[src/trunk]: src/usr.bin/make make(1): initialize global variables in dir.c

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/510440163556
branches:  trunk
changeset: 957488:510440163556
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Nov 29 21:50:50 2020 +0000

description:
make(1): initialize global variables in dir.c

Calling CachedDir_Assign requires that the variable be initialized.  On
most systems, NULL is represented as all-zero bits already.  This change
is only for the few other systems.

Add some comments explaining the implementation of Dir_AddDir since that
is tricky to read from the code alone.

diffstat:

 usr.bin/make/dir.c |  22 +++++++++++++---------
 1 files changed, 13 insertions(+), 9 deletions(-)

diffs (64 lines):

diff -r 7dc95fd1e39c -r 510440163556 usr.bin/make/dir.c
--- a/usr.bin/make/dir.c        Sun Nov 29 21:31:55 2020 +0000
+++ b/usr.bin/make/dir.c        Sun Nov 29 21:50:50 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dir.c,v 1.241 2020/11/29 18:49:36 rillig Exp $ */
+/*     $NetBSD: dir.c,v 1.242 2020/11/29 21:50:50 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
@@ -136,7 +136,7 @@
 #include "job.h"
 
 /*     "@(#)dir.c      8.2 (Berkeley) 1/2/94"  */
-MAKE_RCSID("$NetBSD: dir.c,v 1.241 2020/11/29 18:49:36 rillig Exp $");
+MAKE_RCSID("$NetBSD: dir.c,v 1.242 2020/11/29 21:50:50 rillig Exp $");
 
 #define DIR_DEBUG0(text) DEBUG0(DIR, text)
 #define DIR_DEBUG1(fmt, arg1) DEBUG1(DIR, fmt, arg1)
@@ -269,8 +269,8 @@
 static int nearmisses;         /* Found under search path */
 static int bigmisses;          /* Sought by itself */
 
-static CachedDir *dot;         /* contents of current directory */
-static CachedDir *cur;         /* contents of current directory, if not dot */
+static CachedDir *dot = NULL;  /* contents of current directory */
+static CachedDir *cur = NULL;  /* contents of current directory, if not dot */
 /* A fake path entry indicating we need to look for '.' last. */
 static CachedDir *dotLast = NULL;
 
@@ -1470,11 +1470,8 @@
 }
 
 /*
- * Read the directory and add it to the cache in openDirs, even if it is
- * already there.  If a path is given, add the directory to that path as
- * well.
- *
- * XXX: Why is it added to openDirs unconditionally?
+ * Read the directory and add it to the cache in openDirs.
+ * If a path is given, add the directory to that path as well.
  */
 static CachedDir *
 CacheNewDir(const char *name, SearchPath *path)
@@ -1526,6 +1523,12 @@
  *                     added, or NULL to only add the directory to openDirs
  *     name            The name of the directory to add.
  *                     The name is not normalized in any way.
+ * Output:
+ *     result          If no path is given and the directory exists, the
+ *                     returned CachedDir has a reference count of 0.  It
+ *                     must either be assigned to a variable using
+ *                     CachedDir_Assign or be appended to a SearchPath using
+ *                     Lst_Append and CachedDir_Ref.
  */
 CachedDir *
 Dir_AddDir(SearchPath *path, const char *name)
@@ -1545,6 +1548,7 @@
        }
 
        if (path != NULL) {
+               /* XXX: Why is OpenDirs only checked if path != NULL? */
                CachedDir *dir = OpenDirs_Find(&openDirs, name);
                if (dir != NULL) {
                        if (Lst_FindDatum(path, dir) == NULL)