varname>
environment variable, then sets the FD_CLOEXEC flag for the parsed
number of file descriptors starting from SD_LISTEN_FDS_START.
- Finally, it returns the parsed number.</para>
+ Finally, it returns the parsed
+ number. <function>sd_listen_fds_with_names()</function> does the
+ same but also parses <varname>$LISTEN_FDNAMES</varname> if
+ set.</para>
</refsect1>
<refsect1>
@@ -144,15 +225,14 @@
<varlistentry>
<term><varname>$LISTEN_PID</varname></term>
<term><varname>$LISTEN_FDS</varname></term>
+ <term><varname>$LISTEN_FDNAMES</varname></term>
- <listitem><para>Set by the init system
- for supervised processes that use
- socket-based activation. This
- environment variable specifies the
- data
- <function>sd_listen_fds()</function>
- parses. See above for
- details.</para></listitem>
+ <listitem><para>Set by the service manager for supervised
+ processes that use socket-based activation. This environment
+ variable specifies the data
+ <function>sd_listen_fds()</function> and
+ <function>sd_listen_fds_with_names()</function> parses. See
+ above for details.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
@@ -167,6 +247,7 @@
<citerefentry><refentrytitle>sd_is_socket</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_is_socket_inet</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_is_socket_unix</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_pid_notify_with_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
diff --git a/man/sd_notify.xml b/man/sd_notify.xml
index 14030f56b1..2d73c27f62 100644
--- a/man/sd_notify.xml
+++ b/man/sd_notify.xml
@@ -1,4 +1,4 @@
-<?xml version='1.0'?> <!--*-nxml-*-->
+<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
@@ -229,6 +229,27 @@
below.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term>FDNAME=...</term>
+
+ <listitem><para>When used in combination with
+ <varname>FDSTORE=1</varname> specifies a name for the
+ submitted file descriptors. This name is passed to the service
+ during activation, and may be queried using
+ <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry>. File
+ descriptors submitted without this field set, will implicitly
+ get the name <literal>stored</literal> assigned. Note that if
+ multiple file descriptors are submitted at once the specified
+ name will be assigned to all of them. In order to assign
+ different names to submitted file descriptors, submit them in
+ seperate invocations of
+ <function>sd_pid_notify_with_fds()</function>. The name may
+ consist of any ASCII characters, but must not contain control
+ characters or <literal>:</literal>. It may not be longer than
+ 255 characters. If a submitted name does not follow these
+ restrictions it is ignored.</para></listitem>
+ </varlistentry>
+
</variablelist>
<para>It is recommended to prefix variable names that are not
@@ -358,7 +379,7 @@
in order to continue operation after a service restart without
losing state use <literal>FDSTORE=1</literal>:</para>
- <programlisting>sd_pid_notify_with_fds(0, 0, "FDSTORE=1", &amp;fd, 1);</programlisting>
+ <programlisting>sd_pid_notify_with_fds(0, 0, "FDSTORE=1\nFDNAME=foobar", &amp;fd, 1);</programlisting>
</example>
</refsect1>
@@ -367,9 +388,11 @@
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
diff --git a/man/systemd-activate.xml b/man/systemd-activate.xml
index 3b854fd8ec..90e974c991 100644
--- a/man/systemd-activate.xml
+++ b/man/systemd-activate.xml
@@ -115,6 +115,16 @@
</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>--fdname=</option><replaceable>NAME</replaceable></term>
+
+ <listitem><para>Specify a name for the activation file
+ descriptors. This is equivalent to setting
+ <varname>FileDescriptorName=</varname> in socket unit files, and
+ enables use of
+ <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
+ </varlistentry>
+
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>
@@ -126,6 +136,7 @@
<varlistentry>
<term><varname>$LISTEN_FDS</varname></term>
<term><varname>$LISTEN_PID</varname></term>
+ <term><varname>$LISTEN_FDNAMES</varname></term>
<listitem><para>See
<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
@@ -165,6 +176,8 @@
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>cat</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
diff --git a/man/systemd.socket.xml b/man/systemd.socket.xml
index 212764075d..46a47b2d95 100644
--- a/man/systemd.socket.xml
+++ b/man/systemd.socket.xml
@@ -1,4 +1,4 @@
-<?xml version='1.0'?> <!--*-nxml-*-->
+<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
@@ -748,6 +748,22 @@
list.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>FileDescriptorName=</varname></term>
+ <listitem><para>Assigns a name to all file descriptors this
+ socket unit encapsulates. This is useful to help activated
+ services to identify specific file descriptors, if multiple
+ are passed. Services may use the
+ <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ call to acquire the names configured for the received file
+ descriptors. Names may contain any ASCII character, but must
+ exclude control characters or <literal>:</literal>, and must
+ be at most 255 characters in length. If this setting is not
+ used the file descriptor name defaults to the name of the
+ socket unit, including its <filename>.socket</filename>
+ suffix.</para></listitem>
+ </varlistentry>
+
</variablelist>
<para>Check
@@ -768,9 +784,10 @@
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
-
<para>
For more extensive descriptions see the "systemd for Developers" series:
<ulink url="http://0pointer.de/blog/projects/socket-activation.html">Socket Activation</ulink>,
diff --git a/man/systemd.xml b/man/systemd.xml
index 9e927c3204..391333bfb4 100644
--- a/man/systemd.xml
+++ b/man/systemd.xml
@@ -835,6 +835,7 @@
<varlistentry>
<term><varname>$LISTEN_PID</varname></term>
<term><varname>$LISTEN_FDS</varname></term>
+ <term><varname>$LISTEN_FDNAMES</varname></term>
<listitem><para>Set by systemd for supervised processes during
socket-based activation. See