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15637ed4 RG |
1 | /* blk.c */ |
2 | ||
3 | /* Author: | |
4 | * Steve Kirkendall | |
5 | * 14407 SW Teal Blvd. #C | |
6 | * Beaverton, OR 97005 | |
7 | * kirkenda@cs.pdx.edu | |
8 | */ | |
9 | ||
10 | ||
11 | /* This file contains the functions that get/put blocks from the temp file. | |
12 | * It also contains the "do" and "undo" functions. | |
13 | */ | |
14 | ||
15 | #include "config.h" | |
16 | #include "vi.h" | |
17 | ||
18 | #ifndef NBUFS | |
19 | # define NBUFS 5 /* must be at least 3 -- more is better */ | |
20 | #endif | |
21 | ||
22 | ||
23 | /*------------------------------------------------------------------------*/ | |
24 | ||
25 | BLK hdr; /* buffer for the header block */ | |
26 | ||
27 | static int b4cnt; /* used to count context of beforedo/afterdo */ | |
28 | static struct _blkbuf | |
29 | { | |
30 | BLK buf; /* contents of a text block */ | |
31 | unsigned short logical; /* logical block number */ | |
32 | int dirty; /* must the buffer be rewritten? */ | |
33 | } | |
34 | blk[NBUFS], /* buffers for text[?] blocks */ | |
35 | *toonew, /* buffer which shouldn't be recycled yet */ | |
36 | *newtoo, /* another buffer which should be recycled */ | |
37 | *recycle = blk; /* next block to be recycled */ | |
38 | ||
39 | ||
40 | ||
41 | ||
42 | ||
43 | /* This function wipes out all buffers */ | |
44 | void blkinit() | |
45 | { | |
46 | int i; | |
47 | ||
48 | for (i = 0; i < NBUFS; i++) | |
49 | { | |
50 | blk[i].logical = 0; | |
51 | blk[i].dirty = FALSE; | |
52 | } | |
53 | for (i = 0; i < MAXBLKS; i++) | |
54 | { | |
55 | hdr.n[i] = 0; | |
56 | } | |
57 | } | |
58 | ||
59 | /* This function allocates a buffer and fills it with a given block's text */ | |
60 | BLK *blkget(logical) | |
61 | int logical; /* logical block number to fetch */ | |
62 | { | |
63 | REG struct _blkbuf *this; /* used to step through blk[] */ | |
64 | REG int i; | |
65 | ||
66 | /* if logical is 0, just return the hdr buffer */ | |
67 | if (logical == 0) | |
68 | { | |
69 | return &hdr; | |
70 | } | |
71 | ||
72 | /* see if we have that block in mem already */ | |
73 | for (this = blk; this < &blk[NBUFS]; this++) | |
74 | { | |
75 | if (this->logical == logical) | |
76 | { | |
77 | newtoo = toonew; | |
78 | toonew = this; | |
79 | return &this->buf; | |
80 | } | |
81 | } | |
82 | ||
83 | /* choose a block to be recycled */ | |
84 | do | |
85 | { | |
86 | this = recycle++; | |
87 | if (recycle == &blk[NBUFS]) | |
88 | { | |
89 | recycle = blk; | |
90 | } | |
91 | } while (this == toonew || this == newtoo); | |
92 | ||
93 | /* if it contains a block, flush that block */ | |
94 | blkflush(this); | |
95 | ||
96 | /* fill this buffer with the desired block */ | |
97 | this->logical = logical; | |
98 | if (hdr.n[logical]) | |
99 | { | |
100 | /* it has been used before - fill it from tmp file */ | |
101 | lseek(tmpfd, (long)hdr.n[logical] * (long)BLKSIZE, 0); | |
102 | if (read(tmpfd, this->buf.c, (unsigned)BLKSIZE) != BLKSIZE) | |
103 | { | |
104 | msg("Error reading back from tmp file!"); | |
105 | } | |
106 | } | |
107 | else | |
108 | { | |
109 | /* it is new - zero it */ | |
110 | for (i = 0; i < BLKSIZE; i++) | |
111 | { | |
112 | this->buf.c[i] = 0; | |
113 | } | |
114 | } | |
115 | ||
