File 0002-btrfs-progs-add-sysfs-file-reading-helpers.patch of Package btrfsprogs.24931

From 34f0594bcaafc1dcfe22bfae05f649a7366801cc Mon Sep 17 00:00:00 2001
From: Goldwyn Rodrigues <rgoldwyn@suse.com>
Date: Tue, 25 Aug 2020 10:03:36 -0500
Subject: [PATCH] btrfs-progs: add sysfs file reading helpers

Add helpers to open and read sysfs files from the per-fs directory.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 utils.c |   33 +++++++++++++++++++++++++++++++++
 utils.h |    3 +++
 2 files changed, 36 insertions(+)

--- a/utils.c
+++ b/utils.c
@@ -2598,3 +2598,36 @@
 		print_device_info(dev, "\t");
 	printf("\n");
 }
+
+/*
+ * Open a file in fsid directory in sysfs and return the file descriptor or
+ * error
+ */
+int sysfs_open_fsid_file(int fd, const char *filename)
+{
+	u8 fsid[BTRFS_UUID_SIZE];
+	char fsid_str[BTRFS_UUID_UNPARSED_SIZE];
+	char sysfs_file[PATH_MAX];
+	int ret;
+
+	ret = get_fsid_fd(fd, fsid);
+	if (ret < 0)
+		return ret;
+	uuid_unparse(fsid, fsid_str);
+
+	ret = path_cat3_out(sysfs_file, "/sys/fs/btrfs", fsid_str, filename);
+	if (ret < 0)
+		return ret;
+
+	return open(sysfs_file, O_RDONLY);
+}
+
+/*
+ * Read up to @size bytes to @buf from @fd
+ */
+int sysfs_read_file(int fd, char *buf, size_t size)
+{
+	lseek(fd, 0, SEEK_SET);
+	memset(buf, 0, size);
+	return read(fd, buf, size);
+}
--- a/utils.h
+++ b/utils.h
@@ -191,4 +191,7 @@
 unsigned int rand_range(unsigned int upper);
 void init_rand_seed(u64 seed);
 
+int sysfs_open_fsid_file(int fd, const char *filename);
+int sysfs_read_file(int fd, char *buf, size_t size);
+
 #endif