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pids.c
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pids.c
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#include <stdlib.h>
#include "shm.h"
#include "params.h" // for 'dangerous'
#include "pids.h"
#include "log.h"
int find_pid_slot(pid_t mypid)
{
unsigned int i;
for_each_pidslot(i) {
if (shm->pids[i] == mypid)
return i;
}
return PIDSLOT_NOT_FOUND;
}
bool pidmap_empty(void)
{
unsigned int i;
for_each_pidslot(i) {
if (shm->pids[i] != EMPTY_PIDSLOT)
return FALSE;
}
return TRUE;
}
void dump_pid_slots(void)
{
unsigned int i;
printf("## pids:\n");
for_each_pidslot(i)
printf("## slot%d: %d\n", i, shm->pids[i]);
}
static pid_t pidmax;
int read_pid_max(void)
{
unsigned long result;
char *end, buf[32];
FILE *fp;
int rc;
fp = fopen("/proc/sys/kernel/pid_max", "r");
if (!fp) {
perror("fopen");
return -1;
}
rc = -1;
if (!fgets(buf, sizeof(buf), fp))
goto out;
result = strtoul(buf, &end, 10);
if (end == buf)
goto out;
pidmax = result;
rc = 0;
out:
fclose(fp);
return rc;
}
void pids_init(void)
{
if (read_pid_max()) {
#ifdef __x86_64__
pidmax = 4194304;
#else
pidmax = 32768;
#endif
printf("Couldn't read pid_max from proc\n");
}
printf("Using pid_max = %d\n", pidmax);
}
int pid_is_valid(pid_t pid)
{
if ((pid > pidmax) || (pid < 1)) {
output(0, "Sanity check failed! Found pid %d!\n", pid);
return FALSE;
}
return TRUE;
}
unsigned int get_pid(void)
{
unsigned int i;
pid_t pid = 0;
/* If we get called from the parent, and there are no
* children around yet, we need to not look at the pidmap. */
if (shm->running_childs == 0)
return 0;
switch (rand() % 3) {
case 0:
retry: i = rand() % shm->max_children;
pid = shm->pids[i];
if (pid == EMPTY_PIDSLOT)
goto retry;
break;
case 1: pid = 0;
break;
case 2: if (dangerous == TRUE) // We don't want root trying to kill init.
pid = 1;
break;
default:
break;
}
return pid;
}