Introduce functionality for automatically fetching package versions

Versions of the packages included in update file needs to be entered
manually in sw-description file or provided in as a bitbake variable.

This patch searches for a group in sw-description file containing the
tag `version = "@SWU_AUTO_VERSION"`.
If found, the version of the corresponding package is fetched from it's
package-data-file (`PV`) and the tag is replaced with the version.
Possible trailing strings in `PV` starting with `+` (e.g.
"+gitAUTOINC+...") are dropped to keep semantic versions.

Since the filenames not always belong to the package name (deployed
with another name or the file is a container for the real package)
support providing the correct package name by appending the tag with
`:<package-name>`.
Signed-off-by: Thomas Haemmerle <thomas.haemmerle@leica-geosystems.com>

README

@@ -25,6 +25,18 @@ Image hashing
 During creation of the update file, occurrences of @IMAGE (where IMAGE is an
 image filename) are replaced with the sha256 hash of the image.
 
+BitBake auto versions
+---------------------
+
+By setting the version tag in the update file to `@SWU_AUTO_VERSION` it is
+automatically replaced with `PV` from BitBake's package-data-file for the package
+matching the name of the provided filename tag.
+
+Since the filename can differ from package name (deployed with another name or
+the file is a container for the real package) you can append the correct package
+name to the tag:
+`@SWU_AUTO_VERSION:<package-name>`
+
 SWU image signing
 ------------
 

classes/swupdate-common.bbclass

@@ -88,10 +88,64 @@ def swupdate_expand_bitbake_variables(d, s):
         for line in write_lines:
             f.write(line)
 
+def swupdate_expand_auto_versions(d, s, list_for_cpio):
+    import re
+    import oe.packagedata
+    AUTO_VERSION_TAG = "@SWU_AUTO_VERSION"
+    AUTOVERSION_REGEXP = "version\s*=\s*\"%s" % AUTO_VERSION_TAG
+
+    with open(os.path.join(s, "sw-description"), 'r') as f:
+        data = f.read()
+
+    def get_package_name(group, file_list):
+        m = re.search(r"%s:(?P<package>.+?(?=\"))" % (AUTOVERSION_REGEXP), group)
+        if m:
+            package = m.group('package')
+            return (package, True)
+
+        for filename in file_list:
+            if filename in group:
+                package = filename
+
+        if not package:
+            bb.fatal("Failed to find %s in group with \"%s\"" % (filename, AUTO_VERSION_TAG))
+
+        return (package, False)
+
+    regexp = re.compile(r"\{[^\{]*%s.[^\}]*\}" % (AUTOVERSION_REGEXP))
+    while True:
+        m = regexp.search(data)
+        if not m:
+            break
+
+        group = data[m.start():m.end()]
+
+        (package, pkg_name_defined) = get_package_name(group, list_for_cpio)
+
+        pkg_info = os.path.join(d.getVar('PKGDATA_DIR'), 'runtime-reverse', package)
+        pkgdata = oe.packagedata.read_pkgdatafile(pkg_info)
+
+        if not "PV" in pkgdata.keys():
+            bb.warn("\"PV\" not set for package %s - using \"1.0\"" % (package))
+            version = "1.0"
+        else:
+            version = pkgdata['PV'].split('+')[0]
+
+        replace_str = AUTO_VERSION_TAG
+        if pkg_name_defined:
+            replace_str = replace_str + ":" + package
+
+        group = group.replace(replace_str, version)
+        data = data[:m.start()] + group + data[m.end():]
+
+    with open(os.path.join(s, "sw-description"), 'w+') as f:
+        f.write(data)
+
 def prepare_sw_description(d, s, list_for_cpio):
     import shutil
 
     swupdate_expand_bitbake_variables(d, s)
+    swupdate_expand_auto_versions(d, s, list_for_cpio)
 
     for file in list_for_cpio:
         if file != 'sw-description' and swupdate_is_hash_needed(s, file):