vartree, movefile: Warn when rewriting a symlink

See PMS section 13.4.1 (Rewriting):
Any absolute symlink whose link starts with D must be rewritten with
the leading D removed. The package manager should issue a notice when
doing this.

Bug: https://bugs.gentoo.org/934514
Signed-off-by: Ulrich Müller <[email protected]>

NEWS

@@ -20,6 +20,8 @@ Bug fixes:
  working ebuilds. Future EAPIs will need to adjust the logic
  added by this change. See bug #907061.
 
+* vartree, movefile: Warn when rewriting a symlink (bug #934514).
+
 portage-3.0.65 (2024-06-04)
 --------------
 

lib/portage/dbapi/vartree.py

@@ -5563,6 +5563,16 @@ def mergeme(
  myabsto = myabsto.lstrip(sep)
  if self.settings and self.settings["D"]:
  if myto.startswith(self.settings["D"]):
+ self._eqawarn(
+ "preinst",
+ [
+ _(
+ "QA Notice: Absolute symlink %s points to %s inside the image directory.\n"
+ "Removing the leading %s from its path."
+ )
+ % (mydest, myto, self.settings["D"])
+ ],
+ )
  myto = myto[len(self.settings["D"]) - 1 :]
  # myrealto contains the path of the real file to which this symlink points.
  # we can simply test for existence of this file to see if the target has been merged yet

lib/portage/util/movefile.py

@@ -210,6 +210,11 @@ def movefile(
  try:
  target = os.readlink(src)
  if mysettings and "D" in mysettings and target.startswith(mysettings["D"]):
+ writemsg(
+ f"!!! {_('Absolute symlink points to image directory.')}\n",
+ noiselevel=-1,
+ )
+ writemsg(f"!!! {dest} -> {target}\n", noiselevel=-1)
  target = target[len(mysettings["D"]) - 1 :]
  # Atomically update the path if it exists.
  try: