diff options
Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/api-diff.txt | 4 | ||||
| -rw-r--r-- | Documentation/technical/api-merge.txt | 104 | ||||
| -rw-r--r-- | Documentation/technical/api-parse-options.txt | 17 | ||||
| -rw-r--r-- | Documentation/technical/api-sigchain.txt | 41 | ||||
| -rw-r--r-- | Documentation/technical/api-string-list.txt | 4 | ||||
| -rw-r--r-- | Documentation/technical/api-tree-walking.txt | 2 | ||||
| -rw-r--r-- | Documentation/technical/index-format.txt | 185 | ||||
| -rw-r--r-- | Documentation/technical/protocol-capabilities.txt | 2 |
8 files changed, 347 insertions, 12 deletions
diff --git a/Documentation/technical/api-diff.txt b/Documentation/technical/api-diff.txt index 20b0241d30..2d2ebc04b7 100644 --- a/Documentation/technical/api-diff.txt +++ b/Documentation/technical/api-diff.txt @@ -32,7 +32,7 @@ Calling sequence * As you find different pairs of files, call `diff_change()` to feed modified files, `diff_addremove()` to feed created or deleted files, - or `diff_unmerged()` to feed a file whose state is 'unmerged' to the + or `diff_unmerge()` to feed a file whose state is 'unmerged' to the API. These are thin wrappers to a lower-level `diff_queue()` function that is flexible enough to record any of these kinds of changes. @@ -50,7 +50,7 @@ Data structures This is the internal representation for a single file (blob). It records the blob object name (if known -- for a work tree file it typically is a NUL SHA-1), filemode and pathname. This is what the -`diff_addremove()`, `diff_change()` and `diff_unmerged()` synthesize and +`diff_addremove()`, `diff_change()` and `diff_unmerge()` synthesize and feed `diff_queue()` function with. * `struct diff_filepair` diff --git a/Documentation/technical/api-merge.txt b/Documentation/technical/api-merge.txt new file mode 100644 index 0000000000..9dc1bed768 --- /dev/null +++ b/Documentation/technical/api-merge.txt @@ -0,0 +1,104 @@ +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. + +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 +----------------------------- + +`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. + +Calling sequence: + +* 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 +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. + +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..f6a4a361bd 100644 --- a/Documentation/technical/api-parse-options.txt +++ b/Documentation/technical/api-parse-options.txt @@ -118,13 +118,16 @@ There are some macros to easily define options: `OPT__COLOR(&int_var, description)`:: Add `\--color[=<when>]` and `--no-color`. -`OPT__DRY_RUN(&int_var)`:: +`OPT__DRY_RUN(&int_var, description)`:: Add `-n, \--dry-run`. -`OPT__QUIET(&int_var)`:: +`OPT__FORCE(&int_var, description)`:: + Add `-f, \--force`. + +`OPT__QUIET(&int_var, description)`:: Add `-q, \--quiet`. -`OPT__VERBOSE(&int_var)`:: +`OPT__VERBOSE(&int_var, description)`:: Add `-v, \--verbose`. `OPT_GROUP(description)`:: @@ -201,7 +204,7 @@ 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 +231,10 @@ 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..9e1189ef01 --- /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 typedef 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-string-list.txt b/Documentation/technical/api-string-list.txt index 6d8c24bb1e..3f575bdcff 100644 --- a/Documentation/technical/api-string-list.txt +++ b/Documentation/technical/api-string-list.txt @@ -38,8 +38,8 @@ struct string_list list; int i; memset(&list, 0, sizeof(struct string_list)); -string_list_append("foo", &list); -string_list_append("bar", &list); +string_list_append(&list, "foo"); +string_list_append(&list, "bar"); for (i = 0; i < list.nr; i++) printf("%s\n", list.items[i].string) ---- 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 ------------ diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt new file mode 100644 index 0000000000..7b233ca196 --- /dev/null +++ b/Documentation/technical/index-format.txt @@ -0,0 +1,185 @@ +GIT index format +================ + += The git index file has the following format + + All binary numbers are in network byte order. Version 2 is described + here unless stated otherwise. + + - A 12-byte header consisting of + + 4-byte signature: + The signature is { 'D', 'I', 'R', 'C' } (stands for "dircache") + + 4-byte version number: + The current supported versions are 2 and 3. + + 32-bit number of index entries. + + - A number of sorted index entries (see below). + + - Extensions + + Extensions are identified by signature. Optional extensions can + be ignored if GIT does not understand them. + + GIT currently supports cached tree and resolve undo extensions. + + 4-byte extension signature. If the first byte is 'A'..'Z' the + extension is optional and can be ignored. + + 32-bit size of the extension + + Extension data + + - 160-bit SHA-1 over the content of the index file before this + checksum. + +== Index entry + + Index entries are sorted in ascending order on the name field, + interpreted as a string of unsigned