[PATCH] NVRAM: check NVRAM file size and recover from template

[Hao Wang <wanghao232@xxxxxxxxxx>]

From: Hao Wang <wanghao232@xxxxxxxxxx>
Subject: [PATCH] NVRAM: check NVRAM file size and recover from template

A corrupted nvram file (e.g. caused by last unsuccessful creation due to
insufficient memory) can lead to boot or migration failure.
Check the size of the existed nvram file when qemuPrepareNVRAM, and re-create
if the existed one is unhealthy.

Signed-off-by: Hao Wang <wanghao232@xxxxxxxxxx>
---
 src/qemu/qemu_process.c | 54 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 126fabf5ef..42060bb36c 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -4376,6 +4376,48 @@ qemuProcessUpdateCPU(virQEMUDriverPtr driver,
 }


+static bool
+qemuIsNvramFileHealthy(virQEMUDriverConfigPtr cfg,
+                       virDomainLoaderDefPtr loader)
+{
+    const char *masterNvramPath;
+    off_t nvramSize;
+    off_t masterSize;
+
+    masterNvramPath = loader->templt;
+    if (!loader->templt) {
+        size_t i;
+        for (i = 0; i < cfg->nfirmwares; i++) {
+            if (STREQ(cfg->firmwares[i]->name, loader->path)) {
+                masterNvramPath = cfg->firmwares[i]->nvram;
+                break;
+            }
+        }
+    }
+
+    if (!masterNvramPath) {
+        VIR_WARN("no nvram template is found; assume the nvram file is healthy");
+        return true;
+    }
+
+    if ((nvramSize = virFileLength(loader->nvram, -1)) < 0 ||
+        (masterSize = virFileLength(masterNvramPath, -1)) < 0) {
+        virReportSystemError(errno,
+                             _("unable to get the size of '%s' or '%s'"),
+                             loader->nvram, masterNvramPath);
+        return false;
+    }
+
+    if (nvramSize != masterSize) {
+        VIR_WARN("the size(%zd) of the nvram file is not equal to that of the template %s",
+                 nvramSize, masterNvramPath);
+        return false;
+    }
+
+    return true;
+}
+
+
 static int
 qemuPrepareNVRAM(virQEMUDriverConfigPtr cfg,
                  virDomainObjPtr vm)
@@ -4388,9 +4430,19 @@ qemuPrepareNVRAM(virQEMUDriverConfigPtr cfg,
     const char *master_nvram_path;
     ssize_t r;

-    if (!loader || !loader->nvram || virFileExists(loader->nvram))
+    if (!loader || !loader->nvram)
         return 0;

+    if (virFileExists(loader->nvram)) {
+        if (qemuIsNvramFileHealthy(cfg, loader))
+            return 0;
+
+        ignore_value(virFileRemove(loader->nvram, -1, -1));
+        VIR_WARN("the nvram file %s exists but may be corrupted! "
+                 "Remove it and try to copy a new one from template.",
+                 loader->nvram);
+    }
+
     master_nvram_path = loader->templt;
     if (!loader->templt) {
         size_t i;
--
2.23.0