common/sfio/sftmp.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2010 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#include    "sfhdr.h"

/*  Create a temporary stream for read/write.
**  The stream is originally created as a memory-resident stream.
**  When this memory is exceeded, a real temp file will be created.
**  The temp file creation sequence is somewhat convoluted so that
**  pool/stack/discipline will work correctly.
**
**  Written by David Korn and Kiem-Phong Vo.
*/

#if _tmp_rmfail

/* File not removable while there is an open file descriptor.
** To ensure that temp files are properly removed, we need:
** 1. A discipline to remove a file when the corresponding stream is closed.
**    Care must be taken to close the file descriptor before removing the
**    file because systems such as NT do not allow file removal while
**    there is an open file handle.
** 2. An atexit() function is set up to close temp files when process exits.
** 3. On systems with O_TEMPORARY (e.g., NT), this is used to further ensure
**    that temp files will be removed after the last handle is closed.
*/

typedef struct _file_s      File_t;
struct _file_s
{   File_t* next;       /* link list        */
    Sfio_t* f;      /* associated stream    */
    char    name[1];    /* temp file name   */
};

static File_t*  File;       /* list pf temp files   */

#if __STD_C
static int _tmprmfile(Sfio_t* f, int type, Void_t* val, Sfdisc_t* disc)
#else
static int _tmprmfile(f, type, val, disc)
Sfio_t*     f;
int     type;
Void_t*     val;
Sfdisc_t*   disc;
#endif
{
    reg File_t  *ff, *last;

    NOTUSED(val);

    if(type == SF_DPOP) /* don't allow this to pop */
        return -1;

    if(type == SF_CLOSING)
    {
        (void)vtmtxlock(_Sfmutex);
        for(last = NIL(File_t*), ff = File; ff; last = ff, ff = ff->next)
            if(ff->f == f)
                break;
        if(ff)
        {   if(!last)
                File = ff->next;
            else    last->next = ff->next;

            if(_Sfnotify)
                (*_Sfnotify)(f,SF_CLOSING,f->file);
            CLOSE(f->file);
            f->file = -1;
            while(sysremovef(ff->name) < 0 && errno == EINTR)
                errno = 0;

            free((Void_t*)ff);
        }
        (void)vtmtxunlock(_Sfmutex);
    }

    return 0;
}

#if __STD_C
static void _rmfiles(void)
#else
static void _rmfiles()
#endif
{   reg File_t  *ff, *next;

    (void)vtmtxlock(_Sfmutex);
    for(ff = File; ff; ff = next)
    {   next = ff->next;
        _tmprmfile(ff->f, SF_CLOSING, NIL(Void_t*), ff->f->disc);
    }
    (void)vtmtxunlock(_Sfmutex);
}

static Sfdisc_t Rmdisc =
    { NIL(Sfread_f), NIL(Sfwrite_f), NIL(Sfseek_f), _tmprmfile, NIL(Sfdisc_t*) };

#endif /*_tmp_rmfail*/

#if __STD_C
static int _rmtmp(Sfio_t* f, char* file)
#else
static int _rmtmp(f, file)
Sfio_t* f;
char*   file;
#endif
{
#if _tmp_rmfail /* remove only when stream is closed */
    reg File_t* ff;

    if(!File)
        atexit(_rmfiles);

    if(!(ff = (File_t*)malloc(sizeof(File_t)+strlen(file))) )
        return -1;
    (void)vtmtxlock(_Sfmutex);
    ff->f = f;
    strcpy(ff->name,file);
    ff->next = File;
    File = ff;
    (void)vtmtxunlock(_Sfmutex);

#else   /* can remove now */
    while(sysremovef(file) < 0 && errno == EINTR)
        errno = 0;
#endif

    return 0;
}

#if !_PACKAGE_ast
#define     TMPDFLT     "/tmp"
static char **Tmppath, **Tmpcur;

