[WIP] [PATCH 02/12] erofs-utils: fuse: support read special file

[Gao Xiang]

From: Huang Jianan <huangjianan at oppo.com>

Signed-off-by: Huang Jianan <huangjianan at oppo.com>
Signed-off-by: Guo Weichao <guoweichao at oppo.com>
Signed-off-by: Gao Xiang <hsiangkao at aol.com>
---
 fuse/getattr.c           |  1 +
 fuse/main.c              |  1 +
 fuse/namei.c             | 14 ++++++++++----
 fuse/read.c              | 26 ++++++++++++++++++++++++++
 fuse/read.h              |  1 +
 include/erofs/internal.h |  1 +
 6 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/fuse/getattr.c b/fuse/getattr.c
index 542cf35f6989..d2134f486e19 100644
--- a/fuse/getattr.c
+++ b/fuse/getattr.c
@@ -56,6 +56,7 @@ int erofs_getattr(const char *path, struct stat *stbuf)
 	stbuf->st_blocks = stbuf->st_size / EROFS_BLKSIZ;
 	stbuf->st_uid = le16_to_cpu(v.i_uid);
 	stbuf->st_gid = le16_to_cpu(v.i_gid);
+	stbuf->st_rdev = le32_to_cpu(v.i_rdev);
 	stbuf->st_atime = super.build_time;
 	stbuf->st_mtime = super.build_time;
 	stbuf->st_ctime = super.build_time;
diff --git a/fuse/main.c b/fuse/main.c
index fa9795ef1615..884101374bcf 100644
--- a/fuse/main.c
+++ b/fuse/main.c
@@ -113,6 +113,7 @@ static void signal_handle_sigsegv(int signal)
 }
 
 static struct fuse_operations erofs_ops = {
+	.readlink = erofs_readlink,
 	.getattr = erofs_getattr,
 	.readdir = erofs_readdir,
 	.open = erofs_open,
diff --git a/fuse/namei.c b/fuse/namei.c
index 3503a8d56e15..7ed1168fc14f 100644
--- a/fuse/namei.c
+++ b/fuse/namei.c
@@ -11,6 +11,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <sys/stat.h>
+#include <sys/sysmacros.h>
 
 #include "erofs/defs.h"
 #include "logging.h"
@@ -39,6 +40,13 @@ static uint8_t get_path_token_len(const char *path)
 	return len;
 }
 
+static inline dev_t new_decode_dev(u32 dev)
+{
+	unsigned major = (dev & 0xfff00) >> 8;
+	unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
+	return makedev(major, minor);
+}
+
 int erofs_iget_by_nid(erofs_nid_t nid, struct erofs_vnode *vi)
 {
 	int ret;
@@ -65,13 +73,11 @@ int erofs_iget_by_nid(erofs_nid_t nid, struct erofs_vnode *vi)
 	switch (vi->i_mode & S_IFMT) {
 	case S_IFBLK:
 	case S_IFCHR:
-		/* fixme: add special devices support
-		 * vi->i_rdev = new_decode_dev(le32_to_cpu(v1->i_u.rdev));
-		 */
+		vi->i_rdev = new_decode_dev(le32_to_cpu(v1->i_u.rdev));
 		break;
 	case S_IFIFO:
 	case S_IFSOCK:
-		/*fixme: vi->i_rdev = 0; */
+		vi->i_rdev = 0;
 		break;
 	case S_IFREG:
 	case S_IFLNK:
diff --git a/fuse/read.c b/fuse/read.c
index ffe976e59a11..3ce5c4f2911e 100644
--- a/fuse/read.c
+++ b/fuse/read.c
@@ -112,3 +112,29 @@ int erofs_read(const char *path, char *buffer, size_t size, off_t offset,
 		return -EINVAL;
 	}
 }
+
+int erofs_readlink(const char *path, char *buffer, size_t size)
+{
+	int ret;
+	erofs_nid_t nid;
+	size_t lnksz;
+	struct erofs_vnode v;
+
+	ret = walk_path(path, &nid);
+	if (ret)
+		return ret;
+
+	ret = erofs_iget_by_nid(nid, &v);
+	if (ret)
+		return ret;
+
+	lnksz = min((size_t)v.i_size, size - 1);
+
+	ret = erofs_read(path, buffer, lnksz, 0, NULL);
+	buffer[lnksz] = '\0';
+	if (ret != (int)lnksz)
+		return ret;
+
+	logi("path:%s link=%s size=%llu", path, buffer, lnksz);
+	return 0;
+}
\ No newline at end of file
diff --git a/fuse/read.h b/fuse/read.h
index f2fcebec9d07..89d4b4cd600c 100644
--- a/fuse/read.h
+++ b/fuse/read.h
@@ -12,5 +12,6 @@
 
 int erofs_read(const char *path, char *buffer, size_t size, off_t offset,
 	    struct fuse_file_info *fi);
+int erofs_readlink(const char *path, char *buffer, size_t size);
 
 #endif
diff --git a/include/erofs/internal.h b/include/erofs/internal.h
index cba3ce4695d4..47ad96d0488c 100644
--- a/include/erofs/internal.h
+++ b/include/erofs/internal.h
@@ -153,6 +153,7 @@ struct erofs_vnode {
 	uint16_t i_uid;
 	uint16_t i_gid;
 	uint16_t i_nlink;
+	uint32_t i_rdev;
 
 	/* if file is inline read inline data witch inode */
 	char *idata;
-- 
2.24.0