116 | /* This isn't really a change, but it does potentially invalidate | |
117 | * the kinds of shortcuts that the "changes" variable is supposed | |
118 | * to protect us from... so count it as a change. | |
119 | */ | |
120 | changes++; | |
121 | ||
122 | /* mark it as being "not dirty" */ | |
123 | this->dirty = 0; | |
124 | ||
125 | /* return it */ | |
126 | newtoo = toonew; | |
127 | toonew = this; | |
128 | return &this->buf; | |
129 | } | |
130 | ||
131 | ||
132 | ||
133 | /* This function writes a block out to the temporary file */ | |
134 | void blkflush(this) | |
135 | REG struct _blkbuf *this; /* the buffer to flush */ | |
136 | { | |
137 | long seekpos; /* seek position of the new block */ | |
138 | unsigned short physical; /* physical block number */ | |
139 | ||
140 | /* if its empty (an orphan blkadd() maybe?) then make it dirty */ | |
141 | if (this->logical && !*this->buf.c) | |
142 | { | |
143 | blkdirty(&this->buf); | |
144 | } | |
145 | ||
146 | /* if it's an empty buffer or a clean version is on disk, quit */ | |
147 | if (!this->logical || hdr.n[this->logical] && !this->dirty) | |
148 | { | |
149 | return; | |
150 | } | |
151 | ||
152 | /* find a free place in the file */ | |
153 | #ifndef NO_RECYCLE | |
154 | seekpos = allocate(); | |
155 | lseek(tmpfd, seekpos, 0); | |
156 | #else | |
157 | seekpos = lseek(tmpfd, 0L, 2); | |
158 | #endif | |
159 | physical = seekpos / BLKSIZE; | |
160 | ||
161 | /* put the block there */ | |
162 | if (write(tmpfd, this->buf.c, (unsigned)BLKSIZE) != BLKSIZE) | |
163 | { | |
164 | msg("Trouble writing to tmp file"); | |
165 | } | |
166 | this->dirty = FALSE; | |
167 | ||
168 | /* update the header so it knows we put it there */ | |
169 | hdr.n[this->logical] = physical; | |
170 | } | |
171 | ||
172 | ||
173 | /* This function sets a block's "dirty" flag or deletes empty blocks */ | |
174 | void blkdirty(bp) | |
175 | BLK *bp; /* buffer returned by blkget() */ | |
176 | { | |
177 | REG int i, j; | |
178 | REG char *scan; | |
179 | REG int k; | |
180 | ||
181 | /* find the buffer */ | |
182 | for (i = 0; i < NBUFS && bp != &blk[i].buf; i++) | |
183 | { | |
184 | } | |
185 | #ifdef DEBUG | |
186 | if (i >= NBUFS) | |
187 | { | |
188 | msg("blkdirty() called with unknown buffer at 0x%lx", bp); | |
189 | return; | |
190 | } | |
191 | if (blk[i].logical == 0) | |
192 | { | |
193 | msg("blkdirty called with freed buffer"); | |
194 | return; | |
195 | } | |
196 | #endif | |
197 | ||
198 | /* if this block ends with line# INFINITY, then it must have been | |
199 | * allocated unnecessarily during tmpstart(). Forget it. | |
200 | */ | |
201 | if (lnum[blk[i].logical] == INFINITY) | |
202 | { | |
203 | #ifdef DEBUG | |
204 | if (blk[i].buf.c[0]) | |
205 | { | |
206 | msg("bkldirty called with non-empty extra BLK"); | |
207 | } | |
208 | #endif | |
209 | blk[i].logical = 0; | |
210 | blk[i].dirty = FALSE; | |
211 | return; | |
212 | } | |
213 | ||
214 | /* count lines in this block */ | |
215 | for (j = 0, scan = bp->c; *scan && scan < bp->c + BLKSIZE; scan++) | |
216 | { | |
217 | if (*scan == '\n') | |
218 | { | |
219 | j++; | |
220 | } | |
221 | } | |
222 | ||
223 | /* adjust lnum, if necessary */ | |
224 | k = blk[i].logical; | |
225 | j += (lnum[k - 1] - lnum[k]); | |
226 | if (j != 0) | |
227 | { | |
228 | nlines += j; | |
