chromiumOSPackages.sommelier: fix log spam

Previously, sommelier would output many lines per second saying:

> Failed to send message to virtwl: Success

This made it extremely annoying to use the serial console, and
very difficult to see other log output.

This was happening because Sommelier's check for the return value of
the VIRTWL_IOCTL_SEND ioctl was inverted from what it should be.
That is, the failure message was printed only on success.  If there
actually was an error, no error message would be outputted.

The upstream patch I've added here is a bit vague that this was the
problem, but it does fix the issue.

1 files changed, 245 insertions, 0 deletions

diff --git a/pkgs/os-specific/linux/chromium-os/sommelier/0007-vm_tools-sommelier-Log-the-value-of-strerror-when-as.patch b/pkgs/os-specific/linux/chromium-os/sommelier/0007-vm_tools-sommelier-Log-the-value-of-strerror-when-as.patch
new file mode 100644
index 00000000000..778c481d598
--- /dev/null
+++ b/pkgs/os-specific/linux/chromium-os/sommelier/0007-vm_tools-sommelier-Log-the-value-of-strerror-when-as.patch
@@ -0,0 +1,245 @@
+From 64afc7e7271e0bad332a8a246a4fb4151b3d296f Mon Sep 17 00:00:00 2001
+From: Fergus Dall <sidereal@google.com>
+Date: Fri, 27 Mar 2020 18:34:04 +1100
+Subject: [PATCH 7/7] vm_tools: sommelier: Log the value of strerror when
+ asserting
+
+There's some reports of sommelier crashing with assert failures, and
+right now we don't even have a way to tell what the error was from the
+logs.
+
+BUG=chromium:1053843
+TEST=emerge-tatl vm_guest_tools
+
+Change-Id: Iac9e0470600f7c7a8d8328049a79305251d7ef7f
+Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2124131
+Commit-Queue: Fergus Dall <sidereal@google.com>
+Tested-by: Fergus Dall <sidereal@google.com>
+Reviewed-by: Nic Hollingum <hollingum@google.com>
+---
+ vm_tools/sommelier/sommelier.c | 65 +++++++++++++++++-----------------
+ 1 file changed, 32 insertions(+), 33 deletions(-)
+
+diff --git a/vm_tools/sommelier/sommelier.c b/vm_tools/sommelier/sommelier.c
+index 5e03d8978..ffe6f645c 100644
+--- a/vm_tools/sommelier/sommelier.c
++++ b/vm_tools/sommelier/sommelier.c
+@@ -37,6 +37,15 @@
+ #include "viewporter-client-protocol.h"
+ #include "xdg-shell-client-protocol.h"
+ 
++#define errno_assert(rv)                                          \
++  {                                                               \
++    int macro_private_assert_value = (rv);                        \
++    if (!macro_private_assert_value) {                            \
++      fprintf(stderr, "Unexpected error: %s\n", strerror(errno)); \
++      assert(false);                                              \
++    }                                                             \
++  }
++
+ // Check that required macro definitions exist.
+ #ifndef XWAYLAND_PATH
+ #error XWAYLAND_PATH must be defined
+@@ -239,7 +248,7 @@ struct sl_mmap* sl_mmap_create(int fd,
+   map->buffer_resource = NULL;
+   map->addr =
+       mmap(NULL, size + offset0, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+-  assert(map->addr != MAP_FAILED);
++  errno_assert(map->addr != MAP_FAILED);
+ 
+   return map;
+ }
+@@ -2183,8 +2192,7 @@ int sl_begin_data_source_send(struct sl_context* ctx,
