[PATCH 04/30] qemuFDPassLogFDInfo: Check if FD is valid before 'fstat'-ing it

[Peter Krempa via Devel]

From: Peter Krempa <pkre...@redhat.com>

Some test cases (qemuxmlconftest) currently use made up descriptors,
which cause e.g. valgrind to be unhappy:

 ==831186== File descriptor 1729 Invalid file descriptor
 ==831186==    at 0x531042E: fgetxattr (in /usr/lib64/libc.so.6)
 ==831186==    by 0x5AE2846: ??? (in /usr/lib64/libselinux.so.1)
 ==831186==    by 0x5AE7093: fgetfilecon_raw (in /usr/lib64/libselinux.so.1)
 ==831186==    by 0x4EB736F: qemuFDPassLogFDInfo (qemu_fd.c:92)
 ==831186==    by 0x4EB7B8E: qemuFDPassDirectTransferCommand (qemu_fd.c:443)

when tracking FDs. Since 'qemuFDPassLogFDInfo' just logs information
about the FD we can simply not query the FD if it's made up.

Signed-off-by: Peter Krempa <pkre...@redhat.com>
---
 src/qemu/qemu_fd.c | 65 +++++++++++++++++++++++++---------------------
 1 file changed, 35 insertions(+), 30 deletions(-)

diff --git a/src/qemu/qemu_fd.c b/src/qemu/qemu_fd.c
index ef0a8d8127..8c8b6afcfd 100644
--- a/src/qemu/qemu_fd.c
+++ b/src/qemu/qemu_fd.c
@@ -25,6 +25,8 @@
 #include "virfile.h"
 #include "virlog.h"

+#include <fcntl.h>
+
 /* Used strictly for logging selinux context of passed FD */
 #ifdef WITH_SECDRIVER_SELINUX
 # include <selinux/selinux.h>
@@ -59,40 +61,43 @@ qemuFDPassLogFDInfo(const char *name,
     g_autofree char *selinux = NULL;
     g_autofree char *tmp = NULL;

-    if (fstat(fd, &st) == 0) {
-        switch (st.st_mode & S_IFMT) {
-           case S_IFBLK:
-               type = "block";
-               break;
-           case S_IFCHR:
-               type = "char";
-               break;
-           case S_IFDIR:
-               type = "directory";
-               break;
-           case S_IFIFO:
-               type = "pipe";
-               break;
-           case S_IFLNK:
-               type = "symlink";
-               break;
-           case S_IFREG:
-               type = "file";
-               break;
-           case S_IFSOCK:
-               type = "socket";
-               break;
-           default:
-               type = tmp = g_strdup_printf("unknown:'0x%x')", st.st_mode & 
S_IFMT);
-               break;
+    if (fcntl(fd, F_GETFD) != -1) {
+        if (fstat(fd, &st) == 0) {
+            switch (st.st_mode & S_IFMT) {
+            case S_IFBLK:
+                type = "block";
+                break;
+            case S_IFCHR:
+                type = "char";
+                break;
+            case S_IFDIR:
+                type = "directory";
+                break;
+            case S_IFIFO:
+                type = "pipe";
+                break;
+            case S_IFLNK:
+                type = "symlink";
+                break;
+            case S_IFREG:
+                type = "file";
+                break;
+            case S_IFSOCK:
+                type = "socket";
+                break;
+            default:
+                type = tmp = g_strdup_printf("unknown:'0x%x')", st.st_mode & 
S_IFMT);
+                break;
+            }
         }
-    }

 #ifdef WITH_SECDRIVER_SELINUX
-    ignore_value(fgetfilecon_raw(fd, &selinux));
-#else
-    selinux = g_strdup("N/A");
+        ignore_value(fgetfilecon_raw(fd, &selinux));
 #endif
+    }
+
+    if (!selinux)
+        selinux = g_strdup("N/A");

     VIR_DEBUG("passing fd:'%i', name:'%s'(%zu) type:'%s' selinux:'%s'",
               fd, name, idx, type, selinux);
-- 
2.54.0