1/*	$NetBSD: ifile.c,v 1.5 2023/10/06 05:49:49 simonb Exp $	*/
2
3/*
4 * Copyright (C) 1984-2023  Mark Nudelman
5 *
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Less License, as specified in the README file.
8 *
9 * For more information, see the README file.
10 */
11
12
13/*
14 * An IFILE represents an input file.
15 *
16 * It is actually a pointer to an ifile structure,
17 * but is opaque outside this module.
18 * Ifile structures are kept in a linked list in the order they
19 * appear on the command line.
20 * Any new file which does not already appear in the list is
21 * inserted after the current file.
22 */
23
24#include "less.h"
25
26extern IFILE    curr_ifile;
27
28struct ifile {
29	struct ifile *h_next;           /* Links for command line list */
30	struct ifile *h_prev;
31	char *h_filename;               /* Name of the file */
32	char *h_rfilename;              /* Canonical name of the file */
33	void *h_filestate;              /* File state (used in ch.c) */
34	int h_index;                    /* Index within command line list */
35	int h_hold;                     /* Hold count */
36	char h_opened;                  /* Has this ifile been opened? */
37	struct scrpos h_scrpos;         /* Saved position within the file */
38	void *h_altpipe;                /* Alt pipe */
39	char *h_altfilename;            /* Alt filename */
40};
41
42/*
43 * Convert an IFILE (external representation)
44 * to a struct file (internal representation), and vice versa.
45 */
46#define int_ifile(h)    ((struct ifile *)(h))
47#define ext_ifile(h)    ((IFILE)(h))
48
49/*
50 * Anchor for linked list.
51 */
52static struct ifile anchor = { &anchor, &anchor, NULL, NULL, NULL, 0, 0, '\0',
53				{ NULL_POSITION, 0 } };
54static int ifiles = 0;
55
56static void incr_index(struct ifile *p, int incr)
57{
58	for (;  p != &anchor;  p = p->h_next)
59		p->h_index += incr;
60}
61
62/*
63 * Link an ifile into the ifile list.
64 */
65static void link_ifile(struct ifile *p, struct ifile *prev)
66{
67	/*
68	 * Link into list.
69	 */
70	if (prev == NULL)
71		prev = &anchor;
72	p->h_next = prev->h_next;
73	p->h_prev = prev;
74	prev->h_next->h_prev = p;
75	prev->h_next = p;
76	/*
77	 * Calculate index for the new one,
78	 * and adjust the indexes for subsequent ifiles in the list.
79	 */
80	p->h_index = prev->h_index + 1;
81	incr_index(p->h_next, 1);
82	ifiles++;
83}
84
85/*
86 * Unlink an ifile from the ifile list.
87 */
88static void unlink_ifile(struct ifile *p)
89{
90	p->h_next->h_prev = p->h_prev;
91	p->h_prev->h_next = p->h_next;
92	incr_index(p->h_next, -1);
93	ifiles--;
94}
95
96/*
97 * Allocate a new ifile structure and stick a filename in it.
98 * It should go after "prev" in the list
99 * (or at the beginning of the list if "prev" is NULL).
100 * Return a pointer to the new ifile structure.
101 */
102static struct ifile * new_ifile(char *filename, struct ifile *prev)
103{
104	struct ifile *p;
105
106	/*
107	 * Allocate and initialize structure.
108	 */
109	p = (struct ifile *) ecalloc(1, sizeof(struct ifile));
110	p->h_filename = save(filename);
111	p->h_rfilename = lrealpath(filename);
112	p->h_scrpos.pos = NULL_POSITION;
113	p->h_opened = 0;
114	p->h_hold = 0;
115	p->h_filestate = NULL;
116	p->h_altfilename = NULL;
117	p->h_altpipe = NULL;
118	link_ifile(p, prev);
119	/*
120	 * {{ It's dodgy to call mark.c functions from here;
121	 *    there is potentially dangerous recursion.
122	 *    Probably need to revisit this design. }}
123	 */
124	mark_check_ifile(ext_ifile(p));
125	return (p);
126}
127
128/*
129 * Delete an existing ifile structure.
130 */
131public void del_ifile(IFILE h)
132{
133	struct ifile *p;
134
135	if (h == NULL_IFILE)
136		return;
137	/*
138	 * If the ifile we're deleting is the currently open ifile,
139	 * move off it.
140	 */
141	unmark(h);
142	if (h == curr_ifile)
143		curr_ifile = getoff_ifile(curr_ifile);
144	p = int_ifile(h);
145	unlink_ifile(p);
146	free(p->h_rfilename);
147	free(p->h_filename);
148	free(p);
149}
150
151/*
152 * Get the ifile after a given one in the list.
153 */
154public IFILE next_ifile(IFILE h)
155{
156	struct ifile *p;
157
158	p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
159	if (p->h_next == &anchor)
160		return (NULL_IFILE);
161	return (ext_ifile(p->h_next));
162}
163
164/*
165 * Get the ifile before a given one in the list.
