-/* A file's identity:
-
- - For a file that exists, this is its device and inode.
-
- - For a file that does not exist, but which has a directory
- name that exists, this is the device and inode of the
- directory, plus the file's base name.
-
- - For a file that does not exist and has a nonexistent
- directory, this is the file name.
-
- Windows doesn't have inode numbers, so we just use the name
- there. */
-struct file_identity
-{
- unsigned long long device; /* Device number. */
- unsigned long long inode; /* Inode number. */
- char *name; /* File name, where needed, otherwise NULL. */
-};
-
-/* Returns a pointer to a dynamically allocated structure whose
- value can be used to tell whether two files are actually the
- same file. Returns a null pointer if no information about the
- file is available, perhaps because it does not exist. The
- caller is responsible for freeing the structure with
- fn_free_identity() when finished. */
-struct file_identity *
-fn_get_identity (const char *file_name)
-{
- struct file_identity *identity = xmalloc (sizeof *identity);
-
-#if !(defined _WIN32 || defined __WIN32__)
- struct stat s;
- if (lstat (file_name, &s) == 0)
- {
- identity->device = s.st_dev;
- identity->inode = s.st_ino;
- identity->name = NULL;
- }
- else
- {
- char *dir = dir_name (file_name);
- if (last_component (file_name) != NULL && stat (dir, &s) == 0)
- {
- identity->device = s.st_dev;
- identity->inode = s.st_ino;
- identity->name = base_name (file_name);
- }
- else
- {
- identity->device = 0;
- identity->inode = 0;
- identity->name = xstrdup (file_name);
- }
- free (dir);
- }
-#else /* Windows */
- bool ok = false;
- HANDLE h = CreateFile (file_name, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_READONLY, NULL);
- if (h != INVALID_HANDLE_VALUE)
- {
- BY_HANDLE_FILE_INFORMATION fi;
- ok = GetFileInformationByHandle (h, &fi);
- if (ok)
- {
- identity->device = fi.dwVolumeSerialNumber;
- identity->inode = fi.nFileIndexHigh;
- identity->inode <<= (sizeof fi.nFileIndexLow) * CHAR_BIT;
- identity->inode |= fi.nFileIndexLow;
- identity->name = 0;
- }
- CloseHandle (h);
- }
-
- if (!ok)
- {
- identity->device = 0;
- identity->inode = 0;
-
- size_t bufsize;
- size_t pathlen = 255;
- char *cname = NULL;
- do
- {
- bufsize = pathlen;
- cname = xrealloc (cname, bufsize);
- pathlen = GetFullPathName (file_name, bufsize, cname, NULL);
- }
- while (pathlen > bufsize);
- identity->name = xstrdup (cname);
- free (cname);
- str_lowercase (identity->name);
- }
-#endif /* Windows */
-
- return identity;
-}
-
-/* Frees IDENTITY obtained from fn_get_identity(). */
-void
-fn_free_identity (struct file_identity *identity)
-{
- if (identity != NULL)
- {
- free (identity->name);
- free (identity);
- }
-}
-
-/* Compares A and B, returning a strcmp()-type result. */
-int
-fn_compare_file_identities (const struct file_identity *a,
- const struct file_identity *b)
-{
- if (a->device != b->device)
- return a->device < b->device ? -1 : 1;
- else if (a->inode != b->inode)
- return a->inode < b->inode ? -1 : 1;
- else if (a->name != NULL)
- return b->name != NULL ? strcmp (a->name, b->name) : 1;
- else
- return b->name != NULL ? -1 : 0;
-}
-
-/* Returns a hash value for IDENTITY. */
-unsigned int
-fn_hash_identity (const struct file_identity *identity)
-{
- unsigned int hash = hash_int (identity->device, identity->inode);
- if (identity->name != NULL)
- hash = hash_string (identity->name, hash);
- return hash;
-}
-