From 48a66a7f6a23ee71bcf54da5bd0bbd69a0710582 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Thu, 31 Oct 2013 16:23:06 +0100

Subject: [PATCH] virt: move caching of virtualization check results into

 detect_vm() and detect_container()

After all, we ended up calling detect_container() more often than

detect_virtualization(), hence the former one should cache the results,

since the latter is only a wrapper around the former.

---

 src/detect-virt/detect-virt.c |   2 +-

 src/shared/virt.c             | 180 ++++++++++++++++++++----------------------

 2 files changed, 87 insertions(+), 95 deletions(-)

diff --git a/src/detect-virt/detect-virt.c b/src/detect-virt/detect-virt.c

index bd3ee45..72ff2a8 100644

--- a/src/detect-virt/detect-virt.c

+++ b/src/detect-virt/detect-virt.c

@@ -114,8 +114,8 @@ static int parse_argv(int argc, char *argv[]) {

 int main(int argc, char *argv[]) {

         const char *id = NULL;

-        int r;

         int retval = EXIT_SUCCESS;

+        int r;

         /* This is mostly intended to be used for scripts which want

          * to detect whether we are being run in a virtualized

diff --git a/src/shared/virt.c b/src/shared/virt.c

index 4f8134a..537ccda 100644

--- a/src/shared/virt.c

+++ b/src/shared/virt.c

@@ -60,6 +60,9 @@ int detect_vm(const char **id) {

                 /* http://msdn.microsoft.com/en-us/library/ff542428.aspx */

                 "Microsoft Hv\0"          "microsoft\0";

+        static __thread int cached_found = -1;

+        static __thread const char *cached_id = NULL;

+

         uint32_t eax, ecx;

         union {

                 uint32_t sig32[3];

@@ -69,6 +72,15 @@ int detect_vm(const char **id) {

         const char *j, *k;

         bool hypervisor;

         _cleanup_free_ char *hvtype = NULL;

+        const char *_id = NULL;

+

+        if (_likely_(cached_found >= 0)) {

+

+                if (id)

+                        *id = cached_id;

+

+                return cached_found;

+        }

         /* Try high-level hypervisor sysfs file first:

          *

@@ -76,10 +88,9 @@ int detect_vm(const char **id) {

         r = read_one_line_file("/sys/hypervisor/type", &hvtype);

         if (r >= 0) {

                 if (streq(hvtype, "xen")) {

-                        if (id)

-                                *id = "xen";

-

-                        return 1;

+                        _id = "xen";

+                        r = 1;

+                        goto finish;

                 }

         } else if (r != -ENOENT)

                 return r;

@@ -125,17 +136,14 @@ int detect_vm(const char **id) {

                 NULSTR_FOREACH_PAIR(j, k, cpuid_vendor_table)

                         if (streq(sig.text, j)) {

-

-                                if (id)

-                                        *id = k;

-

-                                return 1;

+                                _id = k;

+                                r = 1;

+                                goto finish;

                         }

         }

         for (i = 0; i < ELEMENTSOF(dmi_vendors); i++) {

                 _cleanup_free_ char *s = NULL;

-                const char *found = NULL;

                 r = read_one_line_file(dmi_vendors[i], &s);

                 if (r < 0) {

@@ -146,22 +154,17 @@ int detect_vm(const char **id) {

                 }

                 NULSTR_FOREACH_PAIR(j, k, dmi_vendor_table)

-                        if (startswith(s, j))

-                                found = k;

-

-                if (found) {

-                        if (id)

-                                *id = found;

-

-                        return 1;

-                }

+                        if (startswith(s, j)) {

+                                _id = k;

+                                r = 1;

+                                goto finish;

+                        }

         }

         if (hypervisor || hvtype) {

-                if (id)

-                        *id = "other";

-

-                return 1;

+                _id = "other";

+                r = 1;

+                goto finish;

         }

 #endif

@@ -171,17 +174,40 @@ int detect_vm(const char **id) {

         if (r < 0)

                 return r;

         if (strstr(cpuinfo_contents, "\nvendor_id\t: User Mode Linux\n")) {

-                *id = "uml";

