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virt: move caching of virtualization check results into detect_vm() and detect_container()

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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.
This commit is contained in:
Lennart Poettering 2013-10-31 16:23:06 +01:00
parent c9197a76ae
commit 0fb533a533
2 changed files with 87 additions and 95 deletions
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2
src/detect-virt/detect-virt.c
View file

@ -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

180
src/shared/virt.c
View file

@ -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)) {
r = detect_container(id);
if (r < 0)
return r;
if (r > 0)
return VIRTUALIZATION_CONTAINER;
if (id && cached_virt > 0)
*id = cached_id;
r = detect_vm(id);
if (r < 0)
return r;
if (r > 0)
return VIRTUALIZATION_VM;
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;
}
if (v >= 0)
cached_virt = v;
return v;
return VIRTUALIZATION_NONE;
}