~ubuntu-branches/ubuntu/feisty/elvis/feisty

/* io.c */
/* Copyright 1995 by Steve Kirkendall */


#include "elvis.h"
#ifdef FEATURE_RCSID
char id_io[] = "$Id: io.c,v 2.62 2003/10/18 04:47:18 steve Exp $";
#endif

#if USE_PROTOTYPES
extern char *parseurl(char *url);
#endif

/* This file contains some generic I/O functions.  They can read/write to
 * either a file or a filter.  They perform efficient character-at-a-time
 * semantics by buffering the I/O requests.
 */


#ifdef FEATURE_COMPLETE
/* This is a list of characters which may have special meaning with filenames */
static CHAR dangerous[] = {' ', '#', '%', '*', '?', '[', '{', '\0'};
#endif

static ELVBOOL	reading;  /* ElvTrue if file/program open for reading */
static ELVBOOL	writing;  /* ElvTrue if file/program open for writing */
static ELVBOOL	forfile;  /* ElvTrue if I/O to file; ElvFalse for program */
static ELVBOOL	forstdio; /* ElvTrue if using stdin/stdout; ElvFalse otherwise */
static ELVBOOL	beautify; /* ElvTrue if we're supposed to strip control chars */
static char	convert;  /* One of {unix, dos, mac} else no conversion */
static ELVBOOL	cvtcr;	  /* did last DOS read end with a CR, before LF? */
static CHAR	tinybuf[100];
static int	tinyqty;
static int	tinyused;

#if defined(PROTOCOL_HTTP) || defined(PROTOCOL_FTP)
static ELVBOOL	forurl;   /* ElvTrue if I/O via HTTP; false otherwise */
#endif

#ifdef DEBUG_ALLOC
static char	*openfile; /* name of source file which opened current file */
static int	openline; /* line number within source file */
#endif

/* This function opens a file or program for either input or output.
 * It returns ElvTrue if successful.  If there are any errors, it issues an
 * error message and returns ElvFalse.
 *
 * "name" is the name of the file to open.  If the name begins with a '!'
 * then the rest of the name is interpretted as a program to be executed
 * instead of a program name.
 *
 * "rwa" can be 'r' to open the file/program for reading, 'w' to open the
 * file/program for writing, or 'a' to open a file for appending.  'a' can't
 * be used with programs.
 *
 * "prgsafe" is only significant if security!=normal, in which case this
 * function will fail if "name" refers to a program and prgsafe is ElvFalse.
 *
 * "force" can cause a file to be overwritten even if "name" and "oldname"
 * don't match.
 */
#ifdef DEBUG_ALLOC
ELVBOOL	_ioopen(file, line, name, rwa, prgsafe, force, eol)
	char	*file;	/* name of caller's source file */
	int	line;	/* line number within caller's source file */
#else
ELVBOOL	ioopen(name, rwa, prgsafe, force, eol)
#endif
	char	*name;	/* name of file, or "!program" */
	_char_	rwa;	/* one of {read, write, append} */
	ELVBOOL	prgsafe;/* If ElvTrue, allow "!program"; else refuse */
	ELVBOOL	force;	/* if ElvTrue, allow files to be clobbered */
	_char_	eol;	/* one of {unix, dos, mac, text, binary} */
{
	DIRPERM perms;

#ifdef DEBUG_ALLOC
	if (openfile)
		msg(MSG_FATAL, "[sdsd]$1,$2: file still open from $3,$4", file, line, openfile, openline);
	openfile = file;
	openline = line;
#endif
	assert(!reading && !writing);

	/* are we going to beautify this text? */
	beautify = (ELVBOOL)(o_beautify && eol != 'b');

	/* if conversion is equivalent to binary, then use binary */
	if ((eol == 'm' && '\n' == 015)
	 || (eol == 'u' && '\n' == 012))
	{
		eol = 'b';
	}

	/* nothing in the tiny buffer */
	tinyqty = tinyused = 0;

	/* If no file name, then fail */
	if (!name || !*name)
	{
		msg(MSG_WARNING, "missing file name");
		return ElvFalse;
	}

