A workaround for a problem on (at least) Linux 2.0.x and UnixWare.

[catagits/fcgi2.git] / libfcgi / os_unix.c

/* 
 * os_unix.c --
 *
 *      Description of file.
 *
 *
 *  Copyright (c) 1995 Open Market, Inc.
 *  All rights reserved.
 *
 *  This file contains proprietary and confidential information and
 *  remains the unpublished property of Open Market, Inc. Use, 
 *  disclosure, or reproduction is prohibited except as permitted by 
 *  express written license agreement with Open Market, Inc. 
 *
 *  Bill Snapper
 *  snapper@openmarket.com
 */

#ifndef lint
static const char rcsid[] = "$Id: os_unix.c,v 1.7 1999/02/05 04:08:56 roberts Exp $";
#endif /* not lint */

#include "fcgimisc.h"
#include "fcgiapp.h"
#include "fcgiappmisc.h"
#include "fastcgi.h"

#include <stdio.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>     /* for memchr() */
#include <errno.h>
#include <stdarg.h>
#include <math.h>
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h> /* for getpeername */
#endif
#include <sys/un.h>
#include <fcntl.h>      /* for fcntl */
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#include <sys/time.h>

#include <sys/types.h>
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <arpa/inet.h>
#include <netinet/tcp.h>

#include "fcgios.h"

#ifndef _CLIENTDATA
#   if defined(__STDC__) || defined(__cplusplus)
    typedef void *ClientData;
#   else
    typedef int *ClientData;
#   endif /* __STDC__ */
#define _CLIENTDATA
#endif

/*
 * This structure holds an entry for each oustanding async I/O operation.
 */
typedef struct {
    OS_AsyncProc procPtr;	    /* callout completion procedure */
    ClientData clientData;	    /* caller private data */
    int fd;
    int len;
    int offset;
    void *buf;
    int inUse;
} AioInfo;

/*
 * Entries in the async I/O table are allocated 2 per file descriptor.
 *
 * Read Entry Index  = fd * 2
 * Write Entry Index = (fd * 2) + 1
 */
#define AIO_RD_IX(fd) (fd * 2)
#define AIO_WR_IX(fd) ((fd * 2) + 1)

static int asyncIoTableSize = 16;
static AioInfo *asyncIoTable = NULL;
#define STDIN_FILENO  0
#define STDOUT_FILENO 1
#define STDERR_FILENO 2

#ifndef FALSE
#define FALSE 0
#endif

#ifndef TRUE
#define TRUE 1
#endif

static int isFastCGI = FALSE;
static int libInitialized = FALSE;

static fd_set readFdSet;
static fd_set writeFdSet;

static fd_set readFdSetPost;
static int numRdPosted = 0;
static fd_set writeFdSetPost;
static int numWrPosted = 0;
static int volatile maxFd = -1;

\f
/*
 *--------------------------------------------------------------
 *
 * OS_LibInit --
 *
 *      Set up the OS library for use.
 *
 *      NOTE: This function is really only needed for application
 *            asynchronous I/O.  It will most likely change in the
 *            future to setup the multi-threaded environment.
 *
 * Results:
 *	Returns 0 if success, -1 if not.
 *
 * Side effects:
 *	Async I/O table allocated and initialized.
 *
 *--------------------------------------------------------------
 */
int OS_LibInit(int stdioFds[3])
{
    if(libInitialized)
        return 0;
    
    asyncIoTable = malloc(asyncIoTableSize * sizeof(AioInfo));
    if(asyncIoTable == NULL) {
        errno = ENOMEM;
        return -1;
    }
    memset((char *) asyncIoTable, 0,
           asyncIoTableSize * sizeof(AioInfo));

    FD_ZERO(&readFdSet);
    FD_ZERO(&writeFdSet);
    FD_ZERO(&readFdSetPost);
    FD_ZERO(&writeFdSetPost);
    libInitialized = TRUE;
    return 0;
}

\f
/*
 *--------------------------------------------------------------
 *
 * OS_LibShutdown --
 *
 *	Shutdown the OS library.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Memory freed, fds closed.
 *
 *--------------------------------------------------------------
 */
void OS_LibShutdown()
{
    if(!libInitialized)
        return;
    
    free(asyncIoTable);
    asyncIoTable = NULL;
    libInitialized = FALSE;
    return;
}

