sftmp.c   [plain text]

#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)
	{
		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(remove(ff->name) < 0 && errno == EINTR)
				errno = 0;

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

	return 0;
}

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

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

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

	return 0;
}

#if !_PACKAGE_ast
#include	<time.h>
#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;
	reg int		fd;
	int		t;

#if !_PACKAGE_ast
	/* 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;
#endif /*!_PACKAGE_ast*/

	file = NIL(char*); fd = -1;
	for(t = 0; t < 10; ++t)
	{	/* compute a random name */
#if !_PACKAGE_ast
		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);
#else
		file = pathtmp(file,NiL,"sf",NiL);
#endif /*!_PACKAGE_ast*/

		if(!file)
			return -1;
#if _has_oflags
		if((fd = open(file,O_RDWR|O_CREAT|O_EXCL|O_TEMPORARY,SF_CREATMODE)) >= 0)
			break;
#else
		if((fd = open(file,O_RDONLY)) >= 0)
		{	/* file already exists */
			CLOSE(fd);
			fd = -1;
		}
		else if((fd = creat(file,SF_CREATMODE)) >= 0)
		{	/* reopen for read and write */
			CLOSE(fd);
			if((fd = open(file,O_RDWR)) >= 0)
				break;

			/* don't know what happened but must remove file */
			while(remove(file) < 0 && errno == EINTR)
				errno = 0;
		}
#endif
	}

	if(fd >= 0)
		_rmtmp(f, file);
#if _PACKAGE_ast
	free(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, int));

	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 */
	{	vtmtxclrlock(newf.mutex);
		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),0);
		if((savf.flags&SF_MALLOC) )
			free((Void_t*)savf.data);
	}

	/* announce change of status */
	if(notifyf)
		(*notifyf)(f,SF_NEW,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(reg size_t s)
#else
Sfio_t* sftmp(s)
reg size_t	s;
#endif
{
	reg 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;
}