	/* Is this stdin/stdout? */
	if (!strcmp(name, "-"))
	{
#ifdef FEATURE_STDIN
		reading = (ELVBOOL)(rwa == 'r');
#else
		if (rwa == 'r')
			return ElvFalse;
		reading = ElvFalse;
#endif
		writing = (ELVBOOL)!reading;
		forstdio = ElvTrue;
		return ElvTrue;
	}
  	/* Is this a program? */
	else if (*name == '!')
	{
		/* check safety */
		if (o_security != 'n' /* normal */ && !prgsafe)
		{
			msg(MSG_ERROR, "unsafe filter");
#ifdef DEBUG_ALLOC
			openfile = NULL;
#endif
			return ElvFalse;
		}

		/* will we be reading or writing? */
		forfile = forstdio = ElvFalse;
		switch (rwa)
		{
		  case 'r':
			/* Open the program for reading, using the GUI-
			 * dependent version of prgopen() if there is one.
			 * Then call prggo() right away, since we aren't going
			 * to be calling prgwrite().
			 */
		  	if ((gui->prgopen
		  		? (*gui->prgopen)(name + 1, ElvFalse, ElvTrue)
				: prgopen(name + 1, ElvFalse, ElvTrue))
			    && prggo())
			{
				/* success! */
				reading = ElvTrue;
				return ElvTrue;
			}
			else
			{
				msg(MSG_ERROR, "[s]can't run $1", name + 1);
			}
#ifdef DEBUG_ALLOC
			openfile = NULL;
#endif
			return ElvFalse;

		  case 'w':
			/* Open the program.  Note that if there is no GUI-
			 * dependent version of prgopen(), then we'll need to
			 * explicitly read the program's output and display it
			 * in the window, so we call the generic prgopen()
			 * for both writing and reading.
			 */
		  	if (gui->prgopen
		  		? (*gui->prgopen)(name + 1, ElvTrue, ElvFalse)
				: prgopen(name + 1, ElvTrue, ElvTrue))
		  	{
				writing = ElvTrue;
				return ElvTrue;
			}
			msg(MSG_ERROR, "[s]can't run $1", name + 1);
#ifdef DEBUG_ALLOC
			openfile = NULL;
#endif
			return ElvFalse;

		  default:
			msg(MSG_ERROR, "can't append to filter");
#ifdef DEBUG_ALLOC
			openfile = NULL;
#endif
			return ElvFalse;
		}
	}

#if defined(PROTOCOL_HTTP) || defined(PROTOCOL_FTP)
	/* is it a remote URL? */
	if (urlremote(name))
	{
		/* try to open the resource via the network */
		if (!urlopen(name, force, rwa))
		{
			/* error message already given */
#ifdef DEBUG_ALLOC
			openfile = NULL;
#endif
			return ElvFalse;
		}

		/* remember that we're using an URL */
		forurl = ElvTrue;
		forstdio = forfile = ElvFalse;
		reading = (ELVBOOL)(rwa == 'r');
		writing = (ELVBOOL)!reading;
		return ElvTrue;
	}
#endif

	/* Anything else must be a plain old file */
	name = urllocal(name);
	if (!name)
	{
		msg(MSG_ERROR, "unsupported protocol");
#ifdef DEBUG_ALLOC
			openfile = NULL;
#endif
		return ElvFalse;
	}

	/* try to open the file */
	forstdio = ElvFalse;
	forfile = ElvTrue;
	convert = eol;
	cvtcr = ElvFalse;
	perms = urlperm(name);
	switch (rwa)
	{
	  case 'r':
		if ((perms == DIR_READONLY || perms == DIR_READWRITE)
			&& txtopen(name, 'r', (ELVBOOL)(convert != 't')) == 0)
		{
			reading = ElvTrue;
			return ElvTrue;
		}
		break;

	  case 'a':
		if (perms == DIR_READWRITE
		     && txtopen(name, 'a', (ELVBOOL)(convert != 't')) == 0)
		{
			writing = ElvTrue;
			return ElvTrue;
		}
		/* else fall through to the 'w' case */

	  case 'w':
		if ((perms == DIR_NEW || perms == DIR_NOTFILE ||
			(perms == DIR_READWRITE && (force || o_writeany)))
		     && txtopen(name, 'w', (ELVBOOL)(convert != 't')) == 0)
		{
			writing = ElvTrue;
			return ElvTrue;
		}
		break;

