xref: /freebsd/contrib/bmake/meta.c (revision d7d962ead0b6e5e8a39202d0590022082bf5bfb6)
1 /*      $NetBSD: meta.c,v 1.181 2021/04/04 10:05:08 rillig Exp $ */
2 
3 /*
4  * Implement 'meta' mode.
5  * Adapted from John Birrell's patches to FreeBSD make.
6  * --sjg
7  */
8 /*
9  * Copyright (c) 2009-2016, Juniper Networks, Inc.
10  * Portions Copyright (c) 2009, John Birrell.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
24  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
25  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
31  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  */
33 #if defined(USE_META)
34 
35 #ifdef HAVE_CONFIG_H
36 # include "config.h"
37 #endif
38 #include <sys/stat.h>
39 #ifdef HAVE_LIBGEN_H
40 #include <libgen.h>
41 #elif !defined(HAVE_DIRNAME)
42 char * dirname(char *);
43 #endif
44 #include <errno.h>
45 #if !defined(HAVE_CONFIG_H) || defined(HAVE_ERR_H)
46 #include <err.h>
47 #endif
48 
49 #include "make.h"
50 #include "dir.h"
51 #include "job.h"
52 
53 #ifdef USE_FILEMON
54 #include "filemon/filemon.h"
55 #endif
56 
57 static BuildMon Mybm;			/* for compat */
58 static StringList metaBailiwick = LST_INIT; /* our scope of control */
59 static char *metaBailiwickStr;		/* string storage for the list */
60 static StringList metaIgnorePaths = LST_INIT; /* paths we deliberately ignore */
61 static char *metaIgnorePathsStr;	/* string storage for the list */
62 
63 #ifndef MAKE_META_IGNORE_PATHS
64 #define MAKE_META_IGNORE_PATHS ".MAKE.META.IGNORE_PATHS"
65 #endif
66 #ifndef MAKE_META_IGNORE_PATTERNS
67 #define MAKE_META_IGNORE_PATTERNS ".MAKE.META.IGNORE_PATTERNS"
68 #endif
69 #ifndef MAKE_META_IGNORE_FILTER
70 #define MAKE_META_IGNORE_FILTER ".MAKE.META.IGNORE_FILTER"
71 #endif
72 
73 bool useMeta = false;
74 static bool useFilemon = false;
75 static bool writeMeta = false;
76 static bool metaMissing = false;	/* oodate if missing */
77 static bool filemonMissing = false;	/* oodate if missing */
78 static bool metaEnv = false;		/* don't save env unless asked */
79 static bool metaVerbose = false;
80 static bool metaIgnoreCMDs = false;	/* ignore CMDs in .meta files */
81 static bool metaIgnorePatterns = false; /* do we need to do pattern matches */
82 static bool metaIgnoreFilter = false;	/* do we have more complex filtering? */
83 static bool metaCurdirOk = false;	/* write .meta in .CURDIR Ok? */
84 static bool metaSilent = false;		/* if we have a .meta be SILENT */
85 
86 extern bool forceJobs;
87 extern char    **environ;
88 
89 #define MAKE_META_PREFIX	".MAKE.META.PREFIX"
90 
91 #ifndef N2U
92 # define N2U(n, u)   (((n) + ((u) - 1)) / (u))
93 #endif
94 #ifndef ROUNDUP
95 # define ROUNDUP(n, u)   (N2U((n), (u)) * (u))
96 #endif
97 
98 #if !defined(HAVE_STRSEP)
99 # define strsep(s, d) stresep((s), (d), '\0')
100 #endif
101 
102 /*
103  * Filemon is a kernel module which snoops certain syscalls.
104  *
105  * C chdir
106  * E exec
107  * F [v]fork
108  * L [sym]link
109  * M rename
110  * R read
111  * W write
112  * S stat
113  *
114  * See meta_oodate below - we mainly care about 'E' and 'R'.
115  *
116  * We can still use meta mode without filemon, but
117  * the benefits are more limited.
118  */
119 #ifdef USE_FILEMON
120 
121 /*
122  * Open the filemon device.
123  */
124 static void
125 meta_open_filemon(BuildMon *pbm)
126 {
127     int dupfd;
128 
129     pbm->mon_fd = -1;
130     pbm->filemon = NULL;
131     if (!useFilemon || pbm->mfp == NULL)
132 	return;
133 
134     pbm->filemon = filemon_open();
135     if (pbm->filemon == NULL) {
136 	useFilemon = false;
137 	warn("Could not open filemon %s", filemon_path());
138 	return;
139     }
140 
141     /*
142      * We use a file outside of '.'
143      * to avoid a FreeBSD kernel bug where unlink invalidates
144      * cwd causing getcwd to do a lot more work.
145      * We only care about the descriptor.
146      */
147     if (!opts.compatMake)
148 	pbm->mon_fd = Job_TempFile("filemon.XXXXXX", NULL, 0);
149     else
150 	pbm->mon_fd = mkTempFile("filemon.XXXXXX", NULL, 0);
151     if ((dupfd = dup(pbm->mon_fd)) == -1) {
152 	err(1, "Could not dup filemon output!");
153     }
154     (void)fcntl(dupfd, F_SETFD, FD_CLOEXEC);
155     if (filemon_setfd(pbm->filemon, dupfd) == -1) {
156 	err(1, "Could not set filemon file descriptor!");
157     }
158     /* we don't need these once we exec */
159     (void)fcntl(pbm->mon_fd, F_SETFD, FD_CLOEXEC);
160 }
161 
162 /*
163  * Read the build monitor output file and write records to the target's
164  * metadata file.
