Fix a potential NULL pointer access in an error message after waitpid()

failure; found using detailed information provided by Ulrich Spoerlein
<uqs at FreeBSD> about FreeBSD Coverity CID 1261304.

diff --git a/usr.bin/mandoc/mandocdb.c b/usr.bin/mandoc/mandocdb.c
index 544e1ff..560e259 100644 (file)
--- a/usr.bin/mandoc/mandocdb.c
+++ b/usr.bin/mandoc/mandocdb.c
@@ -1,7 +1,7 @@
-/*     $OpenBSD: mandocdb.c,v 1.135 2015/01/02 17:01:31 schwarze Exp $ */
+/*     $OpenBSD: mandocdb.c,v 1.136 2015/01/03 12:54:49 schwarze Exp $ */
 /*
  * Copyright (c) 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2011, 2012, 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2011-2015 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -1106,7 +1106,7 @@ mpages_merge(struct mparse *mp)
        mpage = ohash_first(&mpages, &pslot);
        while (mpage != NULL) {
                mlinks_undupe(mpage);
-               if (mpage->mlinks == NULL) {
+               if ((mlink = mpage->mlinks) == NULL) {
                        mpage = ohash_next(&mpages, &pslot);
                        continue;
                }
@@ -1119,9 +1119,9 @@ mpages_merge(struct mparse *mp)
                man = NULL;
                sodest = NULL;
 
-               mparse_open(mp, &fd, mpage->mlinks->file);
+               mparse_open(mp, &fd, mlink->file);
                if (fd == -1) {
-                       say(mpage->mlinks->file, "&open");
+                       say(mlink->file, "&open");
                        goto nextpage;
                }
 
@@ -1130,9 +1130,8 @@ mpages_merge(struct mparse *mp)
                 * source code, unless it is already known to be
                 * formatted.  Fall back to formatted mode.
                 */
-               if (mpage->mlinks->dform != FORM_CAT ||
-                   mpage->mlinks->fform != FORM_CAT) {
-                       lvl = mparse_readfd(mp, fd, mpage->mlinks->file);
+               if (mlink->dform != FORM_CAT || mlink->fform != FORM_CAT) {
+                       lvl = mparse_readfd(mp, fd, mlink->file);
                        if (lvl < MANDOCLEVEL_FATAL)
                                mparse_result(mp, &mdoc, &man, &sodest);
                }
@@ -1151,7 +1150,6 @@ mpages_merge(struct mparse *mp)
                                /* The .so target exists. */
 
                                mpage_dest = mlink_dest->mpage;
-                               mlink = mpage->mlinks;
                                while (1) {
                                        mlink->mpage = mpage_dest;
 
@@ -1191,26 +1189,20 @@ mpages_merge(struct mparse *mp)
                            mandoc_strdup(mdoc_meta(mdoc)->title);
                } else if (man != NULL) {
                        mpage->form = FORM_SRC;
-                       mpage->sec =
-                           mandoc_strdup(man_meta(man)->msec);
-                       mpage->arch =
-                           mandoc_strdup(mpage->mlinks->arch);
-                       mpage->title =
-                           mandoc_strdup(man_meta(man)->title);
+                       mpage->sec = mandoc_strdup(man_meta(man)->msec);
+                       mpage->arch = mandoc_strdup(mlink->arch);
+                       mpage->title = mandoc_strdup(man_meta(man)->title);
                } else {
                        mpage->form = FORM_CAT;
-                       mpage->sec =
-                           mandoc_strdup(mpage->mlinks->dsec);
-                       mpage->arch =
-                           mandoc_strdup(mpage->mlinks->arch);
-                       mpage->title =
-                           mandoc_strdup(mpage->mlinks->name);
+                       mpage->sec = mandoc_strdup(mlink->dsec);
+                       mpage->arch = mandoc_strdup(mlink->arch);
+                       mpage->title = mandoc_strdup(mlink->name);
                }
                putkey(mpage, mpage->sec, TYPE_sec);
                if (*mpage->arch != '\0')
                        putkey(mpage, mpage->arch, TYPE_arch);
 
-               for (mlink = mpage->mlinks; mlink; mlink = mlink->next) {
+               for ( ; mlink != NULL; mlink = mlink->next) {
                        if ('\0' != *mlink->dsec)
                                putkey(mpage, mlink->dsec, TYPE_sec);
                        if ('\0' != *mlink->fsec)
@@ -1236,11 +1228,12 @@ mpages_merge(struct mparse *mp)
                                mlink_check(mpage, mlink);
 
                dbadd(mpage);
+               mlink = mpage->mlinks;
 
 nextpage:
                if (mparse_wait(mp) != MANDOCLEVEL_OK) {
                        exitcode = (int)MANDOCLEVEL_SYSERR;
-                       say(mpage->mlinks->file, "&wait gunzip");
+                       say(mlink->file, "&wait gunzip");
                }
                ohash_delete(&strings);
                ohash_delete(&names);