	}

	/* If we get here, we failed.  "perms" gives clue as to why */
	switch (perms)
	{
	  case DIR_INVALID:	msg(MSG_ERROR, "[s]malformed file name $1", name);	break;
	  case DIR_BADPATH:	msg(MSG_ERROR, "[s]bad path $1", name);			break;
	  case DIR_NOTFILE:	msg(MSG_ERROR, "[s]$1 is not a file", name);		break;
	  case DIR_DIRECTORY:	msg(MSG_ERROR, "[s]$1 is a directory", name);		break;
	  case DIR_NEW:		msg(MSG_ERROR, "[s]$1 doesn't exist", name);		break;
	  case DIR_UNREADABLE:	msg(MSG_ERROR, "[s]$1 unreadable", name);		break;
	  case DIR_READONLY:	msg(MSG_ERROR, "[s]$1 unwritable", name);		break;
	  case DIR_READWRITE:	msg(MSG_ERROR, "[s]$1 exists", name);			break;
	}
#ifdef DEBUG_ALLOC
	openfile = NULL;
#endif
	return ElvFalse;
}

/* This function writes the contents of a given I/O buffer.  "iobuf" points
 * to the buffer, and "len" is the number of CHARs in that buffer.  This
 * function returns the number of CHARs actually written; values less than
 * "len" indicate trouble.
 */
int iowrite(iobuf, len)
	CHAR	*iobuf;	/* RAM buffer containing text */
	int	len;	/* number of CHARs in iobuf */
{
	int	base, okay;
 static	CHAR	crlf[2] = {015, 012};
	assert(writing);

	/* write to the file/program */
	if (forstdio)
	{
		return fwrite(iobuf, sizeof(CHAR), (size_t)len, stdout);
	}
	else if (forfile)
	{
		switch (convert)
		{
		  case 'u':
		  case 'd':
		  case 'm':
			for (base = okay = 0; base + okay < len; okay++)
			{
				if (iobuf[base + okay] == '\n')
				{
					if (okay > 0)
						txtwrite(&iobuf[base], okay);
					switch (convert)
					{
					  case 'u': txtwrite(crlf+1, 1); break;
					  case 'd': txtwrite(crlf, 2);	 break;
					  case 'm': txtwrite(crlf, 1);	 break;
					}
					base += okay + 1;
					okay = -1;
				}
			}
			if (okay > 0)
				txtwrite(&iobuf[base], okay);
			return base + okay;

		  default:
			return txtwrite(iobuf, len);
		}
	}
#if defined(PROTOCOL_HTTP) || defined(PROTOCOL_FTP)
	else if (forurl)
	{
		return urlwrite(iobuf, len);
	}
#endif
	else
	{
		return prgwrite(iobuf, len);
	}
}

/* This function fills a given I/O buffer with text read from the file/program.
 * "iobuf" points to the buffer, and "len" is the maximum number of CHARs that
 * it can hold.  This function returns the number of CHARs actually read, or
 * 0 at the end of the file.  If the "beautify" option is ElvTrue, it strips
 * control characters.
 */
int ioread(iobuf, len)
	CHAR	*iobuf;	/* RAM buffer to receive input text */
	int	len;	/* maximum number of bytes to read */
{
	int	nread;	/* number of CHARs read */
	int	i, j;

	assert(reading);

	/* if trying to read a suitably tiny amount, then use the tinybuf
	 * instead of the user's buffer, so we can reduce syscalls.
	 */
	if (iobuf != tinybuf && len < QTY(tinybuf) && tinyused >= tinyqty)
	{
		tinyqty = ioread(tinybuf, QTY(tinybuf));
		tinyused = 0;
	}

	/* maybe we can fetch from the tiny buffer? */
	if (tinyqty > tinyused)
	{
		if (len > tinyqty - tinyused)
			len = tinyqty - tinyused;
		memcpy(iobuf, tinybuf + tinyused, len);
		tinyused += len;
		return len;
	}

	/* read from the file/program */
	if (forstdio)
	{
#ifdef FEATURE_STDIN
		nread = fread(iobuf, sizeof(CHAR), (size_t)len, origstdin);
#else
		nread = 0;
#endif
	}
	else if (forfile)
	{
		if (cvtcr)
		{
			iobuf[0] = 015;
			nread = 1 + txtread(iobuf + 1, len - 1);
			cvtcr = ElvFalse;
		}
		else
			nread = txtread(iobuf, len);

