通过读取 proc/ 打印过程信息<pid> /地位

Question

I am trying to read processes info from proc//status and I intend to first check whether the process is running or not then if its running I'll display its name for that I store the line which starts with "Name:" in a string called prev then if the process is running I should print its name through this prev but what happens is that prev is overwritten by another value I think.Here's my code: `

char path[40], line[100], *p;
FILE* statusf;

snprintf(path, 40, "/proc/%ld/status", tgid);

statusf = fopen(path, "r");
if(!statusf)
    return;

char * prev;

while(fgets(line, 100, statusf)) {
if (strncmp(line,"Name:", 5) == 0){
   prev = line;
   continue;
}

    if(strncmp(line, "State:", 6) == 0){
    // Ignore "State:" and whitespace
    p = line + 7;
    while(isspace(*p)) ++p;
if(p[strlen(p)-1] == '\n'){
    p[strlen(p)-1] = '\0';
}
}

if (!strcmp(p,"R (running)")){
    prev = prev + 6;
    while(isspace(*prev)) ++prev;
if(prev[strlen(prev)-1] == '\n'){
    prev[strlen(prev)-1] = '\0';
}

printf("%s",prev);
}

break;

}
fclose(statusf);

} `

Answer 1

char path[40], line[100], *p;
char * prev;

while(fgets(line, 100, statusf)) {
if (strncmp(line,"Name:", 5) == 0){
   prev = line;
   continue;
}

prev will now point to line. So when the content of line changes, the changes will appear to happen in prev aswell, since prev points to the same memory as line