bytes (i.e. memcmp() order, no + localization, no special casing of directory separator '/'). Entries + with the same name are sorted by their stage field. + + 32-bit ctime seconds, the last time a file's metadata changed + this is stat(2) data + + 32-bit ctime nanosecond fractions + this is stat(2) data + + 32-bit mtime seconds, the last time a file's data changed + this is stat(2) data + + 32-bit mtime nanosecond fractions + this is stat(2) data + + 32-bit dev + this is stat(2) data + + 32-bit ino + this is stat(2) data + + 32-bit mode, split into (high to low bits) + + 4-bit object type + valid values in binary are 1000 (regular file), 1010 (symbolic link) + and 1110 (gitlink) + + 3-bit unused + + 9-bit unix permission. Only 0755 and 0644 are valid for regular files. + Symbolic links and gitlinks have value 0 in this field. + + 32-bit uid + this is stat(2) data + + 32-bit gid + this is stat(2) data + + 32-bit file size + This is the on-disk size from stat(2), truncated to 32-bit. + + 160-bit SHA-1 for the represented object + + A 16-bit 'flags' field split into (high to low bits) + + 1-bit assume-valid flag + + 1-bit extended flag (must be zero in version 2) + + 2-bit stage (during merge) + + 12-bit name length if the length is less than 0xFFF; otherwise 0xFFF + is stored in this field. + + (Version 3) A 16-bit field, only applicable if the "extended flag" + above is 1, split into (high to low bits). + + 1-bit reserved for future + + 1-bit skip-worktree flag (used by sparse checkout) + + 1-bit intent-to-add flag (used by "git add -N") + + 13-bit unused, must be zero + + Entry path name (variable length) relative to top level directory + (without leading slash). '/' is used as path separator. The special + path components ".", ".." and ".git" (without quotes) are disallowed. + Trailing slash is also disallowed. + + The exact encoding is undefined, but the '.' and '/' characters + are encoded in 7-bit ASCII and the encoding cannot contain a NUL + byte (iow, this is a UNIX pathname). + + 1-8 nul bytes as necessary to pad the entry to a multiple of eight bytes + while keeping the name NUL-terminated. + +== Extensions + +=== Cached tree + + Cached tree extension contains pre-computed hashes for trees that can + be derived from the index. It helps speed up tree object generation + from index for a new commit. + + When a path is updated in index, the path must be invalidated and + removed from tree cache. + + The signature for this extension is { 'T', 'R', 'E', 'E' }. + + A series of entries fill the entire extension; each of which + consists of: + + - NUL-terminated path component (relative to its parent directory); + + - ASCII decimal number of entries in the index that is covered by the + tree this entry represents (entry_count); + + - A space (ASCII 32); + + - ASCII decimal number that represents the number of subtrees this + tree has; + + - A newline (ASCII 10); and + + - 160-bit object name for the object that would result from writing + this span of index as a tree. + + An entry can be in an invalidated state and is represented by having -1 + in the entry_count field. + + The entries are written out in the top-down, depth-first order. The + first entry represents the root level of the repository, followed by the + first subtree---let's call this A---of the root level (with its name + relative to the root level), followed by the first subtree of A (with + its name relative to A), ... + +=== Resolve undo + + A conflict is represented in the index as a set of higher stage entries. + When a conflict is resolved (e.g. with "git add path"), these higher + stage entries will be removed and a stage-0 entry with proper resoluton + is added. + + When these higher stage entries are removed, they are saved in the + resolve undo extension, so that conflicts can be recreated (e.g. with + "git checkout -m"), in case users want to redo a conflict resolution + from scratch. + + The signature for this extension is { 'R', 'E', 'U', 'C' }. + + A series of entries fill the entire extension; each of which + consists of: + + - NUL-terminated pathname the entry describes (relative to the root of + the repository, i.e. full pathname); + + - Three NUL-terminated ASCII octal numbers, entry mode of entries in + stage 1 to 3 (a missing stage is represented by "0" in this field); + and + + - At most three 160-bit object names of the entry in stages from 1 to 3 + (nothing is written for a missing stage). + diff --git a/Documentation/technical/protocol-capabilities.txt b/Documentation/technical/protocol-capabilities.txt index fd1a593149..b15517fa06 100644 --- a/Documentation/technical/protocol-capabilities.txt +++ b/Documentation/technical/protocol-capabilities.txt @@ -119,7 +119,7 @@ both. ofs-delta --------- -Server can send, and client understand PACKv2 with delta refering to +Server can send, and client understand PACKv2 with delta referring to its base by position in pack rather than by an obj-id. That is, they can send/read OBJ_OFS_DELTA (aka type 6) in a packfile. |