/*
 * $Id: diskd.cc,v 1.8 2007/08/16 23:32:28 hno Exp $
 *
 * DEBUG: section --    External DISKD process implementation.
 * AUTHOR: Harvest Derived
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; see the CREDITS file for full details.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

#include "config.h"
#include "squid.h"

#include <sys/ipc.h>
#include <sys/msg.h>
#include <sys/shm.h>

#include "DiskIO/DiskDaemon/diomsg.h"

void
xassert(const char *msg, const char *file, int line)
{
    fprintf(stderr,"assertion failed: %s:%d: \"%s\"\n", file, line, msg);

    abort();
}

const int diomsg::msg_snd_rcv_sz = sizeof(diomsg) - sizeof(mtyp_t);
#define DEBUG(LEVEL) if ((LEVEL) <= DebugLevel)

typedef struct _file_state file_state;

struct _file_state {
    void *key;
    file_state *next;
    int id;
    int fd;
    off_t offset;
};

static hash_table *hash = NULL;
static pid_t mypid;
static char *shmbuf;
static int DebugLevel = 0;

static int
do_open(diomsg * r, int len, const char *buf)
{
    int fd;
    file_state *fs;
    /*
     * note r->offset holds open() flags
     */
    fd = open(buf, r->offset, 0600);

    if (fd < 0) {
        DEBUG(1) {
            fprintf(stderr, "%d %s: ", (int) mypid, buf);
            perror("open");
        }

        return -errno;
    }

    fs = (file_state *)xcalloc(1, sizeof(*fs));
    fs->id = r->id;
    fs->key = &fs->id;		/* gack */
    fs->fd = fd;
    hash_join(hash, (hash_link *) fs);
    DEBUG(2)
    fprintf(stderr, "%d OPEN  id %d, FD %d, fs %p\n",
            (int) mypid,
            fs->id,
            fs->fd,
            fs);
    return fd;
}

static int
do_close(diomsg * r, int len)
{
    int fd;
    file_state *fs;
    fs = (file_state *) hash_lookup(hash, &r->id);

    if (NULL == fs) {
        errno = EBADF;
        DEBUG(1) {
            fprintf(stderr, "%d CLOSE id %d: ", (int) mypid, r->id);
            perror("do_close");
        }

        return -errno;
    }

    fd = fs->fd;
    hash_remove_link(hash, (hash_link *) fs);
    DEBUG(2)
    fprintf(stderr, "%d CLOSE id %d, FD %d, fs %p\n",
            (int) mypid,
            r->id,
            fs->fd,
            fs);
    xfree(fs);
    return close(fd);
}

static int
do_read(diomsg * r, int len, char *buf)
{
    int x;
    int readlen = r->size;
    file_state *fs;
    fs = (file_state *) hash_lookup(hash, &r->id);

    if (NULL == fs) {
        errno = EBADF;
        DEBUG(1) {
            fprintf(stderr, "%d READ  id %d: ", (int) mypid, r->id);
            perror("do_read");
        }

        return -errno;
    }

    if (r->offset > -1 && r->offset != fs->offset) {
        DEBUG(2)
        fprintf(stderr, "seeking to %"PRId64"\n", (int64_t)r->offset);

        if (lseek(fs->fd, r->offset, SEEK_SET) < 0) {
            DEBUG(1) {
                fprintf(stderr, "%d FD %d, offset %"PRId64": ", (int) mypid, fs->fd, (int64_t)r->offset);
                perror("lseek");
            }
        }
    }

    x = read(fs->fd, buf, readlen);
    DEBUG(2)
    fprintf(stderr, "%d READ %d,%d,%"PRId64" ret %d\n", (int) mypid,
            fs->fd, readlen, (int64_t)r->offset, x);

    if (x < 0) {
        DEBUG(1) {
            fprintf(stderr, "%d FD %d: ", (int) mypid, fs->fd);
            perror("read");
        }

        return -errno;
    }

    fs->offset = r->offset + x;
    return x;
}

static int
do_write(diomsg * r, int len, const char *buf)
{
    int wrtlen = r->size;
    int x;
    file_state *fs;
    fs = (file_state *) hash_lookup(hash, &r->id);

    if (NULL == fs) {
        errno = EBADF;
        DEBUG(1) {
            fprintf(stderr, "%d WRITE id %d: ", (int) mypid, r->id);
            perror("do_write");
        }

        return -errno;
    }

    if (r->offset > -1 && r->offset != fs->offset) {
        if (lseek(fs->fd, r->offset, SEEK_SET) < 0) {
            DEBUG(1) {
                fprintf(stderr, "%d FD %d, offset %"PRId64": ", (int) mypid, fs->fd, (int64_t)r->offset);
                perror("lseek");
            }
        }
    }

