flock.c

Apache V2.0.15 Alpha For Linuxhttpd-2_0_15-alpha.tar.Z

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 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
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 */

#include "fileio.h"

#if APR_HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_SYS_FILE_H
#include <sys/file.h>
#endif

apr_status_t apr_file_lock(apr_file_t *thefile, int type)
{
    int rc;

#if defined(HAVE_FCNTL_H)
    {
        struct flock l = { 0 };
        int fc;

        l.l_whence = SEEK_SET;  /* lock from current point */
        l.l_start = 0;          /* begin lock at this offset */
        l.l_len = 0;            /* lock to end of file */
        if ((type & APR_FLOCK_TYPEMASK) == APR_FLOCK_SHARED)
            l.l_type = F_RDLCK;
        else
            l.l_type = F_WRLCK;

        fc = (type & APR_FLOCK_NONBLOCK) ? F_SETLK : F_SETLKW;

        /* keep trying if fcntl() gets interrupted (by a signal) */
        while ((rc = fcntl(thefile->filedes, fc, &l)) < 0 && errno == EINTR)
            continue;

        if (rc == -1)
            return errno;
    }
#elif defined(HAVE_SYS_FILE_H)
    {
        int ltype;

        if ((type & APR_FLOCK_TYPEMASK) == APR_FLOCK_SHARED)
            ltype = LOCK_SH;
        else
            ltype = LOCK_EX;
        if ((type & APR_FLOCK_NONBLOCK) != 0)
            ltype |= LOCK_NB;

        /* keep trying if flock() gets interrupted (by a signal) */
        while ((rc = flock(thefile->filedes, ltype)) < 0 && errno == EINTR)
            continue;

        if (rc == -1)
            return errno;
    }
#else
#error No file locking mechanism is available.
#endif

    return APR_SUCCESS;
}

apr_status_t apr_file_unlock(apr_file_t *thefile)
{
    int rc;

#if defined(HAVE_FCNTL_H)
    {
        struct flock l = { 0 };

        l.l_whence = SEEK_SET;  /* lock from current point */
        l.l_start = 0;          /* begin lock at this offset */
        l.l_len = 0;            /* lock to end of file */
        l.l_type = F_UNLCK;

        /* keep trying if fcntl() gets interrupted (by a signal) */
        while ((rc = fcntl(thefile->filedes, F_SETLKW, &l)) < 0
               && errno == EINTR)
            continue;

        if (rc == -1)
            return errno;
    }
#elif defined(HAVE_SYS_FILE_H)
    {
        /* keep trying if flock() gets interrupted (by a signal) */
        while ((rc = flock(thefile->filedes, LOCK_UN)) < 0 && errno == EINTR)
            continue;

        if (rc == -1)
            return errno;
    }
#else
#error No file locking mechanism is available.
#endif

    return APR_SUCCESS;
}