\f
/*
 *----------------------------------------------------------------------
 *
 * OS_BuildSockAddrUn --
 *
 *      Using the pathname bindPath, fill in the sockaddr_un structure
 *      *servAddrPtr and the length of this structure *servAddrLen.
 *
 *      The format of the sockaddr_un structure changed incompatibly in
 *      4.3BSD Reno.  Digital UNIX supports both formats, other systems
 *      support one or the other.
 *
 * Results:
 *      0 for normal return, -1 for failure (bindPath too long).
 *
 *----------------------------------------------------------------------
 */

static int OS_BuildSockAddrUn(char *bindPath,
                              struct sockaddr_un *servAddrPtr,
                              int *servAddrLen)
{
    int bindPathLen = strlen(bindPath);

#ifdef HAVE_SOCKADDR_UN_SUN_LEN /* 4.3BSD Reno and later: BSDI, DEC */
    if(bindPathLen >= sizeof(servAddrPtr->sun_path)) {
        return -1;
    }
#else                           /* 4.3 BSD Tahoe: Solaris, HPUX, DEC, ... */
    if(bindPathLen > sizeof(servAddrPtr->sun_path)) {
        return -1;
    }
#endif
    memset((char *) servAddrPtr, 0, sizeof(*servAddrPtr));
    servAddrPtr->sun_family = AF_UNIX;
    memcpy(servAddrPtr->sun_path, bindPath, bindPathLen);
#ifdef HAVE_SOCKADDR_UN_SUN_LEN /* 4.3BSD Reno and later: BSDI, DEC */
    *servAddrLen = sizeof(servAddrPtr->sun_len)
            + sizeof(servAddrPtr->sun_family)
            + bindPathLen + 1;
    servAddrPtr->sun_len = *servAddrLen;
#else                           /* 4.3 BSD Tahoe: Solaris, HPUX, DEC, ... */
    *servAddrLen = sizeof(servAddrPtr->sun_family) + bindPathLen;
#endif
    return 0;
}
\f
union SockAddrUnion {
    struct  sockaddr_un	unixVariant;
    struct  sockaddr_in	inetVariant;
};

\f
/*
 * OS_CreateLocalIpcFd --
 *
 *   This procedure is responsible for creating the listener socket
 *   on Unix for local process communication.  It will create a
 *   domain socket or a TCP/IP socket bound to "localhost" and return
 *   a file descriptor to it to the caller.
 *
 * Results:
 *      Listener socket created.  This call returns either a valid
 *      file descriptor or -1 on error.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */
int OS_CreateLocalIpcFd(char *bindPath)
{
    int listenSock, servLen;
    union   SockAddrUnion sa;
    int	    tcp = FALSE;
    char    *tp;
    short   port;
    char    host[MAXPATHLEN];

    strcpy(host, bindPath);
    if((tp = strchr(host, ':')) != 0) {
	*tp++ = 0;
	if((port = atoi(tp)) == 0) {
	    *--tp = ':';
	 } else {
	    tcp = TRUE;
	 }
    }
    if(tcp && (*host && strcmp(host, "localhost") != 0)) {
	fprintf(stderr, "To start a service on a TCP port can not "
			"specify a host name.\n"
			"You should either use \"localhost:<port>\" or "
			" just use \":<port>.\"\n");
	exit(1);
    }

    if(tcp) {
	listenSock = socket(AF_INET, SOCK_STREAM, 0);
        if(listenSock >= 0) {
            int flag = 1;
            if(setsockopt(listenSock, SOL_SOCKET, SO_REUSEADDR,
                          (char *) &flag, sizeof(flag)) < 0) {
                fprintf(stderr, "Can't set SO_REUSEADDR.\n");
	        exit(1001);
	    }
	}
    } else {
	listenSock = socket(AF_UNIX, SOCK_STREAM, 0);
    }
    if(listenSock < 0) {
        return -1;
    }

