From 51e3dd447d57e88ca32c734a76767fbffa7db751 Mon Sep 17 00:00:00 2001
From: Beniamino Galvani <bgalvani@redhat.com>
Date: Tue, 14 Feb 2023 09:23:51 +0100
Subject: [PATCH] core: print stderr from nm-daemon-helper

Currently the only way to return an error code from the daemon helper
is via the process exit code, but that is not enough to fully describe
an error from getaddrinfo(); in fact, the function returns a EAI_*
error code and when the value is EAI_SYSTEM, the error code is
returned in errno.

At the moment, any messages printed to stderr by the helper goes to NM
stderr; instead, we want to capture it and pass it through the logging
mechanism of NM, so that it can be filtered according to level and
domain.

(cherry picked from commit d65702803cb02ddd656f13917a8a9af7bc08b90a)
(cherry picked from commit f1f1aee711515244322a37150de908e26cfa240f)
---
 src/core/nm-core-utils.c | 44 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/src/core/nm-core-utils.c b/src/core/nm-core-utils.c
index 4a23e60784..6dc46664b5 100644
--- a/src/core/nm-core-utils.c
+++ b/src/core/nm-core-utils.c
@@ -4862,11 +4862,14 @@ typedef struct {
 
     int      child_stdin;
     int      child_stdout;
+    int      child_stderr;
     GSource *input_source;
     GSource *output_source;
+    GSource *error_source;
 
     NMStrBuf in_buffer;
     NMStrBuf out_buffer;
+    NMStrBuf err_buffer;
     gsize    out_buffer_offset;
 } HelperInfo;
 
@@ -4902,13 +4905,17 @@ helper_info_free(gpointer data)
 
     nm_str_buf_destroy(&info->in_buffer);
     nm_str_buf_destroy(&info->out_buffer);
+    nm_str_buf_destroy(&info->err_buffer);
     nm_clear_g_source_inst(&info->input_source);
     nm_clear_g_source_inst(&info->output_source);
+    nm_clear_g_source_inst(&info->error_source);
 
     if (info->child_stdout != -1)
         nm_close(info->child_stdout);
     if (info->child_stdin != -1)
         nm_close(info->child_stdin);
+    if (info->child_stderr != -1)
+        nm_close(info->child_stderr);
 
     if (info->pid != -1) {
         nm_assert(info->pid > 1);
@@ -4922,6 +4929,10 @@ static void
 helper_complete(HelperInfo *info, GError *error)
 {
     if (error) {
+        if (info->err_buffer.len > 0) {
+            _LOG2T(info, "stderr: %s", nm_str_buf_get_str(&info->err_buffer));
+        }
+
         nm_clear_g_cancellable_disconnect(g_task_get_cancellable(info->task),
                                           &info->cancellable_id);
         g_task_return_error(info->task, error);
@@ -5017,6 +5028,24 @@ helper_have_data(int fd, GIOCondition condition, gpointer user_data)
     return G_SOURCE_CONTINUE;
 }
 
+static gboolean
+helper_have_err_data(int fd, GIOCondition condition, gpointer user_data)
+{
+    HelperInfo *info = user_data;
+    gssize      n_read;
+
+    n_read = nm_utils_fd_read(fd, &info->err_buffer);
+
+    if (n_read > 0)
+        return G_SOURCE_CONTINUE;
+
+    nm_clear_g_source_inst(&info->error_source);
+    nm_close(info->child_stderr);
+    info->child_stderr = -1;
+
+    return G_SOURCE_CONTINUE;
+}
+
 static void
 helper_child_terminated(GPid pid, int status, gpointer user_data)
 {
@@ -5092,10 +5121,11 @@ nm_utils_spawn_helper(const char *const  *args,
                                   &info->pid,
                                   &info->child_stdin,
                                   &info->child_stdout,
-                                  NULL,
+                                  &info->child_stderr,
                                   &error)) {
         info->child_stdin  = -1;
         info->child_stdout = -1;
+        info->child_stderr = -1;
         info->pid          = -1;
         g_task_return_error(info->task,
                             g_error_new(NM_UTILS_ERROR,
@@ -5124,6 +5154,8 @@ nm_utils_spawn_helper(const char *const  *args,
     fcntl(info->child_stdin, F_SETFL, fd_flags | O_NONBLOCK);
     fd_flags = fcntl(info->child_stdout, F_GETFD, 0);
     fcntl(info->child_stdout, F_SETFL, fd_flags | O_NONBLOCK);
+    fd_flags = fcntl(info->child_stderr, F_GETFD, 0);
+    fcntl(info->child_stderr, F_SETFL, fd_flags | O_NONBLOCK);
 
     /* Watch process stdin */
     info->out_buffer = NM_STR_BUF_INIT(NM_UTILS_GET_NEXT_REALLOC_SIZE_40, TRUE);
@@ -5149,6 +5181,16 @@ nm_utils_spawn_helper(const char *const  *args,
                                                  NULL);
     g_source_attach(info->input_source, g_main_context_get_thread_default());
 
+    /* Watch process stderr */
+    info->err_buffer   = NM_STR_BUF_INIT(0, FALSE);
+    info->error_source = nm_g_unix_fd_source_new(info->child_stderr,
+                                                 G_IO_IN | G_IO_ERR | G_IO_HUP,
+                                                 G_PRIORITY_DEFAULT,
+                                                 helper_have_err_data,
+                                                 info,
+                                                 NULL);
+    g_source_attach(info->error_source, g_main_context_get_thread_default());
+
     if (cancellable) {
         gulong signal_id;