+ 
+   flags = fcntl(fd, F_GETFL, 0);
+   rv = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+-  assert(!rv);
+-  UNUSED(rv);
++  errno_assert(!rv);
+ 
+   ctx->selection_data_source_send_fd = fd;
+   free(reply);
+@@ -2810,7 +2818,7 @@ static void sl_send_data(struct sl_context* ctx, xcb_atom_t data_type) {
+       int p[2];
+ 
+       rv = pipe2(p, O_CLOEXEC | O_NONBLOCK);
+-      assert(!rv);
++      errno_assert(!rv);
+ 
+       fd_to_receive = p[0];
+       fd_to_wayland = p[1];
+@@ -3153,7 +3161,7 @@ static void sl_sd_notify(const char* state) {
+   assert(socket_name);
+ 
+   fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
+-  assert(fd >= 0);
++  errno_assert(fd >= 0);
+ 
+   memset(&addr, 0, sizeof(addr));
+   addr.sun_family = AF_UNIX;
+@@ -3171,8 +3179,7 @@ static void sl_sd_notify(const char* state) {
+   msghdr.msg_iovlen = 1;
+ 
+   rv = sendmsg(fd, &msghdr, MSG_NOSIGNAL);
+-  assert(rv != -1);
+-  UNUSED(rv);
++  errno_assert(rv != -1);
+ }
+ 
+ static int sl_handle_sigchld(int signal_number, void* data) {
+@@ -3304,7 +3311,7 @@ static int sl_handle_display_ready_event(int fd, uint32_t mask, void* data) {
+                       (int)(XCURSOR_SIZE_BASE * ctx->scale + 0.5)));
+ 
+   pid = fork();
+-  assert(pid >= 0);
++  errno_assert(pid >= 0);
+   if (pid == 0) {
+     sl_execvp(ctx->runprog[0], ctx->runprog, -1);
+     _exit(EXIT_FAILURE);
+@@ -3373,8 +3380,7 @@ static int sl_handle_virtwl_ctx_event(int fd, uint32_t mask, void* data) {
+   }
+ 
+   bytes = sendmsg(ctx->virtwl_socket_fd, &msg, MSG_NOSIGNAL);
+-  assert(bytes == ioctl_recv->len);
+-  UNUSED(bytes);
++  errno_assert(bytes == ioctl_recv->len);
+ 
+   while (fd_count--)
+     close(ioctl_recv->fds[fd_count]);
+@@ -3406,10 +3412,7 @@ static int sl_handle_virtwl_socket_event(int fd, uint32_t mask, void* data) {
+   msg.msg_controllen = sizeof(fd_buffer);
+ 
+   bytes = recvmsg(ctx->virtwl_socket_fd, &msg, 0);
+-  if (bytes < 0) {
+-    fprintf(stderr, "Failed to get message from virtwl: %s\n", strerror(errno));
+-  }
+-  assert(bytes > 0);
++  errno_assert(bytes > 0);
+ 
+   // If there were any FDs recv'd by recvmsg, there will be some data in the
+   // msg_control buffer. To get the FDs out we iterate all cmsghdr's within and
+@@ -3437,11 +3440,7 @@ static int sl_handle_virtwl_socket_event(int fd, uint32_t mask, void* data) {
+   // structure which we now pass along to the kernel.
+   ioctl_send->len = bytes;
+   rv = ioctl(ctx->virtwl_ctx_fd, VIRTWL_IOCTL_SEND, ioctl_send);
+-  if (!rv) {
+-    fprintf(stderr, "Failed to send message to virtwl: %s\n", strerror(errno));
+-  }
+-  assert(!rv);
+-  UNUSED(rv);
++  errno_assert(!rv);
+ 
+   while (fd_count--)
+     close(ioctl_send->fds[fd_count]);
+@@ -3765,7 +3764,7 @@ int main(int argc, char** argv) {
+ 
+     lock_fd = open(lock_addr, O_CREAT | O_CLOEXEC,
+                    (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP));
+-    assert(lock_fd >= 0);
++    errno_assert(lock_fd >= 0);
+ 
+     rv = flock(lock_fd, LOCK_EX | LOCK_NB);
+     if (rv < 0) {
+@@ -3781,25 +3780,25 @@ int main(int argc, char** argv) {
+       if (sock_stat.st_mode & (S_IWUSR | S_IWGRP))
