Author: glebius
Date: Tue Oct 15 13:32:01 2013
New Revision: 256537
URL: http://svnweb.freebsd.org/changeset/base/256537
Log:
Make getutxent(3) more robust against bad utx.log files. Whenever we read
zeroes, don't stop processing the file, but read until its end or valid
data.
In collaboration with: ed
Modified:
head/lib/libc/gen/getutxent.c
Modified: head/lib/libc/gen/getutxent.c
==============================================================================
--- head/lib/libc/gen/getutxent.c Tue Oct 15 13:24:10 2013
(r256536)
+++ head/lib/libc/gen/getutxent.c Tue Oct 15 13:32:01 2013
(r256537)
@@ -122,9 +122,20 @@ getfutxent(struct futx *fu)
if (udb == UTXDB_LOG) {
uint16_t len;
+retry:
if (fread(&len, sizeof(len), 1, uf) != 1)
return (-1);
len = be16toh(len);
+ if (len == 0) {
+ /*
+ * XXX: Though zero-size records are valid in theory,
+ * they can never occur in practice. Zero-size records
+ * indicate file corruption. Seek one byte forward, to
+ * see if we can find a record there.
+ */
+ ungetc('\0', uf);
+ goto retry;
+ }
if (len > sizeof *fu) {
/* Forward compatibility. */
if (fread(fu, sizeof(*fu), 1, uf) != 1)
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