165  */
166 static int
167 filemon_read(FILE *mfp, int fd)
168 {
169     char buf[BUFSIZ];
170     int error;
171 
172     /* Check if we're not writing to a meta data file.*/
173     if (mfp == NULL) {
174 	if (fd >= 0)
175 	    close(fd);			/* not interested */
176 	return 0;
177     }
178     /* rewind */
179     if (lseek(fd, (off_t)0, SEEK_SET) < 0) {
180 	error = errno;
181 	warn("Could not rewind filemon");
182 	fprintf(mfp, "\n");
183     } else {
184 	ssize_t n;
185 
186 	error = 0;
187 	fprintf(mfp, "\n-- filemon acquired metadata --\n");
188 
189 	while ((n = read(fd, buf, sizeof buf)) > 0) {
190 	    if ((ssize_t)fwrite(buf, 1, (size_t)n, mfp) < n)
191 		error = EIO;
192 	}
193     }
194     fflush(mfp);
195     if (close(fd) < 0)
196 	error = errno;
197     return error;
198 }
199 #endif
200 
201 /*
202  * when realpath() fails,
203  * we use this, to clean up ./ and ../
204  */
205 static void
206 eat_dots(char *buf, size_t bufsz, int dots)
207 {
208     char *cp;
209     char *cp2;
210     const char *eat;
211     size_t eatlen;
212 
213     switch (dots) {
214     case 1:
215 	eat = "/./";
216 	eatlen = 2;
217 	break;
218     case 2:
219 	eat = "/../";
220 	eatlen = 3;
221 	break;
222     default:
223 	return;
224     }
225 
226     do {
227 	cp = strstr(buf, eat);
228 	if (cp != NULL) {
229 	    cp2 = cp + eatlen;
230 	    if (dots == 2 && cp > buf) {
231 		do {
232 		    cp--;
233 		} while (cp > buf && *cp != '/');
234 	    }
235 	    if (*cp == '/') {
236 		strlcpy(cp, cp2, bufsz - (size_t)(cp - buf));
237 	    } else {
238 		return;			/* can't happen? */
239 	    }
240 	}
241     } while (cp != NULL);
242 }
243 
244 static char *
245 meta_name(char *mname, size_t mnamelen,
246 	  const char *dname,
247 	  const char *tname,
248 	  const char *cwd)
249 {
250     char buf[MAXPATHLEN];
251     char *rp;
252     char *cp;
253     char *tp;
254     char *dtp;
255     size_t ldname;
256 
257     /*
258      * Weed out relative paths from the target file name.
259      * We have to be careful though since if target is a
260      * symlink, the result will be unstable.
261      * So we use realpath() just to get the dirname, and leave the
262      * basename as given to us.
263      */
264     if ((cp = strrchr(tname, '/')) != NULL) {
265 	if (cached_realpath(tname, buf) != NULL) {
266 	    if ((rp = strrchr(buf, '/')) != NULL) {
267 		rp++;
268 		cp++;
269 		if (strcmp(cp, rp) != 0)
270 		    strlcpy(rp, cp, sizeof buf - (size_t)(rp - buf));
271 	    }
272 	    tname = buf;
273 	} else {
274 	    /*
275 	     * We likely have a directory which is about to be made.
276 	     * We pretend realpath() succeeded, to have a chance
277 	     * of generating the same meta file name that we will
278 	     * next time through.
279 	     */
280 	    if (tname[0] == '/') {
281 		strlcpy(buf, tname, sizeof buf);
282 	    } else {
283 		snprintf(buf, sizeof buf, "%s/%s", cwd, tname);
284 	    }
285 	    eat_dots(buf, sizeof buf, 1);	/* ./ */
286 	    eat_dots(buf, sizeof buf, 2);	/* ../ */
287 	    tname = buf;
288 	}
289     }
290     /* on some systems dirname may modify its arg */
291     tp = bmake_strdup(tname);
292     dtp = dirname(tp);
293     if (strcmp(dname, dtp) == 0)
294 	snprintf(mname, mnamelen, "%s.meta", tname);
295     else {
296 	ldname = strlen(dname);
297 	if (strncmp(dname, dtp, ldname) == 0 && dtp[ldname] == '/')
298 	    snprintf(mname, mnamelen, "%s/%s.meta", dname, &tname[ldname+1]);
299 	else
300 	    snprintf(mname, mnamelen, "%s/%s.meta", dname, tname);
301 
302 	/*
303 	 * Replace path separators in the file name after the
304 	 * current object directory path.
305 	 */
306 	cp = mname + strlen(dname) + 1;
307 
308 	while (*cp != '\0') {
309 	    if (*cp == '/')
310 		*cp = '_';
311 	    cp++;
312 	}
313     }
314     free(tp);
315     return mname;
316 }
317 
318 /*
319  * Return true if running ${.MAKE}
320  * Bypassed if target is flagged .MAKE
321  */
322 static bool
323 is_submake(const char *cmd, GNode *gn)
324 {
325     static const char *p_make = NULL;
326     static size_t p_len;
327     char *mp = NULL;
328     char *cp;
329     char *cp2;
330     bool rc = false;
331 
332     if (p_make == NULL) {
333 	p_make = Var_Value(gn, ".MAKE").str;
334 	p_len = strlen(p_make);
335     }
336     cp = strchr(cmd, '$');
337     if (cp != NULL) {
338 	(void)Var_Subst(cmd, gn, VARE_WANTRES, &mp);
339 	/* TODO: handle errors */
340 	cmd = mp;
341     }
342     cp2 = strstr(cmd, p_make);
343     if (cp2 != NULL) {
344 	switch (cp2[p_len]) {
345 	case '\0':
346 	case ' ':
347 	case '\t':
348 	case '\n':
349 	    rc = true;
350 	    break;
351 	}
352 	if (cp2 > cmd && rc) {
353 	    switch (cp2[-1]) {
354 	    case ' ':
355 	    case '\t':
356 	    case '\n':
357 		break;
358 	    default:
359 		rc = false;		/* no match */
360 		break;
361 	    }
362 	}
363     }
364     free(mp);
365     return rc;
366 }
367 
368 static bool
369 any_is_submake(GNode *gn)
370 {
371     StringListNode *ln;
372 
373     for (ln = gn->commands.first; ln != NULL; ln = ln->next)
374 	if (is_submake(ln->datum, gn))
375 	    return true;
376     return false;
377 }
378 
379 static void
380 printCMD(const char *ucmd, FILE *fp, GNode *gn)
381 {
382     FStr xcmd = FStr_InitRefer(ucmd);
383 
384     if (strchr(ucmd, '$') != NULL) {
385     	char *expanded;
386 	(void)Var_Subst(ucmd, gn, VARE_WANTRES, &expanded);
387 	/* TODO: handle errors */
388 	xcmd = FStr_InitOwn(expanded);
389     }
390 
391     fprintf(fp, "CMD %s\n", xcmd.str);
392     FStr_Done(&xcmd);
393 }
394 
395 static void
396 printCMDs(GNode *gn, FILE *fp)
397 {
398     StringListNode *ln;
399 
400     for (ln = gn->commands.first; ln != NULL; ln = ln->next)
401 	printCMD(ln->datum, fp, gn);
402 }
403 
404 /*
405  * Certain node types never get a .meta file
406  */
407 #define SKIP_META_TYPE(_type) do { \
408     if ((gn->type & __CONCAT(OP_, _type))) { \
409 	if (verbose) { \
410 	    debug_printf("Skipping meta for %s: .%s\n", \
411 		    gn->name, __STRING(_type)); \
412 	} \
413 	return false; \
414     } \
415 } while (/*CONSTCOND*/false)
416 
417 
418 /*
419  * Do we need/want a .meta file ?
