Pick a more consistent name for whatis targets

We don't want the targets of whatis entries in the database to depend on
the order in which files were scanned.  Prefer the first name in the
trace out of those that have the best ID.

* src/descriptions_store.c (store_descriptions): Defer adding names that
don't appear in the ultimate source trace (i.e. whatis entries) until we
know the best name to use as the target, and use that best name as the
pointer for each of them.

2 files changed, 82 insertions, 39 deletions

diff --git a/NEWS.md b/NEWS.md
index c27cdab6..3fba6468 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -17,6 +17,8 @@ Improvements:
  * Add more recognized case variants for localized versions of the `NAME`
    section.
  * Maintain multi keys in sorted order, improving database reproducibility.
+ * Pick a more consistent name for the target of a whatis entry in the
+   database.
 
 man-db 2.10.2 (17 March 2022)
 =============================
diff --git a/src/descriptions_store.c b/src/descriptions_store.c
index 16129d99..d0d23441 100644
--- a/src/descriptions_store.c
+++ b/src/descriptions_store.c
@@ -37,7 +37,8 @@
 #define _(String) gettext (String)
 
 #include "error.h"
-#include "gl_list.h"
+#include "gl_array_list.h"
+#include "gl_xlist.h"
 #include "stat-time.h"
 #include "xalloc.h"
 
@@ -76,15 +77,22 @@ void store_descriptions (MYDBM_FILE dbf, gl_list_t descs, struct mandata *info,
 			 const char *path, const char *base, gl_list_t trace)
 {
 	const struct page_description *desc;
-	char save_id = info->id;
-	struct timespec save_mtime = info->mtime;
 	const char *trace_name;
+	gl_list_t whatis_infos;
+	struct mandata *whatis_info;
+	char best_id = WHATIS_CAT + 1;
+	const char *best_name = base;
 
 	if (gl_list_size (descs) && trace) {
 		GL_LIST_FOREACH (trace, trace_name)
 			debug ("trace: '%s'\n", trace_name);
 	}
 
+	whatis_infos = gl_list_create_empty (GL_ARRAY_LIST, NULL, NULL,
+					     (gl_listelement_dispose_fn)
+					     free_mandata_struct,
+					     true);
+
 	GL_LIST_FOREACH (descs, desc) {
 		/* Either it's the real thing or merely a reference. Get the
 		 * id and pointer right in either case.
@@ -92,18 +100,21 @@ void store_descriptions (MYDBM_FILE dbf, gl_list_t descs, struct mandata *info,
 		bool found_real_page = false;
 		bool found_external = false;
 
-		if (STREQ (base, desc->name)) {
-			info->id = save_id;
-			free (info->pointer);
-			info->pointer = NULL;
-			free (info->whatis);
-			if (desc->whatis)
-				info->whatis = xstrdup (desc->whatis);
-			else
-				info->whatis = NULL;
-			info->mtime = save_mtime;
+		whatis_info = XZALLOC (struct mandata);
+		whatis_info->ext = xstrdup (info->ext);
+		whatis_info->sec = xstrdup (info->sec);
+		whatis_info->id = info->id;
+		if (info->comp)
+			whatis_info->comp = xstrdup (info->comp);
+		if (info->filter)
+			whatis_info->filter = xstrdup (info->filter);
+		if (desc->whatis)
+			whatis_info->whatis = xstrdup (desc->whatis);
+		whatis_info->mtime = info->mtime;
+
+		if (STREQ (base, desc->name))
 			found_real_page = true;
-		} else if (trace) {
+		else if (trace) {
 			GL_LIST_FOREACH (trace, trace_name) {
 				struct mandata *trace_info;
 				struct stat st;
@@ -122,25 +133,24 @@ void store_descriptions (MYDBM_FILE dbf, gl_list_t descs, struct mandata *info,
 					free_mandata_struct (trace_info);
 					break;
 				}
-				info->id = save_id;
 				if (!gl_list_next_node (trace, trace_node)) {
-					if (save_id == SO_MAN)
-						info->id = ULT_MAN;
+					if (info->id == SO_MAN)
+						whatis_info->id = ULT_MAN;
 				} else {
-					if (save_id == ULT_MAN)
-						info->id = SO_MAN;
+					if (info->id == ULT_MAN)
+						whatis_info->id = SO_MAN;
 				}
-				free (info->pointer);
-				info->pointer = NULL;
-				free (info->whatis);
-				if (desc->whatis)
-					info->whatis = xstrdup (desc->whatis);
+				free (whatis_info->comp);
+				if (trace_info->comp)
+					whatis_info->comp = xstrdup
+						(trace_info->comp);
 				else
-					info->whatis = NULL;
+					whatis_info->comp = NULL;
 				if (lstat (trace_name, &st) == 0)
-					info->mtime = get_stat_mtime (&st);
+					whatis_info->mtime = get_stat_mtime
+						(&st);
 				else
-					info->mtime = save_mtime;
+					whatis_info->mtime = info->mtime;
 				found_real_page = true;
 
 next_trace:
@@ -151,28 +161,59 @@ next_trace:
 		if (found_external) {
 			debug ("skipping '%s'; link outside manual "
 			       "hierarchy\n", desc->name);
+			free_mandata_struct (whatis_info);
 			continue;
 		}
 
 		if (!found_real_page) {
-			if (save_id < STRAY_CAT)
-				info->id = WHATIS_MAN;
+			whatis_info->name = xstrdup (desc->name);
+			if (info->id < STRAY_CAT)
+				whatis_info->id = WHATIS_MAN;
 			else
-				info->id = WHATIS_CAT;
-			free (info->pointer);
-			info->pointer = xstrdup (base);
+				whatis_info->id = WHATIS_CAT;
 			/* Don't waste space storing the whatis in the db
 			 * more than once.
 			 */
-			free (info->whatis);
-			info->whatis = NULL;
-			info->mtime = save_mtime;
+			free (whatis_info->whatis);
+			whatis_info->whatis = NULL;
+			gl_list_add_last (whatis_infos, whatis_info);
+			continue;
+		}
+
+		if (whatis_info->id < best_id) {
+			best_id = whatis_info->id;
+			best_name = desc->name;
+		}
+
+		debug ("name = '%s', id = %c\n", desc->name, whatis_info->id);
+		if (dbstore (dbf, whatis_info, desc->name) > 0) {
+			gripe_bad_store (base, whatis_info->ext);
+			free_mandata_struct (whatis_info);
+			goto out;
 		}
 
-		debug ("name = '%s', id = %c\n", desc->name, info->id);
-		if (dbstore (dbf, info, desc->name) > 0) {
-			gripe_bad_store (base, info->ext);
-			break;
+		free_mandata_struct (whatis_info);
+	}
+
+	GL_LIST_FOREACH (whatis_infos, whatis_info) {
+		char *name;
+
+		name = whatis_info->name;
+		whatis_info->name = NULL;
+
+		whatis_info->pointer = xstrdup (best_name);
+
+		debug ("name = '%s', id = %c, pointer = '%s'\n",
+		       name, whatis_info->id, whatis_info->pointer);
+		if (dbstore (dbf, whatis_info, name) > 0) {
+			gripe_bad_store (base, whatis_info->ext);
+			free (name);
+			goto out;
 		}
+
+		free (name);
 	}
+
+out:
+	gl_list_free (whatis_infos);
 }