path: root/symlinks.c
AgeCommit message (Collapse)Author
2007-05-12Add has_symlink_leading_path() function.Junio C Hamano
When we are applying a patch that creates a blob at a path, or when we are switching from a branch that does not have a blob at the path to another branch that has one, we need to make sure that there is nothing at the path in the working tree, as such a file is a local modification made by the user that would be lost by the operation. Normally, lstat() on the path and making sure ENOENT is returned is good enough for that purpose. However there is a twist. We may be creating a regular file arch/x86_64/boot/Makefile, while removing an existing symbolic link at arch/x86_64/boot that points at existing ../i386/boot directory that has Makefile in it. We always first check without touching filesystem and then perform the actual operation, so when we verify the new file, arch/x86_64/boot/Makefile, does not exist, we haven't removed the symbolic link arc/x86_64/boot symbolic link yet. lstat() on the file sees through the symbolic link and reports the file is there, which is not what we want. The function has_symlink_leading_path() function takes a path, and sees if any of the leading directory component is a symbolic link. When files in a new directory are created, we tend to process them together because both index and tree are sorted. The function takes advantage of this and allows the caller to cache and reuse which symbolic link on the filesystem caused the function to return true. The calling sequence would be: char last_symlink[PATH_MAX]; *last_symlink = '\0'; for each index entry { if (!lose) continue; if (lstat(it)) if (errno == ENOENT) ; /* happy */ else error; else if (has_symlink_leading_path(it, last_symlink)) ; /* happy */ else error; /* would lose local changes */ unlink_entry(it, last_symlink); } Signed-off-by: Junio C Hamano <>