420  */
421 static bool
422 meta_needed(GNode *gn, const char *dname,
423 	    char *objdir_realpath, bool verbose)
424 {
425     struct cached_stat cst;
426 
427     if (verbose)
428 	verbose = DEBUG(META);
429 
430     /* This may be a phony node which we don't want meta data for... */
431     /* Skip .meta for .BEGIN, .END, .ERROR etc as well. */
432     /* Or it may be explicitly flagged as .NOMETA */
433     SKIP_META_TYPE(NOMETA);
434     /* Unless it is explicitly flagged as .META */
435     if (!(gn->type & OP_META)) {
436 	SKIP_META_TYPE(PHONY);
437 	SKIP_META_TYPE(SPECIAL);
438 	SKIP_META_TYPE(MAKE);
439     }
440 
441     /* Check if there are no commands to execute. */
442     if (Lst_IsEmpty(&gn->commands)) {
443 	if (verbose)
444 	    debug_printf("Skipping meta for %s: no commands\n", gn->name);
445 	return false;
446     }
447     if ((gn->type & (OP_META|OP_SUBMAKE)) == OP_SUBMAKE) {
448 	/* OP_SUBMAKE is a bit too aggressive */
449 	if (any_is_submake(gn)) {
450 	    DEBUG1(META, "Skipping meta for %s: .SUBMAKE\n", gn->name);
451 	    return false;
452 	}
453     }
454 
455     /* The object directory may not exist. Check it.. */
456     if (cached_stat(dname, &cst) != 0) {
457 	if (verbose)
458 	    debug_printf("Skipping meta for %s: no .OBJDIR\n", gn->name);
459 	return false;
460     }
461 
462     /* make sure these are canonical */
463     if (cached_realpath(dname, objdir_realpath) != NULL)
464 	dname = objdir_realpath;
465 
466     /* If we aren't in the object directory, don't create a meta file. */
467     if (!metaCurdirOk && strcmp(curdir, dname) == 0) {
468 	if (verbose)
469 	    debug_printf("Skipping meta for %s: .OBJDIR == .CURDIR\n",
470 			 gn->name);
471 	return false;
472     }
473     return true;
474 }
475 
476 
477 static FILE *
478 meta_create(BuildMon *pbm, GNode *gn)
479 {
480     FILE *fp;
481     char buf[MAXPATHLEN];
482     char objdir_realpath[MAXPATHLEN];
483     char **ptr;
484     FStr dname;
485     const char *tname;
486     char *fname;
487     const char *cp;
488 
489     fp = NULL;
490 
491     dname = Var_Value(gn, ".OBJDIR");
492     tname = GNode_VarTarget(gn);
493 
494     /* if this succeeds objdir_realpath is realpath of dname */
495     if (!meta_needed(gn, dname.str, objdir_realpath, true))
496 	goto out;
497     dname.str = objdir_realpath;
498 
499     if (metaVerbose) {
500 	char *mp;
501 
502 	/* Describe the target we are building */
503 	(void)Var_Subst("${" MAKE_META_PREFIX "}", gn, VARE_WANTRES, &mp);
504 	/* TODO: handle errors */
505 	if (mp[0] != '\0')
506 	    fprintf(stdout, "%s\n", mp);
507 	free(mp);
508     }
509     /* Get the basename of the target */
510     cp = str_basename(tname);
511 
512     fflush(stdout);
513 
514     if (!writeMeta)
515 	/* Don't create meta data. */
516 	goto out;
517 
518     fname = meta_name(pbm->meta_fname, sizeof pbm->meta_fname,
519 		      dname.str, tname, objdir_realpath);
520 
521 #ifdef DEBUG_META_MODE
522     DEBUG1(META, "meta_create: %s\n", fname);
523 #endif
524 
525     if ((fp = fopen(fname, "w")) == NULL)
526 	err(1, "Could not open meta file '%s'", fname);
527 
528     fprintf(fp, "# Meta data file %s\n", fname);
529 
530     printCMDs(gn, fp);
531 
532     fprintf(fp, "CWD %s\n", getcwd(buf, sizeof buf));
533     fprintf(fp, "TARGET %s\n", tname);
534     cp = GNode_VarOodate(gn);
535     if (cp != NULL && *cp != '\0') {
536 	fprintf(fp, "OODATE %s\n", cp);
537     }
538     if (metaEnv) {
539 	for (ptr = environ; *ptr != NULL; ptr++)
540 	    fprintf(fp, "ENV %s\n", *ptr);
541     }
542 
543     fprintf(fp, "-- command output --\n");
544     fflush(fp);
545 
546     Global_Append(".MAKE.META.FILES", fname);
547     Global_Append(".MAKE.META.CREATED", fname);
548 
549     gn->type |= OP_META;		/* in case anyone wants to know */
550     if (metaSilent) {
551 	    gn->type |= OP_SILENT;
552     }
553  out:
554     FStr_Done(&dname);
555 
556     return fp;
557 }
558 
559 static bool
560 boolValue(char *s)
561 {
562     switch(*s) {
563     case '0':
564     case 'N':
565     case 'n':
566     case 'F':
567     case 'f':
568 	return false;
569     }
570     return true;
571 }
572 
573 /*
574  * Initialization we need before reading makefiles.
575  */
576 void
577 meta_init(void)
578 {
579 #ifdef USE_FILEMON
580 	/* this allows makefiles to test if we have filemon support */
581 	Global_Set(".MAKE.PATH_FILEMON", filemon_path());
582 #endif
583 }
584 
585 
586 #define get_mode_bf(bf, token) \
587     if ((cp = strstr(make_mode, token)) != NULL) \
588 	bf = boolValue(cp + sizeof (token) - 1)
589 
590 /*
591  * Initialization we need after reading makefiles.
