git/attr.h
John Cai 44451a2e5e attr: teach "--attr-source=<tree>" global option to "git"
Earlier, 47cfc9bd (attr: add flag `--source` to work with tree-ish,
2023-01-14) taught "git check-attr" the "--source=<tree>" option to
allow it to read attribute files from a tree-ish, but did so only
for the command.  Just like "check-attr" users wanted a way to use
attributes from a tree-ish and not from the working tree files,
users of other commands (like "git diff") would benefit from the
same.

Undo most of the UI change the commit made, while keeping the
internal logic to read attributes from a given tree-ish. Expose the
internal logic via a new "--attr-source=<tree>" command line option
given to "git", so that it can be used with any git command that
runs as part of the main git process.

Additionally, add an environment variable GIT_ATTR_SOURCE that is set
when --attr-source is passed in, so that subprocesses use the same value
for the attributes source tree.

Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-05-06 14:34:09 -07:00

231 lines
6.8 KiB
C

#ifndef ATTR_H
#define ATTR_H
/**
* gitattributes mechanism gives a uniform way to associate various attributes
* to set of paths.
*
*
* Querying Specific Attributes
* ----------------------------
*
* - Prepare `struct attr_check` using attr_check_initl() function, enumerating
* the names of attributes whose values you are interested in, terminated with
* a NULL pointer. Alternatively, an empty `struct attr_check` can be
* prepared by calling `attr_check_alloc()` function and then attributes you
* want to ask about can be added to it with `attr_check_append()` function.
*
* - Call `git_check_attr()` to check the attributes for the path.
*
* - Inspect `attr_check` structure to see how each of the attribute in the
* array is defined for the path.
*
*
* Example
* -------
*
* To see how attributes "crlf" and "ident" are set for different paths.
*
* - Prepare a `struct attr_check` with two elements (because we are checking
* two attributes):
*
* ------------
* static struct attr_check *check;
* static void setup_check(void)
* {
* if (check)
* return; // already done
* check = attr_check_initl("crlf", "ident", NULL);
* }
* ------------
*
* - Call `git_check_attr()` with the prepared `struct attr_check`:
*
* ------------
* const char *path;
*
* setup_check();
* git_check_attr(&the_index, path, check);
* ------------
*
* - Act on `.value` member of the result, left in `check->items[]`:
*
* ------------
* const char *value = check->items[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 neither 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 ...) {
* ...
* }
* ------------
*
* To see how attributes in argv[] are set for different paths, only
* the first step in the above would be different.
*
* ------------
* static struct attr_check *check;
* static void setup_check(const char **argv)
* {
* check = attr_check_alloc();
* while (*argv) {
* struct git_attr *attr = git_attr(*argv);
* attr_check_append(check, attr);
* argv++;
* }
* }
* ------------
*
*
* Querying All Attributes
* -----------------------
*
* To get the values of all attributes associated with a file:
*
* - Prepare an empty `attr_check` structure by calling `attr_check_alloc()`.
*
* - Call `git_all_attrs()`, which populates the `attr_check` with the
* attributes attached to the path.
*
* - Iterate over the `attr_check.items[]` array to examine the attribute
* names and values. The name of the attribute described by an
* `attr_check.items[]` object can be retrieved via
* `git_attr_name(check->items[i].attr)`. (Please note that no items will be
* returned for unset attributes, so `ATTR_UNSET()` will return false for all
* returned `attr_check.items[]` objects.)
*
* - Free the `attr_check` struct by calling `attr_check_free()`.
*/
/**
* The maximum line length for a gitattributes file. If the line exceeds this
* length we will ignore it.
*/
#define ATTR_MAX_LINE_LENGTH 2048
/**
* The maximum size of the giattributes file. If the file exceeds this size we
* will ignore it.
*/
#define ATTR_MAX_FILE_SIZE (100 * 1024 * 1024)
struct index_state;
/**
* An attribute is an opaque object that is identified by its name. Pass the
* name 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. The name of the attribute can be retrieved by calling
* `git_attr_name()`.
*/
struct git_attr;
/* opaque structures used internally for attribute collection */
struct all_attrs_item;
struct attr_stack;
/*
* The textual object name for the tree-ish used by git_check_attr()
* to read attributes from (instead of from the working tree).
*/
void set_git_attr_source(const char *);
/*
* Given a string, return the gitattribute object that
* corresponds to it.
*/
const struct git_attr *git_attr(const char *);
/* Internal use */
extern const char git_attr__true[];
extern const char git_attr__false[];
/**
* 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 attr_check_item` records
* it. The three macros check these, if none of them returns true, `.value`
* member points at a string value of the attribute for the path.
*/
/* Returns true if the attribute is Set for the path. */
#define ATTR_TRUE(v) ((v) == git_attr__true)
/* Returns true if the attribute is Unset for the path. */
#define ATTR_FALSE(v) ((v) == git_attr__false)
/* Returns true if the attribute is Unspecified for the path. */
#define ATTR_UNSET(v) ((v) == NULL)
/* This structure represents one attribute and its value. */
struct attr_check_item {
const struct git_attr *attr;
const char *value;
};
/**
* This structure represents a collection of `attr_check_item`. It is passed to
* `git_check_attr()` function, specifying the attributes to check, and
* receives their values.
*/
struct attr_check {
int nr;
int alloc;
struct attr_check_item *items;
int all_attrs_nr;
struct all_attrs_item *all_attrs;
struct attr_stack *stack;
};
struct attr_check *attr_check_alloc(void);
struct attr_check *attr_check_initl(const char *, ...);
struct attr_check *attr_check_dup(const struct attr_check *check);
struct attr_check_item *attr_check_append(struct attr_check *check,
const struct git_attr *attr);
void attr_check_reset(struct attr_check *check);
void attr_check_clear(struct attr_check *check);
void attr_check_free(struct attr_check *check);
/*
* Return the name of the attribute represented by the argument. The
* return value is a pointer to a null-delimited string that is part
* of the internal data structure; it should not be modified or freed.
*/
const char *git_attr_name(const struct git_attr *);
void git_check_attr(struct index_state *istate,
const char *path,
struct attr_check *check);
/*
* Retrieve all attributes that apply to the specified path.
* check holds the attributes and their values.
*/
void git_all_attrs(struct index_state *istate,
const char *path, struct attr_check *check);
enum git_attr_direction {
GIT_ATTR_CHECKIN,
GIT_ATTR_CHECKOUT,
GIT_ATTR_INDEX
};
void git_attr_set_direction(enum git_attr_direction new_direction);
void attr_start(void);
#endif /* ATTR_H */