dpkg: Split trigger processing types into required, try-queued and try-deferred

Each of these reasons for processing triggers have different requirements
and attributes:

 - The required one, must perform all checks as it is done as part of a
   simple loop to guarantee Pre-Depends satisfiability.
 - The try-deferred one, must not fail on unsatisfiable dependencies, as
   we are doing opportunistic trigger processing, after a normal
   processing queue run.
 - The try-queued one, must perform all checks and fail hard if any
   unsatisfiable scenario occurs.

3 files changed, 8 insertions, 4 deletions

diff --git a/debian/changelog b/debian/changelog
index 409195f0e..a37ad29a2 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -94,6 +94,8 @@ dpkg (1.19.3) UNRELEASED; urgency=medium
     - dpkg: Switch dependtry from an int to an enum.
     - dpkg: Move dependtry description from deferred_configure() to its
       declaration.
+    - dpkg: Split trigger processing types into required, try-queued and
+      try-deferred.
   * Build system:
     - get-version: Use a format string with printf.
     - run-script: Use $() instead of deprecated ``.
diff --git a/src/main.h b/src/main.h
index e43e6d28d..c60ccfab0 100644
--- a/src/main.h
+++ b/src/main.h
@@ -318,8 +318,10 @@ void dpkg_selabel_close(void);
 /* from trigproc.c */
 
 enum trigproc_type {
-	/** Opportunistic trigger processing. */
-	TRIGPROC_TRY,
+	/** Opportunistic deferred trigger processing. */
+	TRIGPROC_TRY_DEFERRED,
+	/** Opportunistic queued trigger processing. */
+	TRIGPROC_TRY_QUEUED,
 	/** Required trigger processing. */
 	TRIGPROC_REQUIRED,
 };
diff --git a/src/trigproc.c b/src/trigproc.c
index 76d901176..5b7066d8a 100644
--- a/src/trigproc.c
+++ b/src/trigproc.c
@@ -162,7 +162,7 @@ trigproc_run_deferred(void)
 
 		ensure_package_clientdata(pkg);
 		pkg->clientdata->trigprocdeferred = NULL;
-		trigproc(pkg, TRIGPROC_TRY);
+		trigproc(pkg, TRIGPROC_TRY_DEFERRED);
 
 		pop_error_context(ehflag_normaltidy);
 	}
@@ -416,7 +416,7 @@ trigproc(struct pkginfo *pkg, enum trigproc_type type)
 			 * requires us to be able to make progress; skip the
 			 * package and silently ignore the error due to
 			 * unsatisfiable dependencies. */
-			if (type == TRIGPROC_TRY) {
+			if (type == TRIGPROC_TRY_DEFERRED) {
 				varbuf_destroy(&depwhynot);
 				return;
 			}