592  */
593 void
594 meta_mode_init(const char *make_mode)
595 {
596     static bool once = false;
597     char *cp;
598     FStr value;
599 
600     useMeta = true;
601     useFilemon = true;
602     writeMeta = true;
603 
604     if (make_mode != NULL) {
605 	if (strstr(make_mode, "env") != NULL)
606 	    metaEnv = true;
607 	if (strstr(make_mode, "verb") != NULL)
608 	    metaVerbose = true;
609 	if (strstr(make_mode, "read") != NULL)
610 	    writeMeta = false;
611 	if (strstr(make_mode, "nofilemon") != NULL)
612 	    useFilemon = false;
613 	if (strstr(make_mode, "ignore-cmd") != NULL)
614 	    metaIgnoreCMDs = true;
615 	if (useFilemon)
616 	    get_mode_bf(filemonMissing, "missing-filemon=");
617 	get_mode_bf(metaCurdirOk, "curdirok=");
618 	get_mode_bf(metaMissing, "missing-meta=");
619 	get_mode_bf(metaSilent, "silent=");
620     }
621     if (metaVerbose && !Var_Exists(SCOPE_GLOBAL, MAKE_META_PREFIX)) {
622 	/*
623 	 * The default value for MAKE_META_PREFIX
624 	 * prints the absolute path of the target.
625 	 * This works be cause :H will generate '.' if there is no /
626 	 * and :tA will resolve that to cwd.
627 	 */
628 	Global_Set(MAKE_META_PREFIX,
629 	    "Building ${.TARGET:H:tA}/${.TARGET:T}");
630     }
631     if (once)
632 	return;
633     once = true;
634     memset(&Mybm, 0, sizeof Mybm);
635     /*
636      * We consider ourselves master of all within ${.MAKE.META.BAILIWICK}
637      */
638     (void)Var_Subst("${.MAKE.META.BAILIWICK:O:u:tA}",
639 		    SCOPE_GLOBAL, VARE_WANTRES, &metaBailiwickStr);
640     /* TODO: handle errors */
641     str2Lst_Append(&metaBailiwick, metaBailiwickStr);
642     /*
643      * We ignore any paths that start with ${.MAKE.META.IGNORE_PATHS}
644      */
645     Global_Append(MAKE_META_IGNORE_PATHS,
646 	       "/dev /etc /proc /tmp /var/run /var/tmp ${TMPDIR}");
647     (void)Var_Subst("${" MAKE_META_IGNORE_PATHS ":O:u:tA}",
648 		    SCOPE_GLOBAL, VARE_WANTRES, &metaIgnorePathsStr);
649     /* TODO: handle errors */
650     str2Lst_Append(&metaIgnorePaths, metaIgnorePathsStr);
651 
652     /*
653      * We ignore any paths that match ${.MAKE.META.IGNORE_PATTERNS}
654      */
655     value = Var_Value(SCOPE_GLOBAL, MAKE_META_IGNORE_PATTERNS);
656     if (value.str != NULL) {
657 	metaIgnorePatterns = true;
658 	FStr_Done(&value);
659     }
660     value = Var_Value(SCOPE_GLOBAL, MAKE_META_IGNORE_FILTER);
661     if (value.str != NULL) {
662 	metaIgnoreFilter = true;
663 	FStr_Done(&value);
664     }
665 }
666 
667 /*
668  * In each case below we allow for job==NULL
669  */
670 void
671 meta_job_start(Job *job, GNode *gn)
672 {
673     BuildMon *pbm;
674 
675     if (job != NULL) {
676 	pbm = &job->bm;
677     } else {
678 	pbm = &Mybm;
679     }
680     pbm->mfp = meta_create(pbm, gn);
681 #ifdef USE_FILEMON_ONCE
682     /* compat mode we open the filemon dev once per command */
683     if (job == NULL)
684 	return;
685 #endif
686 #ifdef USE_FILEMON
687     if (pbm->mfp != NULL && useFilemon) {
688 	meta_open_filemon(pbm);
689     } else {
690 	pbm->mon_fd = -1;
691 	pbm->filemon = NULL;
692     }
693 #endif
694 }
695 
696 /*
697  * The child calls this before doing anything.
698  * It does not disturb our state.
699  */
700 void
701 meta_job_child(Job *job)
702 {
703 #ifdef USE_FILEMON
704     BuildMon *pbm;
705 
706     if (job != NULL) {
707 	pbm = &job->bm;
708     } else {
709 	pbm = &Mybm;
710     }
711     if (pbm->mfp != NULL) {
712 	close(fileno(pbm->mfp));
713 	if (useFilemon && pbm->filemon != NULL) {
714 	    pid_t pid;
715 
716 	    pid = getpid();
717 	    if (filemon_setpid_child(pbm->filemon, pid) == -1) {
718 		err(1, "Could not set filemon pid!");
719 	    }
720 	}
721     }
722 #endif
723 }
724 
725 void
726 meta_job_parent(Job *job, pid_t pid)
727 {
728 #if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
729     BuildMon *pbm;
730 
731     if (job != NULL) {
732 	pbm = &job->bm;
733     } else {
734 	pbm = &Mybm;
735     }
736     if (useFilemon && pbm->filemon != NULL) {
737 	filemon_setpid_parent(pbm->filemon, pid);
738     }
739 #endif
740 }
741 
742 int
743 meta_job_fd(Job *job)
744 {
745 #if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
746     BuildMon *pbm;
747 
748     if (job != NULL) {
749 	pbm = &job->bm;
750     } else {
751 	pbm = &Mybm;
752     }
753     if (useFilemon && pbm->filemon != NULL) {
754 	return filemon_readfd(pbm->filemon);
755     }
756 #endif
757     return -1;
758 }
759 
760 int
761 meta_job_event(Job *job)
762 {
763 #if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
764     BuildMon *pbm;
765 
766     if (job != NULL) {
767 	pbm = &job->bm;
768     } else {
769 	pbm = &Mybm;
770     }
771     if (useFilemon && pbm->filemon != NULL) {
772 	return filemon_process(pbm->filemon);
773     }
774 #endif
775     return 0;
776 }
777 
778 void
779 meta_job_error(Job *job, GNode *gn, bool ignerr, int status)
780 {
781     char cwd[MAXPATHLEN];
782     BuildMon *pbm;
783 
784     if (job != NULL) {
785 	pbm = &job->bm;
786 	if (gn == NULL)
787 	    gn = job->node;
788     } else {
789 	pbm = &Mybm;
790     }
791     if (pbm->mfp != NULL) {
792 	fprintf(pbm->mfp, "\n*** Error code %d%s\n",