		/* convert, if necessary */
		switch (convert)
		{
		  case 'u':
		  	if ('\n' == 012)
		  		break;
			for (i = 0; i < nread; i++)
			{
				if (iobuf[nread] == 012)
					iobuf[nread] = '\n';
			}
			break;

		  case 'd':
			for (i = j = 0; i < nread; i++, j++)
			{
				if (iobuf[i] == 015 && nread > 1)
				{
					if (i + 1 >= nread)
						cvtcr = ElvTrue, j--;
					else if (iobuf[i + 1] == 012)
						iobuf[j] = '\n', i++;
					else
						iobuf[j] = iobuf[i];
				}
				else
					iobuf[j] = iobuf[i];
			}
			nread = j;
			break;

		  case 'm':
			for (i = 0; i < nread; i++)
			{
				if (iobuf[i] == 015)
					iobuf[i] = '\n';
			}
			break;
		}
	}
#if defined(PROTOCOL_HTTP) || defined(PROTOCOL_FTP)
	else if (forurl)
	{
		nread = urlread(iobuf, len);
	}
#endif
	else
	{
		nread = prgread(iobuf, len);
	}

	/* maybe strip control characters */
	if (beautify && nread > 0)
	{
		for (i = j = 0; i < nread; i++)
		{
			if (iobuf[i] >= ' ' || iobuf[i] == '\t' || iobuf[i] == '\n' || iobuf[i] == '\f')
			{
				iobuf[j++] = iobuf[i];
			}
		}
		nread = j;
	}

	/* return number of bytes read */
	return nread;
}

/* Close a file that was opened via ioopen().  Return TRUE if successful, or
 * FALSE if something went wrong.  Generally, the only way something could go
 * wrong is if you're writing to a program, and the program's exit code != 0
 */
ELVBOOL	ioclose()
{
	CHAR	*rdbuf;
	int	nbytes;
	ELVBOOL	origrefresh;

	assert(reading || writing);
#ifdef DEBUG_ALLOC
	openfile = NULL;
#endif

	/* don't really close stdin/stdout; just reset variables */
	if (forstdio)
	{
		if (writing)
			fflush(stdout);
		forstdio = reading = writing = ElvFalse;
		return ElvTrue;
	}

	/* completing I/O for a file is easy */
	if (forfile)
	{
		txtclose();
		reading = writing = ElvFalse;
		return ElvTrue;
	}

#if defined(PROTOCOL_HTTP) || defined(PROTOCOL_FTP)
	/* completing for HTTP is easy */
	if (forurl)
	{
		urlclose();
		reading = writing = forurl = ElvFalse;
		return ElvTrue;
	}
#endif

	/* Writing to a program; we need to call prggo() now.  Also, if there
	 * is no gui->prgopen() function then we need to explicitly copy the
	 * program's output to the current window, so the user can see error
	 * messages and other results.
	 */
	if (writing && prggo() && !gui->prgopen && windefault)
	{
		drawopencomplete(windefault);
		origrefresh = o_exrefresh;
		o_exrefresh = ElvTrue;
		rdbuf = (CHAR *)safealloc(1024, sizeof(CHAR));
		while ((nbytes = prgread(rdbuf, 1024)) > 0)
		{
			drawextext(windefault, rdbuf, nbytes);
		}
		safefree(rdbuf);
		o_exrefresh = origrefresh;
	}

	/* if we wrote to a program with an explicit prgopen() command, then
	 * there may have been output that we don't know about.  Force the
	 * window into DRAW_OPENOUTPUT mode so we have to hit <Enter> to
	 * continue.
	 */
	if (writing && gui->prgopen && windefault)
	{
		drawopencomplete(windefault);
	}

	/* wait for the program to exit.  Succeed only if its exit code is 0 */
	reading = writing = ElvFalse;
	return (ELVBOOL)((gui->prgclose ? (*gui->prgclose)() : prgclose()) == 0);
}



