view tests/test-mq-qdiff.t @ 26375:3686fa2b8eee

windows: insert file positioning call between reads and writes

fopen() and fdopen() have a unique-to-Windows requirement that
transitions between read and write operations in files opened
in modes r+, w+, and a+ perform a file positioning call
(fsetpos, fseek, or rewind) in between. While the MSDN docs don't
say what will happen if this is not done, observations reveal
that Python raises an IOError with errno 0. Furthermore, I
/think/ this behavior isn't deterministic. But I can reproduce
it reliably with subsequent patches applied that open revlogs
in a+ mode and perform both reads and writes.

This patch introduces a proxy class for file handles opened
in r+, w+, and a+ mode on Windows. The class intercepts calls
and audits whether a file positioning function has been called
between read and write operations. If not, a dummy, no-op seek
to the current file position is performed. This appears to be
sufficient to "trick" Windows into allowing transitions between
read and writes without raising errors.

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > [mq]
  > git = keep
  > EOF

  $ hg init a
  $ cd a

  $ echo 'base' > base
  $ hg ci -Ambase
  adding base

  $ hg qnew -mmqbase mqbase

  $ echo 'patched' > base
  $ hg qrefresh

qdiff:

  $ hg qdiff
  diff -r d20a80d4def3 base
  --- a/base	Thu Jan 01 00:00:00 1970 +0000
  +++ b/base* (glob)
  @@ -1,1 +1,1 @@
  -base
  +patched

qdiff dirname:

  $ hg qdiff --nodates .
  diff -r d20a80d4def3 base
  --- a/base
  +++ b/base
  @@ -1,1 +1,1 @@
  -base
  +patched

qdiff filename:

  $ hg qdiff --nodates base
  diff -r d20a80d4def3 base
  --- a/base
  +++ b/base
  @@ -1,1 +1,1 @@
  -base
  +patched

  $ hg revert -a

  $ hg qpop
  popping mqbase
  patch queue now empty

  $ hg qdelete mqbase

  $ printf '1\n2\n3\n4\nhello world\ngoodbye world\n7\n8\n9\n' > lines
  $ hg ci -Amlines -d '2 0'
  adding lines

  $ hg qnew -mmqbase2 mqbase2
  $ printf '\n\n1\n2\n3\n4\nhello  world\n     goodbye world\n7\n8\n9\n' > lines

  $ hg qdiff --nodates -U 1
  diff -r b0c220e1cf43 lines
  --- a/lines
  +++ b/lines
  @@ -1,1 +1,3 @@
  +
  +
   1
  @@ -4,4 +6,4 @@
   4
  -hello world
  -goodbye world
  +hello  world
  +     goodbye world
   7

  $ hg qdiff --nodates -b
  diff -r b0c220e1cf43 lines
  --- a/lines
  +++ b/lines
  @@ -1,9 +1,11 @@
  +
  +
   1
   2
   3
   4
   hello world
  -goodbye world
  +     goodbye world
   7
   8
   9

  $ hg qdiff --nodates -U 1 -B
  diff -r b0c220e1cf43 lines
  --- a/lines
  +++ b/lines
  @@ -4,4 +4,4 @@
   4
  -hello world
  -goodbye world
  +hello  world
  +     goodbye world
   7

  $ hg qdiff --nodates -w
  diff -r b0c220e1cf43 lines
  --- a/lines
  +++ b/lines
  @@ -1,3 +1,5 @@
  +
  +
   1
   2
   3

  $ hg qdiff --nodates --reverse
  diff -r b0c220e1cf43 lines
  --- a/lines
  +++ b/lines
  @@ -1,11 +1,9 @@
  -
  -
   1
   2
   3
   4
  -hello  world
  -     goodbye world
  +hello world
  +goodbye world
   7
   8
   9

qdiff preserve existing git flag:

  $ hg qrefresh --git
  $ echo a >> lines
  $ hg qdiff
  diff --git a/lines b/lines
  --- a/lines
  +++ b/lines
  @@ -1,9 +1,12 @@
  +
  +
   1
   2
   3
   4
  -hello world
  -goodbye world
  +hello  world
  +     goodbye world
   7
   8
   9
  +a

  $ hg qdiff --stat
   lines |  7 +++++--
   1 files changed, 5 insertions(+), 2 deletions(-)
  $ hg qrefresh

qdiff when file deleted (but not removed) in working dir:

  $ hg qnew deleted-file
  $ echo a > newfile
  $ hg add newfile
  $ hg qrefresh
  $ rm newfile
  $ hg qdiff

  $ cd ..