793 		status, ignerr ? "(ignored)" : "");
794     }
795     if (gn != NULL)
796 	Global_Set(".ERROR_TARGET", GNode_Path(gn));
797     getcwd(cwd, sizeof cwd);
798     Global_Set(".ERROR_CWD", cwd);
799     if (pbm->meta_fname[0] != '\0') {
800 	Global_Set(".ERROR_META_FILE", pbm->meta_fname);
801     }
802     meta_job_finish(job);
803 }
804 
805 void
806 meta_job_output(Job *job, char *cp, const char *nl)
807 {
808     BuildMon *pbm;
809 
810     if (job != NULL) {
811 	pbm = &job->bm;
812     } else {
813 	pbm = &Mybm;
814     }
815     if (pbm->mfp != NULL) {
816 	if (metaVerbose) {
817 	    static char *meta_prefix = NULL;
818 	    static size_t meta_prefix_len;
819 
820 	    if (meta_prefix == NULL) {
821 		char *cp2;
822 
823 		(void)Var_Subst("${" MAKE_META_PREFIX "}",
824 				SCOPE_GLOBAL, VARE_WANTRES, &meta_prefix);
825 		/* TODO: handle errors */
826 		if ((cp2 = strchr(meta_prefix, '$')) != NULL)
827 		    meta_prefix_len = (size_t)(cp2 - meta_prefix);
828 		else
829 		    meta_prefix_len = strlen(meta_prefix);
830 	    }
831 	    if (strncmp(cp, meta_prefix, meta_prefix_len) == 0) {
832 		cp = strchr(cp + 1, '\n');
833 		if (cp == NULL)
834 		    return;
835 		cp++;
836 	    }
837 	}
838 	fprintf(pbm->mfp, "%s%s", cp, nl);
839     }
840 }
841 
842 int
843 meta_cmd_finish(void *pbmp)
844 {
845     int error = 0;
846     BuildMon *pbm = pbmp;
847 #ifdef USE_FILEMON
848     int x;
849 #endif
850 
851     if (pbm == NULL)
852 	pbm = &Mybm;
853 
854 #ifdef USE_FILEMON
855     if (pbm->filemon != NULL) {
856 	while (filemon_process(pbm->filemon) > 0)
857 	    continue;
858 	if (filemon_close(pbm->filemon) == -1)
859 	    error = errno;
860 	x = filemon_read(pbm->mfp, pbm->mon_fd);
861 	if (error == 0 && x != 0)
862 	    error = x;
863 	pbm->mon_fd = -1;
864 	pbm->filemon = NULL;
865 	return error;
866     }
867 #endif
868 
869     fprintf(pbm->mfp, "\n");	/* ensure end with newline */
870     return error;
871 }
872 
873 int
874 meta_job_finish(Job *job)
875 {
876     BuildMon *pbm;
877     int error = 0;
878     int x;
879 
880     if (job != NULL) {
881 	pbm = &job->bm;
882     } else {
883 	pbm = &Mybm;
884     }
885     if (pbm->mfp != NULL) {
886 	error = meta_cmd_finish(pbm);
887 	x = fclose(pbm->mfp);
888 	if (error == 0 && x != 0)
889 	    error = errno;
890 	pbm->mfp = NULL;
891 	pbm->meta_fname[0] = '\0';
892     }
893     return error;
894 }
895 
896 void
897 meta_finish(void)
898 {
899     Lst_Done(&metaBailiwick);
900     free(metaBailiwickStr);
901     Lst_Done(&metaIgnorePaths);
902     free(metaIgnorePathsStr);
903 }
904 
905 /*
906  * Fetch a full line from fp - growing bufp if needed
907  * Return length in bufp.
908  */
909 static int
910 fgetLine(char **bufp, size_t *szp, int o, FILE *fp)
911 {
912     char *buf = *bufp;
913     size_t bufsz = *szp;
914     struct stat fs;
915     int x;
916 
917     if (fgets(&buf[o], (int)bufsz - o, fp) != NULL) {
918     check_newline:
919 	x = o + (int)strlen(&buf[o]);
920 	if (buf[x - 1] == '\n')
921 	    return x;
922 	/*
923 	 * We need to grow the buffer.
924 	 * The meta file can give us a clue.
925 	 */
926 	if (fstat(fileno(fp), &fs) == 0) {
927 	    size_t newsz;
928 	    char *p;
929 
930 	    newsz = ROUNDUP(((size_t)fs.st_size / 2), BUFSIZ);
931 	    if (newsz <= bufsz)
932 		newsz = ROUNDUP((size_t)fs.st_size, BUFSIZ);
933 	    if (newsz <= bufsz)
934 		return x;		/* truncated */
935 	    DEBUG2(META, "growing buffer %u -> %u\n",
936 		   (unsigned)bufsz, (unsigned)newsz);
937 	    p = bmake_realloc(buf, newsz);
938 	    *bufp = buf = p;
939 	    *szp = bufsz = newsz;
940 	    /* fetch the rest */
941 	    if (fgets(&buf[x], (int)bufsz - x, fp) == NULL)
942 		return x;		/* truncated! */
943 	    goto check_newline;
944 	}
945     }
946     return 0;
947 }
948 
949 static bool
950 prefix_match(const char *prefix, const char *path)
951 {
952     size_t n = strlen(prefix);
953 
954     return strncmp(path, prefix, n) == 0;
955 }
956 
957 static bool
958 has_any_prefix(const char *path, StringList *prefixes)
959 {
960     StringListNode *ln;
961 
962     for (ln = prefixes->first; ln != NULL; ln = ln->next)
963 	if (prefix_match(ln->datum, path))
964 	    return true;
965     return false;
966 }
967 
968 /* See if the path equals prefix or starts with "prefix/". */
969 static bool
970 path_starts_with(const char *path, const char *prefix)
971 {
972     size_t n = strlen(prefix);
973 
974     if (strncmp(path, prefix, n) != 0)
975 	return false;
976     return path[n] == '\0' || path[n] == '/';
977 }
978 
979 static bool
980 meta_ignore(GNode *gn, const char *p)
981 {
982     char fname[MAXPATHLEN];
983 
984     if (p == NULL)
985 	return true;
986 
987     if (*p == '/') {
988 	cached_realpath(p, fname); /* clean it up */
989 	if (has_any_prefix(fname, &metaIgnorePaths)) {
990 #ifdef DEBUG_META_MODE
991 	    DEBUG1(META, "meta_oodate: ignoring path: %s\n", p);
992 #endif
993 	    return true;
994 	}
995     }
996 
997     if (metaIgnorePatterns) {
998 	const char *expr;
999 	char *pm;
1000 
1001 	/*
1002 	 * XXX: This variable is set on a target GNode but is not one of
1003 	 * the usual local variables.  It should be deleted afterwards.
