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Diffstat (limited to 'Documentation/technical')
23 files changed, 644 insertions, 0 deletions
diff --git a/Documentation/technical/.gitignore b/Documentation/technical/.gitignore new file mode 100644 index 0000000000..8aa891daee --- /dev/null +++ b/Documentation/technical/.gitignore @@ -0,0 +1 @@ +api-index.txt diff --git a/Documentation/technical/api-allocation-growing.txt b/Documentation/technical/api-allocation-growing.txt new file mode 100644 index 0000000000..43dbe09f73 --- /dev/null +++ b/Documentation/technical/api-allocation-growing.txt @@ -0,0 +1,34 @@ +allocation growing API +====================== + +Dynamically growing an array using realloc() is error prone and boring. + +Define your array with: + +* a pointer (`ary`) that points at the array, initialized to `NULL`; + +* an integer variable (`alloc`) that keeps track of how big the current + allocation is, initialized to `0`; + +* another integer variable (`nr`) to keep track of how many elements the + array currently has, initialized to `0`. + +Then before adding `n`th element to the array, call `ALLOC_GROW(ary, n, +alloc)`. This ensures that the array can hold at least `n` elements by +calling `realloc(3)` and adjusting `alloc` variable. + +------------ +sometype *ary; +size_t nr; +size_t alloc + +for (i = 0; i < nr; i++) + if (we like ary[i] already) + return; + +/* we did not like any existing one, so add one */ +ALLOC_GROW(ary, nr + 1, alloc); +ary[nr++] = value you like; +------------ + +You are responsible for updating the `nr` variable. diff --git a/Documentation/technical/api-builtin.txt b/Documentation/technical/api-builtin.txt new file mode 100644 index 0000000000..52cdb4c520 --- /dev/null +++ b/Documentation/technical/api-builtin.txt @@ -0,0 +1,63 @@ +builtin API +=========== + +Adding a new built-in +--------------------- + +There are 4 things to do to add a bulit-in command implementation to +git: + +. Define the implementation of the built-in command `foo` with + signature: + + int cmd_foo(int argc, const char **argv, const char *prefix); + +. Add the external declaration for the function to `builtin.h`. + +. Add the command to `commands[]` table in `handle_internal_command()`, + defined in `git.c`. The entry should look like: + + { "foo", cmd_foo, <options> }, + + where options is the bitwise-or of: + +`RUN_SETUP`:: + + Make sure there is a git directory to work on, and if there is a + work tree, chdir to the top of it if the command was invoked + in a subdirectory. If there is no work tree, no chdir() is + done. + +`USE_PAGER`:: + + If the standard output is connected to a tty, spawn a pager and + feed our output to it. + +. Add `builtin-foo.o` to `BUILTIN_OBJS` in `Makefile`. + +Additionally, if `foo` is a new command, there are 3 more things to do: + +. Add tests to `t/` directory. + +. Write documentation in `Documentation/git-foo.txt`. + +. Add an entry for `git-foo` to the list at the end of + `Documentation/cmd-list.perl`. + + +How a built-in is called +------------------------ + +The implementation `cmd_foo()` takes three parameters, `argc`, `argv, +and `prefix`. The first two are similar to what `main()` of a +standalone command would be called with. + +When `RUN_SETUP` is specified in the `commands[]` table, and when you +were started from a subdirectory of the work tree, `cmd_foo()` is called +after chdir(2) to the top of the work tree, and `prefix` gets the path +to the subdirectory the command started from. This allows you to +convert a user-supplied pathname (typically relative to that directory) +to a pathname relative to the top of the work tree. + +The return value from `cmd_foo()` becomes the exit status of the +command. diff --git a/Documentation/technical/api-decorate.txt b/Documentation/technical/api-decorate.txt new file mode 100644 index 0000000000..1d52a6ce14 --- /dev/null +++ b/Documentation/technical/api-decorate.txt @@ -0,0 +1,6 @@ +decorate API +============ + +Talk about <decorate.h> + +(Linus) diff --git a/Documentation/technical/api-diff.txt b/Documentation/technical/api-diff.txt new file mode 100644 index 0000000000..822609bcd1 --- /dev/null +++ b/Documentation/technical/api-diff.txt @@ -0,0 +1,166 @@ +diff API +======== + +The diff API is for programs that compare two sets of files (e.g. two +trees, one tree and the index) and present the found difference in +various ways. The calling program