4 files changed, 120 insertions, 4 deletions
diff --git a/Documentation/technical/api-merge.txt b/Documentation/technical/api-merge.txt
new file mode 100644
index 0000000000..a7e050bb7a
--- /dev/null
+++ b/Documentation/technical/api-merge.txt
@@ -0,0 +1,73 @@
+merge API
+=========
+
+The merge API helps a program to reconcile two competing sets of
+improvements to some files (e.g., unregistered changes from the work
+tree versus changes involved in switching to a new branch), reporting
+conflicts if found.  The library called through this API is
+responsible for a few things.
+
+ * determining which trees to merge (recursive ancestor consolidation);
+
+ * lining up corresponding files in the trees to be merged (rename
+   detection, subtree shifting), reporting edge cases like add/add
+   and rename/rename conflicts to the user;
+
+ * performing a three-way merge of corresponding files, taking
+   path-specific merge drivers (specified in `.gitattributes`)
+   into account.
+
+Low-level (single file) merge
+-----------------------------
+
+`ll_merge`::
+
+	Perform a three-way single-file merge in core.  This is
+	a thin wrapper around `xdl_merge` that takes the path and
+	any merge backend specified in `.gitattributes` or
+	`.git/info/attributes` into account.  Returns 0 for a
+	clean merge.
+
+The caller:
+
+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);).
+
+If the modifications do not merge cleanly, `ll_merge` will return a
+nonzero value and `result_buf` will generally include a description of
+the conflict bracketed by markers such as the traditional `<<<<<<<`
+and `>>>>>>>`.
+
+The `ancestor_label`, `our_label`, and `their_label` parameters are
+used to label the different sides of a conflict if the merge driver
+supports this.
+
+The `flag` parameter is a bitfield:
+
+ - The `LL_OPT_VIRTUAL_ANCESTOR` bit indicates whether this is an
+   internal merge to consolidate ancestors for a recursive merge.
+
+ - The `LL_OPT_FAVOR_MASK` bits allow local conflicts to be automatically
+   resolved in favor of one side or the other (as in 'git merge-file'
+   `--ours`/`--theirs`/`--union`).
+   They can be populated by `create_ll_flag`, whose argument can be
+   `XDL_MERGE_FAVOR_OURS`, `XDL_MERGE_FAVOR_THEIRS`, or
+   `XDL_MERGE_FAVOR_UNION`.
+
+Everything else
+---------------
+
+Talk about <merge-recursive.h> and merge_file():
+
+ - merge_trees() to merge with rename detection
+ - merge_recursive() for ancestor consolidation
+ - try_merge_command() for other strategies
+ - conflict format
+ - merge options
+
+(Daniel, Miklos, Stephan, JC)
diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt
index 312e3b2e2b..c5d141cd63 100644
--- a/Documentation/technical/api-parse-options.txt
+++ b/Documentation/technical/api-parse-options.txt
@@ -201,7 +201,7 @@ The last element of the array must be `OPT_END()`.
 If not stated otherwise, interpret the arguments as follows:
 
 * `short` is a character for the short option
-  (e.g. `\'e\'` for `-e`, use `0` to omit),
+  (e.g. `{apostrophe}e{apostrophe}` for `-e`, use `0` to omit),
 
 * `long` is a string for the long option
   (e.g. `"example"` for `\--example`, use `NULL` to omit),
@@ -228,10 +228,10 @@ The function must be defined in this form:
 The callback mechanism is as follows:
 
 * Inside `func`, the only interesting member of the structure
-  given by `opt` is the void pointer `opt->value`.
-  `\*opt->value` will be the value that is saved into `var`, if you
+  given by `opt` is the void pointer `opt\->value`.
+  `\*opt\->value` will be the value that is saved into `var`, if you
   use `OPT_CALLBACK()`.
-  For example, do `*(unsigned long *)opt->value = 42;` to get 42
+  For example, do `*(unsigned long *)opt\->value = 42;` to get 42
   into an `unsigned long` variable.
 
 * Return value `0` indicates success and non-zero return
diff --git a/Documentation/technical/api-sigchain.txt b/Documentation/technical/api-sigchain.txt
new file mode 100644
index 0000000000..535cdff164
--- /dev/null
+++ b/Documentation/technical/api-sigchain.txt
@@ -0,0 +1,41 @@
+sigchain API
+============
+
+Code often wants to set a signal handler to clean up temporary files or
+other work-in-progress when we die unexpectedly. For multiple pieces of
+code to do this without conflicting, each piece of code must remember
+the old value of the handler and restore it either when:
+
+  1. The work-in-progress is finished, and the handler is no longer
+     necessary. The handler should revert to the original behavior
+     (either another handler, SIG_DFL, or SIG_IGN).
+
+  2. The signal is received. We should then do our cleanup, then chain
+     to the next handler (or die if it is SIG_DFL).
+
+Sigchain is a tiny library for keeping a stack of handlers. Your handler
+and installation code should look something like:
+
+------------------------------------------
+  void clean_foo_on_signal(int sig)
+  {
+	  clean_foo();
+	  sigchain_pop(sig);
+	  raise(sig);
+  }
+
+  void other_func()
+  {
+	  sigchain_push_common(clean_foo_on_signal);
+	  mess_up_foo();
+	  clean_foo();
+  }
+------------------------------------------
+
+Handlers are given the typdef of sigchain_fun. This is the same type
+that is given to signal() or sigaction(). It is perfectly reasonable to
+push SIG_DFL or SIG_IGN onto the stack.
+
+You can sigchain_push and sigchain_pop individual signals. For
+convenience, sigchain_push_common will push the handler onto the stack
+for many common signals.
diff --git a/Documentation/technical/api-tree-walking.txt b/Documentation/technical/api-tree-walking.txt
index 55b728632c..14af37c3f1 100644
--- a/Documentation/technical/api-tree-walking.txt
+++ b/Documentation/technical/api-tree-walking.txt
@@ -42,6 +42,8 @@ information.
 
 * `data` can be anything the `fn` callback would want to use.
 
+* `show_all_errors` tells whether to stop at the first error or not.
+
 Initializing
 ------------