path-specific merge drivers (specified in `.gitattributes`)
into account.
+Data structures
+---------------
+
+* `mmbuffer_t`, `mmfile_t`
+
+These store data usable for use by the xdiff backend, for writing and
+for reading, respectively. See `xdiff/xdiff.h` for the definitions
+and `diff.c` for examples.
+
+* `struct ll_merge_options`
+
+This describes the set of options the calling program wants to affect
+the operation of a low-level (single file) merge. Some options:
+
+`virtual_ancestor`::
+ Behave as though this were part of a merge between common
+ ancestors in a recursive merge.
+ If a helper program is specified by the
+ `[merge "<driver>"] recursive` configuration, it will
+ be used (see linkgit:gitattributes[5]).
+
+`variant`::
+ Resolve local conflicts automatically in favor
+ of one side or the other (as in 'git merge-file'
+ `--ours`/`--theirs`/`--union`). Can be `0`,
+ `XDL_MERGE_FAVOR_OURS`, `XDL_MERGE_FAVOR_THEIRS`, or
+ `XDL_MERGE_FAVOR_UNION`.
+
+`renormalize`::
+ Resmudge and clean the "base", "theirs" and "ours" files
+ before merging. Use this when the merge is likely to have
+ overlapped with a change in smudge/clean or end-of-line
+ normalization rules.
+
Low-level (single file) merge
-----------------------------
`.git/info/attributes` into account. Returns 0 for a
clean merge.
-The caller:
+Calling sequence:
-1. allocates an mmbuffer_t variable for the result;
-2. allocates and fills variables with the file's original content
- and two modified versions (using `read_mmfile`, for example);
-3. calls ll_merge();
-4. reads the output from result_buf.ptr and result_buf.size;
-5. releases buffers when finished (free(ancestor.ptr); free(ours.ptr);
- free(theirs.ptr); free(result_buf.ptr);).
+* Prepare a `struct ll_merge_options` to record options.
+ If you have no special requests, skip this and pass `NULL`
+ as the `opts` parameter to use the default options.
+
+* Allocate an mmbuffer_t variable for the result.
+
+* Allocate and fill variables with the file's original content
+ and two modified versions (using `read_mmfile`, for example).
+
+* Call `ll_merge()`.
+
+* Read the merged content from `result_buf.ptr` and `result_buf.size`.
+
+* Release buffers when finished. A simple
+ `free(ancestor.ptr); free(ours.ptr); free(theirs.ptr);
+ free(result_buf.ptr);` will do.
If the modifications do not merge cleanly, `ll_merge` will return a
nonzero value and `result_buf` will generally include a description of
used to label the different sides of a conflict if the merge driver
supports this.
-The `flag` parameter is a bitfield:
-
- - The least significant bit indicates whether this is an internal
- merge to consolidate ancestors for a recursive merge.
-
- - The next two bits allow local conflicts to be automatically
- resolved in favor of one side or the other (as in 'git merge-file'
- `--ours`/`--theirs`/`--union` for 01, 10, and 11, respectively).
-
Everything else
---------------