is responsible for feeding the API +pairs of files, one from the "old" set and the corresponding one from +"new" set, that are different. The library called through this API is +called diffcore, and is responsible for two things. + +* finding total rewrites (`-B`), renames (`-M`) and copies (`-C`), and + changes that touch a string (`-S`), as specified by the caller. + +* outputting the differences in various formats, as specified by the + caller. + +Calling sequence +---------------- + +* Prepare `struct diff_options` to record the set of diff options, and + then call `diff_setup()` to initialize this structure. This sets up + the vanilla default. + +* Fill in the options structure to specify desired output format, rename + detection, etc. `diff_opt_parse()` can be used to parse options given + from the command line in a way consistent with existing git-diff + family of programs. + +* Call `diff_setup_done()`; this inspects the options set up so far for + internal consistency and make necessary tweaking to it (e.g. if + textual patch output was asked, recursive behaviour is turned on). + +* 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 + API. These are thin wrappers to a lower-level `diff_queue()` function + that is flexible enough to record any of these kinds of changes. + +* Once you finish feeding the pairs of files, call `diffcore_std()`. + This will tell the diffcore library to go ahead and do its work. + +* Calling `diffcore_flush()` will produce the output. + + +Data structures +--------------- + +* `struct diff_filespec` + +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 +feed `diff_queue()` function with. + +* `struct diff_filepair` + +This records a pair of `struct diff_filespec`; the filespec for a file +in the "old" set (i.e. preimage) is called `one`, and the filespec for a +file in the "new" set (i.e. postimage) is called `two`. A change that +represents file creation has NULL in `one`, and file deletion has NULL +in `two`. + +A `filepair` starts pointing at `one` and `two` that are from the same +filename, but `diffcore_std()` can break pairs and match component +filespecs with other filespecs from a different filepair to form new +filepair. This is called 'rename detection'. + +* `struct diff_queue` + +This is a collection of filepairs. Notable members are: + +`queue`:: + + An array of pointers to `struct diff_filepair`. This + dynamically grows as you add filepairs; + +`alloc`:: + + The allocated size of the `queue` array; + +`nr`:: + + The number of elements in the `queue` array. + + +* `struct diff_options` + +This describes the set of options the calling program wants to affect +the operation of diffcore library with. + +Notable members are: + +`output_format`:: + The output format used when `diff_flush()` is run. + +`context`:: + Number of context lines to generate in patch output. + +`break_opt`, `detect_rename`, `rename-score`, `rename_limit`:: + Affects the way detection logic for complete rewrites, renames + and copies. + +`abbrev`:: + Number of hexdigits to abbrevate raw format output to. + +`pickaxe`:: + A constant string (can and typically does contain newlines to + look for a block of text, not just a single line) to filter out + the filepairs that do not change the number of strings contained + in its preimage and postmage of the diff_queue. + +`flags`:: + This is mostly a collection of boolean options that affects the + operation, but some do not have anything to do with the diffcore + library. + +BINARY, TEXT;; + Affects the way how a file that is seemingly binary is treated. + +FULL_INDEX;; + Tells the patch output format not to use abbreviated object + names on the "index" lines. + +FIND_COPIES_HARDER;; + Tells the diffcore library that the caller is feeding unchanged + filepairs to allow copies from unmodified files be detected. + +COLOR_DIFF;; + Output should be colored. + +COLOR_DIFF_WORDS;; + Output is a colored word-diff. + +NO_INDEX;; + Tells diff-files that the input is not tracked files but files + in random locations on the filesystem. + +ALLOW_EXTERNAL;; + Tells output routine that it is Ok to call user specified patch + output routine. Plumbing disables this to ensure stable output. + +QUIET;; + Do not show any output. + +REVERSE_DIFF;; + Tells the library that the calling program is feeding the + filepairs reversed; `one` is two, and `two` is one. + +EXIT_WITH_STATUS;; + For communication