From d20a9afc0ab96250cfd416c8a4f45fe32840be26 Mon Sep 17 00:00:00 2001
From: Benedikt Steinbusch <b.steinbusch@fz-juelich.de>
Date: Thu, 11 Feb 2021 11:54:39 +0100
Subject: [PATCH] fix out of bounds exception on 0 length pread and pwrite
messages
---
CHANGELOG.md | 4 ++++
src/server.cxx | 4 ++--
src/test-client.c | 8 ++++++++
3 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ec40bbc..9390e97 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,4 +12,8 @@
- `boost::variant` has been replaced by `std::variant` and Boost is no longer needed as a dependency
- If no explicit choice is made via `CMAKE_POSITION_INDEPENDENT_CODE`, the client library defaults to being built as position independent code
+### Fixed
+
+- Pread and pwrite messages of length 0 were handled incorrectly by the server, leading to an out of bounds exception
+
[Unreleased]: https://gitlab.version.fz-juelich.de/SIONlib/SIONfwd/-/compare/v1.0.0...main
diff --git a/src/server.cxx b/src/server.cxx
index 36ebe26..b427c50 100644
--- a/src/server.cxx
+++ b/src/server.cxx
@@ -362,7 +362,7 @@ struct CommunicatorReceiver {
std::vector<char> buf = (args.nbyte() > 0) ? communicator_.receive_data(args.nbyte()) : std::vector<char>{};
ssize_t written = 0;
while (true) {
- ssize_t k = pwrite(args.fd(), &buf.at(written), args.nbyte() - written, args.offset() + written);
+ ssize_t k = pwrite(args.fd(), (args.nbyte() > 0) ? &buf.at(written) : nullptr, args.nbyte() - written, args.offset() + written);
if (k == -1) {
if (errno != EINTR) {
written = -1;
@@ -385,7 +385,7 @@ struct CommunicatorReceiver {
std::vector<char> buf(args.nbyte());
ssize_t read = 0;
while (true) {
- ssize_t k = pread(args.fd(), &buf.at(read), args.nbyte() - read, args.offset() + read);
+ ssize_t k = pread(args.fd(), (args.nbyte() > 0) ? &buf.at(read) : nullptr, args.nbyte() - read, args.offset() + read);
if (k == -1) {
if (errno != EINTR) {
read = -1;
diff --git a/src/test-client.c b/src/test-client.c
index bc06e52..d62b2bb 100644
--- a/src/test-client.c
+++ b/src/test-client.c
@@ -26,6 +26,10 @@ int main(int argc, char *argv[]) {
fprintf(stderr, "wrote %" PRId64 " bytes to %d\n", written, fd);
assert(written == strlen(wbuf));
+ written = sionfwd_pwrite(fd, wbuf, 0, 0);
+ fprintf(stderr, "wrote %" PRId64 " bytes to %d\n", written, fd);
+ assert(written == 0);
+
int status = sionfwd_flush(fd);
fprintf(stderr, "flushed file descriptor %d\n", fd);
assert(status == 0);
@@ -51,6 +55,10 @@ int main(int argc, char *argv[]) {
assert(read == strlen(wbuf));
assert(strcmp(wbuf, rbuf) == 0);
+ read = sionfwd_pread(fd, rbuf, 0, 0);
+ fprintf(stderr, "read %" PRId64 " bytes from %d\n", read, fd);
+ assert(read == 0);
+
status = sionfwd_close(fd);
fprintf(stderr, "closed file descriptor %d with status %d\n", fd, status);
assert(status == 0);
--
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