#if __STD_C
char** _sfgetpath(char* path)
#else
char** _sfgetpath(path)
char*   path;
#endif
{   reg char    *p, **dirs;
    reg int     n;

    if(!(path = getenv(path)) )
        return NIL(char**);

    for(p = path, n = 0;;)  /* count number of directories */
    {   while(*p == ':')
            ++p;
        if(*p == 0)
            break;
        n += 1;
        while(*p && *p != ':')  /* skip dir name */
            ++p;
    }
    if(n == 0 || !(dirs = (char**)malloc((n+1)*sizeof(char*))) )
        return NIL(char**);
    if(!(p = (char*)malloc(strlen(path)+1)) )
    {   free(dirs);
        return NIL(char**);
    }
    strcpy(p,path);
    for(n = 0;; ++n)
    {   while(*p == ':')
            ++p;
        if(*p == 0)
            break;
        dirs[n] = p;
        while(*p && *p != ':')
            ++p;
        if(*p == ':')
            *p++ = 0;
    }
    dirs[n] = NIL(char*);

    return dirs;
}

#endif /*!_PACKAGE_ast*/

#if __STD_C
static int _tmpfd(Sfio_t* f)
#else
static int _tmpfd(f)
Sfio_t* f;
#endif
{
    reg char*   file;
    int     fd;

#if _PACKAGE_ast
    if(!(file = pathtemp(NiL,PATH_MAX,NiL,"sf",&fd)))
        return -1;
    _rmtmp(f, file);
    free(file);
#else
    int     t;

    /* set up path of dirs to create temp files */
    if(!Tmppath && !(Tmppath = _sfgetpath("TMPPATH")) )
    {   if(!(Tmppath = (char**)malloc(2*sizeof(char*))) )
            return -1;
        if(!(file = getenv("TMPDIR")) )
            file = TMPDFLT;
        if(!(Tmppath[0] = (char*)malloc(strlen(file)+1)) )
        {   free(Tmppath);
            Tmppath = NIL(char**);
            return -1;
        }
        strcpy(Tmppath[0],file);
        Tmppath[1] = NIL(char*);
    }

    /* set current directory to create this temp file */
    if(Tmpcur)
        Tmpcur += 1;
    if(!Tmpcur || !Tmpcur[0])
        Tmpcur = Tmppath;

    fd = -1;
    for(t = 0; t < 10; ++t)
    {   /* compute a random name */
        static ulong    Key, A;
        if(A == 0 || t > 0) /* get a quasi-random coefficient */
        {   reg int r;
            A = (ulong)time(NIL(time_t*)) ^ (((ulong)(&t)) >> 3);
            if(Key == 0)
                Key = (A >> 16) | ((A&0xffff)<<16);
            A ^= Key;
            if((r = (A-1) & 03) != 0) /* Knuth vol.2, page.16, Thm.A */
                A += 4-r;
        }

        Key = A*Key + 987654321;
        file = sfprints("%s/sf%3.3.32lu.%3.3.32lu",
                Tmpcur[0], (Key>>15)&0x7fff, Key&0x7fff);
        if(!file)
            return -1;
#if _has_oflags
        if((fd = sysopenf(file,O_RDWR|O_CREAT|O_EXCL|O_TEMPORARY,SF_CREATMODE)) >= 0)
            break;
#else
        if((fd = sysopenf(file,O_RDONLY)) >= 0)
        {   /* file already exists */
            CLOSE(fd);
            fd = -1;
        }
        else if((fd = syscreatf(file,SF_CREATMODE)) >= 0)
        {   /* reopen for read and write */
            CLOSE(fd);
            if((fd = sysopenf(file,O_RDWR)) >= 0)
                break;

            /* don't know what happened but must remove file */
            while(sysremovef(file) < 0 && errno == EINTR)
                errno = 0;
        }
#endif /* _has_oflags */
    }
    if(fd >= 0)
        _rmtmp(f, file);
#endif /* _PACKAGE_ast */
    return fd;
}

#if __STD_C
static int _tmpexcept(Sfio_t* f, int type, Void_t* val, Sfdisc_t* disc)
#else
static int _tmpexcept(f,type,val,disc)
Sfio_t*     f;
int     type;
Void_t*     val;
Sfdisc_t*   disc;
#endif
{
    reg int     fd, m;
    reg Sfio_t* sf;
    Sfio_t      newf, savf;
    void        (*notifyf)_ARG_((Sfio_t*, int, void*));