between the calling program and the options + parser; tell the calling program to signal the presense of + difference using program exit code. + +HAS_CHANGES;; + Internal; used for optimization to see if there is any change. + +SILENT_ON_REMOVE;; + Affects if diff-files shows removed files. + +RECURSIVE, TREE_IN_RECURSIVE;; + Tells if tree traversal done by tree-diff should recursively + descend into a tree object pair that are different in preimage + and postimage set. + +(JC) diff --git a/Documentation/technical/api-directory-listing.txt b/Documentation/technical/api-directory-listing.txt new file mode 100644 index 0000000000..5bbd18f020 --- /dev/null +++ b/Documentation/technical/api-directory-listing.txt @@ -0,0 +1,76 @@ +directory listing API +===================== + +The directory listing API is used to enumerate paths in the work tree, +optionally taking `.git/info/exclude` and `.gitignore` files per +directory into account. + +Data structure +-------------- + +`struct dir_struct` structure is used to pass directory traversal +options to the library and to record the paths discovered. The notable +options are: + +`exclude_per_dir`:: + + The name of the file to be read in each directory for excluded + files (typically `.gitignore`). + +`collect_ignored`:: + + Include paths that are to be excluded in the result. + +`show_ignored`:: + + The traversal is for finding just ignored files, not unignored + files. + +`show_other_directories`:: + + Include a directory that is not tracked. + +`hide_empty_directories`:: + + Do not include a directory that is not tracked and is empty. + +`no_gitlinks`:: + + If set, recurse into a directory that looks like a git + directory. Otherwise it is shown as a directory. + +The result of the enumeration is left in these fields:: + +`entries[]`:: + + An array of `struct dir_entry`, each element of which describes + a path. + +`nr`:: + + The number of members in `entries[]` array. + +`alloc`:: + + Internal use; keeps track of allocation of `entries[]` array. + + +Calling sequence +---------------- + +* Prepare `struct dir_struct dir` and clear it with `memset(&dir, 0, + sizeof(dir))`. + +* Call `add_exclude()` to add single exclude pattern, + `add_excludes_from_file()` to add patterns from a file + (e.g. `.git/info/exclude`), and/or set `dir.exclude_per_dir`. A + short-hand function `setup_standard_excludes()` can be used to set up + the standard set of exclude settings. + +* Set options described in the Data Structure section above. + +* Call `read_directory()`. + +* Use `dir.entries[]`. + +(JC) diff --git a/Documentation/technical/api-gitattributes.txt b/Documentation/technical/api-gitattributes.txt new file mode 100644 index 0000000000..9d97eaa9de --- /dev/null +++ b/Documentation/technical/api-gitattributes.txt @@ -0,0 +1,111 @@ +gitattributes API +================= + +gitattributes mechanism gives a uniform way to associate various +attributes to set of paths. + + +Data Structure +-------------- + +`struct git_attr`:: + + An attribute is an opaque object that is identified by its name. + Pass the name and its length to `git_attr()` function to obtain + the object of this type. The internal representation of this + structure is of no interest to the calling programs. + +`struct git_attr_check`:: + + This structure represents a set of attributes to check in a call + to `git_checkattr()` function, and receives the results. + + +Calling Sequence +---------------- + +* Prepare an array of `struct git_attr_check` to define the list of + attributes you would want to check. To populate this array, you would + need to define necessary attributes by calling `git_attr()` function. + +* Call git_checkattr() to check the attributes for the path. + +* Inspect `git_attr_check` structure to see how each of the attribute in + the array is defined for the path. + + +Attribute Values +---------------- + +An attribute for a path can be in one of four states: Set, Unset, +Unspecified or set to a string, and `.value` member of `struct +git_attr_check` records it. There are three macros to check these: + +`ATTR_TRUE()`:: + + Returns true if the attribute is Set for the path. + +`ATTR_FALSE()`:: + + Returns true if the attribute is Unset for the path. + +`ATTR_UNSET()`:: + + Returns true if the attribute is Unspecified for the path. + +If none of the above returns true, `.value` member points at a string +value of the attribute for the