view tests/test-copies-in-changeset.t @ 42562:97ada9b8d51b stable 5.0.2

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 >> $HGRCPATH << EOF
  > [experimental]
  > copies.write-to=changeset-only
  > copies.read-from=changeset-only
  > [alias]
  > changesetcopies = log -r . -T 'files: {files}
  >   {extras % "{ifcontains("copies", key, "{key}: {value}\n")}"}'
  > showcopies = log -r . -T '{file_copies % "{source} -> {name}\n"}'
  > EOF

Check that copies are recorded correctly

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg add a
  $ hg ci -m initial
  $ hg cp a b
  $ hg cp a c
  $ hg cp a d
  $ hg ci -m 'copy a to b, c, and d'
  $ hg changesetcopies
  files: b c d
  p1copies: b\x00a (esc)
  c\x00a (esc)
  d\x00a (esc)
  $ hg showcopies
  a -> b
  a -> c
  a -> d
  $ hg showcopies --config experimental.copies.read-from=compatibility
  a -> b
  a -> c
  a -> d
  $ hg showcopies --config experimental.copies.read-from=filelog-only

Check that renames are recorded correctly

  $ hg mv b b2
  $ hg ci -m 'rename b to b2'
  $ hg changesetcopies
  files: b b2
  p1copies: b2\x00b (esc)
  $ hg showcopies
  b -> b2

Rename onto existing file. This should get recorded in the changeset files list and in the extras,
even though there is no filelog entry.

  $ hg cp b2 c --force
  $ hg st --copies
  M c
    b2
  $ hg debugindex c
     rev linkrev nodeid       p1           p2
       0       1 b789fdd96dc2 000000000000 000000000000
  $ hg ci -m 'move b onto d'
  $ hg changesetcopies
  files: c
  p1copies: c\x00b2 (esc)
  $ hg showcopies
  b2 -> c
  $ hg debugindex c
     rev linkrev nodeid       p1           p2
       0       1 b789fdd96dc2 000000000000 000000000000

Create a merge commit with copying done during merge.

  $ hg co 0
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ hg cp a e
  $ hg cp a f
  $ hg ci -m 'copy a to e and f'
  created new head
  $ hg merge 3
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
File 'a' exists on both sides, so 'g' could be recorded as being from p1 or p2, but we currently
always record it as being from p1
  $ hg cp a g
File 'd' exists only in p2, so 'h' should be from p2
  $ hg cp d h
File 'f' exists only in p1, so 'i' should be from p1
  $ hg cp f i
  $ hg ci -m 'merge'
  $ hg changesetcopies
  files: g h i
  p1copies: g\x00a (esc)
  i\x00f (esc)
  p2copies: h\x00d (esc)
  $ hg showcopies
  a -> g
  d -> h
  f -> i

Test writing to both changeset and filelog

  $ hg cp a j
  $ hg ci -m 'copy a to j' --config experimental.copies.write-to=compatibility
  $ hg changesetcopies
  files: j
  p1copies: j\x00a (esc)
  $ hg debugdata j 0
  \x01 (esc)
  copy: a
  copyrev: b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
  \x01 (esc)
  a
  $ hg showcopies
  a -> j
  $ hg showcopies --config experimental.copies.read-from=compatibility
  a -> j
  $ hg showcopies --config experimental.copies.read-from=filelog-only
  a -> j

Test writing only to filelog

  $ hg cp a k
  $ hg ci -m 'copy a to k' --config experimental.copies.write-to=filelog-only
  $ hg changesetcopies
  files: k
  $ hg debugdata k 0
  \x01 (esc)
  copy: a
  copyrev: b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
  \x01 (esc)
  a
  $ hg showcopies
  $ hg showcopies --config experimental.copies.read-from=compatibility
  a -> k
  $ hg showcopies --config experimental.copies.read-from=filelog-only
  a -> k

  $ cd ..