    DEBUG(2)
    fprintf(stderr, "%d WRITE %d,%d,%"PRId64"\n", (int) mypid,
            fs->fd, wrtlen, (int64_t)r->offset);
    x = write(fs->fd, buf, wrtlen);

    if (x < 0) {
        DEBUG(1) {
            fprintf(stderr, "%d FD %d: ", (int) mypid, fs->fd);
            perror("write");
        }

        return -errno;
    }

    fs->offset = r->offset + x;
    return x;
}

static int
do_unlink(diomsg * r, int len, const char *buf)
{
    if (unlink(buf) < 0) {
        DEBUG(1) {
            fprintf(stderr, "%d UNLNK id %d %s: ", (int) mypid, r->id, buf);
            perror("unlink");
        }

        return -errno;
    }

    DEBUG(2)
    fprintf(stderr, "%d UNLNK %s\n", (int) mypid, buf);
    return 0;
}

static void
msg_handle(diomsg * r, int rl, diomsg * s)
{
    char *buf = NULL;
    s->mtype = r->mtype;
    s->id = r->id;
    s->seq_no = r->seq_no;	/* optional, debugging */
    s->callback_data = r->callback_data;
    s->requestor = r->requestor;
    s->size = 0;		/* optional, debugging */
    s->offset = 0;		/* optional, debugging */
    s->shm_offset = r->shm_offset;
    s->newstyle = r->newstyle;

    if (s->shm_offset > -1)
        buf = shmbuf + s->shm_offset;

    switch (r->mtype) {

    case _MQD_OPEN:

    case _MQD_CREATE:
        s->status = do_open(r, rl, buf);
        break;

    case _MQD_CLOSE:
        s->status = do_close(r, rl);
        break;

    case _MQD_READ:
        s->status = do_read(r, rl, buf);
        break;

    case _MQD_WRITE:
        s->status = do_write(r, rl, buf);
        break;

    case _MQD_UNLINK:
        s->status = do_unlink(r, rl, buf);
        break;

    default:
        assert(0);
        break;
    }
}

static int
fsCmp(const void *a, const void *b)
{
    const int *A = (const int *)a;
    const int *B = (const int *)b;
    return *A != *B;
}

static unsigned int
fsHash(const void *key, unsigned int n)
{
    /* note, n must be a power of 2! */
    const int *k = (const int *)key;
    return (*k & (--n));
}

static void
alarm_handler(int sig)
{
    (void) 0;
}

int
main(int argc, char *argv[])
{
    int key;
    int rmsgid;
    int smsgid;
    int shmid;
    diomsg rmsg;
    diomsg smsg;
    int rlen;
    char rbuf[512];

    struct sigaction sa;
    setbuf(stdout, NULL);
    setbuf(stderr, NULL);
    mypid = getpid();
    assert(4 == argc);
    key = atoi(argv[1]);
    rmsgid = msgget(key, 0600);

    if (rmsgid < 0) {
        perror("msgget");
        return 1;
    }

    key = atoi(argv[2]);
    smsgid = msgget(key, 0600);

    if (smsgid < 0) {
        perror("msgget");
        return 1;
    }

    key = atoi(argv[3]);
    shmid = shmget(key, 0, 0600);

    if (shmid < 0) {
        perror("shmget");
        return 1;
    }

    shmbuf = (char *)shmat(shmid, NULL, 0);

    if (shmbuf == (void *) -1) {
        perror("shmat");
        return 1;
    }

    hash = hash_create(fsCmp, 1 << 4, fsHash);
    assert(hash);
    fcntl(0, F_SETFL, SQUID_NONBLOCK);
    memset(&sa, '\0', sizeof(sa));
    sa.sa_handler = alarm_handler;
    sa.sa_flags = SA_RESTART;
    sigaction(SIGALRM, &sa, NULL);

    for (;;) {
        alarm(1);
        memset(&rmsg, '\0', sizeof(rmsg));
        DEBUG(2)
        std::cerr << "msgrcv: " << rmsgid << ", "
                  << &rmsg << ", " << diomsg::msg_snd_rcv_sz
                  << ", " << 0 << ", " << 0 << std::endl;
        rlen = msgrcv(rmsgid, &rmsg, diomsg::msg_snd_rcv_sz, 0, 0);

        if (rlen < 0) {
            if (EINTR == errno) {
                if (read(0, rbuf, 512) <= 0) {
                    if (EWOULDBLOCK == errno)
                        (void) 0;
                    else if (EAGAIN == errno)
                        (void) 0;
                    else
                        break;
                }
            }

            if (EAGAIN == errno) {
                continue;
            }

            perror("msgrcv");
            break;
        }

        alarm(0);
        msg_handle(&rmsg, rlen, &smsg);

        if (msgsnd(smsgid, &smsg, diomsg::msg_snd_rcv_sz, 0) < 0) {
            perror("msgsnd");
            break;
        }
    }

    DEBUG(2)
    fprintf(stderr, "%d diskd exiting\n", (int) mypid);

    if (msgctl(rmsgid, IPC_RMID, 0) < 0)
        perror("msgctl IPC_RMID");

    if (msgctl(smsgid, IPC_RMID, 0) < 0)
        perror("msgctl IPC_RMID");

    if (shmdt(shmbuf) < 0)
        perror("shmdt");

    if (shmctl(shmid, IPC_RMID, 0) < 0)
        perror("shmctl IPC_RMID");

    return 0;
}
