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htop/linux/SystemdMeter.c

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/*
htop - SystemdMeter.c
(C) 2020 Christian Göttsche
Released under the GNU GPLv2, see the COPYING file
in the source distribution for its full text.
*/
#include "SystemdMeter.h"
#include <dlfcn.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "CRT.h"
#include "XUtils.h"
#define INVALID_VALUE ((unsigned int)-1)
typedef void sd_bus;
typedef void sd_bus_error;
static int (*sym_sd_bus_open_system)(sd_bus**);
static int (*sym_sd_bus_get_property_string)(sd_bus*, const char*, const char*, const char*, const char*, sd_bus_error*, char**);
static int (*sym_sd_bus_get_property_trivial)(sd_bus*, const char*, const char*, const char*, const char*, sd_bus_error*, char, void*);
static sd_bus* (*sym_sd_bus_unref)(sd_bus*);
static char* systemState = NULL;
static unsigned int nFailedUnits = INVALID_VALUE;
static unsigned int nInstalledJobs = INVALID_VALUE;
static unsigned int nNames = INVALID_VALUE;
static unsigned int nJobs = INVALID_VALUE;
static void* dlopenHandle = NULL;
static sd_bus* bus = NULL;
static void SystemdMeter_done(ATTR_UNUSED Meter* this) {
free(systemState);
systemState = NULL;
if (bus && dlopenHandle) {
sym_sd_bus_unref(bus);
}
bus = NULL;
if (dlopenHandle) {
dlclose(dlopenHandle);
dlopenHandle = NULL;
}
}
static int updateViaLib(void) {
if (!dlopenHandle) {
dlopenHandle = dlopen("libsystemd.so.0", RTLD_LAZY);
if (!dlopenHandle)
goto dlfailure;
/* Clear any errors */
dlerror();
#define resolve(symbolname) do { \
*(void **)(&sym_##symbolname) = dlsym(dlopenHandle, #symbolname); \
if (!sym_##symbolname || dlerror() != NULL) \
goto dlfailure; \
} while(0)
resolve(sd_bus_open_system);
resolve(sd_bus_get_property_string);
resolve(sd_bus_get_property_trivial);
resolve(sd_bus_unref);
#undef resolve
}
int r;
/* Connect to the system bus */
if (!bus) {
r = sym_sd_bus_open_system(&bus);
if (r < 0)
goto busfailure;
}
static const char* const busServiceName = "org.freedesktop.systemd1";
static const char* const busObjectPath = "/org/freedesktop/systemd1";
static const char* const busInterfaceName = "org.freedesktop.systemd1.Manager";
r = sym_sd_bus_get_property_string(bus,
busServiceName, /* service to contact */
busObjectPath, /* object path */
busInterfaceName, /* interface name */
"SystemState", /* property name */
NULL, /* object to return error in */
&systemState);
if (r < 0)
goto busfailure;
r = sym_sd_bus_get_property_trivial(bus,
busServiceName, /* service to contact */
busObjectPath, /* object path */
busInterfaceName, /* interface name */
"NFailedUnits", /* property name */
NULL, /* object to return error in */
'u', /* property type */
&nFailedUnits);
if (r < 0)
goto busfailure;
r = sym_sd_bus_get_property_trivial(bus,
busServiceName, /* service to contact */
busObjectPath, /* object path */
busInterfaceName, /* interface name */
"NInstalledJobs", /* property name */
NULL, /* object to return error in */
'u', /* property type */
&nInstalledJobs);
if (r < 0)
goto busfailure;
r = sym_sd_bus_get_property_trivial(bus,
busServiceName, /* service to contact */
busObjectPath, /* object path */
busInterfaceName, /* interface name */
"NNames", /* property name */
NULL, /* object to return error in */
'u', /* property type */
&nNames);
if (r < 0)
goto busfailure;
r = sym_sd_bus_get_property_trivial(bus,
busServiceName, /* service to contact */
busObjectPath, /* object path */
busInterfaceName, /* interface name */
"NJobs", /* property name */
NULL, /* object to return error in */
'u', /* property type */
&nJobs);
if (r < 0)
goto busfailure;
/* success */
return 0;
busfailure:
sym_sd_bus_unref(bus);
bus = NULL;
return -2;
dlfailure:
if (dlopenHandle) {
dlclose(dlopenHandle);
dlopenHandle = NULL;
}
return -1;
}
static void updateViaExec(void) {
int fdpair[2];
if (pipe(fdpair) < 0)
return;
pid_t child = fork();
if (child < 0) {
close(fdpair[1]);
close(fdpair[0]);
return;
}
if (child == 0) {
close(fdpair[0]);