    /*
     * Bind the listening socket.
     */
    if(tcp) {
	memset((char *) &sa.inetVariant, 0, sizeof(sa.inetVariant));
	sa.inetVariant.sin_family = AF_INET;
	sa.inetVariant.sin_addr.s_addr = htonl(INADDR_ANY);
	sa.inetVariant.sin_port = htons(port);
	servLen = sizeof(sa.inetVariant);
    } else {
	unlink(bindPath);
	if(OS_BuildSockAddrUn(bindPath, &sa.unixVariant, &servLen)) {
	    fprintf(stderr, "Listening socket's path name is too long.\n");
	    exit(1000);
	}
    }
    if(bind(listenSock, (struct sockaddr *) &sa.unixVariant, servLen) < 0
       || listen(listenSock, 5) < 0) {
	perror("bind/listen");
        exit(errno);
    }

    return listenSock;
}

\f
/*
 *----------------------------------------------------------------------
 *
 * OS_FcgiConnect --
 *
 *	Create the socket and connect to the remote application if
 *      possible.
 *
 *      This was lifted from the cgi-fcgi application and was abstracted
 *      out because Windows NT does not have a domain socket and must
 *      use a named pipe which has a different API altogether.
 *
 * Results:
 *      -1 if fail or a valid file descriptor if connection succeeds.
 *
 * Side effects:
 *      Remote connection established.
 *
 *----------------------------------------------------------------------
 */
int OS_FcgiConnect(char *bindPath)
{
    union   SockAddrUnion sa;
    int servLen, resultSock;
    int connectStatus;
    char    *tp;
    char    host[MAXPATHLEN];
    short   port;
    int	    tcp = FALSE;

    strcpy(host, bindPath);
    if((tp = strchr(host, ':')) != 0) {
	*tp++ = 0;
	if((port = atoi(tp)) == 0) {
	    *--tp = ':';
	 } else {
	    tcp = TRUE;
	 }
    }
    if(tcp == TRUE) {
	struct	hostent	*hp;
	if((hp = gethostbyname((*host ? host : "localhost"))) == NULL) {
	    fprintf(stderr, "Unknown host: %s\n", bindPath);
	    exit(1000);
	}
	sa.inetVariant.sin_family = AF_INET;
	memcpy(&sa.inetVariant.sin_addr, hp->h_addr, hp->h_length);
	sa.inetVariant.sin_port = htons(port);
	servLen = sizeof(sa.inetVariant);
	resultSock = socket(AF_INET, SOCK_STREAM, 0);
    } else {
	if(OS_BuildSockAddrUn(bindPath, &sa.unixVariant, &servLen)) {
	    fprintf(stderr, "Listening socket's path name is too long.\n");
	    exit(1000);
	}
	resultSock = socket(AF_UNIX, SOCK_STREAM, 0);
    }

    assert(resultSock >= 0);
    connectStatus = connect(resultSock, (struct sockaddr *) &sa.unixVariant,
                             servLen);
    if(connectStatus >= 0) {
        return resultSock;
    } else {
        /*
         * Most likely (errno == ENOENT || errno == ECONNREFUSED)
         * and no FCGI application server is running.
         */
        close(resultSock);
        return -1;
    }
}
     
\f
/*
 *--------------------------------------------------------------
 *
 * OS_Read --
 *
 *	Pass through to the unix read function.
 *
 * Results:
 *	Returns number of byes read, 0, or -1 failure: errno
 *      contains actual error.
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */
int OS_Read(int fd, char * buf, size_t len)
{
    return(read(fd, buf, len));
}
\f
/*
 *--------------------------------------------------------------
 *
 * OS_Write --
 *
 *	Pass through to unix write function.
 *
 * Results:
 *	Returns number of byes read, 0, or -1 failure: errno
 *      contains actual error.
 *
 * Side effects:
 *	none.
 *
 *--------------------------------------------------------------
 */
int OS_Write(int fd, char * buf, size_t len)
{
    return(write(fd, buf, len));
}