path. + + +Example +------- + +To see how attributes "crlf" and "indent" are set for different paths. + +. Prepare an array of `struct git_attr_check` with two elements (because + we are checking two attributes). Initialize their `attr` member with + pointers to `struct git_attr` obtained by calling `git_attr()`: + +------------ +static struct git_attr_check check[2]; +static void setup_check(void) +{ + if (check[0].attr) + return; /* already done */ + check[0].attr = git_attr("crlf", 4); + check[1].attr = git_attr("ident", 5); +} +------------ + +. Call `git_checkattr()` with the prepared array of `struct git_attr_check`: + +------------ + const char *path; + + setup_check(); + git_checkattr(path, ARRAY_SIZE(check), check); +------------ + +. Act on `.value` member of the result, left in `check[]`: + +------------ + const char *value = check[0].value; + + if (ATTR_TRUE(value)) { + The attribute is Set, by listing only the name of the + attribute in the gitattributes file for the path. + } else if (ATTR_FALSE(value)) { + The attribute is Unset, by listing the name of the + attribute prefixed with a dash - for the path. + } else if (ATTR_UNSET(value)) { + The attribute is not set nor unset for the path. + } else if (!strcmp(value, "input")) { + If none of ATTR_TRUE(), ATTR_FALSE(), or ATTR_UNSET() is + true, the value is a string set in the gitattributes + file for the path by saying "attr=value". + } else if (... other check using value as string ...) { + ... + } +------------ + +(JC) diff --git a/Documentation/technical/api-grep.txt b/Documentation/technical/api-grep.txt new file mode 100644 index 0000000000..a69cc8964d --- /dev/null +++ b/Documentation/technical/api-grep.txt @@ -0,0 +1,8 @@ +grep API +======== + +Talk about <grep.h>, things like: + +* grep_buffer() + +(JC) diff --git a/Documentation/technical/api-hash.txt b/Documentation/technical/api-hash.txt new file mode 100644 index 0000000000..c784d3edcb --- /dev/null +++ b/Documentation/technical/api-hash.txt @@ -0,0 +1,6 @@ +hash API +======== + +Talk about <hash.h> + +(Linus) diff --git a/Documentation/technical/api-in-core-index.txt b/Documentation/technical/api-in-core-index.txt new file mode 100644 index 0000000000..adbdbf5d75 --- /dev/null +++ b/Documentation/technical/api-in-core-index.txt @@ -0,0 +1,21 @@ +in-core index API +================= + +Talk about <read-cache.c> and <cache-tree.c>, things like: + +* cache -> the_index macros +* read_index() +* write_index() +* ie_match_stat() and ie_modified(); how they are different and when to + use which. +* index_name_pos() +* remove_index_entry_at() +* remove_file_from_index() +* add_file_to_index() +* add_index_entry() +* refresh_index() +* discard_index() +* cache_tree_invalidate_path() +* cache_tree_update() + +(JC, Linus) diff --git a/Documentation/technical/api-index-skel.txt b/Documentation/technical/api-index-skel.txt new file mode 100644 index 0000000000..af7cc2e395 --- /dev/null +++ b/Documentation/technical/api-index-skel.txt @@ -0,0 +1,15 @@ +GIT API Documents +================= + +GIT has grown a set of internal API over time. This collection +documents them. + +//////////////////////////////////////////////////////////////// +// table of contents begin +//////////////////////////////////////////////////////////////// + +//////////////////////////////////////////////////////////////// +// table of contents end +//////////////////////////////////////////////////////////////// + +2007-11-24 diff --git a/Documentation/technical/api-index.sh b/Documentation/technical/api-index.sh new file mode 100755 index 0000000000..9c3f4131b8 --- /dev/null +++ b/Documentation/technical/api-index.sh @@ -0,0 +1,28 @@ +#!/bin/sh + +( + c=//////////////////////////////////////////////////////////////// + skel=api-index-skel.txt + sed -e '/^\/\/ table of contents begin/q' "$skel" + echo "$c" + + ls api-*.txt | + while read filename + do + case "$filename" in + api-index-skel.txt | api-index.txt) continue ;; + esac + title=$(sed -e 1q "$filename") + html=${filename%.txt}.html + echo "* link:$html[$title]" + done + echo "$c" + sed -n -e '/^\/\/ table of contents end/,$p' "$skel" +) >api-index.txt+ + +if test -f api-index.txt && cmp api-index.txt api-index.txt+ >/dev/null +then + rm -f api-index.txt+ +else + mv api-index.txt+ api-index.txt +fi diff --git a/Documentation/technical/api-lockfile.txt b/Documentation/technical/api-lockfile.txt new file mode 100644 