1004 	 * Ideally it would not be created in the first place, just like
1005 	 * in a .for loop.
1006 	 */
1007 	Var_Set(gn, ".p.", p);
1008 	expr = "${" MAKE_META_IGNORE_PATTERNS ":@m@${.p.:M$m}@}";
1009 	(void)Var_Subst(expr, gn, VARE_WANTRES, &pm);
1010 	/* TODO: handle errors */
1011 	if (pm[0] != '\0') {
1012 #ifdef DEBUG_META_MODE
1013 	    DEBUG1(META, "meta_oodate: ignoring pattern: %s\n", p);
1014 #endif
1015 	    free(pm);
1016 	    return true;
1017 	}
1018 	free(pm);
1019     }
1020 
1021     if (metaIgnoreFilter) {
1022 	char *fm;
1023 
1024 	/* skip if filter result is empty */
1025 	snprintf(fname, sizeof fname,
1026 		 "${%s:L:${%s:ts:}}",
1027 		 p, MAKE_META_IGNORE_FILTER);
1028 	(void)Var_Subst(fname, gn, VARE_WANTRES, &fm);
1029 	/* TODO: handle errors */
1030 	if (*fm == '\0') {
1031 #ifdef DEBUG_META_MODE
1032 	    DEBUG1(META, "meta_oodate: ignoring filtered: %s\n", p);
1033 #endif
1034 	    free(fm);
1035 	    return true;
1036 	}
1037 	free(fm);
1038     }
1039     return false;
1040 }
1041 
1042 /*
1043  * When running with 'meta' functionality, a target can be out-of-date
1044  * if any of the references in its meta data file is more recent.
1045  * We have to track the latestdir on a per-process basis.
1046  */
1047 #define LCWD_VNAME_FMT ".meta.%d.lcwd"
1048 #define LDIR_VNAME_FMT ".meta.%d.ldir"
1049 
1050 /*
1051  * It is possible that a .meta file is corrupted,
1052  * if we detect this we want to reproduce it.
1053  * Setting oodate true will have that effect.
1054  */
1055 #define CHECK_VALID_META(p) if (!(p != NULL && *p != '\0')) { \
1056     warnx("%s: %d: malformed", fname, lineno); \
1057     oodate = true; \
1058     continue; \
1059     }
1060 
1061 #define DEQUOTE(p) if (*p == '\'') {	\
1062     char *ep; \
1063     p++; \
1064     if ((ep = strchr(p, '\'')) != NULL) \
1065 	*ep = '\0'; \
1066     }
1067 
1068 static void
1069 append_if_new(StringList *list, const char *str)
1070 {
1071     StringListNode *ln;
1072 
1073     for (ln = list->first; ln != NULL; ln = ln->next)
1074 	if (strcmp(ln->datum, str) == 0)
1075 	    return;
1076     Lst_Append(list, bmake_strdup(str));
1077 }
1078 
1079 bool
1080 meta_oodate(GNode *gn, bool oodate)
1081 {
1082     static char *tmpdir = NULL;
1083     static char cwd[MAXPATHLEN];
1084     char lcwd_vname[64];
1085     char ldir_vname[64];
1086     char lcwd[MAXPATHLEN];
1087     char latestdir[MAXPATHLEN];
1088     char fname[MAXPATHLEN];
1089     char fname1[MAXPATHLEN];
1090     char fname2[MAXPATHLEN];
1091     char fname3[MAXPATHLEN];
1092     FStr dname;
1093     const char *tname;
1094     char *p;
1095     char *link_src;
1096     char *move_target;
1097     static size_t cwdlen = 0;
1098     static size_t tmplen = 0;
1099     FILE *fp;
1100     bool needOODATE = false;
1101     StringList missingFiles;
1102     bool have_filemon = false;
1103 
1104     if (oodate)
1105 	return oodate;		/* we're done */
1106 
1107     dname = Var_Value(gn, ".OBJDIR");
1108     tname = GNode_VarTarget(gn);
1109 
1110     /* if this succeeds fname3 is realpath of dname */
1111     if (!meta_needed(gn, dname.str, fname3, false))
1112 	goto oodate_out;
1113     dname.str = fname3;
1114 
1115     Lst_Init(&missingFiles);
1116 
1117     /*
1118      * We need to check if the target is out-of-date. This includes
1119      * checking if the expanded command has changed. This in turn
1120      * requires that all variables are set in the same way that they
1121      * would be if the target needs to be re-built.