\f
/*
 *----------------------------------------------------------------------
 *
 * OS_SpawnChild --
 *
 *	Spawns a new FastCGI listener process.
 *
 * Results:
 *      0 if success, -1 if error.
 *
 * Side effects:
 *      Child process spawned.
 *
 *----------------------------------------------------------------------
 */
int OS_SpawnChild(char *appPath, int listenFd)
{
    int forkResult;

    forkResult = fork();
    if(forkResult < 0) {
        exit(errno);
    }

    if(forkResult == 0) {
        /*
         * Close STDIN unconditionally.  It's used by the parent
         * process for CGI communication.  The FastCGI applciation
         * will be replacing this with the FastCGI listenFd IF
         * STDIN_FILENO is the same as FCGI_LISTENSOCK_FILENO
         * (which it is on Unix).  Regardless, STDIN, STDOUT, and
         * STDERR will be closed as the FastCGI process uses a
         * multiplexed socket in their place.
         */
        close(STDIN_FILENO);

        /*
         * If the listenFd is already the value of FCGI_LISTENSOCK_FILENO
         * we're set.  If not, change it so the child knows where to
         * get the listen socket from.
         */
        if(listenFd != FCGI_LISTENSOCK_FILENO) {
            dup2(listenFd, FCGI_LISTENSOCK_FILENO);
            close(listenFd);
        }

	close(STDOUT_FILENO);
	close(STDERR_FILENO);

        /*
	 * We're a child.  Exec the application.
         *
         * XXX: entire environment passes through
	 */
	execl(appPath, appPath, NULL);
	/*
	 * XXX: Can't do this as we've already closed STDERR!!!
	 *
	 * perror("exec");
	 */
	exit(errno);
    }
    return 0;
}

\f
/*
 *--------------------------------------------------------------
 *
 * OS_AsyncReadStdin --
 *
 *	This initiates an asynchronous read on the standard
 *	input handle.
 *
 *      The abstraction is necessary because Windows NT does not
 *      have a clean way of "select"ing a file descriptor for
 *      I/O.
 *
 * Results:
 *	-1 if error, 0 otherwise.
 *
 * Side effects:
 *	Asynchronous bit is set in the readfd variable and
 *      request is enqueued.
 *
 *--------------------------------------------------------------
 */
int OS_AsyncReadStdin(void *buf, int len, OS_AsyncProc procPtr, 
                      ClientData clientData)
{
    int index = AIO_RD_IX(STDIN_FILENO);

    ASSERT(asyncIoTable[index].inUse == 0);
    asyncIoTable[index].procPtr = procPtr;
    asyncIoTable[index].clientData = clientData;
    asyncIoTable[index].fd = STDIN_FILENO;
    asyncIoTable[index].len = len;
    asyncIoTable[index].offset = 0;
    asyncIoTable[index].buf = buf;
    asyncIoTable[index].inUse = 1;
    FD_SET(STDIN_FILENO, &readFdSet);
    if(STDIN_FILENO > maxFd)
        maxFd = STDIN_FILENO;
    return 0;
}

static void GrowAsyncTable(void)
{
    int oldTableSize = asyncIoTableSize;
    
    asyncIoTableSize = asyncIoTableSize * 2;
    asyncIoTable = realloc(asyncIoTable, asyncIoTableSize * sizeof(AioInfo));
    if(asyncIoTable == NULL) {
        errno = ENOMEM;
        exit(errno);
    }
    memset((char *) &asyncIoTable[oldTableSize], 0,
           oldTableSize * sizeof(AioInfo));

}

\f
/*
 *--------------------------------------------------------------
 *
 * OS_AsyncRead --
 *
 *	This initiates an asynchronous read on the file
 *	handle which may be a socket or named pipe.
 *
 *	We also must save the ProcPtr and ClientData, so later
 *	when the io completes, we know who to call.
 *
 *	We don't look at any results here (the ReadFile may
 *	return data if it is cached) but do all completion
 *	processing in OS_Select when we get the io completion
 *	port done notifications.  Then we call the callback.
 *
 * Results:
 *	-1 if error, 0 otherwise.
 *
 * Side effects:
 *	Asynchronous I/O operation is queued for completion.
 *
 *--------------------------------------------------------------
 */
int OS_AsyncRead(int fd, int offset, void *buf, int len,
		 OS_AsyncProc procPtr, ClientData clientData)
{
    int index = AIO_RD_IX(fd);
    