/* This function parses a "path" string into directory names, and checks each
 * directory until finds a readable file named "filename".  If the "usefile"
 * flag is ElvTrue, then if an element of the path happens to be a file name
 * instead of a directory name, then it will also use that as the file name.
 *
 * If NULL is passed instead of a "path" string, then this function will
 * continue the previous path search instead of starting a new one.
 *
 * Returns the full pathname of the first readable file that it finds, or
 * NULL if it reaches the end of the path without finding one.
 */
char *iopath(path, filename, usefile)
	char	    *path;	/* list of directories to search */
	char	    *filename;	/* name of file to look for in each directory */
	ELVBOOL	    usefile;	/* allow path to contain filenames */
{
	static char *next;	/* the directory after this one */
	static char name[256];	/* full pathname, possibly of a readable file */
	int	    i;		/* used for building name */
	DIRPERM	    perms;	/* permissions of the file */

	/* if path was named, start from there; else continue previous search */
	if (path)
	{
		next = path;
	}

	/* repeat until we find a readable file... */
	do
	{
		/* if no place left to try, then quit */
		if (!next)
		{
			return (char *)0;
		}

		/* if next path element starts with ~, then use HOME instead */
		if (next[0] == '~' && !elvalnum(next[1]))
		{
			/* copy HOME into name buffer */
			strcpy(name, tochar8(o_home));
			i = strlen(name);
			next++;

			/* bug in MS network, we don't want \\ in filename */
			if (i > 0 && (name[i-1] == '/' || name[i-1] == '\\') &&
			    next != NULL && (*next == '/' || *next == '\\'))
                                i--;
		}
		/* else if path element starts with "./" then use the current
		 * file's directory.  (unless there is no current file)
		 */
		else if (next[0] == '.'
		     && (next[1] == '/' || next[1] == '\\')
		     && bufdefault
		     && o_filename(bufdefault))
		{
			/* copy file's directory into name buffer */
			strcpy(name, dirdir(tochar8(o_filename(bufdefault))));
			i = strlen(name);
			next++;
		}
		else
		{
			i = 0;
		}

		/* copy characters up to next delimiter or end */
		while (*next && *next != OSPATHDELIM)
		{
			name[i++] = *next++;
		}
		name[i] = '\0';

		/* if this was the end of the path, then there is no "next" */
		if (!*next)
		{
			next = (char *)0;
		}
		else
		{
			/* skip delimiter */
			next++;
		}

		/* If files are allowed and this is a readable file, use it.
		 * Otherwise we'll need to append the filename and try that.
		 */
		if (!usefile ||
		   ((perms = dirperm(name)) != DIR_READONLY && perms != DIR_READWRITE))
		{
			/* append the filename */
			path = dirpath(*name ? name : ".", filename);
			strcpy(name, path);
			perms = dirperm(name);
		}
	} while (perms != DIR_READONLY && perms != DIR_READWRITE);

	/* return the found name */
	return name;
}

#ifdef FEATURE_COMPLETE

# if FILES_IGNORE_CASE
/* Compare two strings for equality, ignoring case differences.  Note that
 * unlike strcmp(), this function does *NOT* indicate which string comes first
 * if they don't match.
 */
static int ustrncmp(s1, s2, len)
	char	*s1, *s2;
	int	len;
{
	while (--len >= 0 && (*s1 || *s2))
	{
		if (elvtoupper(*s1) != elvtoupper(*s2))
			return 1;
		s1++;
		s2++;
	}
	return 0;
}
# endif /* FILES_IGNORE_CASE */

/* This function implements filename completion.  You pass it a partial
 * filename and it uses dirfirst()/dirnext() to extend the name.  If you've
 * given enough to uniquely identify a file, then it will also append a
 * tab after the filename.
 */
char *iofilename(partial, endchar)
	char	*partial;	/* a partial filenam to expand */
	_char_	endchar;	/* char to append if match found */
{
	char		homed[256];	/* partial, with "~" replaced by home */
	static char	match[256];	/* the matching text */
	unsigned	matchlen;	/* # of leading identical characters */
	int		nmatches;	/* number of matches */
	char		*fname;		/* name of a matching file */
	char		*bname;		/* basename (fname without path) */
	CHAR		*str;		/* name with/without quotes */
	int		col;		/* width of directory listing */
	ELVFNR		rules;		/* file name parsing rules */
	CHAR		slashstr[1];

	/* If paranoid, then don't allow filename completion either */
	if (o_security == 'r' /* restricted */)
		return NULL;

	/* parse the rules */
	rules = exfilenamerules(o_filenamerules);

	/* remove quotes (backslashes) from before certain characters */
	str = removequotes(dangerous, toCHAR(partial));

