code: plan9front

ref: 75d6267a5f788162d92e7a5ae126cd8b0770aa8a
dir: /sys/src/libc/9sys/postnote.c/

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#include <u.h>
#include <libc.h>

int
postnote(int group, int pid, char *note)
{
	char file[32];
	int f, r;

	switch(group) {
	case PNPROC:
		snprint(file, sizeof(file), "/proc/%lud/note", (ulong)pid);
		break;
	case PNGROUP:
		snprint(file, sizeof(file), "/proc/%lud/notepg", (ulong)pid);
		break;
	default:
		return -1;
	}

	f = open(file, OWRITE|OCEXEC);
	if(f < 0)
		return -1;

	r = strlen(note);
	if(write(f, note, r) != r) {
		close(f);
		return -1;
	}
	close(f);
	return 0;
}