From 625646aede90554fed8d46fd0e081238e071ac5e Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 11 Jul 2023 16:01:26 -0700 Subject: [PATCH] KVM: selftests: Use pread() to read binary stats header Use pread() with an explicit offset when reading the header and the header name for a binary stats fd so that the common helper and the binary stats test don't subtly rely on the file effectively being untouched, e.g. to allow multiple reads of the header, name, etc. Signed-off-by: Sean Christopherson Message-Id: <20230711230131.648752-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/include/kvm_util_base.h | 6 ++++-- tools/testing/selftests/kvm/kvm_binary_stats_test.c | 6 ++++-- 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h index 07732a1..eb1ff59 100644 --- a/tools/testing/selftests/kvm/include/kvm_util_base.h +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h @@ -362,8 +362,10 @@ static inline void read_stats_header(int stats_fd, struct kvm_stats_header *head { ssize_t ret; - ret = read(stats_fd, header, sizeof(*header)); - TEST_ASSERT(ret == sizeof(*header), "Read stats header"); + ret = pread(stats_fd, header, sizeof(*header), 0); + TEST_ASSERT(ret == sizeof(*header), + "Failed to read '%lu' header bytes, ret = '%ld'", + sizeof(*header), ret); } struct kvm_stats_desc *read_stats_descriptors(int stats_fd, diff --git a/tools/testing/selftests/kvm/kvm_binary_stats_test.c b/tools/testing/selftests/kvm/kvm_binary_stats_test.c index a7001e2..eae99d0 100644 --- a/tools/testing/selftests/kvm/kvm_binary_stats_test.c +++ b/tools/testing/selftests/kvm/kvm_binary_stats_test.c @@ -43,8 +43,10 @@ static void stats_test(int stats_fd) id = malloc(header.name_size); TEST_ASSERT(id, "Allocate memory for id string"); - ret = read(stats_fd, id, header.name_size); - TEST_ASSERT(ret == header.name_size, "Read id string"); + ret = pread(stats_fd, id, header.name_size, sizeof(header)); + TEST_ASSERT(ret == header.name_size, + "Expected header size '%u', read '%lu' bytes", + header.name_size, ret); /* Check id string, that should start with "kvm" */ TEST_ASSERT(!strncmp(id, "kvm", 3) && strlen(id) < header.name_size, -- 2.7.4