229 | while (k < MAXBLKS && lnum[k] != INFINITY) | |
230 | { | |
231 | lnum[k++] += j; | |
232 | } | |
233 | } | |
234 | ||
235 | /* if it still has text, mark it as dirty */ | |
236 | if (*bp->c) | |
237 | { | |
238 | blk[i].dirty = TRUE; | |
239 | } | |
240 | else /* empty block, so delete it */ | |
241 | { | |
242 | /* adjust the cache */ | |
243 | k = blk[i].logical; | |
244 | for (j = 0; j < NBUFS; j++) | |
245 | { | |
246 | if (blk[j].logical >= k) | |
247 | { | |
248 | blk[j].logical--; | |
249 | } | |
250 | } | |
251 | ||
252 | /* delete it from hdr.n[] and lnum[] */ | |
253 | blk[i].logical = 0; | |
254 | blk[i].dirty = FALSE; | |
255 | while (k < MAXBLKS - 1) | |
256 | { | |
257 | hdr.n[k] = hdr.n[k + 1]; | |
258 | lnum[k] = lnum[k + 1]; | |
259 | k++; | |
260 | } | |
261 | hdr.n[MAXBLKS - 1] = 0; | |
262 | lnum[MAXBLKS - 1] = INFINITY; | |
263 | } | |
264 | } | |
265 | ||
266 | ||
267 | /* insert a new block into hdr, and adjust the cache */ | |
268 | BLK *blkadd(logical) | |
269 | int logical; /* where to insert the new block */ | |
270 | { | |
271 | REG int i; | |
272 | ||
273 | /* adjust hdr and lnum[] */ | |
274 | for (i = MAXBLKS - 1; i > logical; i--) | |
275 | { | |
276 | hdr.n[i] = hdr.n[i - 1]; | |
277 | lnum[i] = lnum[i - 1]; | |
278 | } | |
279 | hdr.n[logical] = 0; | |
280 | lnum[logical] = lnum[logical - 1]; | |
281 | ||
282 | /* adjust the cache */ | |
283 | for (i = 0; i < NBUFS; i++) | |
284 | { | |
285 | if (blk[i].logical >= logical) | |
286 | { | |
287 | blk[i].logical++; | |
288 | } | |
289 | } | |
290 | ||
291 | /* return the new block, via blkget() */ | |
292 | return blkget(logical); | |
293 | } | |
294 | ||
295 | ||
296 | /* This function forces all dirty blocks out to disk */ | |
297 | void blksync() | |
298 | { | |
299 | int i; | |
300 | ||
301 | for (i = 0; i < NBUFS; i++) | |
302 | { | |
303 | /* blk[i].dirty = TRUE; */ | |
304 | blkflush(&blk[i]); | |
305 | } | |
306 | if (*o_sync) | |
307 | { | |
308 | sync(); | |
309 | } | |
310 | } | |
311 | ||
312 | /*------------------------------------------------------------------------*/ | |
313 | ||
314 | static MARK undocurs; /* where the cursor should go if undone */ | |
315 | static long oldnlines; | |
316 | static long oldlnum[MAXBLKS]; | |
317 | ||
318 | ||
319 | /* This function should be called before each command that changes the text. | |
320 | * It defines the state that undo() will reset the file to. | |
321 | */ | |
322 | void beforedo(forundo) | |
323 | int forundo; /* boolean: is this for an undo? */ | |
324 | { | |
325 | REG int i; | |
326 | REG long l; | |
327 | ||
328 | /* if this is a nested call to beforedo, quit! Use larger context */ | |
329 | if (b4cnt++ > 0) | |
330 | { | |
331 | return; | |
332 | } | |
333 | ||
334 | /* force all block buffers to disk */ | |
335 | blksync(); | |
336 | ||
337 | #ifndef NO_RECYCLE | |
338 | /* perform garbage collection on blocks from tmp file */ | |
339 | garbage(); | |
340 | #endif | |
341 | ||
342 | /* force the header out to disk */ | |
343 | lseek(tmpfd, 0L, 0); | |
344 | if (write(tmpfd, hdr.c, (unsigned)BLKSIZE) != BLKSIZE) | |
345 | { | |
346 | msg("Trouble writing header to tmp file "); | |
347 | } | |
348 | ||
349 | /* copy or swap oldnlines <--> nlines, oldlnum <--> lnum */ | |
350 | if (forundo) | |
351 | { | |
