tests/test-rebuildstate.t

posix: always seek to EOF when opening a file in append mode

Python 3 already does this, so skip it there.

Consider the program:

   #include <stdio.h>

   int main() {
     FILE *f = fopen("narf", "w");
     fprintf(f, "narf\n");
     fclose(f);

     f = fopen("narf", "a");
     printf("%ld\n", ftell(f));
     fprintf(f, "troz\n");
     printf("%ld\n", ftell(f));

     return 0;
   }

on macOS, FreeBSD, and Linux with glibc, this program prints

   5
   10

but on musl libc (Alpine Linux and probably others) this prints

   0
   10

By my reading of
https://pubs.opengroup.org/onlinepubs/009695399/functions/fopen.html
this is technically correct, specifically:

> Opening a file with append mode (a as the first character in the
> mode argument) shall cause all subsequent writes to the file to be
> forced to the then current end-of-file, regardless of intervening
> calls to fseek().

in other words, the file position doesn't really matter in append-mode
files, and we can't depend on it being at all meaningful unless we
perform a seek() before tell() after open(..., 'a'). Experimentally
after a .write() we can do a .tell() and it'll always be reasonable,
but I'm unclear from reading the specification if that's a smart thing
to rely on. This matches what we do on Windows and what Python 3 does
for free, so let's just be consistent. Thanks to Yuya for the idea.

  $ cat > adddrop.py <<EOF
  > from mercurial import registrar
  > cmdtable = {}
  > command = registrar.command(cmdtable)
  > @command(b'debugadddrop',
  >   [(b'', b'drop', False, b'drop file from dirstate', b'FILE'),
  >    (b'', b'normal-lookup', False, b'add file to dirstate', b'FILE')],
  >     b'hg debugadddrop')
  > def debugadddrop(ui, repo, *pats, **opts):
  >   '''Add or drop unnamed arguments to or from the dirstate'''
  >   drop = opts.get('drop')
  >   nl = opts.get('normal_lookup')
  >   if nl and drop:
  >       raise error.Abort('drop and normal-lookup are mutually exclusive')
  >   wlock = repo.wlock()
  >   try:
  >     for file in pats:
  >       if opts.get('normal_lookup'):
  >         repo.dirstate.normallookup(file)
  >       else:
  >         repo.dirstate.drop(file)
  > 
  >     repo.dirstate.write(repo.currenttransaction())
  >   finally:
  >     wlock.release()
  > EOF

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "debugadddrop=`pwd`/adddrop.py" >> $HGRCPATH

basic test for hg debugrebuildstate

  $ hg init repo
  $ cd repo

  $ touch foo bar
  $ hg ci -Am 'add foo bar'
  adding bar
  adding foo

  $ touch baz
  $ hg add baz
  $ hg rm bar

  $ hg debugrebuildstate

state dump after

  $ hg debugstate --no-dates | sort
  n   0         -1 unset               bar
  n   0         -1 unset               foo

  $ hg debugadddrop --normal-lookup file1 file2
  $ hg debugadddrop --drop bar
  $ hg debugadddrop --drop
  $ hg debugstate --no-dates
  n   0         -1 unset               file1
  n   0         -1 unset               file2
  n   0         -1 unset               foo
  $ hg debugrebuildstate

status

  $ hg st -A
  ! bar
  ? baz
  C foo

Test debugdirstate --minimal where a file is not in parent manifest
but in the dirstate
  $ touch foo bar qux
  $ hg add qux
  $ hg remove bar
  $ hg status -A
  A qux
  R bar
  ? baz
  C foo
  $ hg debugadddrop --normal-lookup baz
  $ hg debugdirstate --no-dates
  r   0          0 * bar (glob)
  n   0         -1 * baz (glob)
  n 644          0 * foo (glob)
  a   0         -1 * qux (glob)
  $ hg debugrebuilddirstate --minimal
  $ hg debugdirstate --no-dates
  r   0          0 * bar (glob)
  n 644          0 * foo (glob)
  a   0         -1 * qux (glob)
  $ hg status -A
  A qux
  R bar
  ? baz
  C foo

Test debugdirstate --minimal where file is in the parent manifest but not the
dirstate
  $ hg manifest
  bar
  foo
  $ hg status -A
  A qux
  R bar
  ? baz
  C foo
  $ hg debugdirstate --no-dates
  r   0          0 * bar (glob)
  n 644          0 * foo (glob)
  a   0         -1 * qux (glob)
  $ hg debugadddrop --drop foo
  $ hg debugdirstate --no-dates
  r   0          0 * bar (glob)
  a   0         -1 * qux (glob)
  $ hg debugrebuilddirstate --minimal
  $ hg debugdirstate --no-dates
  r   0          0 * bar (glob)
  n   0         -1 * foo (glob)
  a   0         -1 * qux (glob)
  $ hg status -A
  A qux
  R bar
  ? baz
  C foo