dup2(fdpair[1], STDOUT_FILENO);
close(fdpair[1]);
int fdnull = open("/dev/null", O_WRONLY);
if (fdnull < 0)
exit(1);
dup2(fdnull, STDERR_FILENO);
close(fdnull);
execl("/bin/systemctl",
"/bin/systemctl",
"show",
"--property=SystemState",
"--property=NFailedUnits",
"--property=NNames",
"--property=NJobs",
"--property=NInstalledJobs",
NULL);
exit(127);
}
close(fdpair[1]);
int wstatus;
if (waitpid(child, &wstatus, 0) < 0 || !WIFEXITED(wstatus) || WEXITSTATUS(wstatus) != 0) {
close(fdpair[0]);
return;
}
FILE* commandOutput = fdopen(fdpair[0], "r");
if (!commandOutput) {
close(fdpair[0]);
return;
}
char lineBuffer[128];
while (fgets(lineBuffer, sizeof(lineBuffer), commandOutput)) {
if (String_startsWith(lineBuffer, "SystemState=")) {
char* newline = strchr(lineBuffer + strlen("SystemState="), '\n');
if (newline)
*newline = '\0';
systemState = xStrdup(lineBuffer + strlen("SystemState="));
} else if (String_startsWith(lineBuffer, "NFailedUnits=")) {
nFailedUnits = strtoul(lineBuffer + strlen("NFailedUnits="), NULL, 10);
} else if (String_startsWith(lineBuffer, "NNames=")) {
nNames = strtoul(lineBuffer + strlen("NNames="), NULL, 10);
} else if (String_startsWith(lineBuffer, "NJobs=")) {
nJobs = strtoul(lineBuffer + strlen("NJobs="), NULL, 10);
} else if (String_startsWith(lineBuffer, "NInstalledJobs=")) {
nInstalledJobs = strtoul(lineBuffer + strlen("NInstalledJobs="), NULL, 10);
}
}
fclose(commandOutput);
}
static void SystemdMeter_updateValues(ATTR_UNUSED Meter* this, char* buffer, int size) {
free(systemState);
systemState = NULL;
nFailedUnits = nInstalledJobs = nNames = nJobs = INVALID_VALUE;
if (updateViaLib() < 0)
updateViaExec();
xSnprintf(buffer, size, "%s", systemState ? systemState : "???");
}
static int zeroDigitColor(unsigned int value) {
switch (value) {
case 0:
return CRT_colors[METER_VALUE];
case INVALID_VALUE:
return CRT_colors[METER_VALUE_ERROR];
default:
return CRT_colors[METER_VALUE_NOTICE];
}
}
static int valueDigitColor(unsigned int value) {
switch (value) {
case 0:
return CRT_colors[METER_VALUE_NOTICE];
case INVALID_VALUE:
return CRT_colors[METER_VALUE_ERROR];
default:
return CRT_colors[METER_VALUE];
}
}
static void SystemdMeter_display(ATTR_UNUSED const Object* cast, RichString* out) {
char buffer[16];
int color = (systemState && 0 == strcmp(systemState, "running")) ? METER_VALUE_OK : METER_VALUE_ERROR;
RichString_write(out, CRT_colors[color], systemState ? systemState : "???");
RichString_append(out, CRT_colors[METER_TEXT], " (");
if (nFailedUnits == INVALID_VALUE) {
buffer[0] = '?';
buffer[1] = '\0';
} else {
xSnprintf(buffer, sizeof(buffer), "%u", nFailedUnits);
}
RichString_append(out, zeroDigitColor(nFailedUnits), buffer);
RichString_append(out, CRT_colors[METER_TEXT], "/");
if (nNames == INVALID_VALUE) {
buffer[0] = '?';
buffer[1] = '\0';
} else {
xSnprintf(buffer, sizeof(buffer), "%u", nNames);
}
RichString_append(out, valueDigitColor(nNames), buffer);
RichString_append(out, CRT_colors[METER_TEXT], " failed) (");
if (nJobs == INVALID_VALUE) {
buffer[0] = '?';
buffer[1] = '\0';
} else {
xSnprintf(buffer, sizeof(buffer), "%u", nJobs);
}
RichString_append(out, zeroDigitColor(nJobs), buffer);
RichString_append(out, CRT_colors[METER_TEXT], "/");
if (nInstalledJobs == INVALID_VALUE) {
buffer[0] = '?';
buffer[1] = '\0';
} else {
xSnprintf(buffer, sizeof(buffer), "%u", nInstalledJobs);
}
RichString_append(out, valueDigitColor(nInstalledJobs), buffer);
RichString_append(out, CRT_colors[METER_TEXT], " jobs)");
}
static const int SystemdMeter_attributes[] = {
METER_VALUE
};
const MeterClass SystemdMeter_class = {
.super = {
.extends = Class(Meter),
.delete = Meter_delete,
.display = SystemdMeter_display
},
.updateValues = SystemdMeter_updateValues,
.done = SystemdMeter_done,
.defaultMode = TEXT_METERMODE,
.maxItems = 0,
.total = 100.0,
.attributes = SystemdMeter_attributes,
.name = "Systemd",
.uiName = "Systemd state",
.description = "Systemd system state and unit overview",
.caption = "Systemd: ",
};
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