[PATCH] erofs-utils: add I/O control for tarerofs stream via `erofs_vfile`

[Hongzhen Luo]

This adds I/O control for tarerofs stream.

Signed-off-by: Hongzhen Luo <hongzhen at linux.alibaba.com>
---
 include/erofs/io.h  |  1 +
 include/erofs/tar.h |  2 +-
 lib/tar.c           | 16 ++++++++++------
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/include/erofs/io.h b/include/erofs/io.h
index c82dfdf..a501685 100644
--- a/include/erofs/io.h
+++ b/include/erofs/io.h
@@ -26,6 +26,7 @@ struct erofs_vfile;
 
 struct erofs_vfops {
 	int (*pread)(struct erofs_vfile *vf, void *buf, u64 offset, size_t len);
+	int (*read)(struct erofs_vfile *vf, void *buf, size_t len);
 	int (*pwrite)(struct erofs_vfile *vf, const void *buf, u64 offset, size_t len);
 	int (*fsync)(struct erofs_vfile *vf);
 	int (*fallocate)(struct erofs_vfile *vf, u64 offset, size_t len, bool pad);
diff --git a/include/erofs/tar.h b/include/erofs/tar.h
index b5c966b..e1de0df 100644
--- a/include/erofs/tar.h
+++ b/include/erofs/tar.h
@@ -39,7 +39,7 @@ struct erofs_iostream_liblzma {
 
 struct erofs_iostream {
 	union {
-		int fd;			/* original fd */
+		struct erofs_vfile vf;
 		void *handler;
 #ifdef HAVE_LIBLZMA
 		struct erofs_iostream_liblzma *lzma;
diff --git a/lib/tar.c b/lib/tar.c
index 3514381..77e09ae 100644
--- a/lib/tar.c
+++ b/lib/tar.c
@@ -79,7 +79,7 @@ void erofs_iostream_close(struct erofs_iostream *ios)
 #endif
 		return;
 	}
-	close(ios->fd);
+	close(ios->vf.fd);
 }
 
 int erofs_iostream_open(struct erofs_iostream *ios, int fd, int decoder)
@@ -119,7 +119,7 @@ int erofs_iostream_open(struct erofs_iostream *ios, int fd, int decoder)
 		return -EOPNOTSUPP;
 #endif
 	} else {
-		ios->fd = fd;
+		ios->vf.fd = fd;
 		fsz = lseek(fd, 0, SEEK_END);
 		if (fsz <= 0) {
 			ios->feof = !fsz;
@@ -218,8 +218,12 @@ int erofs_iostream_read(struct erofs_iostream *ios, void **buf, u64 bytes)
 			return -EOPNOTSUPP;
 #endif
 		} else {
-			ret = erofs_read_from_fd(ios->fd, ios->buffer + rabytes,
-						 ios->bufsize - rabytes);
+			if (ios->vf.ops)
+				ret = ios->vf.ops->read(&ios->vf, ios->buffer + rabytes,
+							 ios->bufsize - rabytes);
+			else
+				ret = erofs_read_from_fd(ios->vf.fd, ios->buffer + rabytes,
+							 ios->bufsize - rabytes);
 			if (ret < 0)
 				return ret;
 			ios->tail += ret;
@@ -270,8 +274,8 @@ int erofs_iostream_lskip(struct erofs_iostream *ios, u64 sz)
 	if (ios->feof)
 		return sz;
 
-	if (ios->sz && likely(ios->dumpfd < 0)) {
-		s64 cur = lseek(ios->fd, sz, SEEK_CUR);
+	if (ios->sz && likely(ios->dumpfd < 0) && !ios->vf.ops) {
+		s64 cur = lseek(ios->vf.fd, sz, SEEK_CUR);
 
 		if (cur > ios->sz)
 			return cur - ios->sz;
-- 
2.39.3