1122      */
1123     GNode_SetLocalVars(gn);
1124 
1125     meta_name(fname, sizeof fname, dname.str, tname, dname.str);
1126 
1127 #ifdef DEBUG_META_MODE
1128     DEBUG1(META, "meta_oodate: %s\n", fname);
1129 #endif
1130 
1131     if ((fp = fopen(fname, "r")) != NULL) {
1132 	static char *buf = NULL;
1133 	static size_t bufsz;
1134 	int lineno = 0;
1135 	int lastpid = 0;
1136 	int pid;
1137 	int x;
1138 	StringListNode *cmdNode;
1139 	struct cached_stat cst;
1140 
1141 	if (buf == NULL) {
1142 	    bufsz = 8 * BUFSIZ;
1143 	    buf = bmake_malloc(bufsz);
1144 	}
1145 
1146 	if (cwdlen == 0) {
1147 	    if (getcwd(cwd, sizeof cwd) == NULL)
1148 		err(1, "Could not get current working directory");
1149 	    cwdlen = strlen(cwd);
1150 	}
1151 	strlcpy(lcwd, cwd, sizeof lcwd);
1152 	strlcpy(latestdir, cwd, sizeof latestdir);
1153 
1154 	if (tmpdir == NULL) {
1155 	    tmpdir = getTmpdir();
1156 	    tmplen = strlen(tmpdir);
1157 	}
1158 
1159 	/* we want to track all the .meta we read */
1160 	Global_Append(".MAKE.META.FILES", fname);
1161 
1162 	cmdNode = gn->commands.first;
1163 	while (!oodate && (x = fgetLine(&buf, &bufsz, 0, fp)) > 0) {
1164 	    lineno++;
1165 	    if (buf[x - 1] == '\n')
1166 		buf[x - 1] = '\0';
1167 	    else {
1168 		warnx("%s: %d: line truncated at %u", fname, lineno, x);
1169 		oodate = true;
1170 		break;
1171 	    }
1172 	    link_src = NULL;
1173 	    move_target = NULL;
1174 	    /* Find the start of the build monitor section. */
1175 	    if (!have_filemon) {
1176 		if (strncmp(buf, "-- filemon", 10) == 0) {
1177 		    have_filemon = true;
1178 		    continue;
1179 		}
1180 		if (strncmp(buf, "# buildmon", 10) == 0) {
1181 		    have_filemon = true;
1182 		    continue;
1183 		}
1184 	    }
1185 
1186 	    /* Delimit the record type. */
1187 	    p = buf;
1188 #ifdef DEBUG_META_MODE
1189 	    DEBUG3(META, "%s: %d: %s\n", fname, lineno, buf);
1190 #endif
1191 	    strsep(&p, " ");
1192 	    if (have_filemon) {
1193 		/*
1194 		 * We are in the 'filemon' output section.
1195 		 * Each record from filemon follows the general form:
1196 		 *
1197 		 * <key> <pid> <data>
1198 		 *
1199 		 * Where:
1200 		 * <key> is a single letter, denoting the syscall.
1201 		 * <pid> is the process that made the syscall.
1202 		 * <data> is the arguments (of interest).
1203 		 */
1204 		switch(buf[0]) {
1205 		case '#':		/* comment */
1206 		case 'V':		/* version */
1207 		    break;
1208 		default:
1209 		    /*
1210 		     * We need to track pathnames per-process.
1211 		     *
1212 		     * Each process run by make starts off in the 'CWD'
1213 		     * recorded in the .meta file, if it chdirs ('C')
1214 		     * elsewhere we need to track that - but only for
1215 		     * that process.  If it forks ('F'), we initialize
1216 		     * the child to have the same cwd as its parent.
1217 		     *
1218 		     * We also need to track the 'latestdir' of
1219 		     * interest.  This is usually the same as cwd, but
1220 		     * not if a process is reading directories.
1221 		     *
1222 		     * Each time we spot a different process ('pid')
1223 		     * we save the current value of 'latestdir' in a
1224 		     * variable qualified by 'lastpid', and
1225 		     * re-initialize 'latestdir' to any pre-saved
1226 		     * value for the current 'pid' and 'CWD' if none.
1227 		     */
1228 		    CHECK_VALID_META(p);
1229 		    pid = atoi(p);
1230 		    if (pid > 0 && pid != lastpid) {
1231 			FStr ldir;
1232 
1233 			if (lastpid > 0) {
1234 			    /* We need to remember these. */
1235 			    Global_SetExpand(lcwd_vname, lcwd);
1236 			    Global_SetExpand(ldir_vname, latestdir);
1237 			}
1238 			snprintf(lcwd_vname, sizeof lcwd_vname, LCWD_VNAME_FMT, pid);
1239 			snprintf(ldir_vname, sizeof ldir_vname, LDIR_VNAME_FMT, pid);
1240 			lastpid = pid;
1241 			ldir = Var_Value(SCOPE_GLOBAL, ldir_vname);
1242 			if (ldir.str != NULL) {
1243 			    strlcpy(latestdir, ldir.str, sizeof latestdir);
1244 			    FStr_Done(&ldir);
1245 			}
1246 			ldir = Var_Value(SCOPE_GLOBAL, lcwd_vname);
1247 			if (ldir.str != NULL) {
1248 			    strlcpy(lcwd, ldir.str, sizeof lcwd);
1249 			    FStr_Done(&ldir);
1250 			}
1251 		    }
1252 		    /* Skip past the pid. */
1253 		    if (strsep(&p, " ") == NULL)
1254 			continue;
1255 #ifdef DEBUG_META_MODE
1256 		    if (DEBUG(META))
1257 			debug_printf("%s: %d: %d: %c: cwd=%s lcwd=%s ldir=%s\n",
1258 				     fname, lineno,
1259 				     pid, buf[0], cwd, lcwd, latestdir);
1260 #endif
1261 		    break;
1262 		}
1263 
1264 		CHECK_VALID_META(p);
1265 
1266 		/* Process according to record type. */
1267 		switch (buf[0]) {
1268 		case 'X':		/* eXit */
1269 		    Var_DeleteExpand(SCOPE_GLOBAL, lcwd_vname);
1270 		    Var_DeleteExpand(SCOPE_GLOBAL, ldir_vname);
1271 		    lastpid = 0;	/* no need to save ldir_vname */
1272 		    break;
1273 
1274 		case 'F':		/* [v]Fork */
1275 		    {
1276 			char cldir[64];
1277 			int child;
1278 
1279 			child = atoi(p);
1280 			if (child > 0) {
1281 			    snprintf(cldir, sizeof cldir, LCWD_VNAME_FMT, child);
1282 			    Global_SetExpand(cldir, lcwd);
1283 			    snprintf(cldir, sizeof cldir, LDIR_VNAME_FMT, child);
1284 			    Global_SetExpand(cldir, latestdir);
1285 #ifdef DEBUG_META_MODE
1286 			    if (DEBUG(META))
1287 				debug_printf(
1288 					"%s: %d: %d: cwd=%s lcwd=%s ldir=%s\n",
1289 					fname, lineno,
1290 					child, cwd, lcwd, latestdir);
1291 #endif
1292 			}
1293 		    }
1294 		    break;
1295 
1296 		case 'C':		/* Chdir */
1297 		    /* Update lcwd and latest directory. */
1298 		    strlcpy(latestdir, p, sizeof latestdir);
1299 		    strlcpy(lcwd, p, sizeof lcwd);
1300 		    Global_SetExpand(lcwd_vname, lcwd);
1301 		    Global_SetExpand(ldir_vname, lcwd);
1302 #ifdef DEBUG_META_MODE
1303 		    DEBUG4(META, "%s: %d: cwd=%s ldir=%s\n",
1304 			   fname, lineno, cwd, lcwd);
1305 #endif
1306 		    break;
1307 
1308 		case 'M':		/* renaMe */
1309 		    /*
1310 		     * For 'M'oves we want to check
1311 		     * the src as for 'R'ead
1312 		     * and the target as for 'W'rite.
