From d83dc950b3ec1fbde33b23d42c5154091a74f4d9 Mon Sep 17 00:00:00 2001
From: Robert Yang <liezhi.yang@windriver.com>
Date: Mon, 23 Dec 2013 03:44:03 -0500
Subject: [PATCH 09/11] misc/create_inode.c: handle hardlinks

Create the inode and save the native inode number when we meet the hard
link (st_nlink > 1) at the first time, use ext2fs_link() to link the
name to the target inode number when we meet the same native inode
number again.

This algorithm is referred from the genext2fs.

Upstream-Status: Backport

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Reviewed-by: Darren Hart <dvhart@linux.intel.com>
---
 misc/create_inode.c |   88 +++++++++++++++++++++++++++++++++++++++++++++++++++
 misc/create_inode.h |   18 +++++++++++
 misc/mke2fs.c       |   12 +++++++
 3 files changed, 118 insertions(+)

diff --git a/misc/create_inode.c b/misc/create_inode.c
index aad7354..763504d 100644
--- a/misc/create_inode.c
+++ b/misc/create_inode.c
@@ -18,6 +18,44 @@
 #define S_BLKSIZE 512
 #endif
 
+/* For saving the hard links */
+int hdlink_cnt = HDLINK_CNT;
+
+/* Link an inode number to a directory */
+static errcode_t add_link(ext2_ino_t parent_ino, ext2_ino_t ino, const char *name)
+{
+	struct ext2_inode	inode;
+	errcode_t		retval;
+
+	retval = ext2fs_read_inode(current_fs, ino, &inode);
+        if (retval) {
+		com_err(__func__, retval, "while reading inode %u", ino);
+		return retval;
+	}
+
+	retval = ext2fs_link(current_fs, parent_ino, name, ino, inode.i_flags);
+	if (retval == EXT2_ET_DIR_NO_SPACE) {
+		retval = ext2fs_expand_dir(current_fs, parent_ino);
+		if (retval) {
+			com_err(__func__, retval, "while expanding directory");
+			return retval;
+		}
+		retval = ext2fs_link(current_fs, parent_ino, name, ino, inode.i_flags);
+	}
+	if (retval) {
+		com_err(__func__, retval, "while linking %s", name);
+		return retval;
+	}
+
+	inode.i_links_count++;
+
+	retval = ext2fs_write_inode(current_fs, ino, &inode);
+	if (retval)
+		com_err(__func__, retval, "while writing inode %u", ino);
+
+	return retval;
+}
+
 /* Fill the uid, gid, mode and time for the inode */
 static void fill_inode(struct ext2_inode *inode, struct stat *st)
 {
@@ -278,6 +316,17 @@ fail:
 	return retval;
 }
 
+int is_hardlink(ext2_ino_t ino)
+{
+	int i;
+
+	for(i = 0; i < hdlinks.count; i++) {
+		if(hdlinks.hdl[i].src_ino == ino)
+			return i;
+	}
+	return -1;
+}
+
 /* Copy the native file to the fs */
 errcode_t do_write_internal(ext2_ino_t cwd, const char *src, const char *dest)
 {
@@ -388,9 +437,11 @@ errcode_t populate_fs(ext2_ino_t parent_ino, const char *source_dir)
 	struct dirent	*dent;
 	struct stat	st;
 	char		ln_target[PATH_MAX];
+	unsigned int	save_inode;
 	ext2_ino_t	ino;
 	errcode_t	retval;
 	int		read_cnt;
+	int		hdlink;
 
 	root = EXT2_ROOT_INO;
 
@@ -412,6 +463,22 @@ errcode_t populate_fs(ext2_ino_t parent_ino, const char *source_dir)
 		lstat(dent->d_name, &st);
 		name = dent->d_name;
 
+		/* Check for hardlinks */
+		save_inode = 0;
+		if (!S_ISDIR(st.st_mode) && !S_ISLNK(st.st_mode) && st.st_nlink > 1) {
+			hdlink = is_hardlink(st.st_ino);
+			if (hdlink >= 0) {
+				retval = add_link(parent_ino,
+						hdlinks.hdl[hdlink].dst_ino, name);
+				if (retval) {
+					com_err(__func__, retval, "while linking %s", name);
+					return retval;
+				}
+				continue;
+			} else
+				save_inode = 1;
+		}
+
 		switch(st.st_mode & S_IFMT) {
 			case S_IFCHR:
 			case S_IFBLK:
@@ -480,6 +547,27 @@ errcode_t populate_fs(ext2_ino_t parent_ino, const char *source_dir)
 				_("while setting inode for \"%s\""), name);
 			return retval;
 		}
+
+		/* Save the hardlink ino */
+		if (save_inode) {
+			/*
+			 * Check whether need more memory, and we don't need
+			 * free() since the lifespan will be over after the fs
+			 * populated.
+			 */
+			if (hdlinks.count == hdlink_cnt) {
+				if ((hdlinks.hdl = realloc (hdlinks.hdl,
+						(hdlink_cnt + HDLINK_CNT) *
+						sizeof (struct hdlink_s))) == NULL) {
+					com_err(name, errno, "Not enough memory");
+					return errno;
+				}
+				hdlink_cnt += HDLINK_CNT;
+			}
+			hdlinks.hdl[hdlinks.count].src_ino = st.st_ino;
+			hdlinks.hdl[hdlinks.count].dst_ino = ino;
+			hdlinks.count++;
+		}
 	}
 	closedir(dh);
 	return retval;
diff --git a/misc/create_inode.h b/misc/create_inode.h
index 9fc97fa..2b6d429 100644
--- a/misc/create_inode.h
+++ b/misc/create_inode.h
@@ -6,9 +6,27 @@
 #include "ext2fs/ext2fs.h"
 #include "nls-enable.h"
 
+struct hdlink_s
+{
+	ext2_ino_t src_ino;
+	ext2_ino_t dst_ino;
+};
+
+struct hdlinks_s
+{
+	int count;
+	struct hdlink_s *hdl;
+};
+
+struct hdlinks_s hdlinks;
+
 ext2_filsys    current_fs;
 ext2_ino_t     root;
 
+/* For saving the hard links */
+#define HDLINK_CNT     4
+extern int hdlink_cnt;
+
 /* For populating the filesystem */
 extern errcode_t populate_fs(ext2_ino_t parent_ino, const char *source_dir);
 extern errcode_t do_mknod_internal(ext2_ino_t cwd, const char *name, struct stat *st);
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 578b62d..a63f0b7 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -2730,6 +2730,18 @@ no_journal:
 		if (!quiet)
 			printf("%s", _("Copying files into the device: "));
 
+		/*
+		 * Allocate memory for the hardlinks, we don't need free()
+		 * since the lifespan will be over after the fs populated.
+		 */
+		if ((hdlinks.hdl = (struct hdlink_s *)
+				malloc(hdlink_cnt * sizeof(struct hdlink_s))) == NULL) {
+			fprintf(stderr, "%s", _("\nNot enough memory\n"));
+			retval = ext2fs_close(fs);
+			return retval;
+		}
+
+		hdlinks.count = 0;
 		current_fs = fs;
 		root = EXT2_ROOT_INO;
 		retval = populate_fs(root, root_dir);
-- 
1.7.10.4