    ASSERT(asyncIoTable != NULL);

    if(fd > maxFd)
        maxFd = fd;

    if(index >= asyncIoTableSize) {
        GrowAsyncTable();
    }

    ASSERT(asyncIoTable[index].inUse == 0);
    asyncIoTable[index].procPtr = procPtr;
    asyncIoTable[index].clientData = clientData;
    asyncIoTable[index].fd = fd;
    asyncIoTable[index].len = len;
    asyncIoTable[index].offset = offset;
    asyncIoTable[index].buf = buf;
    asyncIoTable[index].inUse = 1;
    FD_SET(fd, &readFdSet);
    return 0;
}
\f
/*
 *--------------------------------------------------------------
 *
 * OS_AsyncWrite --
 *
 *	This initiates an asynchronous write on the "fake" file
 *	descriptor (which may be a file, socket, or named pipe).
 *	We also must save the ProcPtr and ClientData, so later
 *	when the io completes, we know who to call.
 *
 *	We don't look at any results here (the WriteFile generally
 *	completes immediately) but do all completion processing
 *	in OS_DoIo when we get the io completion port done
 *	notifications.  Then we call the callback.
 *
 * Results:
 *	-1 if error, 0 otherwise.
 *
 * Side effects:
 *	Asynchronous I/O operation is queued for completion.
 *
 *--------------------------------------------------------------
 */
int OS_AsyncWrite(int fd, int offset, void *buf, int len, 
		  OS_AsyncProc procPtr, ClientData clientData)
{
    int index = AIO_WR_IX(fd);

    if(fd > maxFd)
        maxFd = fd;

    if(index >= asyncIoTableSize) {
        GrowAsyncTable();
    }

    ASSERT(asyncIoTable[index].inUse == 0);
    asyncIoTable[index].procPtr = procPtr;
    asyncIoTable[index].clientData = clientData;
    asyncIoTable[index].fd = fd;
    asyncIoTable[index].len = len;
    asyncIoTable[index].offset = offset;
    asyncIoTable[index].buf = buf;
    asyncIoTable[index].inUse = 1;
    FD_SET(fd, &writeFdSet);
    return 0;
}
\f
/*
 *--------------------------------------------------------------
 *
 * OS_Close --
 *
 *	Closes the descriptor.  This is a pass through to the
 *      Unix close.
 *
 * Results:
 *	0 for success, -1 on failure
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */
int OS_Close(int fd)
{
    int index = AIO_RD_IX(fd);
    
    FD_CLR(fd, &readFdSet);
    FD_CLR(fd, &readFdSetPost);
    if(asyncIoTable[index].inUse != 0) {
        asyncIoTable[index].inUse = 0;
    }
    
    FD_CLR(fd, &writeFdSet);
    FD_CLR(fd, &writeFdSetPost);
    index = AIO_WR_IX(fd);
    if(asyncIoTable[index].inUse != 0) {
        asyncIoTable[index].inUse = 0;
    }
    if(maxFd == fd)
        maxFd--;
    return close(fd);
}
\f
/*
 *--------------------------------------------------------------
 *
 * OS_CloseRead --
 *
 *	Cancel outstanding asynchronous reads and prevent subsequent
 *      reads from completing.
 *
 * Results:
 *	Socket or file is shutdown. Return values mimic Unix shutdown:
 *		0 success, -1 failure
 *
 *--------------------------------------------------------------
 */
int OS_CloseRead(int fd)
{
    if(asyncIoTable[AIO_RD_IX(fd)].inUse != 0) {
        asyncIoTable[AIO_RD_IX(fd)].inUse = 0;
        FD_CLR(fd, &readFdSet);
    }
    
    return shutdown(fd, 0);
}

\f
/*
 *--------------------------------------------------------------
 *
 * OS_DoIo --
 *
 *	This function was formerly OS_Select.  It's purpose is
 *      to pull I/O completion events off the queue and dispatch
 *      them to the appropriate place.
 *
 * Results:
 *	Returns 0.
 *
 * Side effects:
 *	Handlers are called.
 *
 *--------------------------------------------------------------
 */
int OS_DoIo(struct timeval *tmo)
{
    int fd, len, selectStatus;
    OS_AsyncProc procPtr;
    ClientData clientData;
    AioInfo *aioPtr;
    fd_set readFdSetCpy;
    fd_set writeFdSetCpy;

