dummyshell reads vmem/cpu usage and handles ctrl+c in a correct way

1 files changed, 134 insertions, 2 deletions

diff --git a/dummyshell.c b/dummyshell.c
index 177423a..fc7c795 100644
--- a/dummyshell.c
+++ b/dummyshell.c
@@ -4,13 +4,121 @@
 #include <termios.h>
 #include <fcntl.h>
 #include <time.h>
+#ifdef _HAS_SIGNAL
+#include <signal.h>      /* signal(...) */
+#else
+#warn "SIGNAL disabled!"
+#endif
+#if defined(_HAS_UTMP) || defined(_HAS_SYSINFO)
+#include <string.h>      /* memset */
+#endif
+#ifdef _HAS_UTMP
+#include <utmp.h>        /* utmp structure */
+#else
+#warn "UTMP disabled!"
+#endif
+#ifdef _HAS_SYSINFO
+#include "sys/types.h"   /* sysinfo structture */
+#include "sys/sysinfo.h" /* sysinfo(...) */
+#else
+#warn "SYSINFO disabled!"
+#endif
 
+/* for print_memusage() and print cpuusage() see: http://stackoverflow.com/questions/63166/how-to-determine-cpu-and-memory-consumption-from-inside-a-process */
 
+
+static const char keymsg[] = " [PRESS ANY KEY TO QUIT] ";
 static const char txtheader[] =
   "**************\n"
   "* dummyshell *\n"
   "**************\n";
 
+static volatile unsigned char doLoop = 1;
+
+
+#ifdef _HAS_UTMP
+static void print_utmp(void)
+{
+  int utmpfd = open("/var/run/utmp", O_RDONLY);
+  if (utmpfd >= 0) {
+    struct utmp ut;
+    memset(&ut, '\0', sizeof(struct utmp));
+    printf("\33[2K\ruser online...: ");
+    while (read(utmpfd, &ut, sizeof(struct utmp)) == sizeof(struct utmp)) {
+      printf("%.*s ", UT_NAMESIZE, ut.ut_user);
+    }
+    printf("\n");
+  }
+}
+#endif
+
+#ifdef _HAS_SYSINFO
+static unsigned long long lastTotalUser, lastTotalUserLow, lastTotalSys, lastTotalIdle;
+
+static void init_cpuusage(){
+  FILE* file = fopen("/proc/stat", "r");
+  if (file) {
+    fscanf(file, "cpu %llu %llu %llu %llu", &lastTotalUser, &lastTotalUserLow,
+      &lastTotalSys, &lastTotalIdle);
+    fclose(file);
+  }
+}
+
+static void print_cpuusage(){
+  double percent;
+  FILE* file;
+  unsigned long long totalUser, totalUserLow, totalSys, totalIdle, total;
+
+  file = fopen("/proc/stat", "r");
+  fscanf(file, "cpu %llu %llu %llu %llu", &totalUser, &totalUserLow,
+    &totalSys, &totalIdle);
+  fclose(file);
+
+  if (totalUser < lastTotalUser || totalUserLow < lastTotalUserLow ||
+    totalSys < lastTotalSys || totalIdle < lastTotalIdle){
+    //Overflow detection. Just skip this value.
+    percent = -1.0;
+  } else{
+    total = (totalUser - lastTotalUser) + (totalUserLow - lastTotalUserLow) +
+      (totalSys - lastTotalSys);
+    percent = total;
+    total += (totalIdle - lastTotalIdle);
+    percent /= total;
+    percent *= 100;
+  }
+
+  lastTotalUser = totalUser;
+  lastTotalUserLow = totalUserLow;
+  lastTotalSys = totalSys;
+  lastTotalIdle = totalIdle;
+
+  printf("CPU...........: %.02f%%\n", percent);
+}
+
+static void print_memusage(void)
+{
+  struct sysinfo meminfo;
+  memset(&meminfo, '\0', sizeof(struct sysinfo));
+  if (sysinfo(&meminfo) == 0) {
+    unsigned long long totalvmem = meminfo.totalram;
+    totalvmem += meminfo.totalswap;
+    totalvmem *= meminfo.mem_unit;
+    unsigned long long usedvmem = meminfo.totalram - meminfo.freeram;
+    usedvmem += meminfo.totalswap - meminfo.freeswap;
+    usedvmem *= meminfo.mem_unit;
+    printf("VMEM(used/max): %llu/%lld (Mb)\n", (usedvmem/(1024*1024)), (totalvmem/(1024*1024)));
+  }
+}
+#endif
+
+#ifdef _HAS_SIGNAL
+void SigIntHandler(int signum)
+{
+  if (signum == SIGINT) {
+    doLoop = 0;
+  }
+}
+#endif
 
 int main(int argc, char** argv)
 {
@@ -18,6 +126,12 @@ int main(int argc, char** argv)
   tv.tv_sec = 1;
   tv.tv_usec = 0;
 
+#ifdef _HAS_SIGNAL
+  signal(SIGINT, SigIntHandler);
+#endif
+#ifdef _HAS_SYSINFO
+  init_cpuusage();
+#endif
   int flags = fcntl(STDIN_FILENO, F_GETFL, 0);
   fcntl(STDIN_FILENO, F_SETFL, flags | O_NONBLOCK);
 
@@ -34,16 +148,34 @@ int main(int argc, char** argv)
   while (1) {
     cur = time(NULL);
     double diff = difftime(cur, start);
-    printf("\r( %0.fs ) [PRESS ANY KEY TO QUIT] ", diff);
+#if defined(_HAS_UTMP) || defined(_HAS_SYSINFO)
+    if ((unsigned int)diff % 60 == 0) {
+      struct tm localtime;
+      if (localtime_r(&cur, &localtime) != NULL) {
+        printf("--- %02d:%02d:%02d ---\n", localtime.tm_hour, localtime.tm_min, localtime.tm_sec);
+      }
+#ifdef _HAS_UTMP
+      print_utmp();
+#endif
+#ifdef _HAS_SYSINFO
+      print_memusage();
+      print_cpuusage();
+#endif
+    }
+#endif
+    printf("\r( %0.fs )%s", diff, keymsg);
     fflush(stdout);
     fflush(stdin);
     FD_ZERO(&fds);
     FD_SET(STDIN_FILENO, &fds);
     int ret = select(FD_SETSIZE, &fds, NULL, NULL, &tv);
-    if (ret == 0) {
+    if (doLoop == 1 && ret == 0) {
       tv.tv_sec = 1;
       tv.tv_usec = 0;
     } else {
+#ifdef _HAS_SIGNAL
+      signal(SIGINT, SIG_IGN);
+#endif
       printf("quit in 3 .. ");
       fflush(stdout);
       sleep(1);