352 | for (i = 0; i < MAXBLKS; i++) | |
353 | { | |
354 | l = lnum[i]; | |
355 | lnum[i] = oldlnum[i]; | |
356 | oldlnum[i] = l; | |
357 | } | |
358 | l = nlines; | |
359 | nlines = oldnlines; | |
360 | oldnlines = l; | |
361 | } | |
362 | else | |
363 | { | |
364 | for (i = 0; i < MAXBLKS; i++) | |
365 | { | |
366 | oldlnum[i] = lnum[i]; | |
367 | } | |
368 | oldnlines = nlines; | |
369 | } | |
370 | ||
371 | /* save the cursor position */ | |
372 | undocurs = cursor; | |
373 | ||
374 | /* upon return, the calling function continues and makes changes... */ | |
375 | } | |
376 | ||
377 | /* This function marks the end of a (nested?) change to the file */ | |
378 | void afterdo() | |
379 | { | |
380 | if (--b4cnt) | |
381 | { | |
382 | /* after abortdo(), b4cnt may decribe nested beforedo/afterdo | |
383 | * pairs incorrectly. If it is decremented to often, then | |
384 | * keep b4cnt sane but don't do anything else. | |
385 | */ | |
386 | if (b4cnt < 0) | |
387 | b4cnt = 0; | |
388 | ||
389 | return; | |
390 | } | |
391 | ||
392 | /* make sure the cursor wasn't left stranded in deleted text */ | |
393 | if (markline(cursor) > nlines) | |
394 | { | |
395 | cursor = MARK_LAST; | |
396 | } | |
397 | /* NOTE: it is still possible that markidx(cursor) is after the | |
398 | * end of a line, so the Vi mode will have to take care of that | |
399 | * itself */ | |
400 | ||
401 | /* if a significant change has been made to this file, then set the | |
402 | * MODIFIED flag. | |
403 | */ | |
404 | if (significant) | |
405 | { | |
406 | setflag(file, MODIFIED); | |
407 | setflag(file, UNDOABLE); | |
408 | } | |
409 | } | |
410 | ||
411 | /* This function cuts short the current set of changes. It is called after | |
412 | * a SIGINT. | |
413 | */ | |
414 | void abortdo() | |
415 | { | |
416 | /* finish the operation immediately. */ | |
417 | if (b4cnt > 0) | |
418 | { | |
419 | b4cnt = 1; | |
420 | afterdo(); | |
421 | } | |
422 | ||
423 | /* in visual mode, the screen is probably screwed up */ | |
424 | if (mode == MODE_COLON) | |
425 | { | |
426 | mode = MODE_VI; | |
427 | } | |
428 | if (mode == MODE_VI) | |
429 | { | |
430 | redraw(MARK_UNSET, FALSE); | |
431 | } | |
432 | } | |
433 | ||
434 | /* This function discards all changes made since the last call to beforedo() */ | |
435 | int undo() | |
436 | { | |
437 | BLK oldhdr; | |
438 | ||
439 | /* if beforedo() has never been run, fail */ | |
440 | if (!tstflag(file, UNDOABLE)) | |
441 | { | |
442 | msg("You haven't modified this file yet."); | |
443 | return FALSE; | |
444 | } | |
445 | ||
446 | /* read the old header form the tmp file */ | |
447 | lseek(tmpfd, 0L, 0); | |
448 | if (read(tmpfd, oldhdr.c, (unsigned)BLKSIZE) != BLKSIZE) | |
449 | { | |
450 | msg("Trouble rereading the old header from tmp file"); | |
451 | } | |
452 | ||
453 | /* "do" the changed version, so we can undo the "undo" */ | |
454 | cursor = undocurs; | |
455 | beforedo(TRUE); | |
456 | afterdo(); | |
457 | ||
458 | /* wipe out the block buffers - we can't assume they're correct */ | |
459 | blkinit(); | |
460 | ||
461 | /* use the old header -- and therefore the old text blocks */ | |
462 | hdr = oldhdr; | |
463 | ||
464 | /* This is a change */ | |
465 | significant = TRUE; | |
466 | changes++; | |
467 | ||
468 | return TRUE; | |
469 | } |