From 34245376babfe266dd9644326affe4d74f38fe74 Mon Sep 17 00:00:00 2001
From: Martin Stein <martin.stein@genode-labs.com>
Date: Fri, 12 Mar 2021 08:33:20 +0100
Subject: [PATCH] vfs/cbe: fix size of extend/rekey fs

Stat calls on the control/extend and control/rekey files returned a bogus file
size that led to an error in the VFS File_content tool. The tool complained
that the size of the file determined while reading the content differs from the
one reported by the stat operation. Now, the stat call will always determine
the actual size of what would be read.  However, it isn't guaranteed that this
size doesn't change in the time after the stat operation and before the read
operation.

Ref #4032
---
 repos/gems/src/lib/vfs/cbe/vfs.cc | 100 +++++++++++++++++++-----------
 1 file changed, 64 insertions(+), 36 deletions(-)

diff --git a/repos/gems/src/lib/vfs/cbe/vfs.cc b/repos/gems/src/lib/vfs/cbe/vfs.cc
index 03759d0d8d..d4d246a05e 100644
--- a/repos/gems/src/lib/vfs/cbe/vfs.cc
+++ b/repos/gems/src/lib/vfs/cbe/vfs.cc
@@ -1856,6 +1856,35 @@ class Vfs_cbe::Extend_file_system : public Vfs::Single_file_system
 
 		Wrapper &_w;
 
+		using Content_string = String<32>;
+
+		static Content_string content_string(Wrapper const &wrapper)
+		{
+			Wrapper::Extending const & extending_progress {
+				wrapper.extending_progress() };
+
+			bool const in_progress {
+				extending_progress.state ==
+					Wrapper::Extending::State::IN_PROGRESS };
+
+			bool const last_result {
+				!in_progress &&
+				extending_progress.last_result !=
+					Wrapper::Extending::Result::NONE };
+
+			bool const success {
+				extending_progress.last_result ==
+					Wrapper::Extending::Result::SUCCESS };
+
+			Content_string const result {
+				Wrapper::Extending::state_to_cstring(extending_progress.state),
+				" last-result:",
+				last_result ? success ? "success" : "failed" : "none",
+				"\n" };
+
+			return result;
+		}
+
 		struct Vfs_handle : Single_vfs_handle
 		{
 			Wrapper &_w;
@@ -1876,28 +1905,12 @@ class Vfs_cbe::Extend_file_system : public Vfs::Single_file_system
 					out_count = 0;
 					return READ_OK;
 				}
-
-				using Extending = Wrapper::Extending;
-
-				Extending const exp = _w.extending_progress();
-
-				bool const in_progress =
-					exp.state == Extending::State::IN_PROGRESS;
-				bool const last_result =
-					!in_progress && exp.last_result != Extending::Result::NONE;
-				bool const success =
-					exp.last_result == Extending::Result::SUCCESS;
-
-				using Result = Genode::String<32>;
-				Result result {
-					Extending::state_to_cstring(exp.state),
-					" last-result:", last_result ? success ?
-					                 "success" : "failed" : "none",
-					"\n" };
+				Content_string const result { content_string(_w) };
 				copy_cstring(dst, result.string(), count);
 				size_t const length_without_nul = result.length() - 1;
 				out_count = count > length_without_nul - 1 ?
 				            length_without_nul : count;
+
 				return READ_OK;
 			}
 
@@ -1970,6 +1983,7 @@ class Vfs_cbe::Extend_file_system : public Vfs::Single_file_system
 		Stat_result stat(char const *path, Stat &out) override
 		{
 			Stat_result result = Single_file_system::stat(path, out);
+			out.size = content_string(_w).length() - 1;
 			return result;
 		}
 
@@ -1991,6 +2005,35 @@ class Vfs_cbe::Rekey_file_system : public Vfs::Single_file_system
 
 		Wrapper &_w;
 
+		using Content_string = String<32>;
+
+		static Content_string content_string(Wrapper const &wrapper)
+		{
+			Wrapper::Rekeying const & rekeying_progress {
+				wrapper.rekeying_progress() };
+
+			bool const in_progress {
+				rekeying_progress.state ==
+					Wrapper::Rekeying::State::IN_PROGRESS };
+
+			bool const last_result {
+				!in_progress &&
+				rekeying_progress.last_result !=
+					Wrapper::Rekeying::Result::NONE };
+
+			bool const success {
+				rekeying_progress.last_result ==
+					Wrapper::Rekeying::Result::SUCCESS };
+
+			Content_string const result {
+				Wrapper::Rekeying::state_to_cstring(rekeying_progress.state),
+				" last-result:",
+				last_result ? success ? "success" : "failed" : "none",
+				"\n" };
+
+			return result;
+		}
+
 		struct Vfs_handle : Single_vfs_handle
 		{
 			Wrapper &_w;
@@ -2011,28 +2054,12 @@ class Vfs_cbe::Rekey_file_system : public Vfs::Single_file_system
 					out_count = 0;
 					return READ_OK;
 				}
-
-				Wrapper::Rekeying const & rkp =
-					_w.rekeying_progress();
-
-				using Result = Genode::String<32>;
-				using Rekeying = Wrapper::Rekeying;
-				bool const in_progress =
-					rkp.state == Rekeying::State::IN_PROGRESS;
-				bool const last_result =
-					!in_progress && rkp.last_result != Rekeying::Result::NONE;
-				bool const success =
-					rkp.last_result == Rekeying::Result::SUCCESS;
-
-				Result result {
-					Rekeying::state_to_cstring(rkp.state),
-					" last-result:", last_result ? success ?
-					                 "success" : "failed" : "none",
-					"\n" };
+				Content_string const result { content_string(_w) };
 				copy_cstring(dst, result.string(), count);
 				size_t const length_without_nul = result.length() - 1;
 				out_count = count > length_without_nul - 1 ?
 				            length_without_nul : count;
+
 				return READ_OK;
 			}
 
@@ -2098,6 +2125,7 @@ class Vfs_cbe::Rekey_file_system : public Vfs::Single_file_system
 		Stat_result stat(char const *path, Stat &out) override
 		{
 			Stat_result result = Single_file_system::stat(path, out);
+			out.size = content_string(_w).length() - 1;
 			return result;
 		}