166 */
167public IFILE prev_ifile(IFILE h)
168{
169	struct ifile *p;
170
171	p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
172	if (p->h_prev == &anchor)
173		return (NULL_IFILE);
174	return (ext_ifile(p->h_prev));
175}
176
177/*
178 * Return a different ifile from the given one.
179 */
180public IFILE getoff_ifile(IFILE ifile)
181{
182	IFILE newifile;
183
184	if ((newifile = prev_ifile(ifile)) != NULL_IFILE)
185		return (newifile);
186	if ((newifile = next_ifile(ifile)) != NULL_IFILE)
187		return (newifile);
188	return (NULL_IFILE);
189}
190
191/*
192 * Return the number of ifiles.
193 */
194public int nifile(void)
195{
196	return (ifiles);
197}
198
199/*
200 * Find an ifile structure, given a filename.
201 */
202static struct ifile * find_ifile(char *filename)
203{
204	struct ifile *p;
205	char *rfilename = lrealpath(filename);
206
207	for (p = anchor.h_next;  p != &anchor;  p = p->h_next)
208	{
209		if (strcmp(rfilename, p->h_rfilename) == 0)
210		{
211			/*
212			 * If given name is shorter than the name we were
213			 * previously using for this file, adopt shorter name.
214			 */
215			if (strlen(filename) < strlen(p->h_filename))
216			{
217				free(p->h_filename);
218				p->h_filename = save(filename);
219			}
220			break;
221		}
222	}
223	free(rfilename);
224	if (p == &anchor)
225		p = NULL;
226	return (p);
227}
228
229/*
230 * Get the ifile associated with a filename.
231 * If the filename has not been seen before,
232 * insert the new ifile after "prev" in the list.
233 */
234public IFILE get_ifile(char *filename, IFILE prev)
235{
236	struct ifile *p;
237
238	if ((p = find_ifile(filename)) == NULL)
239		p = new_ifile(filename, int_ifile(prev));
240	return (ext_ifile(p));
241}
242
243/*
244 * Get the display filename associated with a ifile.
245 */
246public char * get_filename(IFILE ifile)
247{
248	if (ifile == NULL)
249		return (NULL);
250	return (int_ifile(ifile)->h_filename);
251}
252
253/*
254 * Get the canonical filename associated with a ifile.
255 */
256public char * get_real_filename(IFILE ifile)
257{
258	if (ifile == NULL)
259		return (NULL);
260	return (int_ifile(ifile)->h_rfilename);
261}
262
263/*
264 * Get the index of the file associated with a ifile.
265 */
266public int get_index(IFILE ifile)
267{
268	return (int_ifile(ifile)->h_index);
269}
270
271/*
272 * Save the file position to be associated with a given file.
273 */
274public void store_pos(IFILE ifile, struct scrpos *scrpos)
275{
276	int_ifile(ifile)->h_scrpos = *scrpos;
277}
278
279/*
280 * Recall the file position associated with a file.
281 * If no position has been associated with the file, return NULL_POSITION.
282 */
283public void get_pos(IFILE ifile, struct scrpos *scrpos)
284{
285	*scrpos = int_ifile(ifile)->h_scrpos;
286}
287
288/*
289 * Mark the ifile as "opened".
290 */
291public void set_open(IFILE ifile)
292{
293	int_ifile(ifile)->h_opened = 1;
294}
295
296/*
297 * Return whether the ifile has been opened previously.
298 */
299public int opened(IFILE ifile)
300{
301	return (int_ifile(ifile)->h_opened);
302}
303
304public void hold_ifile(IFILE ifile, int incr)
305{
306	int_ifile(ifile)->h_hold += incr;
307}
308
309public int held_ifile(IFILE ifile)
310{
311	return (int_ifile(ifile)->h_hold);
312}
313
314public void * get_filestate(IFILE ifile)
315{
316	return (int_ifile(ifile)->h_filestate);
317}
318
319public void set_filestate(IFILE ifile, void *filestate)
320{
321	int_ifile(ifile)->h_filestate = filestate;
322}
323
324public void set_altpipe(IFILE ifile, void *p)
325{
326	int_ifile(ifile)->h_altpipe = p;
327}
328
329public void *get_altpipe(IFILE ifile)
330{
331	return (int_ifile(ifile)->h_altpipe);
332}
333
334public void set_altfilename(IFILE ifile, char *altfilename)
335{
336	struct ifile *p = int_ifile(ifile);
337	if (p->h_altfilename != NULL && p->h_altfilename != altfilename)
338		free(p->h_altfilename);
339	p->h_altfilename = altfilename;
340}
341
342public char * get_altfilename(IFILE ifile)
343{
344	return (int_ifile(ifile)->h_altfilename);
345}
346
347#if 0
348public void if_dump(void)
349{
350	struct ifile *p;
351
352	for (p = anchor.h_next;  p != &anchor;  p = p->h_next)
353	{
354		printf("%x: %d. <%s> pos %d,%x\n",
355			p, p->h_index, p->h_filename,
356			p->h_scrpos.ln, p->h_scrpos.pos);
357		ch_dump(p->h_filestate);
358	}
359}
360#endif
361