Add upper limit to -c in s6-svscan

 Also document it, and document changes to s6-supervise

Signed-off-by: Laurent Bercot <ska@appnovation.com>

3 files changed, 33 insertions, 13 deletions

diff --git a/doc/s6-supervise.html b/doc/s6-supervise.html
index 404e896..86d97a6 100644
--- a/doc/s6-supervise.html
+++ b/doc/s6-supervise.html
@@ -135,7 +135,12 @@ effective group id as the s6-supervise process.
 If it already exists, it uses it as is, without modifying the subscription rights. </li>
  <li> It <a href="libs6/ftrigw.html">sends</a> a <tt>'s'</tt> event to <tt>./event</tt>. </li>
  <li> If the default service state is up (i.e. there is no <tt>./down</tt> file),
-s6-supervise spawns <tt>./run</tt>. </li>
+s6-supervise spawns <tt>./run</tt>. One argument is given to the <tt>./run</tt>
+program: <em>servicedir</em>, the name of the directory s6-supervise is being
+run on. It is given exactly as given to s6-supervise, without recanonicalization.
+In particular, if s6-supervise is being managed by <a href="s6-svscan.html">s6-svscan</a>,
+<em>servicedir</em> is always of the form <tt><em>foo</em></tt> or <tt><em>foo</em>/log</tt>,
+and <em>foo</em> contains no slashes. </li>
  <li> s6-supervise sends a <tt>'u'</tt> event to <tt>./event</tt> whenever it
 successfully spawns <tt>./run</tt>. </li>
  <li> If there is a <tt>./notification-fd</tt> file in the service directory and,
@@ -152,7 +157,8 @@ service for readiness. </li>
 It then spawns <tt>./finish</tt> if it exists.
 <tt>./finish</tt> will have <tt>./run</tt>'s exit code as first argument, or 256 if
 <tt>./run</tt> was signaled; it will have the number of the signal that killed <tt>./run</tt>
-as second argument, or an undefined number if <tt>./run</tt> was not signaled. </li>
+as second argument, or an undefined number if <tt>./run</tt> was not signaled;
+and it will have <em>servicedir</em> as third argument. </li>
  <li> By default, <tt>./finish</tt> must exit in less than 5 seconds. If it takes more than that,
 s6-supervise kills it with a SIGKILL. This can be configured via the
 <tt>./timeout-finish</tt> file, see the description in the
diff --git a/doc/s6-svscan.html b/doc/s6-svscan.html
index 5c031c6..8b94cf4 100644
--- a/doc/s6-svscan.html
+++ b/doc/s6-svscan.html
@@ -76,10 +76,11 @@ where all error messages go to the <tt>s6-svscan-log</tt> catch-all logger servi
 default, except messages from this service itself, which fall back to <em>consoleholder</em>.
 If you're not sure what to use this option for, or how, you don't need it. </li>
  <li> <tt>-c&nbsp;<em>max</em></tt>&nbsp;: maintain services for up to <em>max</em>
-service directories. Default is 500. Lower limit is 2. There is no upper limit, but:
+service directories. Default is 500. Lower limit is 2. Upper limit is 90000. If
+you're increasing this value from the default, please note that:
  <ul>
   <li> The higher <em>max</em> is, the more stack memory s6-svscan will use,
-approximately 50 bytes per service. </li>
+up to 100 bytes per service. </li>
   <li> s6-svscan uses 2 file descriptors per logged service. </li>
  </ul>
  It is the admin's responsibility to make sure that s6-svscan has enough available
diff --git a/doc/servicedir.html b/doc/servicedir.html
index 2ced33e..4ae06c2 100644
--- a/doc/servicedir.html
+++ b/doc/servicedir.html
@@ -45,11 +45,22 @@ file (such as a binary file or a link to any other executable file),
 but most of the time it will be a script, called <em>run script</em>.
 This file is the most important one in your service directory: it
 contains the commands that will setup and run your <em>foo</em> service.
-It is forked and executed by <a href="s6-supervise.html">s6-supervise</a>
+ <ul>
+  <li> It is forked and executed by <a href="s6-supervise.html">s6-supervise</a>
 every time the service must be started, i.e. normally when
 <a href="s6-supervise.html">s6-supervise</a> starts, and whenever
-the service goes down when it is supposed to be up. A run script
-should normally:
+the service goes down when it is supposed to be up. </li>
+  <li> It is given one argument, which is the same argument that the
+<a href="s6-supervise.html">s6-supervise</a> process is running with,
+i.e. the name of the service directory &mdash; or, if
+<a href="s6-supervise.html">s6-supervise</a> is run under
+<a href="s6-svscan.html">s6-svscan</a>, the name of the service directory
+as seen by <a href="s6-svscan.html">s6-svscan</a> in its
+<a href="scandir.html">scan directory</a>. That is, <tt><em>foo</em></tt>
+or <tt><em>foo</em>/log</tt>, if <em>foo</em> is the name of the
+<em>symbolic link</em> in the scan directory. </li> </ul>
+
+<p> A run script should normally: </p>
  <ul>
   <li> adjust redirections for stdin, stdout and stderr. When a run
 script starts, it inherits its standard file descriptors from
@@ -107,10 +118,12 @@ process has been killed. If the <em>foo</em> service is supposed to be up,
 script, not the finish script, should be running; the finish script should really
 be short-lived.) The maximum duration of a <tt>finish</tt> execution can be
 configured via the <tt>timeout-finish</tt> file, see below. </li>
-  <li> The finish script is
-executed with two arguments: the exit code from the run script (resp. 256 if the
-run script was killed by a signal), and an undefined number (resp. the number of
-the signal that killed the run script). </li>
+  <li> The finish script is executed with three arguments:
+   <ol>
+    <li> the exit code from the run script (resp. 256 if the run script was killed by a signal) </li>
+    <li> an undefined number (resp. the number of the signal that killed the run script) </li>
+    <li> the name of the service directory, the same that has been given to <tt>./run</tt>. </li>
+   </ol>
   <li> If the finish script exits 125, then <a href="s6-supervise.html">s6-supervise</a>
 interprets this as a permanent failure for the service, and does not restart it,
 as if an <a href="s6-svc.html">s6-svc -O</a> command had been sent. </li>
@@ -122,8 +135,8 @@ stdin and stdout pointing to <tt>/dev/null</tt>. </li>
 
  <li style="margin-bottom:1em"> A directory named <tt>supervise</tt>. It is automatically created by
 <a href="s6-supervise.html">s6-supervise</a> if it does not exist. This is where
-<a href="s6-supervise.html">s6-supervise</a> stores its information. The directory
-must be writable. </li>
+<a href="s6-supervise.html">s6-supervise</a> stores its internal information.
+The directory must be writable. </li>
 
  <li style="margin-bottom:1em"> An optional, empty, regular file named <tt>down</tt>. If such a file exists,
 the default state of the service is considered down, not up: s6-supervise will not