Optimization for fast-export by avoiding unnecessarily resolving
arbitrary object name and parsing object when only presence and
type information is necessary, etc.

* fc/fast-export-persistent-marks:
  fast-{import,export}: use get_sha1_hex() to read from marks file
  fast-export: don't parse commits while reading marks file
  fast-export: do not parse non-commit objects while reading marks file

It's wrong to call get_sha1() if they should be SHA-1s, plus
inefficient.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Sparse issues 68 errors (two errors for each main() function) such
as the following:

      SP git.c
  git.c:510:5: error: too many arguments for function mingw_main
  git.c:510:5: error: symbol 'mingw_main' redeclared with different type \
    (originally declared at git.c:510) - different argument counts

The errors are caused by the 'main' macro used by the MinGW build
to provide a replacement main() function. The original main function
is effectively renamed to 'mingw_main' and is called from the new
main function. The replacement main is used to execute certain actions
common to all git programs on MinGW (e.g. ensure the standard I/O
streams are in binary mode).

In order to suppress the errors, we change the macro to include the
parameters in the declaration of the mingw_main function.

Unfortunately, this change provokes both sparse and gcc to complain
about 9 calls to mingw_main(), such as the following:

      CC git.o
  git.c: In function 'main':
  git.c:510: warning: passing argument 2 of 'mingw_main' from \
    incompatible pointer type
  git.c:510: note: expected 'const char **' but argument is of \
    type 'char **'

In order to suppress these warnings, since both of the main
functions need to be declared with the same prototype, we
change the declaration of the 9 main functions, thus:

    int main(int argc, char **argv)

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Commit cbfd5e1c ("drop some obsolete "x = x" compiler warning hacks",
21-03-2013) removed a gcc hack that suppressed an "might be used
uninitialized" warning issued by older versions of gcc.

However, commit 3aa99df8 ('fast-import: clarify "inline" logic in
file_change_m', 21-03-2013) addresses an (almost) identical issue
(with very similar code), but includes additional code in it's
resolution. The solution used by this commit, unlike that used by
commit cbfd5e1c, also suppresses the -Wuninitialized warning on
older versions of gcc.

In order to suppress the warning (against the 'oe' symbol) in the
note_change_n() function, we adopt the same solution used by commit
3aa99df8.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

When we read a fast-import line like:

  M 100644 :1 foo.c

we point the local object_entry variable "oe" to the object
named by the mark ":1". When the input uses the "inline"
construct, however, we do not have such an object_entry.

The current code is careful not to access "oe" in the inline
case, but we can make the assumption even more obvious (and
catch violations of it) by setting oe to NULL and adding a
comment. As a bonus, this also squelches an over-zealous gcc
-Wuninitialized warning, which means we can drop the "oe =
oe" initialization hack.

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

In cases where the setting and access of a variable are
protected by the same conditional flag, older versions of
gcc would generate a "might be used unitialized" warning. We
silence the warning by initializing the variable to itself,
a hack that gcc recognizes.

Modern versions of gcc are smart enough to get this right,
going back to at least version 4.3.5. gcc 4.1 does get it
wrong in both cases, but is sufficiently old that we
probably don't need to care about it anymore.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

This is shorter, idiomatic, and it means the compiler does
not get confused about whether our "e" pointer is valid,
letting us drop the "e = e" hack.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Optimise the "merge-base" computation a bit, and also update its
users that do not need the full merge-base information to call a
cheaper subset.

* jc/merge-bases:
  reduce_heads(): reimplement on top of remove_redundant()
  merge-base: "--is-ancestor A B"
  get_merge_bases_many(): walk from many tips in parallel
  in_merge_bases(): use paint_down_to_common()
  merge_bases_many(): split out the logic to paint history
  in_merge_bases(): omit unnecessary redundant common ancestor reduction
  http-push: use in_merge_bases() for fast-forward check
  receive-pack: use in_merge_bases() for fast-forward check
  in_merge_bases(): support only one "other" commit

In early days of its life, I planned to make it possible to compute
"is a commit contained in all of these other commits?" with this
function, but it turned out that no caller needed it.

Just make it take two commit objects and add a comment to say what
these two functions do.

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

The syntax for the use of mark references in fast-import
demands either a SP (space) or LF (end-of-line) after
a mark reference.  Fast-import does not complain when garbage
appears after a mark reference in some cases.

Factor out parsing of mark references and complain if
errant characters are found.  Also be a little more careful
when parsing "inline" and SHA1s, complaining if extra
characters appear or if the form of the dataref is unrecognized.

Buggy input can cause fast-import to produce the wrong output,
silently, without error.  This makes it difficult to track
down buggy generators of fast-import streams.  An example is
seen in the last line of this commit command:

    commit refs/heads/S2
    committer Name <name@example.com> 1112912893 -0400
    data <<COMMIT
    commit message
    COMMIT
    from :1M 100644 :103 hello.c

It is missing a newline and should be:

    [...]
    from :1
    M 100644 :103 hello.c

What fast-import does is to produce a commit with the same
contents for hello.c as in refs/heads/S2^.  What the buggy
program was expecting was the contents of blob :103.  While
the resulting commit graph looked correct, the contents in
some commits were wrong.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>