    FD_ZERO(&readFdSetCpy);
    FD_ZERO(&writeFdSetCpy);

    for(fd = 0; fd <= maxFd; fd++) {
        if(FD_ISSET(fd, &readFdSet)) {
            FD_SET(fd, &readFdSetCpy);
        }
        if(FD_ISSET(fd, &writeFdSet)) {
            FD_SET(fd, &writeFdSetCpy);
        }
    }
    
    /*
     * If there were no completed events from a prior call, see if there's
     * any work to do.
     */
    if(numRdPosted == 0 && numWrPosted == 0) {
        selectStatus = select((maxFd+1), &readFdSetCpy, &writeFdSetCpy,
                              NULL, tmo);
        if(selectStatus < 0) {
            exit(errno);
	}

        for(fd = 0; fd <= maxFd; fd++) {
	    /*
	     * Build up a list of completed events.  We'll work off of
	     * this list as opposed to looping through the read and write
	     * fd sets since they can be affected by a callbacl routine.
	     */
	    if(FD_ISSET(fd, &readFdSetCpy)) {
	        numRdPosted++;
		FD_SET(fd, &readFdSetPost);
		FD_CLR(fd, &readFdSet);
	    }

            if(FD_ISSET(fd, &writeFdSetCpy)) {
	        numWrPosted++;
	        FD_SET(fd, &writeFdSetPost);
		FD_CLR(fd, &writeFdSet);
	    }
        }
    }

    if(numRdPosted == 0 && numWrPosted == 0)
        return 0;
	    
    for(fd = 0; fd <= maxFd; fd++) {
        /*
	 * Do reads and dispatch callback.
	 */
        if(FD_ISSET(fd, &readFdSetPost) 
	   && asyncIoTable[AIO_RD_IX(fd)].inUse) {

	    numRdPosted--;
	    FD_CLR(fd, &readFdSetPost);
	    aioPtr = &asyncIoTable[AIO_RD_IX(fd)];
	    
	    len = read(aioPtr->fd, aioPtr->buf, aioPtr->len);

	    procPtr = aioPtr->procPtr;
	    aioPtr->procPtr = NULL;
	    clientData = aioPtr->clientData;
	    aioPtr->inUse = 0;

	    (*procPtr)(clientData, len);
	}

        /*
	 * Do writes and dispatch callback.
	 */
        if(FD_ISSET(fd, &writeFdSetPost) &&
           asyncIoTable[AIO_WR_IX(fd)].inUse) {

	    numWrPosted--;
	    FD_CLR(fd, &writeFdSetPost);
	    aioPtr = &asyncIoTable[AIO_WR_IX(fd)];
	    
	    len = write(aioPtr->fd, aioPtr->buf, aioPtr->len);

	    procPtr = aioPtr->procPtr;
	    aioPtr->procPtr = NULL;
	    clientData = aioPtr->clientData;
	    aioPtr->inUse = 0;
	    (*procPtr)(clientData, len);
	}
    }
    return 0;
}

\f
/*
 *----------------------------------------------------------------------
 *
 * ClientAddrOK --
 *
 *      Checks if a client address is in a list of allowed addresses
 *
 * Results:
 *	TRUE if address list is empty or client address is present
 *      in the list, FALSE otherwise.
 *
 *----------------------------------------------------------------------
 */
static int ClientAddrOK(struct sockaddr_in *saPtr, char *clientList)
{
    int result = FALSE;
    char *clientListCopy, *cur, *next;
    char *newString = NULL;
    int strLen;

    if(clientList == NULL || *clientList == '\0') {
        return TRUE;
    }

    strLen = strlen(clientList);
    clientListCopy = malloc(strLen + 1);
    assert(newString != NULL);
    memcpy(newString, clientList, strLen);
    newString[strLen] = '\000';
    
    for(cur = clientListCopy; cur != NULL; cur = next) {
        next = strchr(cur, ',');
        if(next != NULL) {
            *next++ = '\0';
	}
        if(inet_addr(cur) == saPtr->sin_addr.s_addr) {
            result = TRUE;
            break;
        }
    }
    free(clientListCopy);
    return result;
}

