Our fts(3) API, as inherited from 4.4BSD, suffers from integer

fields in FTS and FTSENT structs being too narrow.  In addition,
the narrow types creep from there into fts.c.  As a result, fts(3)
consumers, e.g., find(1) or rm(1), can't handle file trees an ordinary
user can create, which can have security implications.

To fix the historic implementation of fts(3), OpenBSD and NetBSD
have already changed <fts.h> in somewhat incompatible ways, so we
are free to do so, too.  This change is a superset of changes from
the other BSDs with a few more improvements.  It doesn't touch
fts(3) functionality; it just extends integer types used by it to
match modern reality and the C standard.

Here are its points:

o For C object sizes, use size_t unless it's 100% certain that
  the object will be really small.  (Note that fts(3) can construct
  pathnames _much_ longer than PATH_MAX for its consumers.)

o Avoid the short types because on modern platforms using them
  results in larger and slower code.  Change shorts to ints as
  follows:

	- For variables than count simple, limited things like states,
	  use plain vanilla `int' as it's the type of choice in C.

	- For a limited number of bit flags use `unsigned' because signed
	  bit-wise operations are implementation-defined, i.e., unportable,
	  in C.

o For things that should be at least 64 bits wide, use long long
  and not int64_t, as the latter is an optional type.  See
  FTSENT.fts_number aka FTS.fts_bignum.  Extending fts_number `to
  satisfy future needs' is pointless because there is fts_pointer,
  which can be used to link to arbitrary data from an FTSENT.
  However, there already are fts(3) consumers that require fts_number,
  or fts_bignum, have at least 64 bits in it, so we must allow for them.

o For the tree depth, use `long'.  This is a trade-off between making
  this field too wide and allowing for 64-bit inode numbers and/or
  chain-mounted filesystems.  On the one hand, `long' is almost
  enough for 32-bit filesystems on a 32-bit platform (our ino_t is
  uint32_t now).  On the other hand, platforms with a 64-bit (or
  wider) `long' will be ready for 64-bit inode numbers, as well as
  for several 32-bit filesystems mounted one under another.  Note
  that fts_level has to be signed because -1 is a magic value for it,
  FTS_ROOTPARENTLEVEL.

o For the `nlinks' local var in fts_build(), use `long'.  The logic
  in fts_build() requires that `nlinks' be signed, but our nlink_t
  currently is uint16_t.  Therefore let's make the signed var wide
  enough to be able to represent 2^16-1 in pure C99, and even 2^32-1
  on a 64-bit platform.  Perhaps the logic should be changed just
  to use nlink_t, but it can be done later w/o breaking fts(3) ABI
  any more because `nlinks' is just a local var.

This commit also inludes supporting stuff for the fts change:

o Preserve the old versions of fts(3) functions through libc symbol
versioning because the old versions appeared in all our former releases.

o Bump __FreeBSD_version just in case.  There is a small chance that
some ill-written 3-rd party apps may fail to build or work correctly
if compiled after this change.

o Update the fts(3) manpage accordingly.  In particular, remove
references to fts_bignum, which was a FreeBSD-specific hack to work
around the too narrow types of FTSENT members.  Now fts_number is
at least 64 bits wide (long long) and fts_bignum is an undocumented
alias for fts_number kept around for compatibility reasons.  According
to Google Code Search, the only big consumers of fts_bignum are in
our own source tree, so they can be fixed easily to use fts_number.

o Mention the change in src/UPDATING.

PR:		bin/104458
Approved by:	re (quite a while ago)
Discussed with:	deischen (the symbol versioning part)
Reviewed by:	-arch (mostly silence); das (generally OK, but we didn't
		agree on some types used; assuming that no objections on
		-arch let me to stick to my opinion)

1 files changed, 11 insertions, 8 deletions

diff --git a/lib/libc/gen/Symbol.map b/lib/libc/gen/Symbol.map
index e2f62d6..8167aaa 100644
--- a/lib/libc/gen/Symbol.map
+++ b/lib/libc/gen/Symbol.map
@@ -134,14 +134,6 @@ FBSD_1.0 {
 	setfsent;
 	endfsent;
 	ftok;
-	fts_open;
-	fts_close;
-	fts_read;
-	fts_set;
-	fts_children;
-	fts_get_clientptr;
-	fts_get_stream;
-	fts_set_clientptr;
 	ftw;
 	glob;
 	globfree;
@@ -336,6 +328,17 @@ FBSD_1.0 {
 	wordfree;
 };
 
+FBSD_1.1 {
+	fts_open;
+	fts_close;
+	fts_read;
+	fts_set;
+	fts_children;
+	fts_get_clientptr;
+	fts_get_stream;
+	fts_set_clientptr;
+};
+
 FBSDprivate_1.0 {
 	/* needed by thread libraries */
 	__thr_jtable;