1 files changed, 27 insertions, 0 deletions
diff --git a/lib/io.c b/lib/io.c
index 7f5f94d..52f9424 100644
--- a/lib/io.c
+++ b/lib/io.c
@@ -207,3 +207,30 @@ int dev_resize(unsigned int blocks)
 	return dev_fillzero(st.st_size, length, true);
 }
 
+int dev_read(void *buf, u64 offset, size_t len)
+{
+	int ret;
+
+	if (cfg.c_dry_run)
+		return 0;
+
+	if (!buf) {
+		erofs_err("buf is NULL");
+		return -EINVAL;
+	}
+	if (offset >= erofs_devsz || len > erofs_devsz ||
+	    offset > erofs_devsz - len) {
+		erofs_err("read posion[%" PRIu64 ", %zd] is too large beyond"
+			  "the end of device(%" PRIu64 ").",
+			  offset, len, erofs_devsz);
+		return -EINVAL;
+	}
+
+	ret = pread64(erofs_devfd, buf, len, (off64_t)offset);
+	if (ret != (int)len) {
+		erofs_err("Failed to read data from device - %s:[%" PRIu64 ", %zd].",
+			  erofs_devname, offset, len);
+		return -errno;
+	}
+	return 0;
+}