+         unlink(addr.sun_path);
+     } else {
+-      assert(errno == ENOENT);
++      errno_assert(errno == ENOENT);
+     }
+ 
+     sock_fd = socket(PF_LOCAL, SOCK_STREAM, 0);
+-    assert(sock_fd >= 0);
++    errno_assert(sock_fd >= 0);
+ 
+     rv = bind(sock_fd, (struct sockaddr*)&addr,
+               offsetof(struct sockaddr_un, sun_path) + strlen(addr.sun_path));
+-    assert(rv >= 0);
++    errno_assert(rv >= 0);
+ 
+     rv = listen(sock_fd, 128);
+-    assert(rv >= 0);
++    errno_assert(rv >= 0);
+ 
+     // Spawn optional child process before we notify systemd that we're ready
+     // to accept connections. WAYLAND_DISPLAY will be set but any attempt to
+     // connect to this socket at this time will fail.
+     if (ctx.runprog && ctx.runprog[0]) {
+       pid = fork();
+-      assert(pid != -1);
++      errno_assert(pid != -1);
+       if (pid == 0) {
+         setenv("WAYLAND_DISPLAY", socket_name, 1);
+         sl_execvp(ctx.runprog[0], ctx.runprog, -1);
+@@ -3816,7 +3815,7 @@ int main(int argc, char** argv) {
+     sigemptyset(&sa.sa_mask);
+     sa.sa_flags = SA_RESTART;
+     rv = sigaction(SIGCHLD, &sa, NULL);
+-    assert(rv >= 0);
++    errno_assert(rv >= 0);
+ 
+     do {
+       struct ucred ucred;
+@@ -3833,7 +3832,7 @@ int main(int argc, char** argv) {
+       rv = getsockopt(client_fd, SOL_SOCKET, SO_PEERCRED, &ucred, &length);
+ 
+       pid = fork();
+-      assert(pid != -1);
++      errno_assert(pid != -1);
+       if (pid == 0) {
+         char* client_fd_str;
+         char* peer_pid_str;
+@@ -3963,7 +3962,7 @@ int main(int argc, char** argv) {
+ 
+       // Connection to virtwl channel.
+       rv = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, vws);
+-      assert(!rv);
++      errno_assert(!rv);
+ 
+       ctx.virtwl_socket_fd = vws[0];
+       virtwl_display_fd = vws[1];
+@@ -4083,7 +4082,7 @@ int main(int argc, char** argv) {
+   if (ctx.runprog || ctx.xwayland) {
+     // Wayland connection from client.
+     rv = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, sv);
+-    assert(!rv);
++    errno_assert(!rv);
+ 
+     client_fd = sv[0];
+   }
+@@ -4199,7 +4198,7 @@ int main(int argc, char** argv) {
+ 
+       // Xwayland display ready socket.
+       rv = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ds);
+-      assert(!rv);
++      errno_assert(!rv);
+ 
+       ctx.display_ready_event_source =
+           wl_event_loop_add_fd(event_loop, ds[0], WL_EVENT_READABLE,
+@@ -4207,12 +4206,12 @@ int main(int argc, char** argv) {
+ 
+       // X connection to Xwayland.
+       rv = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, wm);
+-      assert(!rv);
++      errno_assert(!rv);
+ 
+       ctx.wm_fd = wm[0];
+ 
+       pid = fork();
+-      assert(pid != -1);
++      errno_assert(pid != -1);
+       if (pid == 0) {
+         char* display_fd_str;
+         char* wm_fd_str;
+@@ -4280,7 +4279,7 @@ int main(int argc, char** argv) {
+       ctx.xwayland_pid = pid;
+     } else {
+       pid = fork();
+-      assert(pid != -1);
++      errno_assert(pid != -1);
+       if (pid == 0) {
+         sl_execvp(ctx.runprog[0], ctx.runprog, sv[1]);
+         _exit(EXIT_FAILURE);
+-- 
+2.26.2
+