move attachment pagespec extensions docs to its own page

in the basewiki, so I can link to it there

1 files changed, 52 insertions, 0 deletions

diff --git a/doc/ikiwiki/pagespec/attachment.mdwn b/doc/ikiwiki/pagespec/attachment.mdwn
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+[[!meta robots="noindex, follow"]]
+[[!if test="enabled(attachment)"
+     then="This wiki has attachments **enabled**."
+     else="This wiki has attachments **disabled**."]]
+
+If attachments are enabled, the wiki admin can control what types of
+attachments will be accepted, by entering a [[ikiwiki/PageSpec]] in the
+"Allowed Attachments" field of their preferences page.
+
+For example, to limit arbitrary files to 50 kilobytes, but allow
+larger mp3 files to be uploaded by joey, a something like this could be
+used:
+  
+	(user(joey) and *.mp3 and mimetype(audio/mpeg) and maxsize(15mb)) or (!ispage() and maxsize(50kb))
+
+The regular [[ikiwiki/PageSpec]] syntax is expanded with thw following
+additional tests:
+
+* maxsize(size)
+
+  Tests whether the attachment is no larger than the specified size.
+  The size defaults to being in bytes, but "kb", "mb", "gb" etc can be
+  used to specify the units.
+  
+* minsize(size)
+
+  Tests whether the attachment is no smaller than the specified size.
+
+* ispage()
+
+  Tests whether the attachment will be treated by ikiwiki as a wiki page.
+  (Ie, if it has an extension of ".mdwn", or of any other enabled page
+  format).
+
+  So, if you don't want to allow wiki pages to be uploaded as attachments,
+  use `!ispage()` ; if you only want to allow wiki pages to be uploaded
+  as attachments, use `ispage()`.
+
+* user(username)
+
+  Tests whether the attachment is being uploaded by a user with the
+  specified username. If openid is enabled, an openid can also be put here.
+
+* ip(address)
+
+  Tests whether the attacment is being uploaded from the specified IP
+  address.
+
+* mimetype(foo/bar)
+
+  This checks the MIME type of the attachment. You can include a glob
+  in the type, for example `mimetype(image/*)`.