added sleep, some error checking and details to README.md

README.md

@@ -38,6 +38,8 @@ You must provide the temperature at which you wish to step down the maximum freq
 
 `homemade_speedstep <max temp> <min temp>`
 
+**Important**: max temp and min temp must be passed as 5 digit integers, like so: 82ºC = 82000
+
 ---
 **Recomendation**: add a service to your init script that runs this program at startup in the background so you don't need to keep a terminal emulator open running it.
 

src/homemade_speedstep.c

@@ -1,6 +1,8 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 
+#define POLLING_TIME 1
 #define CURGOV "/sys/devices/system/cpu/cpufreq/policy0/scaling_governor"
 #define FREQS "/sys/devices/system/cpu/cpufreq/policy0/scaling_available_frequencies"
 #define MAXSPDPATH "/sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq"
@@ -113,9 +115,15 @@ int main(int argc, char** argv){
     fprintf(stderr, "       see homemade_speedstep --help\n");
     return 1;
   }
-  /* set maxtemp and mintemp TODO: check for integer and difference */
+  /* set maxtemp and mintemp TODO: check for integer */
   const int maxtemp = stringtoint(argv[1], stringlength(argv[1]));
   const int mintemp = stringtoint(argv[2], stringlength(argv[2]));
+  /* check that the values are, at the very least, different
+     and that max is higher than min */
+  if (maxtemp <= mintemp){
+    fprintf(stderr, "error: maxtemp must be higher than mintemp\n");
+    return 2;
+  }
   /* try to open scaling_current_governor, exit on fail */
   FILE* govfile = fopen(CURGOV, "r");
   if (govfile == NULL){
@@ -124,7 +132,7 @@ int main(int argc, char** argv){
     fprintf(stderr, "       and the userspace governor in your kernel\n");
     fprintf(stderr, "       also check that you're running this program\n");
     fprintf(stderr, "       as root\n");
-    return 2;
+    return 3;
   }
   /* assign content of govfile to a temporary char array */
   char* gov = malloc(sizeof(char) * 20);
@@ -135,7 +143,7 @@ int main(int argc, char** argv){
     /* free memory and close file */
     free(gov);
     fclose(govfile);
-    return 3;
+    return 4;
   }
   /* free memory and close file */
   free(gov);
@@ -147,7 +155,7 @@ int main(int argc, char** argv){
     fprintf(stderr, "       check that you have support for cpufreq\n");
     fprintf(stderr, "       in your kernel and that the program is\n");
     fprintf(stderr, "       running as root\n");
-    return 4;
+    return 5;
   }
   /* assign content of freqsfile to a temporary char array */
   char* freqsfilec = malloc(sizeof(char) * 200);
@@ -170,7 +178,7 @@ int main(int argc, char** argv){
     fprintf(stderr, "       check that you have support for cpufreq\n");
     fprintf(stderr, "       in your kernel and that the program is\n");
     fprintf(stderr, "       running as root\n");
-    return 5;
+    return 6;
   }
   /* assign content of curmaxfile to a temporary char array */
   char *curmaxfreq = malloc(sizeof(char) * 20);
@@ -193,7 +201,7 @@ int main(int argc, char** argv){
     fprintf(stderr, "       check that you have support for cpufreq\n");
     fprintf(stderr, "       in your kernel and that the program is\n");
     fprintf(stderr, "       running as root\n");
-    return 6;
+    return 7;
   }
   FILE* curtempfile;
   /* from here onwards an infinite while loop should start */
@@ -201,22 +209,39 @@ int main(int argc, char** argv){
     char* temperature = malloc(sizeof(char) * 8);
     getfilec(curtempfile, temperature);
     newlinetonullbyte(temperature);
+    /* check if current temp is higher than max and step down */
     if (stringtoint(temperature, stringlength(temperature)) >= maxtemp
         && curstep < stepc - 1){
       curstep++;
       curmaxfile = fopen(MAXSPDPATH, "w");
+      if (curmaxfile == NULL){
+        fprintf(stderr, "error: couldn't open scaling_maximum_frequency\n");
+        fprintf(stderr, "       check that you have support for cpufreq\n");
+        fprintf(stderr, "       in your kernel and that the program is\n");
+        fprintf(stderr, "       running as root\n");
+        return 6;
+      }
       fprintf(curmaxfile, "%s\n", steps[curstep]);
       fclose(curmaxfile);
     }
+    /* check if current temp is lower than min and step down */
     if (stringtoint(temperature, stringlength(temperature)) <= mintemp
         && curstep > 0){
       curstep--;
       curmaxfile = fopen(MAXSPDPATH, "w");
+      if (curmaxfile == NULL){
+        fprintf(stderr, "error: couldn't open scaling_maximum_frequency\n");
+        fprintf(stderr, "       check that you have support for cpufreq\n");
+        fprintf(stderr, "       in your kernel and that the program is\n");
+        fprintf(stderr, "       running as root\n");
+        return 6;
+      }
       fprintf(curmaxfile, "%s\n", steps[curstep]);
       fclose(curmaxfile);
     }
     free(temperature);
     fclose(curtempfile);
+    sleep(POLLING_TIME);
   }
   /* cleanup for graceful exit */
   free(steps);