\f
/*
 *----------------------------------------------------------------------
 *
 * AcquireLock --
 *
 *      On platforms that implement concurrent calls to accept
 *      on a shared listening ipcFd, returns 0.  On other platforms,
 *	acquires an exclusive lock across all processes sharing a
 *      listening ipcFd, blocking until the lock has been acquired.
 *
 * Results:
 *      0 for successful call, -1 in case of system error (fatal).
 *
 * Side effects:
 *      This process now has the exclusive lock.
 *
 *----------------------------------------------------------------------
 */
static int AcquireLock(int blocking)
{
#ifdef USE_LOCKING
    struct flock lock;
    lock.l_type = F_WRLCK;
    lock.l_start = 0;
    lock.l_whence = SEEK_SET;
    lock.l_len = 0;

    if(fcntl(FCGI_LISTENSOCK_FILENO, 
             blocking ? F_SETLKW : F_SETLK, &lock) < 0) {
        if (errno != EINTR)
            return -1;
    }
#endif /* USE_LOCKING */
    return 0;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * ReleaseLock --
 *
 *      On platforms that implement concurrent calls to accept
 *      on a shared listening ipcFd, does nothing.  On other platforms,
 *	releases an exclusive lock acquired by AcquireLock.
 *
 * Results:
 *      0 for successful call, -1 in case of system error (fatal).
 *
 * Side effects:
 *      This process no longer holds the lock.
 *
 *----------------------------------------------------------------------
 */
static int ReleaseLock(void)
{
#ifdef USE_LOCKING
    struct flock lock;
    lock.l_type = F_UNLCK;
    lock.l_start = 0;
    lock.l_whence = SEEK_SET;
    lock.l_len = 0;

    if(fcntl(FCGI_LISTENSOCK_FILENO, F_SETLK, &lock) < 0) {
        return -1;
    }
#endif /* USE_LOCKING */
    return 0;
}

\f
/*
 *----------------------------------------------------------------------
 *
 * OS_FcgiIpcAccept --
 *
 *	Accepts a new FastCGI connection.  This routine knows whether
 *      we're dealing with TCP based sockets or NT Named Pipes for IPC.
 *
 * Results:
 *      -1 if the operation fails, otherwise this is a valid IPC fd.
 *
 * Side effects:
 *      New IPC connection is accepted.
 *
 *----------------------------------------------------------------------
 */
int OS_FcgiIpcAccept(char *clientAddrList)
{
    int socket;
    union u_sockaddr {
        struct sockaddr_un un;
        struct sockaddr_in in;
    } sa;
#if defined __linux__
    socklen_t len;
#else
    int len;
#endif    

    if (AcquireLock(TRUE) < 0) {
        return (-1);
    }
    for (;;) {
        do {
            len = sizeof(sa);
            socket = accept(FCGI_LISTENSOCK_FILENO,
                            (struct sockaddr *) &sa.un, &len);
        } while ((socket < 0) && (errno == EINTR));

        if (socket >= 0) {
        
            if (sa.in.sin_family == AF_INET) {
#ifdef TCP_NODELAY
                /* No replies to outgoing data, so disable Nagle algorithm */
                int set = 1;
                setsockopt(socket, IPPROTO_TCP, TCP_NODELAY, 
                           (char *)&set, sizeof(set));
#endif            
                
                /* Check that the client IP address is OK */
                if (ClientAddrOK(&sa.in, clientAddrList))
                    break;
            }
            else {
                /* This works around a problem on Linux 2.0.x and
                 * SCO Unixware (maybe others?).  When a connect() is made to 
                 * a Unix Domain socket, but its not accept()ed before the 
                 * web server gets impatient and close()s, an accept()
                 * here results in a valid file descriptor, but no data to
                 * read.  This causes a block on the first read() - and 
                 * never returns!  
                 *
                 * Another approach to this is to write()
                 * to the socket to provoke a SIGPIPE, but this is a pain
                 * because of the FastCGI protocol, the fact that whatever
                 * is written has to be universally ignored by all FastCGI
                 * web servers, and a SIGPIPE handler has to be installed
                 * which returns (or SIGPIPE is ignored).
                 * 
                 * READABLE_UNIX_FD_DROP_DEAD_TIMEVAL = 2,0  by default.
                 *
                 * Making it shorter is probably safe, but I'll leave that
                 * to you.  Making it 0,0 doesn't work reliably.  The 
                 * shorter you can reliably make it, the faster your
                 * application will be able to recover (waiting 2 seconds
                 * may _cause_ the problem when there is a very high demand).
                 * At any rate, this is better than perma-blocking. */
                 
                struct timeval tval = { READABLE_UNIX_FD_DROP_DEAD_TIMEVAL };
                fd_set read_fds;

