fixed formatting

Author: Fabian Holler

c/getusage.c

@@ -1,4 +1,4 @@
-//Last modified: 17/10/11 18:52:02(CEST) by Fabian Holler
+//Last modified: 25/02/12 17:50:17(CET) by Fabian Holler
 #include <stdlib.h> 
 #include <sys/types.h>
 #include <stdio.h>
@@ -24,43 +24,51 @@ int get_usage(const pid_t pid, struct pstat* result){
     //convert  pid to string
     char pid_s[20];
     snprintf(pid_s, sizeof(pid_s), "%d", pid);
-    char stat_filepath[30] = "/proc/";
-    strncat(stat_filepath, pid_s, sizeof(stat_filepath) - strlen(stat_filepath) -1);
-    strncat(stat_filepath, "/stat", sizeof(stat_filepath) - strlen(stat_filepath) -1);
+    char stat_filepath[30] = "/proc/"; strncat(stat_filepath, pid_s,
+            sizeof(stat_filepath) - strlen(stat_filepath) -1);
+    strncat(stat_filepath, "/stat", sizeof(stat_filepath) -
+            strlen(stat_filepath) -1);
 
-    //open /proc/pid/stat
+    //Open /proc/stat and /proc/$pid/stat fds successive(dont want that cpu
+    //ticks increases too much during measurements)
     FILE *fpstat = fopen(stat_filepath, "r");
     if(fpstat == NULL){
-        printf("FOPEN ERROR pid stat %s:\n", stat_filepath);
+        perror("FOPEN ERROR ");
         return -1;
     }
 
-    //open /proc/stat
     FILE *fstat = fopen("/proc/stat", "r");
     if(fstat == NULL){
-        printf("FOPEN ERROR");
+        perror("FOPEN ERROR ");
         fclose(fstat);
         return -1;
     }
-    bzero(result, sizeof(struct pstat));
 
     //read values from /proc/pid/stat
+    bzero(result, sizeof(struct pstat));
     long int rss;
-    if(fscanf(fpstat, "%*d %*s %*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %lu %lu %ld %ld %*d %*d %*d %*d %*u %lu %ld", &result->utime_ticks, &result->stime_ticks, &result->cutime_ticks, &result->cstime_ticks, &result->vsize, &rss) == EOF){
+    if(fscanf(fpstat, "%*d %*s %*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %lu"
+                "%lu %ld %ld %*d %*d %*d %*d %*u %lu %ld",
+                &result->utime_ticks, &result->stime_ticks,
+                &result->cutime_ticks, &result->cstime_ticks, &result->vsize,
+                &rss) == EOF) {
         fclose(fpstat);
-        fclose(fstat);
         return -1;
     }
     fclose(fpstat);
     result->rss = rss * getpagesize();
 
-    //read+calc cpu total time from /proc/stat, on linux 2.6.35-23 x86_64 the cpu row has 10values could differ on different architectures :/
+    //read+calc cpu total time from /proc/stat
     long unsigned int cpu_time[10];
     bzero(cpu_time, sizeof(cpu_time));
-    if(fscanf(fstat, "%*s %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu", &cpu_time[0], &cpu_time[1], &cpu_time[2], &cpu_time[3], &cpu_time[4], &cpu_time[5], &cpu_time[6], &cpu_time[7], &cpu_time[8], &cpu_time[9]) == EOF){
+    if(fscanf(fstat, "%*s %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
+                &cpu_time[0], &cpu_time[1], &cpu_time[2], &cpu_time[3],
+                &cpu_time[4], &cpu_time[5], &cpu_time[6], &cpu_time[7],
+                &cpu_time[8], &cpu_time[9]) == EOF) {
         fclose(fstat);
         return -1;
     }
+
     fclose(fstat);
 
     for(int i=0; i < 10;i++){
@@ -75,8 +83,17 @@ int get_usage(const pid_t pid, struct pstat* result){
 * cur_usage, last_usage: both last measured get_usage() results
 * ucpu_usage, scpu_usage: result parameters: user and sys cpu usage in %
 */
-void calc_cpu_usage(const struct pstat* cur_usage, const struct pstat* last_usage, float* ucpu_usage, float* scpu_usage){
-    *ucpu_usage = 100 * ((((cur_usage->utime_ticks + cur_usage->cutime_ticks) - (last_usage->utime_ticks + last_usage->cutime_ticks))) / (float)((cur_usage->cpu_total_time - last_usage->cpu_total_time)));
-    *scpu_usage = 100 * ((((cur_usage->stime_ticks + cur_usage->cstime_ticks) - (last_usage->stime_ticks + last_usage->cstime_ticks))) / (float)((cur_usage->cpu_total_time - last_usage->cpu_total_time)));
+void calc_cpu_usage(const struct pstat* cur_usage, const struct pstat*
+                    last_usage, double* ucpu_usage, double* scpu_usage){
+    const long unsigned int total_time_diff = cur_usage->cpu_total_time -
+                                              last_usage->cpu_total_time;
+
+    *ucpu_usage = 100 * (((cur_usage->utime_ticks + cur_usage->cutime_ticks)
+                    - (last_usage->utime_ticks + last_usage->cutime_ticks))
+                    / (double) total_time_diff);
+
+    *scpu_usage = 100 * ((((cur_usage->stime_ticks + cur_usage->cstime_ticks)
+                    - (last_usage->stime_ticks + last_usage->cstime_ticks))) /
+                    (double) total_time_diff);
 }