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chdir-notify.h
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75 lines (70 loc) · 2.59 KB
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#ifndef CHDIR_NOTIFY_H
#define CHDIR_NOTIFY_H
/*
* An API to let code "subscribe" to changes to the current working directory.
* The general idea is that some code asks to be notified when the working
* directory changes, and other code that calls chdir uses a special wrapper
* that notifies everyone.
*/
/*
* Callers who need to know about changes can do:
*
* void foo(const char *old_path, const char *new_path, void *data)
* {
* warning("switched from %s to %s!", old_path, new_path);
* }
* ...
* chdir_notify_register("description", foo, data);
*
* In practice most callers will want to move a relative path to the new root;
* they can use the reparent_relative_path() helper for that. If that's all
* you're doing, you can also use the convenience function:
*
* chdir_notify_reparent("description", &my_path);
*
* Whenever a chdir event occurs, that will update my_path (if it's relative)
* to adjust for the new cwd by freeing any existing string and allocating a
* new one.
*
* Registered functions are called in the order in which they were added. Note
* that there's currently no way to remove a function, so make sure that the
* data parameter remains valid for the rest of the program.
*
* The "name" argument is used only for printing trace output from
* $GIT_TRACE_SETUP. It may be NULL, but if non-NULL should point to
* storage which lasts as long as the registration is active.
*/
typedef void (*chdir_notify_callback)(const char *name,
const char *old_cwd,
const char *new_cwd,
void *data);
void chdir_notify_register(const char *name, chdir_notify_callback cb, void *data);
void chdir_notify_unregister(const char *name, chdir_notify_callback cb,
void *data);
void chdir_notify_reparent(const char *name, char **path);
/*
*
* Callers that want to chdir:
*
* chdir_notify(new_path);
*
* to switch to the new path and notify any callbacks.
*
* Note that you don't need to chdir_notify() if you're just temporarily moving
* to a directory and back, as long as you don't call any subscribed code in
* between (but it should be safe to do so if you're unsure).
*/
int chdir_notify(const char *new_cwd);
/*
* Reparent a relative path from old_root to new_root. For example:
*
* reparent_relative_path("/a", "/a/b", "b/rel");
*
* would return the (newly allocated) string "rel". Note that we may return an
* absolute path in some cases (e.g., if the resulting path is not inside
* new_cwd).
*/
char *reparent_relative_path(const char *old_cwd,
const char *new_cwd,
const char *path);
#endif /* CHDIR_NOTIFY_H */