Previous: dopatch, Up: Introducing Changesets
What if a tree patched by dopatch is not exactly the same as the
original tree seen by mkpatch?
Below is a brief description of what to expect. Complete
documentation of the dopatch process is included with the source
code.
dopatch takes an inventory of the tree being patched. It uses
inventory ids to decide which files and directories expected by the
changeset are present or missing from the tree, and to figure out
where each file and directory is located in the tree.
Simple Patches If the changeset contains an ordinary patch or
metadata patch for a link, directory or file, and that file is present
in the tree, dopatch applies the patch in the ordinary way. If the
patch applies cleanly, the modified file, link, or directory is left
in place.
If a simple patch fails to apply cleanly, dopatch will always leave
behind a .orig file (the file originally in the tree being patched,
without any changes) and a .rej file (the part of the patch that
could not be applied).
If the patch was a context diff, dopatch will also leave behind the
file itself – partially patched.
If an (unsuccessful) patch was for a binary file, no partially-patched file will be left. Instead, there will be:
.orig -- the file originally in the tree being patched,
without modifications.
.rej -- a complete copy of the file from the modified tree,
with permissions copied from `.orig'.
.patch-orig -- a complete copy of the file from the original
tree seen by `mkpatch', with permissions
retained from that original
-or-
the symbolic link from the original tree seen
by `mkpatch' with permissions as in the original
tree.
If an (unsuccessful) patch was for a symbolic link, no partially patched file will be left. Instead there will be:
.orig -- the unmodified file from the original tree
.rej -- a symbolic link with the target intended by the
patch and permissions copied from .orig
.patch-orig -- a complete copy of the file from the original
tree seen by `mkpatch', with permissions
retained from that original
-or-
the symbolic link from the original tree seen
by `mkpatch' with permissions as in the original
tree.
Patches for Missing Files
All patches for missing files and directories are stored in a subdirectory of the root of the tree being patched called
==missing-file-patches-PATCH-DATE
where PATCH is the basename of the changeset directory and DATE a
time-stamp.
Directory Rearrangements and New Directories
Directories are added, deleted, and rearranged much as you would expect, even if you don't know it's what you'd expect.
Suppose that when mkpatch was called the ORIGINAL tree had:
Directory or file: Id:
a/x.c id_1
a/bar.c id_2
but the MODIFIED tree had:
a/x.c id_1
a/y.c id_2
with changes to both files. The patch will want to rename the file
with id id_2 to y.c, and change the contents of the files with
ids id_1 and id_2.
Suppose, for example, that you have a tree with:
a/foo.c id_1
a/zip.c id_2
and the you apply the patch to that tree. After the patch, you'll be left with:
a/foo.c id_1
a/y.c (was zip.c) id_2
with patches made to the contents of both files.
Here's a sample of some subtleties and ways of handling conflicts:
Suppose that the original tree seen by mkpatch has:
Directory or file: Id:
./a id_a
./a/b id_b
./a/b/c id_c
and that the modified directory has:
./a id_a
./a/c id_c
./a/c/b id_b
Finally, suppose that the tree has:
./x id_a
./x/b id_b
./x/c id_new_directory
./x/c/b id_different_file_named_b
./x/c/q id_c
When patch gets done with the tree, it will have:
./x id_a
Since the patch doesn't do anything
to change the directory with id_a.
./x/c.orig id_new_directory
./x/c.rej id_c
Since the patch wants to make the
directory with id_c a subdirectory named "c"
of the directory with id_a, but the tree
already had a different directory there,
with the id id_new_directory.
./x/c.rej/b id_b
Since the patch wants to rename the directory
with id_b to be a subdirectory named "b"
of the directory with id_c.
./x/c.orig/b id_different_file_named_b
Since the patch made new changes to this file,
it stayed with its parent directory.