Nicht lesen/proc/[pid]/stat in Unix zeigt Segmentierung Fehler

Question

Ich versuche,/proc/[pid]/stat in Ubuntu UNIX.Aber die Ausgabe kommt als Segmentierung Fehler. Ich gebe pid an get_usage() weiter.

#include <stdlib.h> 
#include <sys/types.h> 
#include <stdio.h> 
#include <string.h> 
#include <unistd.h> 

struct pstat { 
long unsigned int utime_ticks; 
long int cutime_ticks; 
long unsigned int stime_ticks; 
long int cstime_ticks; 
long unsigned int vsize; // virtual memory size in bytes 
long unsigned int rss; //Resident Set Size in bytes 

long unsigned int cpu_total_time; 
}; 

void main(){ 
    int pid_t; 
    struct pstat *result; 
    pid_t = getpid(); 
    get_usage(pid_t,result); 
    } 
int get_usage(const pid_t pid, struct pstat* result) { 

printf("%d",pid); 
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); 
printf("%s",stat_filepath); 

FILE *fpstat = fopen(stat_filepath, "r"); 

if (fpstat == NULL) { 
    perror("FOPEN ERROR "); 
    return -1; 
} 

FILE *fstat = fopen("/proc/stat", "r"); 
if (fstat == NULL) { 
    perror("FOPEN ERROR "); 
    fclose(fstat); 
    return -1; 
} 


//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) { 
    fclose(fpstat); 
    return -1; 
} 
fclose(fpstat); 
result->rss = rss * getpagesize(); 

//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) { 
    fclose(fstat); 
    return -1; 
} 

fclose(fstat); 

for(int i=0; i < 10;i++) 
    result->cpu_total_time += cpu_time[i]; 

return 0; 
    } 

Ausgang:

Segmentation fault(core dumped) 

-Code Quelle: https://github.com/fho/code_snippets/blob/master/c/getusage.c

Answer 1

In get_usage() Sie bzero() fordern und dann zu fscanf() versucht, eine Variable mit result genannt, die Speicher nie zugeordnet wurde.

Sie müssen die Ergebnisvariable in Ihrer main() Funktion struct stat result und &result an die get_usage() Funktion übergeben machen.