From: Ralph Boehme <slow@samba.org>
Date: Tue, 25 Jun 2019 12:13:28 +0000 (+0200)
Subject: s3/lib: add make_file_index_from_itime()
X-Git-Tag: ldb-2.0.5~108
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=a5a2ce953bbfff72ab66f24604c347259321f266;p=thirdparty%2Fsamba.git

s3/lib: add make_file_index_from_itime()

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
---

diff --git a/source3/lib/file_id.c b/source3/lib/file_id.c
index f8295ce738a..7d4fb006afe 100644
--- a/source3/lib/file_id.c
+++ b/source3/lib/file_id.c
@@ -90,3 +90,37 @@ void pull_file_id_24(const char *buf, struct file_id *id)
 	id->extid  = IVAL(buf,  16);
 	id->extid |= ((uint64_t)IVAL(buf,20))<<32;
 }
+
+uint64_t make_file_id_from_itime(SMB_STRUCT_STAT *st)
+{
+	struct timespec itime = st->st_ex_itime;
+	ino_t ino = st->st_ex_ino;
+	uint64_t file_id_low;
+	uint64_t file_id;
+
+	if (st->st_ex_iflags & ST_EX_IFLAG_CALCULATED_ITIME) {
+		return ino;
+	}
+
+	file_id_low = itime.tv_nsec;
+	if (file_id_low == 0) {
+		/*
+		 * This could be by coincidence, but more likely the filesystem
+		 * is only giving us seconds granularity. We need more fine
+		 * grained granularity for the File-ID, so combine with the
+		 * inode number.
+		 */
+		file_id_low = ino & ((1 << 30) - 1);
+	}
+
+	/*
+	 * Set the high bit so ideally File-IDs based on inode numbers and
+	 * File-IDs based on Birth Time use disjoint ranges, given inodes never
+	 * have the high bit set.
+	 */
+	file_id = ((uint64_t)1) << 63;
+	file_id |= (uint64_t)itime.tv_sec << 30;
+	file_id |= file_id_low;
+
+	return file_id;
+}
diff --git a/source3/lib/file_id.h b/source3/lib/file_id.h
index 6fa98400b85..509e924c1fe 100644
--- a/source3/lib/file_id.h
+++ b/source3/lib/file_id.h
@@ -35,3 +35,8 @@ const char *file_id_string(TALLOC_CTX *mem_ctx, const struct file_id *id);
 void push_file_id_16(char *buf, const struct file_id *id);
 void push_file_id_24(char *buf, const struct file_id *id);
 void pull_file_id_24(const char *buf, struct file_id *id);
+
+/*
+ * Make a SMB File-ID from itime
+ */
+uint64_t make_file_id_from_itime(SMB_STRUCT_STAT *st);