Tighten codepaths that parse timestamps in commit objects.
* jk/commit-dates-parsing-fix:
show_ident_date: fix tz range check
log: do not segfault on gmtime errors
log: handle integer overflow in timestamps
date: check date overflow against time_t
fsck: report integer overflow in author timestamps
t4212: test bogus timestamps with git-log
Many code paths assume that show_date and show_ident_date
cannot return NULL. For the most part, we handle missing or
corrupt timestamps by showing the epoch time t=0.
However, we might still return NULL if gmtime rejects the
time_t we feed it, resulting in a segfault. Let's catch this
case and just format t=0.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If an ident line has a ridiculous date value like (2^64)+1,
we currently just pass ULONG_MAX along to the date code,
which can produce nonsensical dates.
On systems with a signed long time_t (e.g., 64-bit glibc
systems), this actually doesn't end up too bad. The
ULONG_MAX is converted to -1, we apply the timezone field to
that, and the result ends up somewhere between Dec 31, 1969
and Jan 1, 1970.
However, there is still a few good reasons to detect the
overflow explicitly:
1. On systems where "unsigned long" is smaller than
time_t, we get a nonsensical date in the future.
2. Even where it would produce "Dec 31, 1969", it's easier
to recognize "midnight Jan 1" as a consistent sentinel
value for "we could not parse this".
3. Values which do not overflow strtoul but do overflow a
signed time_t produce nonsensical values in the past.
For example, on a 64-bit system with a signed long
time_t, a timestamp of 18446744073000000000 produces a
date in 1947.
We also recognize overflow in the timezone field, which
could produce nonsensical results. In this case we show the
parsed date, but in UTC.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When t4212 was originally added by 9dbe7c3d (pretty: handle
broken commit headers gracefully, 2013-04-17), it tested our
handling of commits with broken ident lines in which the
timestamps could not be parsed. It does so using a bogus line
like "Name <email>-<> 1234 -0000", because that simulates an
error that was seen in the wild.
Later, 03818a4 (split_ident: parse timestamp from end of
line, 2013-10-14) made our parser smart enough to actually
find the timestamp on such a line, and t4212 was adjusted to
match. While it's nice that we handle this real-world case,
this meant that we were not actually testing the
bogus-timestamp case anymore.
This patch adds a test with a totally incomprehensible
timestamp to make sure we are testing the code path.
Note that the behavior is slightly different between regular log
output and "--format=%ad". In the former case, we produce a
sentinel value and in the latter, we produce an empty
string. While at first this seems unnecessarily
inconsistent, it matches the original behavior given by
9dbe7c3d.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Split_ident currently parses left to right. Given this
input:
Your Name <email@example.com> 123456789 -0500\n
We assume the name starts the line and runs until the first
"<". That starts the email address, which runs until the
first ">". Everything after that is assumed to be the
timestamp.
This works fine in the normal case, but is easily broken by
corrupted ident lines that contain an extra ">". Some
examples seen in the wild are:
1. Name <email>-<> 123456789 -0500\n
2. Name <email> <Name<email>> 123456789 -0500\n
3. Name1 <email1>, Name2 <email2> 123456789 -0500\n
Currently each of these produces some email address (which
is not necessarily the one the user intended) and end up
with a NULL date (which is generally interpreted as the
epoch by "git log" and friends).
But in each case we could get the correct timestamp simply
by parsing from the right-hand side, looking backwards for
the final ">", and then reading the timestamp from there.
In general, it's a losing battle to try to automatically
guess what the user meant with their broken crud. But this
particular workaround is probably worth doing. One, it's
dirt simple, and can't impact non-broken cases. Two, it
doesn't catch a single breakage we've seen, but rather a
large class of errors (i.e., any breakage inside the email
angle brackets may affect the email, but won't spill over
into the timestamp parsing). And three, the timestamp is
arguably more valuable to get right, because it can affect
correctness (e.g., in --until cutoffs).
This patch implements the right-to-left scheme described
above. We adjust the tests in t4212, which generate a commit
with such a broken ident, and now gets the timestamp right.
We also add a test that fsck continues to detect the
breakage.
For reference, here are pointers to the breakages seen (as
numbered above):
[1] http://article.gmane.org/gmane.comp.version-control.git/221441
[2] http://article.gmane.org/gmane.comp.version-control.git/222362
[3] http://perl5.git.perl.org/perl.git/commit/13b79730adea97e660de84bbe67f9d7cbe344302
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Centralize the parsing of the date and time zone strings in the new
helper function show_ident_date() and make sure it checks the pointers
provided by split_ident_line() for NULL before use.
Reported-by: Ivan Lyapunov <dront78@gmail.com>
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