-                return 1;

+                _id = "uml";

+                r = 1;

+                goto finish;

         }

-        return 0;

+        r = 0;

+

+finish:

+        cached_found = r;

+

+        cached_id = _id;

+        if (id)

+                *id = _id;

+

+        return r;

 }

 int detect_container(const char **id) {

+

+        static __thread int cached_found = -1;

+        static __thread const char *cached_id = NULL;

+

         _cleanup_free_ char *e = NULL;

+        const char *_id = NULL;

         int r;

+        if (_likely_(cached_found >= 0)) {

+

+                if (id)

+                        *id = cached_id;

+

+                return cached_found;

+        }

+

         /* Unfortunately many of these operations require root access

          * in one way or another */

@@ -189,95 +215,61 @@ int detect_container(const char **id) {

         if (r < 0)

                 return r;

         if (r > 0) {

-

-                if (id)

-                        *id = "chroot";

-

-                return 1;

+                _id = "chroot";

+                goto finish;

         }

         /* /proc/vz exists in container and outside of the container,

          * /proc/bc only outside of the container. */

         if (access("/proc/vz", F_OK) >= 0 &&

             access("/proc/bc", F_OK) < 0) {

-

-                if (id)

-                        *id = "openvz";

-

-                return 1;

+                _id = "openvz";

+                r = 1;

+                goto finish;

         }

         r = getenv_for_pid(1, "container", &e);

-        if (r <= 0)

+        if (r < 0)

                 return r;

+        if (r == 0)

+                goto finish;

         /* We only recognize a selected few here, since we want to

          * enforce a redacted namespace */

-        if (streq(e, "lxc")) {

-                if (id)

-                        *id = "lxc";

-        } else if (streq(e, "lxc-libvirt")) {

-                if (id)

-                        *id = "lxc-libvirt";

-        } else if (streq(e, "systemd-nspawn")) {

-                if (id)

-                        *id = "systemd-nspawn";

-        } else {

-                if (id)

-                        *id = "other";

-        }

+        if (streq(e, "lxc"))

+                _id ="lxc";

+        else if (streq(e, "lxc-libvirt"))

+                _id = "lxc-libvirt";

+        else if (streq(e, "systemd-nspawn"))

+                _id = "systemd-nspawn";

+        else

+                _id = "other";

+

+finish:

+        cached_found = r;

+

+        cached_id = _id;

+        if (id)

+                *id = _id;

         return r;

 }

 /* Returns a short identifier for the various VM/container implementations */

 Virtualization detect_virtualization(const char **id) {

-

-        static __thread Virtualization cached_virt = _VIRTUALIZATION_INVALID;

-        static __thread const char *cached_id = NULL;

-

-        const char *_id;

         int r;

-        Virtualization v;

-

-        if (_likely_(cached_virt >= 0)) {

-

-                if (id && cached_virt > 0)

-                        *id = cached_id;

-                return cached_virt;

-        }

-

-        r = detect_container(&_id);

-        if (r < 0) {

-                v = r;

-                goto finish;

-        } else if (r > 0) {

-                v = VIRTUALIZATION_CONTAINER;

-                goto finish;

-        }

-

-        r = detect_vm(&_id);

-        if (r < 0) {

-                v = r;

-                goto finish;

-        } else if (r > 0) {

-                v = VIRTUALIZATION_VM;

-                goto finish;

-        }

-

-        v = VIRTUALIZATION_NONE;

-

-finish:

-        if (v > 0) {

-                cached_id = _id;

-

-                if (id)

-                        *id = _id;

-        }

+        r = detect_container(id);

+        if (r < 0)

+                return r;

+        if (r > 0)

+                return VIRTUALIZATION_CONTAINER;

-        if (v >= 0)

-                cached_virt = v;

+        r = detect_vm(id);

+        if (r < 0)

+                return r;

+        if (r > 0)

+                return VIRTUALIZATION_VM;

-        return v;

+        return VIRTUALIZATION_NONE;

 }