index 0000000000..73ac1025fd --- /dev/null +++ b/Documentation/technical/api-lockfile.txt @@ -0,0 +1,12 @@ +lockfile API +============ + +Talk about <lockfile.c>, things like: + +* lockfile lifetime -- atexit(3) looks at them, do not put them on the + stack; +* hold_lock_file_for_update() +* commit_lock_file() +* rollback_rock_file() + +(JC, Dscho, Shawn) diff --git a/Documentation/technical/api-object-access.txt b/Documentation/technical/api-object-access.txt new file mode 100644 index 0000000000..03bb0e950d --- /dev/null +++ b/Documentation/technical/api-object-access.txt @@ -0,0 +1,15 @@ +object access API +================= + +Talk about <sha1_file.c> and <object.h> family, things like + +* read_sha1_file() +* read_object_with_reference() +* has_sha1_file() +* write_sha1_file() +* pretend_sha1_file() +* lookup_{object,commit,tag,blob,tree} +* parse_{object,commit,tag,blob,tree} +* Use of object flags + +(JC, Shawn, Daniel, Dscho, Linus) diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt new file mode 100644 index 0000000000..b7cda94f54 --- /dev/null +++ b/Documentation/technical/api-parse-options.txt @@ -0,0 +1,6 @@ +parse-options API +================= + +Talk about <parse-options.h> + +(Pierre) diff --git a/Documentation/technical/api-path-list.txt b/Documentation/technical/api-path-list.txt new file mode 100644 index 0000000000..d077683171 --- /dev/null +++ b/Documentation/technical/api-path-list.txt @@ -0,0 +1,9 @@ +path-list API +============= + +Talk about <path-list.h>, things like + +* it is not just paths but strings in general; +* the calling sequence. + +(Dscho) diff --git a/Documentation/technical/api-quote.txt b/Documentation/technical/api-quote.txt new file mode 100644 index 0000000000..e8a1bce94e --- /dev/null +++ b/Documentation/technical/api-quote.txt @@ -0,0 +1,10 @@ +quote API +========= + +Talk about <quote.h>, things like + +* sq_quote and unquote +* c_style quote and unquote +* quoting for foreign languages + +(JC) diff --git a/Documentation/technical/api-revision-walking.txt b/Documentation/technical/api-revision-walking.txt new file mode 100644 index 0000000000..01a24551af --- /dev/null +++ b/Documentation/technical/api-revision-walking.txt @@ -0,0 +1,9 @@ +revision walking API +==================== + +Talk about <revision.h>, things like: + +* two diff_options, one for path limiting, another for output; +* calling sequence: init_revisions(), setup_revsions(), get_revision(); + +(Linus, JC, Dscho) diff --git a/Documentation/technical/api-run-command.txt b/Documentation/technical/api-run-command.txt new file mode 100644 index 0000000000..19d2f64f73 --- /dev/null +++ b/Documentation/technical/api-run-command.txt @@ -0,0 +1,10 @@ +run-command API +=============== + +Talk about <run-command.h>, and things like: + +* Environment the command runs with (e.g. GIT_DIR); +* File descriptors and pipes; +* Exit status; + +(Hannes, Dscho, Shawn) diff --git a/Documentation/technical/api-setup.txt b/Documentation/technical/api-setup.txt new file mode 100644 index 0000000000..4f63a04d7d --- /dev/null +++ b/Documentation/technical/api-setup.txt @@ -0,0 +1,13 @@ +setup API +========= + +Talk about + +* setup_git_directory() +* setup_git_directory_gently() +* is_inside_git_dir() +* is_inside_work_tree() +* setup_work_tree() +* get_pathspec() + +(Dscho) diff --git a/Documentation/technical/api-strbuf.txt b/Documentation/technical/api-strbuf.txt new file mode 100644 index 0000000000..a52e4f36d5 --- /dev/null +++ b/Documentation/technical/api-strbuf.txt @@ -0,0 +1,6 @@ +strbuf API +========== + +Talk about <strbuf.h> + +(Pierre, JC) diff --git a/Documentation/technical/api-tree-walking.txt b/Documentation/technical/api-tree-walking.txt new file mode 100644 index 0000000000..e3ddf91284 --- /dev/null +++ b/Documentation/technical/api-tree-walking.txt @@ -0,0 +1,12 @@ +tree walking API +================ + +Talk about <tree-walk.h>, things like + +* struct tree_desc +* init_tree_desc +* tree_entry_extract +* update_tree_entry +* get_tree_entry + +(JC, Linus) diff --git a/Documentation/technical/api-xdiff-interface.txt b/Documentation/technical/api-xdiff-interface.txt new file mode 100644 index 0000000000..6296ecad1d --- /dev/null +++ b/Documentation/technical/api-xdiff-interface.txt @@ -0,0 +1,7 @@ +xdiff interface API +=================== + +Talk about our calling convention to xdiff library, including +xdiff_emit_consume_fn. + +(Dscho, JC) |