diff options
Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/api-argv-array.txt | 46 | ||||
| -rw-r--r-- | Documentation/technical/api-credentials.txt | 245 | ||||
| -rw-r--r-- | Documentation/technical/api-parse-options.txt | 21 | ||||
| -rw-r--r-- | Documentation/technical/api-sha1-array.txt | 79 | ||||
| -rw-r--r-- | Documentation/technical/pack-protocol.txt | 7 |
5 files changed, 393 insertions, 5 deletions
diff --git a/Documentation/technical/api-argv-array.txt b/Documentation/technical/api-argv-array.txt new file mode 100644 index 0000000000..49b3d52952 --- /dev/null +++ b/Documentation/technical/api-argv-array.txt @@ -0,0 +1,46 @@ +argv-array API +============== + +The argv-array API allows one to dynamically build and store +NULL-terminated lists. An argv-array maintains the invariant that the +`argv` member always points to a non-NULL array, and that the array is +always NULL-terminated at the element pointed to by `argv[argc]`. This +makes the result suitable for passing to functions expecting to receive +argv from main(), or the link:api-run-command.html[run-command API]. + +The link:api-string-list.html[string-list API] is similar, but cannot be +used for these purposes; instead of storing a straight string pointer, +it contains an item structure with a `util` field that is not compatible +with the traditional argv interface. + +Each `argv_array` manages its own memory. Any strings pushed into the +array are duplicated, and all memory is freed by argv_array_clear(). + +Data Structures +--------------- + +`struct argv_array`:: + + A single array. This should be initialized by assignment from + `ARGV_ARRAY_INIT`, or by calling `argv_array_init`. The `argv` + member contains the actual array; the `argc` member contains the + number of elements in the array, not including the terminating + NULL. + +Functions +--------- + +`argv_array_init`:: + Initialize an array. This is no different than assigning from + `ARGV_ARRAY_INIT`. + +`argv_array_push`:: + Push a copy of a string onto the end of the array. + +`argv_array_pushf`:: + Format a string and push it onto the end of the array. This is a + convenience wrapper combining `strbuf_addf` and `argv_array_push`. + +`argv_array_clear`:: + Free all memory associated with the array and return it to the + initial, empty state. diff --git a/Documentation/technical/api-credentials.txt b/Documentation/technical/api-credentials.txt new file mode 100644 index 0000000000..21ca6a2553 --- /dev/null +++ b/Documentation/technical/api-credentials.txt @@ -0,0 +1,245 @@ +credentials API +=============== + +The credentials API provides an abstracted way of gathering username and +password credentials from the user (even though credentials in the wider +world can take many forms, in this document the word "credential" always +refers to a username and password pair). + +Data Structures +--------------- + +`struct credential`:: + + This struct represents a single username/password combination + along with any associated context. All string fields should be + heap-allocated (or NULL if they are not known or not applicable). + The meaning of the individual context fields is the same as + their counterparts in the helper protocol; see the section below + for a description of each field. ++ +The `helpers` member of the struct is a `string_list` of helpers. Each +string specifies an external helper which will be run, in order, to +either acquire or store credentials. See the section on credential +helpers below. ++ +This struct should always be initialized with `CREDENTIAL_INIT` or +`credential_init`. + + +Functions +--------- + +`credential_init`:: + + Initialize a credential structure, setting all fields to empty. + +`credential_clear`:: + + Free any resources associated with the credential structure, + returning it to a pristine initialized state. + +`credential_fill`:: + + Instruct the credential subsystem to fill the username and + password fields of the passed credential struct by first + consulting helpers, then asking the user. After this function + returns, the username and password fields of the credential are + guaranteed to be non-NULL. If an error occurs, the function will + die(). + +`credential_reject`:: + + Inform the credential subsystem that the provided credentials + have been rejected. This will cause the credential subsystem to + notify any helpers of the rejection (which allows them, for + example, to purge the invalid credentials from storage). It + will also free() the username and password fields of the + credential and set them to NULL (readying the credential for + another call to `credential_fill`). Any errors from helpers are + ignored. + +`credential_approve`:: + + Inform the credential subsystem that the provided credentials + were successfully used for authentication. This will cause the + credential subsystem to notify any helpers of the approval, so + that they may store the result to be used again. Any errors + from helpers are ignored. + +`credential_from_url`:: + + Parse a URL into broken-down credential fields. + +Example +------- + +The example below shows how the functions of the credential API could be +used to login to a fictitious "foo" service on a remote host: + +----------------------------------------------------------------------- +int foo_login(struct foo_connection *f) +{ + int status; + /* + * Create a credential with some context; we don't yet know the + * username or password. + */ + + struct credential c = CREDENTIAL_INIT; + c.protocol = xstrdup("foo"); + c.host = xstrdup(f->hostname); + + /* + * Fill in the username and password fields by contacting + * helpers and/or asking the user. The function will die if it + * fails. + */ + credential_fill(&c); + + /* + * Otherwise, we have a username and password. Try to use it. + */ + status = send_foo_login(f, c.username, c.password); + switch (status) { + case FOO_OK: + /* It worked. Store the credential for later use. */ + credential_accept(&c); + break; + case FOO_BAD_LOGIN: + /* Erase the credential from storage so we don't try it + * again. */ + credential_reject(&c); + break; + default: + /* + * Some other error occured. We don't know if the + * credential is good or bad, so report nothing to the + * credential subsystem. + */ + } + + /* Free any associated resources. */ + credential_clear(&c); + + return status; +} +----------------------------------------------------------------------- + + +Credential Helpers +------------------ + +Credential helpers are programs executed by git to fetch or save +credentials from and to long-term storage (where "long-term" is simply +longer than a single git process; e.g., credentials may be stored +in-memory for a few minutes, or indefinitely on disk). + +Each helper is specified by a single string. The string is transformed +by git into a command to be executed using these rules: + + 1. If the helper string begins with "!", it is considered a shell + snippet, and everything after the "!" becomes the command. + + 2. Otherwise, if the helper string begins with an absolute path, the + verbatim helper string becomes the command. + + 3. Otherwise, the string "git credential-" is prepended to the helper + string, and the result becomes the command. + +The resulting command then has an "operation" argument appended to it +(see below for details), and the result is executed by the shell. + +Here are some example specifications: + +---------------------------------------------------- +# run "git credential-foo" +foo + +# same as above, but pass an argument to the helper +foo --bar=baz + +# the arguments are parsed by the shell, so use shell +# quoting if necessary +foo --bar="whitespace arg" + +# you can also use an absolute path, which will not use the git wrapper +/path/to/my/helper --with-arguments + +# or you can specify your own shell snippet +!f() { echo "password=`cat $HOME/.secret`"; }; f +---------------------------------------------------- + +Generally speaking, rule (3) above is the simplest for users to specify. +Authors of credential helpers should make an effort to assist their +users by naming their program "git-credential-$NAME", and putting it in +the $PATH or $GIT_EXEC_PATH during installation, which will allow a user +to enable it with `git config credential.helper $NAME`. + +When a helper is executed, it will have one "operation" argument +appended to its command line, which is one of: + +`get`:: + + Return a matching credential, if any exists. + +`store`:: + + Store the credential, if applicable to the helper. + +`erase`:: + + Remove a matching credential, if any, from the helper's storage. + +The details of the credential will be provided on the helper's stdin +stream. The credential is split into a set of named attributes. +Attributes are provided to the helper, one per line. Each attribute is +specified by a key-value pair, separated by an `=` (equals) sign, +followed by a newline. The key may contain any bytes except `=`, +newline, or NUL. The value may contain any bytes except newline or NUL. +In both cases, all bytes are treated as-is (i.e., there is no quoting, +and one cannot transmit a value with newline or NUL in it). The list of +attributes is terminated by a blank line or end-of-file. + +Git will send the following attributes (but may not send all of +them for a given credential; for example, a `host` attribute makes no +sense when dealing with a non-network protocol): + +`protocol`:: + + The protocol over which the credential will be used (e.g., + `https`). + +`host`:: + + The remote hostname for a network credential. + +`path`:: + + The path with which the credential will be used. E.g., for + accessing a remote https repository, this will be the + repository's path on the server. + +`username`:: + + The credential's username, if we already have one (e.g., from a + URL, from the user, or from a previously run helper). + +`password`:: + + The credential's password, if we are asking it to be stored. + +For a `get` operation, the helper should produce a list of attributes +on stdout in the same format. A helper is free to produce a subset, or +even no values at all if it has nothing useful to provide. Any provided +attributes will overwrite those already known about by git. + +For a `store` or `erase` operation, the helper's output is ignored. +If it fails to perform the requested operation, it may complain to +stderr to inform the user. If it does not support the requested +operation (e.g., a read-only store), it should silently ignore the +request. + +If a helper receives any other operation, it should silently ignore the +request. This leaves room for future operations to be added (older +helpers will just ignore the new requests). diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt index f6a4a361bd..4b92514f60 100644 --- a/Documentation/technical/api-parse-options.txt +++ b/Documentation/technical/api-parse-options.txt @@ -135,9 +135,14 @@ There are some macros to easily define options: describes the group or an empty string. Start the description with an upper-case letter. -`OPT_BOOLEAN(short, long, &int_var, description)`:: - Introduce a boolean option. - `int_var` is incremented on each use. +`OPT_BOOL(short, long, &int_var, description)`:: + Introduce a boolean option. `int_var` is set to one with + `--option` and set to zero with `--no-option`. + +`OPT_COUNTUP(short, long, &int_var, description)`:: + Introduce a count-up option. + `int_var` is incremented on each use of `--option`, and + reset to zero with `--no-option`. `OPT_BIT(short, long, &int_var, description, mask)`:: Introduce a boolean option. @@ -148,8 +153,9 @@ There are some macros to easily define options: If used, `int_var` is bitwise-anded with the inverted `mask`. `OPT_SET_INT(short, long, &int_var, description, integer)`:: - Introduce a boolean option. - If used, set `int_var` to `integer`. + Introduce an integer option. + `int_var` is set to `integer` with `--option`, and + reset to zero with `--no-option`. `OPT_SET_PTR(short, long, &ptr_var, description, ptr)`:: Introduce a boolean option. @@ -198,6 +204,11 @@ There are some macros to easily define options: "auto", set `int_var` to 1 if stdout is a tty or a pager, 0 otherwise. +`OPT_NOOP_NOARG(short, long)`:: + Introduce an option that has no effect and takes no arguments. + Use it to hide deprecated options that are still to be recognized + and ignored silently. + The last element of the array must be `OPT_END()`. diff --git a/Documentation/technical/api-sha1-array.txt b/Documentation/technical/api-sha1-array.txt new file mode 100644 index 0000000000..4a4bae8109 --- /dev/null +++ b/Documentation/technical/api-sha1-array.txt @@ -0,0 +1,79 @@ +sha1-array API +============== + +The sha1-array API provides storage and manipulation of sets of SHA1 +identifiers. The emphasis is on storage and processing efficiency, +making them suitable for large lists. Note that the ordering of items is +not preserved over some operations. + +Data Structures +--------------- + +`struct sha1_array`:: + + A single array of SHA1 hashes. This should be initialized by + assignment from `SHA1_ARRAY_INIT`. The `sha1` member contains + the actual data. The `nr` member contains the number of items in + the set. The `alloc` and `sorted` members are used internally, + and should not be needed by API callers. + +Functions +--------- + +`sha1_array_append`:: + Add an item to the set. The sha1 will be placed at the end of + the array (but note that some operations below may lose this + ordering). + +`sha1_array_sort`:: + Sort the elements in the array. + +`sha1_array_lookup`:: + Perform a binary search of the array for a specific sha1. + If found, returns the offset (in number of elements) of the + sha1. If not found, returns a negative integer. If the array is + not sorted, this function has the side effect of sorting it. + +`sha1_array_clear`:: + Free all memory associated with the array and return it to the + initial, empty state. + +`sha1_array_for_each_unique`:: + Efficiently iterate over each unique element of the list, + executing the callback function for each one. If the array is + not sorted, this function has the side effect of sorting it. + +Examples +-------- + +----------------------------------------- +void print_callback(const unsigned char sha1[20], + void *data) +{ + printf("%s\n", sha1_to_hex(sha1)); +} + +void some_func(void) +{ + struct sha1_array hashes = SHA1_ARRAY_INIT; + unsigned char sha1[20]; + + /* Read objects into our set */ + while (read_object_from_stdin(sha1)) + sha1_array_append(&hashes, sha1); + + /* Check if some objects are in our set */ + while (read_object_from_stdin(sha1)) { + if (sha1_array_lookup(&hashes, sha1) >= 0) + printf("it's in there!\n"); + + /* + * Print the unique set of objects. We could also have + * avoided adding duplicate objects in the first place, + * but we would end up re-sorting the array repeatedly. + * Instead, this will sort once and then skip duplicates + * in linear time. + */ + sha1_array_for_each_unique(&hashes, print_callback, NULL); +} +----------------------------------------- diff --git a/Documentation/technical/pack-protocol.txt b/Documentation/technical/pack-protocol.txt index a7004c63e7..546980c0a4 100644 --- a/Documentation/technical/pack-protocol.txt +++ b/Documentation/technical/pack-protocol.txt @@ -60,6 +60,13 @@ process on the server side over the Git protocol is this: "0039git-upload-pack /schacon/gitbook.git\0host=example.com\0" | nc -v example.com 9418 +If the server refuses the request for some reasons, it could abort +gracefully with an error message. + +---- + error-line = PKT-LINE("ERR" SP explanation-text) +---- + SSH Transport ------------- |