[PATCH] sstate.bbclass: Add a string representing the lsb release to native/cross sstate

[Richard Purdie <richard.purdie@linuxfoundation.org>]

This patch adds the lsb name and revision to the path used for sstate files.
This means that reuse of sstate files between different distributions is restricted
by default. The behaviour can be configured using mirror urls, for example:

SSTATE_MIRRORS = "file://Ubuntu-11.10/(.*) file://Ubuntu/\1 \n"

would map Ubuntu 11.10 to a more generic "Ubuntu" named sstate feed.

Usually, more modern distros have increased libc versions for example
so whilst more older native/cross sstate packages will usually work on newer
distros, the opposite is not true. This patch allows development of policy
to better handle this although no default policy is currently being used.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
diff --git a/meta/classes/sstate.bbclass b/meta/classes/sstate.bbclass
index d00779a..e87f3c0 100644
--- a/meta/classes/sstate.bbclass
+++ b/meta/classes/sstate.bbclass
@@ -11,14 +11,17 @@ def generate_sstatefn(spec, hash, d):
 
 SSTATE_PKGARCH    = "${PACKAGE_ARCH}"
 SSTATE_PKGSPEC    = "sstate-${PN}-${PACKAGE_ARCH}${TARGET_VENDOR}-${TARGET_OS}-${PV}-${PR}-${SSTATE_PKGARCH}-${SSTATE_VERSION}-"
-SSTATE_PKGNAME    = "${@generate_sstatefn(d.getVar('SSTATE_PKGSPEC', True), d.getVar('BB_TASKHASH', True), d)}"
+SSTATE_PKGNAME    = "${SSTATE_EXTRAPATH}${@generate_sstatefn(d.getVar('SSTATE_PKGSPEC', True), d.getVar('BB_TASKHASH', True), d)}"
 SSTATE_PKG        = "${SSTATE_DIR}/${SSTATE_PKGNAME}"
-SSTATE_PATHSPEC   = "${SSTATE_DIR}/*/${SSTATE_PKGSPEC}"
+SSTATE_EXTRAPATH   = ""
+SSTATE_EXTRAPATHWILDCARD = ""
+SSTATE_PATHSPEC   = "${SSTATE_DIR}/${SSTATE_EXTRAPATHWILDCARD}*/${SSTATE_PKGSPEC}"
+
 
 SSTATE_SCAN_FILES ?= "*.la *-config *_config"
 SSTATE_SCAN_CMD ?= 'find ${SSTATE_BUILDDIR} \( -name "${@"\" -o -name \"".join(d.getVar("SSTATE_SCAN_FILES", True).split())}" \) -type f'
 
-BB_HASHFILENAME = "${SSTATE_PKGSPEC}"
+BB_HASHFILENAME = "${SSTATE_EXTRAPATH} ${SSTATE_PKGSPEC}"
 
 SSTATE_MANMACH ?= "${SSTATE_PKGARCH}"
 
@@ -43,6 +46,10 @@ python () {
     else:
         d.setVar('SSTATE_MANMACH', d.expand("${MACHINE}"))
 
+    if bb.data.inherits_class('native', d) or bb.data.inherits_class('crosssdk', d) or bb.data.inherits_class('cross', d):
+        d.setVar('SSTATE_EXTRAPATH', "${NATIVELSBSTRING}/")
+        d.setVar('SSTATE_EXTRAPATHWILDCARD', "*/")
+
     # These classes encode staging paths into their scripts data so can only be
     # reused if we manipulate the paths
     if bb.data.inherits_class('native', d) or bb.data.inherits_class('cross', d) or bb.data.inherits_class('sdk', d) or bb.data.inherits_class('crosssdk', d):
@@ -524,7 +531,10 @@ def sstate_checkhashes(sq_fn, sq_task, sq_hash, sq_hashfn, d):
     }
 
     for task in range(len(sq_fn)):
-        sstatefile = d.expand("${SSTATE_DIR}/" + generate_sstatefn(sq_hashfn[task], sq_hash[task], d) + "_" + mapping[sq_task[task]] + ".tgz")
+        spec = sq_hashfn[task].split(" ")[1]
+        extrapath = sq_hashfn[task].split(" ")[0]
+
+        sstatefile = d.expand("${SSTATE_DIR}/" + extrapath + generate_sstatefn(spec, sq_hash[task], d) + "_" + mapping[sq_task[task]] + ".tgz")
         if os.path.exists(sstatefile):
             bb.debug(2, "SState: Found valid sstate file %s" % sstatefile)
             ret.append(task)
@@ -548,7 +558,9 @@ def sstate_checkhashes(sq_fn, sq_task, sq_hash, sq_hashfn, d):
             if task in ret:
                 continue
 
-            sstatefile = d.expand(generate_sstatefn(sq_hashfn[task], sq_hash[task], d) + "_" + mapping[sq_task[task]] + ".tgz")
+            spec = sq_hashfn[task].split(" ")[1]
+            extrapath = sq_hashfn[task].split(" ")[0]
+            sstatefile = d.expand(extrapath + generate_sstatefn(spec, sq_hash[task], d) + "_" + mapping[sq_task[task]] + ".tgz")
 
             srcuri = "file://" + sstatefile
             localdata.setVar('SRC_URI', srcuri)