	/* replace ~ with home directory name, ~+ with current directory name,
	 * ~- with previous directory name, or (for Unix only) ~user with the
	 * home directory of the named user.
	 */
	if (rules & ELVFNR_TILDE)
	{
#if defined(ANY_UNIX) && defined(FEATURE_MISC)
		if (str[0] == '~' && elvalpha(str[1]))
		{
			expanduserhome(tochar8(str), homed);
		}
		else
#endif /* ANY_UNIX && FEATURE_MISC */
		if (str[0] == '~' && str[1] == OSDIRDELIM)
		{
			strcpy(homed, dirpath(tochar8(o_home), tochar8(str + 2)));
		}
		else if (str[0] == '~' && str[1] == '+' && str[2] == OSDIRDELIM)
		{
			strcpy(homed, dirpath(dircwd(), tochar8(str + 3)));
		}
		else if (str[0] == '~' && str[1] == '-' && str[2] == OSDIRDELIM)
		{
			strcpy(homed, dirpath(tochar8(o_previousdir), tochar8(str + 3)));
		}
		else
		{
			strcpy(homed, tochar8(str));
		}
	}
	else
	{
		strcpy(homed, tochar8(str));
	}
	partial = homed;
	safefree(str);

	/* count the matching filenames */
	for (nmatches = matchlen = 0, fname = dirfirst(partial, ElvTrue);
	     fname;
	     nmatches++, fname = dirnext())
	{
		/* skip if binary.  Keep directories, though */
		if (!o_completebinary		    /* we want to skip binaries */
		 && dirperm(fname) != DIR_DIRECTORY /* but not directories */
		 && *ioeol(fname) == 'b')	    /* and this is a binary */
		{
			nmatches--;
			continue;
		}

		if (nmatches == 0)
		{
			strcpy(match, fname);
			matchlen = strlen(match);
		}
		else
		{
#if FILES_IGNORE_CASE
			while (matchlen > 0 && ustrncmp(match, fname, (size_t)matchlen))
				matchlen--;
#else
			while (matchlen > 0 && strncmp(match, fname, (size_t)matchlen))
				matchlen--;
#endif
		}
	}

	/* Filename completion should never reduce the partial file name!
	 * We need to guard against this, because if the filesystem is
	 * case-insensitive (as with Windows, but not Unix), then the list
	 * of matching file names could contain both upper- and lowercase
	 * names, which have *zero* matching characters.
	 */
	if (matchlen < strlen(partial))
		matchlen = strlen(partial);

	/* so what did we come up with? */
	if (nmatches == 1)
	{
		/* unique match... */

		/* decide whether to append a slash or tab */
		if (dirperm(match) == DIR_DIRECTORY)
			endchar = OSDIRDELIM;
		
		/* append a tab or slash, and return it */
		match[matchlen] = endchar;
		match[matchlen + 1] = '\0';
		return match;
	}
	else if (nmatches > 0 && matchlen > 0)
	{
		/* multiple matches... */

		/* can we add any chars to the partial name? */
		if ((unsigned)matchlen <= strlen(partial) && !strncmp(partial, match, matchlen))
		{
			/* No - list all matches */
			for (fname = dirfirst(partial, ElvTrue), col = 0;
			     fname;
			     fname = dirnext())
			{
				/* skip binary files */
				if (!o_completebinary
				 && dirperm(fname) != DIR_DIRECTORY
				 && *ioeol(fname) == 'b')
					continue;

				/* space between names */
				bname = dirfile(fname);
				if (col + strlen(bname) + 2 >= (unsigned)o_columns(windefault))
				{
					drawextext(windefault, toCHAR("\n"), 1);
					col = 0;
				}
				else if (col > 0)
				{
					drawextext(windefault, toCHAR(" "), 1);
					col++;
				}

				/* show the name, without its path */
				drawextext(windefault, toCHAR(bname), strlen(bname));
				col += strlen(bname);

				/* if directory, then append a slash */
				if (dirperm(fname) == DIR_DIRECTORY)
				{
					slashstr[0] = OSDIRDELIM;
					drawextext(windefault, slashstr, 1);
					col++;
				}
			}
			if (col > 0)
			{
				drawextext(windefault, toCHAR("\n"), 1);
			}
		}

