basic/virt: provide a nicer message is /proc/cpuinfo is not available

$ sudo systemd-run -p RootDirectory=/usr -E LD_LIBRARY_PATH=/lib/systemd/ -E SYSTEMD_LOG_LEVEL=debug /bin/systemd-detect-virt

Before
systemd-detect-virt[18498]: No virtualization found in DMI
systemd-detect-virt[18498]: No virtualization found in CPUID
systemd-detect-virt[18498]: Virtualization XEN not found, /proc/xen does not exist
systemd-detect-virt[18498]: This platform does not support /proc/device-tree
systemd-detect-virt[18498]: Failed to check for virtualization: No such file or directory

The first four lines are at debug level, so the user would only see that last
one usually, which is not very enlightening.

This now becomes:
systemd-detect-virt[21172]: No virtualization found in DMI
systemd-detect-virt[21172]: No virtualization found in CPUID
systemd-detect-virt[21172]: Virtualization XEN not found, /proc/xen does not exist
systemd-detect-virt[21172]: This platform does not support /proc/device-tree
systemd-detect-virt[21172]: /proc/cpuinfo not found, assuming no UML virtualization.
systemd-detect-virt[21172]: This platform does not support /proc/sysinfo
systemd-detect-virt[21172]: Found VM virtualization none
systemd-detect-virt[21172]: none

We do more checks, which is good too.

diff --git a/src/basic/virt.c b/src/basic/virt.c
index c4335ab909e041355950a7ff62825b6afbb37026..39b4a98d896920384bf7455ce42f836d5cc12894 100644 (file)
--- a/src/basic/virt.c
+++ b/src/basic/virt.c
@@ -282,6 +282,10 @@ static int detect_vm_uml(void) {
 
         /* Detect User-Mode Linux by reading /proc/cpuinfo */
         r = read_full_file("/proc/cpuinfo", &cpuinfo_contents, NULL);
+        if (r == -ENOENT) {
+                log_debug("/proc/cpuinfo not found, assuming no UML virtualization.");
+                return VIRTUALIZATION_NONE;
+        }
         if (r < 0)
                 return r;
 
@@ -290,7 +294,7 @@ static int detect_vm_uml(void) {
                 return VIRTUALIZATION_UML;
         }
 
-        log_debug("No virtualization found in /proc/cpuinfo.");
+        log_debug("UML virtualization not found in /proc/cpuinfo.");
         return VIRTUALIZATION_NONE;
 }
 
@@ -604,16 +608,16 @@ int running_in_userns(void) {
 }
 
 int running_in_chroot(void) {
-        int ret;
+        int r;
 
         if (getenv_bool("SYSTEMD_IGNORE_CHROOT") > 0)
                 return 0;
 
-        ret = files_same("/proc/1/root", "/", 0);
-        if (ret < 0)
-                return ret;
+        r = files_same("/proc/1/root", "/", 0);
+        if (r < 0)
+                return r;
 
-        return ret == 0;
+        return r == 0;
 }
 
 static const char *const virtualization_table[_VIRTUALIZATION_MAX] = {