/var/lib/pcp/testsuite/src/drain-server.c is in pcp-testsuite 3.10.8build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127  | /*
 * Copyright (c) 1997-2001 Silicon Graphics, Inc.  All Rights Reserved.
 * Copyright (c) 2011 Ken McDonell.  All Rights Reserved.
 *
 * Drain server ...
 *	accepts a connection and then reads until end of input
 *
 * Based on pdu-server.c
 */
#include <pcp/pmapi.h>
#include <pcp/impl.h>
int
main(int argc, char *argv[])
{
    int		fd;
    int		port = 1214;
		    /* default port assigned to kazaa what ever that is! */
    int		hang = 0;
    int		i, sts;
    int		c;
    int		newfd;
    struct sockaddr_in	myAddr;
    struct linger	noLinger = {1, 0};
    char	*endnum;
    int		errflag = 0;
    __pmSetProgname(argv[0]);
    while ((c = getopt(argc, argv, "D:hp:?")) != EOF) {
	switch (c) {
	case 'D':	/* debug flag */
	    sts = __pmParseDebug(optarg);
	    if (sts < 0) {
		fprintf(stderr, "%s: unrecognized debug flag specification (%s)\n",
		    pmProgname, optarg);
		errflag++;
	    }
	    else
		pmDebug |= sts;
	    break;
	case 'h':	/* hang after accept */
	    hang = 1;
	    break;
	case 'p':
	    port = (int)strtol(optarg, &endnum, 10);
	    if (*endnum != '\0') {
		fprintf(stderr, "%s: port argument must be a numeric internet port number\n", pmProgname);
		exit(1);
	    }
	    break;
	case '?':
	default:
	    errflag++;
	    break;
	}
    }
    if (errflag || optind != argc) {
	fprintf(stderr, "Usage: %s [-D n] [-h] [-p port]\n", pmProgname);
	exit(1);
    }
    fd = socket(AF_INET, SOCK_STREAM, 0);
    if (fd < 0) {
	perror("socket");
	exit(1);
    }
    if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, (char *) &i,
		   sizeof(i)) < 0) {
	perror("setsockopt(nodelay)");
	exit(1);
    }
    /* Don't linger on close */
    if (setsockopt(fd, SOL_SOCKET, SO_LINGER, (char *) &noLinger, sizeof(noLinger)) < 0) {
	perror("setsockopt(nolinger)");
	exit(1);
    }
    memset(&myAddr, 0, sizeof(myAddr));
    myAddr.sin_family = AF_INET;
    myAddr.sin_addr.s_addr = htonl(INADDR_ANY);
    myAddr.sin_port = htons(port);
    sts = bind(fd, (struct sockaddr*)&myAddr, sizeof(myAddr));
    if (sts < 0) {
	fprintf(stderr, "bind(%d): %s\n", port, strerror(errno));
	exit(1);
    }
    sts = listen(fd, 5);	/* Max. of 5 pending connection requests */
    if (sts == -1) {
	perror("listen");
	exit(1);
    }
    newfd = accept(fd, (struct sockaddr *)0, 0);
    if (newfd < 0) {
	fprintf(stderr, "%s: accept: %s\n", pmProgname, strerror(errno));
	exit(1);
    }
    if (hang) {
	/* wait for a signal ... */
	pause();
	exit(0);
    }
    /* drain input */
    while ((sts = read(newfd, &c, 1)) == 1)
	;
    
    if (sts < 0) {
	/*
	 * ECONNRESET is expected when client exits w/out closing
	 * socket.
	 */
	if (errno != ECONNRESET)
	    fprintf(stderr, "%s: read error: %s\n", pmProgname, pmErrStr(-errno));
    }
    exit(0);
}
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