		/* Either way - return the common part of all matches */
		match[matchlen] = '\0';
		return match;
	}
	else
	{
		/* no match, or matches have nothing in common */
		return (char *)0;
	}
}
#endif /* FEATURE_COMPLETE */


/* This function tries to guess what type of newline a given file uses.
 * Returns "binary" if there is a NUL in the first few bytes.
 *         "unix"   if there is a solitary LF character.
 *         "dos"    if the first CR is followed by a LF.
 *         "mac"    if the first CR is followed by anything but LF.
 *         "text"   otherwise; e.g., for new or empty files.
 */
char *ioeol(filename)
	char	*filename;	/* name of file to check */
{
	int	nbytes;	/* number of bytes read from file */
	int	i;

#ifdef PROTOCOL_HTTP
	/* check for a protocol */
	for (i = 0; elvalpha(filename[i]); i++)
	{
	}
	if (i < 2 || filename[i] != ':')
		i = 0;

	/* assume all protocols are binary except "file:" */
	if (!strncmp(filename, "file:", 5))
		filename += i + 1;
	else if (i > 0)
		return "binary";
#endif

#ifdef FEATURE_STDIN
	/* we don't dare read from stdin to check */
	if (!strcmp(filename, "-"))
		return "text";
#endif

	/* fill tinybuf with bytes from the beginning of the file */
	nbytes = 0;
	if (txtopen(filename, 'r', ElvTrue) == 0)
	{
		nbytes = txtread(tinybuf, QTY(tinybuf));
		txtclose();
	}

	/* look for a NUL */
	for (i = 0; i < nbytes; i++)
	{
		if (tinybuf[i] == 0)
			return "binary";
	}

	/* look for an LF that isn't preceeded by a CR */
	for (i = 0; i < nbytes - 1; i++)
	{
		if (tinybuf[i] == 012 /* linefeed */
		 && (i == 0 || tinybuf[i - 1] != 015)) /* carriage return */
			return "unix";
	}

	/* look for the CR -- is it followed by a LF? */
	for (i = 0; i < nbytes - 1; i++)
	{
		if (tinybuf[i] == 015) /* carriage return */
		{
			if (tinybuf[i + 1] == 012) /* linefeed */
				return "dos";
			else
				return "mac";
		}
	}

	/* if all else fails, assume "text" */
	return "text";
}

/* return an absolute version of a filename */
char *ioabsolute(filename)
	char	*filename;
{
	char	*c, *dir;

	/* If not a local URL then just return it unchanged */
	c = urllocal(filename);
	if (!c)
		return filename;

#ifdef FEATURE_STDIN
	/* if "-" (meaning stdin/stdout) then leave it unchanged */
	if (!strcmp(filename, "-"))
		return filename;
#endif

	/* Combine the given filename and the current working directory.
	 * Note that dirpath() is smart enough to leave names that are already
	 * absolute unchanged.
	 */
	filename = dirpath(dircwd(), c);

	/* Now we need to eliminate "dir/.." from the name, if it occurs */
	for (c = filename; *c; c++)
	{
		/* skip if not "/../" */
		if (c[0] != OSDIRDELIM
		 || c[1] != '.'
		 || c[2] != '.'
		 || (c[3] != OSDIRDELIM && c[3] != '\0'))
			continue;

		/* search backward for the previous directory */
		c[0] = '\0';
		dir = strrchr(filename, OSDIRDELIM);
		if (!dir)
			dir = c;
		c += 3;
		memmove(dir, c, strlen(c)+1);
		c = dir - 1; /* plus 1, in the for-loop reinitializer */
	}

	/* We also want to eliminate "/./" from the name, if it occurs */
	for (c = filename; *c; c++)
	{
		/* skip if not "/./" */
		if (c[0] != OSDIRDELIM
		 || c[1] != '.'
		 || c[2] != OSDIRDELIM)
			continue;

		/* eliminate it */
		memmove(c, c+2, strlen(c+2) + 1);

		/* decrement c to counteract the "c++" in the for loop,
		 * because we want to recheck this char to detect consecutive
		 * instances of "/./"
		 */
		c--;
	}

	/* If the name was reduced to "" (which can only happen if we're given
	 * a directory name ending with "/..", by the way) then use "/" instead.
	 */
	if (!*filename)
	{
		filename[0] = OSDIRDELIM;
		filename[1] = '\0';
	}

	/* return the name */
	return filename;
}