[src/trunk]: src/lib/libc/net Move more code into the macro, and fix the bug ...

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

details:   https://anonhg.NetBSD.org/src/rev/e83233c30719
branches:  trunk
changeset: 326062:e83233c30719
user:      christos <christos%NetBSD.org@localhost>
date:      Fri Jan 17 02:03:44 2014 +0000

description:
Move more code into the macro, and fix the bug where realloc would cause
a dangling pointer and memory corruption.

diffstat:

 lib/libc/net/gethnamaddr.c |  52 ++++++++++++++++++++-------------------------
 1 files changed, 23 insertions(+), 29 deletions(-)

diffs (117 lines):

diff -r 71dd600cbdbb -r e83233c30719 lib/libc/net/gethnamaddr.c
--- a/lib/libc/net/gethnamaddr.c        Fri Jan 17 01:32:53 2014 +0000
+++ b/lib/libc/net/gethnamaddr.c        Fri Jan 17 02:03:44 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: gethnamaddr.c,v 1.86 2014/01/16 20:59:21 christos Exp $        */
+/*     $NetBSD: gethnamaddr.c,v 1.87 2014/01/17 02:03:44 christos Exp $        */
 
 /*
  * ++Copyright++ 1985, 1988, 1993
@@ -57,7 +57,7 @@
 static char sccsid[] = "@(#)gethostnamadr.c    8.1 (Berkeley) 6/4/93";
 static char rcsid[] = "Id: gethnamaddr.c,v 8.21 1997/06/01 20:34:37 vixie Exp ";
 #else
-__RCSID("$NetBSD: gethnamaddr.c,v 1.86 2014/01/16 20:59:21 christos Exp $");
+__RCSID("$NetBSD: gethnamaddr.c,v 1.87 2014/01/17 02:03:44 christos Exp $");
 #endif
 #endif /* LIBC_SCCS and not lint */
 
@@ -108,18 +108,22 @@
 #define maybe_hnok(res, hn) maybe_ok((res), (hn), res_hnok)
 #define maybe_dnok(res, dn) maybe_ok((res), (dn), res_dnok)
 
-#define grow(arr, siz) do {                    \
-       void *xptr = realloc(arr, siz + 10);    \
-       if (xptr == NULL)                       \
-               goto nospc;                     \
-       arr = xptr;                             \
-       siz += 10;                              \
+#define addalias(d, s, arr, siz) do {                  \
+       if (d >= &arr[siz - 1]) {                       \
+               char **xptr = realloc(arr, siz + 10);   \
+               if (xptr == NULL)                       \
+                       goto nospc;                     \
+               d = xptr + (d - arr);                   \
+               arr = xptr;                             \
+               siz += 10;                              \
+       }                                               \
+       *d++ = s;                                       \
 } while (/*CONSTCOND*/0)
 
-#define setup(arr, siz) do {                   \
-       arr = malloc(siz = 10);                 \
-       if (arr == NULL)                        \
-               goto nospc;                     \
+#define setup(arr, siz) do {                           \
+       arr = malloc(siz = 10);                         \
+       if (arr == NULL)                                \
+               goto nospc;                             \
 } while (/*CONSTCOND*/0)
 
 
@@ -307,8 +311,6 @@
                        continue;               /* XXX - had_error++ ? */
                }
                if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
-                       if (ap >= &aliases[maxaliases - 1])
-                               grow(aliases, maxaliases);
                        n = dn_expand(answer->buf, eom, cp, tbuf,
                            (int)sizeof tbuf);
                        if ((n < 0) || !maybe_ok(res, tbuf, name_ok)) {
@@ -319,7 +321,7 @@
                        if (cp != erdata)
                                goto no_recovery;
                        /* Store alias. */
-                       *ap++ = bp;
+                       addalias(ap, bp, aliases, maxaliases);
                        n = (int)strlen(bp) + 1;        /* for the \0 */
                        if (n >= MAXHOSTNAMELEN) {
                                had_error++;
@@ -386,11 +388,8 @@
                                goto no_recovery;
                        if (!haveanswer)
                                hent->h_name = bp;
-                       else {
-                               if (ap >= &aliases[maxaliases - 1])
-                                       grow(aliases, maxaliases);
-                               *ap++ = bp;
-                       }
+                       else
+                               addalias(ap, bp, aliases, maxaliases);
                        if (n != -1) {
                                n = (int)strlen(bp) + 1;        /* for the \0 */
                                if (n >= MAXHOSTNAMELEN) {
@@ -808,8 +807,7 @@
                        cp++;
                        continue;
                }
-               if (q >= &aliases[maxaliases - 1])
-                       grow(aliases, maxaliases);
+               addalias(q, cp, aliases, maxaliases);
                *q++ = cp;
                if ((cp = strpbrk(cp, " \t")) != NULL)
                        *cp++ = '\0';
@@ -1173,11 +1171,8 @@
                hp->h_name = p;
        else if (strcmp(hp->h_name, p) == 0)
                ;
-       else {
-               if (q >= &aliases[maxaliases - 1])
-                       grow(aliases, maxaliases);
-               *q++ = p;
-       }
+       else
+               addalias(q, p, aliases, maxaliases);
        p = cp;
        if (more)
                goto nextline;
@@ -1191,8 +1186,7 @@
                        cp++;
                        goto nextline;
                }
-               if (q >= &aliases[maxaliases - 1])
-                       grow(aliases, maxaliases);
+               addalias(q, cp, aliases, maxaliases);
                *q++ = cp;
                cp = strpbrk(cp, " \t");
                if (cp != NULL)