                FD_ZERO(&read_fds);
                FD_SET(socket, &read_fds);
                if (select(socket + 1, &read_fds, NULL, NULL, &tval) > 0
                    && FD_ISSET(socket, &read_fds))
                { 
                    break;
                }
            }

            close(socket);
            continue;
        }

        /* Based on Apache's (v1.3.1) http_main.c accept() handling and 
         * Stevens' Unix Network Programming Vol 1, 2nd Ed, para. 15.6
         */
        switch (errno) {
#ifdef EPROTO
            /* EPROTO on certain older kernels really means
             * ECONNABORTED, so we need to ignore it for them.
             * See discussion in new-httpd archives nh.9701
             * search for EPROTO.
             *
             * Also see nh.9603, search for EPROTO:
             * There is potentially a bug in Solaris 2.x x<6,
             * and other boxes that implement tcp sockets in
             * userland (i.e. on top of STREAMS).  On these
             * systems, EPROTO can actually result in a fatal
             * loop.  See PR#981 for example.  It's hard to
             * handle both uses of EPROTO.
             */
            case EPROTO:
#endif
#ifdef ECONNABORTED
            case ECONNABORTED:
#endif
            /* Linux generates the rest of these, other tcp
             * stacks (i.e. bsd) tend to hide them behind
             * getsockopt() interfaces.  They occur when
             * the net goes sour or the client disconnects
             * after the three-way handshake has been done
             * in the kernel but before userland has picked
             * up the socket.
             */
#ifdef ECONNRESET
            case ECONNRESET:
#endif
#ifdef ETIMEDOUT
            case ETIMEDOUT:
#endif
#ifdef EHOSTUNREACH
            case EHOSTUNREACH:
#endif
#ifdef ENETUNREACH
            case ENETUNREACH:
#endif
                break;  /* switch(errno) */

            default: {
                    int errnoSave = errno;
                    ReleaseLock();
                    errno = errnoSave;
                }
                return (-1);
        }  /* switch(errno) */
    }  /* for(;;) */

    if (ReleaseLock() < 0) {
        return (-1);
    }
    return (socket);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * OS_IpcClose
 *
 *	OS IPC routine to close an IPC connection.
 *
 * Results:
 *
 *
 * Side effects:
 *      IPC connection is closed.
 *
 *----------------------------------------------------------------------
 */
int OS_IpcClose(int ipcFd)
{
    return OS_Close(ipcFd);
}

\f
/*
 *----------------------------------------------------------------------
 *
 * OS_IsFcgi --
 *
 *	Determines whether this process is a FastCGI process or not.
 *
 * Results:
 *      Returns 1 if FastCGI, 0 if not.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */
int OS_IsFcgi()
{
	union {
        struct sockaddr_in in;
        struct sockaddr_un un;
    } sa;
#if defined __linux__
    socklen_t len = sizeof(sa);
#else
    int len = sizeof(sa);
#endif

    if (getpeername(FCGI_LISTENSOCK_FILENO, (struct sockaddr *)&sa, &len) != 0 
            && errno == ENOTCONN)
        isFastCGI = TRUE;
    else
        isFastCGI = FALSE;
        
    return (isFastCGI);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * OS_SetFlags --
 *
 *      Sets selected flag bits in an open file descriptor.
 *
 *----------------------------------------------------------------------
 */
void OS_SetFlags(int fd, int flags)
{
    int val;
    if((val = fcntl(fd, F_GETFL, 0)) < 0) {
        exit(errno);
    }
    val |= flags;
    if(fcntl(fd, F_SETFL, val) < 0) {
        exit(errno);
    }
}