Get PID resident memory size for MacOS, FreeBSD and Linux

getpidmemory.c

#ifdef __APPLE__
#include <libproc.h>
#endif

#include <sys/resource.h>
#include <sys/param.h>
#include <sys/user.h>
#include <sys/sysctl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

long getpidmemory(pid_t pid) {
#ifdef __APPLE__
	struct proc_taskallinfo pti;

	if (proc_pidinfo(pid, PROC_PIDTASKALLINFO, 0, &pti, sizeof(pti)) >= sizeof(pti)) {
		return (long)pti.ptinfo.pti_resident_size;
	} 
	else return -1;
#endif
	
#ifdef __FreeBSD__
	int mib[4];
	struct kinfo_proc proc;
	size_t procsize;

	mib[0] = CTL_KERN;
 	mib[1] = KERN_PROC;
	mib[2] = KERN_PROC_PID;
	mib[3] = pid;

	procsize = sizeof(struct kinfo_proc);

	if (sysctl((int*)mib, 4, &proc, &procsize, NULL, 0) >= 0) {
		return (long)proc.ki_rssize;
	} 
	else return -1;
#endif

#ifdef __GNUC__
	char *statm_path;
	long resident_size, nul;
	FILE *statm;

	sprintf (statm_path, "/proc/%d/statm", pid);
	statm = fopen (statm_path, "r");

	if (!statm) return -1;

	if (7 != fscanf(statm, "%ld %ld %ld %ld %ld %ld %ld", &nul, &resident_size, &nul, &nul, &nul, &nul, &nul)) return -1;
	else return resident_size;
#endif
}