    NOTUSED(val);

    /* the discipline needs to change only under the following exceptions */
    if(type != SF_WRITE && type != SF_SEEK &&
       type != SF_DPUSH && type != SF_DPOP && type != SF_DBUFFER)
        return 0;

    /* notify function */
    notifyf = _Sfnotify;

    /* try to create the temp file */
    SFCLEAR(&newf,NIL(Vtmutex_t*));
    newf.flags = SF_STATIC;
    newf.mode = SF_AVAIL;

    if((fd = _tmpfd(f)) < 0 )
        return -1;

    /* make sure that the notify function won't be called here since
       we are only interested in creating the file, not the stream */
    _Sfnotify = 0;
    sf = sfnew(&newf,NIL(Void_t*),(size_t)SF_UNBOUND,fd,SF_READ|SF_WRITE);
    _Sfnotify = notifyf;
    if(!sf)
        return -1;

    if(newf.mutex) /* don't need a mutex for this stream */
    {   (void)vtmtxclrlock(newf.mutex);
        (void)vtmtxclose(newf.mutex);
        newf.mutex = NIL(Vtmutex_t*);
    }

    /* make sure that new stream has the same mode */
    if((m = f->flags&(SF_READ|SF_WRITE)) != (SF_READ|SF_WRITE))
        sfset(sf, ((~m)&(SF_READ|SF_WRITE)), 0);
    sfset(sf, (f->mode&(SF_READ|SF_WRITE)), 1);

    /* now remake the old stream into the new image */
    memcpy((Void_t*)(&savf), (Void_t*)f, sizeof(Sfio_t));
    memcpy((Void_t*)f, (Void_t*)sf, sizeof(Sfio_t));
    f->push = savf.push;
    f->pool = savf.pool;
    f->rsrv = savf.rsrv;
    f->proc = savf.proc;
    f->mutex = savf.mutex;
    f->stdio = savf.stdio;

    if(savf.data)
    {   SFSTRSIZE(&savf);
        if(!(savf.flags&SF_MALLOC) )
            (void)sfsetbuf(f,(Void_t*)savf.data,savf.size);
        if(savf.extent > 0)
            (void)sfwrite(f,(Void_t*)savf.data,(size_t)savf.extent);
        (void)sfseek(f,(Sfoff_t)(savf.next - savf.data),SEEK_SET);
        if((savf.flags&SF_MALLOC) )
            free((Void_t*)savf.data);
    }

    /* announce change of status */
    if(notifyf)
        (*notifyf)(f, SF_NEW, (void*)((long)f->file));

    f->disc = disc->disc;

    /* erase all traces of newf */
    newf.data = newf.endb = newf.endr = newf.endw = NIL(uchar*);
    newf.file = -1;
    sfclose(&newf);

    return 1;
}

#if __STD_C
Sfio_t* sftmp(size_t s)
#else
Sfio_t* sftmp(s)
size_t  s;
#endif
{
    Sfio_t*     f;
    static Sfdisc_t Tmpdisc =
            { NIL(Sfread_f), NIL(Sfwrite_f), NIL(Sfseek_f), _tmpexcept,
#if _tmp_rmfail
              &Rmdisc
#else
            NIL(Sfdisc_t*)
#endif
            };

    /* start with a memory resident stream */
    if(!(f = sfnew(NIL(Sfio_t*),NIL(char*),s,-1,SF_STRING|SF_READ|SF_WRITE)) )
        return NIL(Sfio_t*);

    if(s != (size_t)SF_UNBOUND) /* set up a discipline for out-of-bound, etc. */
        f->disc = &Tmpdisc;

    /* make the file now */
    if(s == 0 && _tmpexcept(f,SF_DPOP,NIL(Void_t*),f->disc) < 0)
    {   sfclose(f);
        return NIL(Sfio_t*);
    }

    return f;
}