Code clean-up to avoid using a variable string that compilers may
feel untrustable as printf-style format given to write_file()
helper function.

* jk/printf-format:
  commit.c: remove print_commit_list()
  avoid using sha1_to_hex output as printf format
  walker: let walker_say take arbitrary formats

"git commit --amend --allow-empty-message -S" for a commit without
any message body could have misidentified where the header of the
commit object ends.

* js/sign-empty-commit-fix:
  commit -S: avoid invalid pointer with empty message

A helper function that takes the contents of a commit object and
finds its subject line did not ignore leading blank lines, as is
commonly done by other codepaths.  Make it ignore leading blank
lines to match.

* js/find-commit-subject-ignore-leading-blanks:
  reset --hard: skip blank lines when reporting the commit subject
  sequencer: use skip_blank_lines() to find the commit subject
  commit -C: skip blank lines at the beginning of the message
  commit.c: make find_commit_subject() more robust
  pretty: make the skip_blank_lines() function public

The helper function tries to offer a way to conveniently show the
last one differently from others, presumably to allow you to say
something like

	A, B, and C.

while iterating over a list that has these three elements.

However, there is only one caller, and it passes the same format
string "%s\n" for both the last one and the other ones.  Retire the
helper function and update the caller with a simplified version.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

While it is not recommended, fsck.c says:

	Not having a body is not a crime [...]

... which means that we cannot assume that the commit buffer
contains an empty line to separate header from body.  A commit
object with only a header without any body, not even without
a blank line after the header, is valid.

So let's tread carefully here.  strstr("\n\n") may find nothing
and return NULL.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Just like the pretty printing machinery, we should simply ignore
blank lines at the beginning of the commit messages.

This discrepancy was noticed when an early version of the
rebase--helper produced commit objects with more than one empty line
between the header and the commit message.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

If our size computation overflows size_t, we may allocate a
much smaller buffer than we expected and overflow it. It's
probably impossible to trigger an overflow in most of these
sites in practice, but it is easy enough convert their
additions and multiplications into overflow-checking
variants. This may be fixing real bugs, and it makes
auditing the code easier.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Each of these cases can be converted to use ALLOC_ARRAY or
REALLOC_ARRAY, which has two advantages:

  1. It automatically checks the array-size multiplication
     for overflow.

  2. It always uses sizeof(*array) for the element-size,
     so that it can never go out of sync with the declared
     type of the array.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Code simplification.

* rs/pop-commit:
  use pop_commit() for consuming the first entry of a struct commit_list

Convert all instances of get_object_hash to use an appropriate reference
to the hash member of the oid member of struct object.  This provides no
functional change, as it is essentially a macro substitution.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>