virprocess: Passthru error from virProcessRunInForkHelper

When running a function in a forked child, so far the only thing
we could report is exit status of the child and the error
message. However, it may be beneficial to the caller to know the
actual error that happened in the child.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Pavel Mores <pmores@redhat.com>

diff --git a/build-aux/syntax-check.mk b/build-aux/syntax-check.mk
index 3020921be84b4b229e5cc7a46610432603efb26d..2a38c03ba9e025fbf483603946cc78f7a375e8d7 100644 (file)
--- a/build-aux/syntax-check.mk
+++ b/build-aux/syntax-check.mk
@@ -1987,7 +1987,7 @@ exclude_file_name_regexp--sc_flags_usage = \
 exclude_file_name_regexp--sc_libvirt_unmarked_diagnostics = \
   ^(src/rpc/gendispatch\.pl$$|tests/)
 
-exclude_file_name_regexp--sc_po_check = ^(docs/|src/rpc/gendispatch\.pl$$)
+exclude_file_name_regexp--sc_po_check = ^(docs/|src/rpc/gendispatch\.pl$$|tests/commandtest.c$$)
 
 exclude_file_name_regexp--sc_prohibit_VIR_ERR_NO_MEMORY = \
   ^(build-aux/syntax-check\.mk|include/libvirt/virterror\.h|src/remote/remote_daemon_dispatch\.c|src/util/virerror\.c|docs/internals/oomtesting\.html\.in)$$

diff --git a/src/util/virprocess.c b/src/util/virprocess.c
index 24135070b7297ad9a4ca7764e0f57a3c9086d107..b126c3c9afd2c11a70af0a433d5ba282724c5494 100644 (file)
--- a/src/util/virprocess.c
+++ b/src/util/virprocess.c
@@ -1126,6 +1126,23 @@ virProcessRunInMountNamespace(pid_t pid G_GNUC_UNUSED,
 
 
 #ifndef WIN32
+typedef struct {
+    int code;
+    int domain;
+    char message[VIR_ERROR_MAX_LENGTH];
+    virErrorLevel level;
+    char str1[VIR_ERROR_MAX_LENGTH];
+    char str2[VIR_ERROR_MAX_LENGTH];
+    char str3[VIR_ERROR_MAX_LENGTH];
+    int int1;
+    int int2;
+} errorData;
+
+typedef union {
+    errorData data;
+    char bindata[sizeof(errorData)];
+} errorDataBin;
+
 static int
 virProcessRunInForkHelper(int errfd,
                           pid_t ppid,
@@ -1134,9 +1151,24 @@ virProcessRunInForkHelper(int errfd,
 {
     if (cb(ppid, opaque) < 0) {
         virErrorPtr err = virGetLastError();
+
         if (err) {
-            size_t len = strlen(err->message) + 1;
-            ignore_value(safewrite(errfd, err->message, len));
+            g_autofree errorDataBin *bin = g_new0(errorDataBin, 1);
+
+            bin->data.code = err->code;
+            bin->data.domain = err->domain;
+            ignore_value(virStrcpy(bin->data.message, err->message, sizeof(bin->data.message)));
+            bin->data.level = err->level;
+            if (err->str1)
+                ignore_value(virStrcpy(bin->data.str1, err->str1, sizeof(bin->data.str1)));
+            if (err->str2)
+                ignore_value(virStrcpy(bin->data.str2, err->str2, sizeof(bin->data.str2)));
+            if (err->str3)
+                ignore_value(virStrcpy(bin->data.str3, err->str3, sizeof(bin->data.str3)));
+            bin->data.int1 = err->int1;
+            bin->data.int2 = err->int2;
+
+            ignore_value(safewrite(errfd, bin->bindata, sizeof(*bin)));
         }
 
         return -1;
@@ -1188,16 +1220,38 @@ virProcessRunInFork(virProcessForkCallback cb,
     } else {
         int status;
         g_autofree char *buf = NULL;
+        g_autofree errorDataBin *bin = NULL;
+        int nread;
 
         VIR_FORCE_CLOSE(errfd[1]);
-        ignore_value(virFileReadHeaderFD(errfd[0], 1024, &buf));
+        nread = virFileReadHeaderFD(errfd[0], sizeof(*bin), &buf);
         ret = virProcessWait(child, &status, false);
         if (ret == 0) {
             ret = status == EXIT_CANCELED ? -1 : status;
             if (ret) {
-                virReportError(VIR_ERR_INTERNAL_ERROR,
-                               _("child reported (status=%d): %s"),
-                               status, NULLSTR(buf));
+                if (nread == sizeof(*bin)) {
+                    bin = g_new0(errorDataBin, 1);
+                    memcpy(bin->bindata, buf, sizeof(*bin));
+
+                    virReportError(VIR_ERR_INTERNAL_ERROR,
+                                   _("child reported (status=%d): %s"),
+                                   status, NULLSTR(bin->data.message));
+
+                    virRaiseErrorFull(__FILE__, __FUNCTION__, __LINE__,
+                                      bin->data.domain,
+                                      bin->data.code,
+                                      bin->data.level,
+                                      bin->data.str1,
+                                      bin->data.str2,
+                                      bin->data.str3,
+                                      bin->data.int1,
+                                      bin->data.int2,
+                                      "%s", bin->data.message);
+                } else {
+                    virReportError(VIR_ERR_INTERNAL_ERROR,
+                                   _("child didn't write error (status=%d)"),
+                                   status);
+                }
             }
         }
     }

diff --git a/tests/commandtest.c b/tests/commandtest.c
index a64aa9ad339da6da4c940b44af2bbb87707f210c..f4a2c67c058079762f790bea3d88df2a7630a023 100644 (file)
--- a/tests/commandtest.c
+++ b/tests/commandtest.c
@@ -1257,6 +1257,48 @@ static int test27(const void *unused G_GNUC_UNUSED)
 }
 
 
+static int
+test28Callback(pid_t pid G_GNUC_UNUSED,
+               void *opaque G_GNUC_UNUSED)
+{
+    virReportSystemError(ENODATA, "%s", "some error message");
+    return -1;
+}
+
+
+static int
+test28(const void *unused G_GNUC_UNUSED)
+{
+    /* Not strictly a virCommand test, but this is the easiest place
+     * to test this lower-level interface. */
+    virErrorPtr err;
+
+    if (virProcessRunInFork(test28Callback, NULL) != -1) {
+        fprintf(stderr, "virProcessRunInFork did not fail\n");
+        return -1;
+    }
+
+    if (!(err = virGetLastError())) {
+        fprintf(stderr, "Expected error but got nothing\n");
+        return -1;
+    }
+
+    if (!(err->code == VIR_ERR_SYSTEM_ERROR &&
+          err->domain == 0 &&
+          STREQ(err->message, "some error message: No data available") &&
+          err->level == VIR_ERR_ERROR &&
+          STREQ(err->str1, "%s") &&
+          STREQ(err->str2, "some error message: No data available") &&
+          err->int1 == ENODATA &&
+          err->int2 == -1)) {
+        fprintf(stderr, "Unexpected error object\n");
+        return -1;
+    }
+
+    return 0;
+}
+
+
 static int
 mymain(void)
 {
@@ -1354,6 +1396,7 @@ mymain(void)
     DO_TEST(test25);
     DO_TEST(test26);
     DO_TEST(test27);
+    DO_TEST(test28);
 
     return ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 }