1313 		     */
1314 		    {
1315 			char *cp = p;	/* save this for a second */
1316 			/* now get target */
1317 			if (strsep(&p, " ") == NULL)
1318 			    continue;
1319 			CHECK_VALID_META(p);
1320 			move_target = p;
1321 			p = cp;
1322 		    }
1323 		    /* 'L' and 'M' put single quotes around the args */
1324 		    DEQUOTE(p);
1325 		    DEQUOTE(move_target);
1326 		    /* FALLTHROUGH */
1327 		case 'D':		/* unlink */
1328 		    if (*p == '/') {
1329 			/* remove any missingFiles entries that match p */
1330 			StringListNode *ln = missingFiles.first;
1331 			while (ln != NULL) {
1332 			    StringListNode *next = ln->next;
1333 			    if (path_starts_with(ln->datum, p)) {
1334 				free(ln->datum);
1335 				Lst_Remove(&missingFiles, ln);
1336 			    }
1337 			    ln = next;
1338 			}
1339 		    }
1340 		    if (buf[0] == 'M') {
1341 			/* the target of the mv is a file 'W'ritten */
1342 #ifdef DEBUG_META_MODE
1343 			DEBUG2(META, "meta_oodate: M %s -> %s\n",
1344 			       p, move_target);
1345 #endif
1346 			p = move_target;
1347 			goto check_write;
1348 		    }
1349 		    break;
1350 		case 'L':		/* Link */
1351 		    /*
1352 		     * For 'L'inks check
1353 		     * the src as for 'R'ead
1354 		     * and the target as for 'W'rite.
1355 		     */
1356 		    link_src = p;
1357 		    /* now get target */
1358 		    if (strsep(&p, " ") == NULL)
1359 			continue;
1360 		    CHECK_VALID_META(p);
1361 		    /* 'L' and 'M' put single quotes around the args */
1362 		    DEQUOTE(p);
1363 		    DEQUOTE(link_src);
1364 #ifdef DEBUG_META_MODE
1365 		    DEBUG2(META, "meta_oodate: L %s -> %s\n", link_src, p);
1366 #endif
1367 		    /* FALLTHROUGH */
1368 		case 'W':		/* Write */
1369 		check_write:
1370 		    /*
1371 		     * If a file we generated within our bailiwick
1372 		     * but outside of .OBJDIR is missing,
1373 		     * we need to do it again.
1374 		     */
1375 		    /* ignore non-absolute paths */
1376 		    if (*p != '/')
1377 			break;
1378 
1379 		    if (Lst_IsEmpty(&metaBailiwick))
1380 			break;
1381 
1382 		    /* ignore cwd - normal dependencies handle those */
1383 		    if (strncmp(p, cwd, cwdlen) == 0)
1384 			break;
1385 
1386 		    if (!has_any_prefix(p, &metaBailiwick))
1387 			break;
1388 
1389 		    /* tmpdir might be within */
1390 		    if (tmplen > 0 && strncmp(p, tmpdir, tmplen) == 0)
1391 			break;
1392 
1393 		    /* ignore anything containing the string "tmp" */
1394 		    /* XXX: The arguments to strstr must be swapped. */
1395 		    if (strstr("tmp", p) != NULL)
1396 			break;
1397 
1398 		    if ((link_src != NULL && cached_lstat(p, &cst) < 0) ||
1399 			(link_src == NULL && cached_stat(p, &cst) < 0)) {
1400 			if (!meta_ignore(gn, p))
1401 			    append_if_new(&missingFiles, p);
1402 		    }
1403 		    break;
1404 		check_link_src:
1405 		    p = link_src;
1406 		    link_src = NULL;
1407 #ifdef DEBUG_META_MODE
1408 		    DEBUG1(META, "meta_oodate: L src %s\n", p);
1409 #endif
1410 		    /* FALLTHROUGH */
1411 		case 'R':		/* Read */
1412 		case 'E':		/* Exec */
1413 		    /*
1414 		     * Check for runtime files that can't
1415 		     * be part of the dependencies because
1416 		     * they are _expected_ to change.
1417 		     */
1418 		    if (meta_ignore(gn, p))
1419 			break;
1420 
1421 		    /*
1422 		     * The rest of the record is the file name.
1423 		     * Check if it's not an absolute path.
1424 		     */
1425 		    {
1426 			char *sdirs[4];
1427 			char **sdp;
1428 			int sdx = 0;
1429 			bool found = false;
1430 
1431 			if (*p == '/') {
1432 			    sdirs[sdx++] = p; /* done */
1433 			} else {
1434 			    if (strcmp(".", p) == 0)
1435 				continue; /* no point */
1436 
1437 			    /* Check vs latestdir */
1438 			    snprintf(fname1, sizeof fname1, "%s/%s", latestdir, p);
1439 			    sdirs[sdx++] = fname1;
1440 
1441 			    if (strcmp(latestdir, lcwd) != 0) {
1442 				/* Check vs lcwd */
1443 				snprintf(fname2, sizeof fname2, "%s/%s", lcwd, p);
1444 				sdirs[sdx++] = fname2;
1445 			    }
1446 			    if (strcmp(lcwd, cwd) != 0) {
1447 				/* Check vs cwd */
1448 				snprintf(fname3, sizeof fname3, "%s/%s", cwd, p);
1449 				sdirs[sdx++] = fname3;
1450 			    }
1451 			}
1452 			sdirs[sdx++] = NULL;
1453 
1454 			for (sdp = sdirs; *sdp != NULL && !found; sdp++) {
1455 #ifdef DEBUG_META_MODE
1456 			    DEBUG3(META, "%s: %d: looking for: %s\n",
1457 				   fname, lineno, *sdp);
1458 #endif
1459 			    if (cached_stat(*sdp, &cst) == 0) {
1460 				found = true;
1461 				p = *sdp;
1462 			    }
1463 			}
1464 			if (found) {
1465 #ifdef DEBUG_META_MODE
1466 			    DEBUG3(META, "%s: %d: found: %s\n",
1467 				   fname, lineno, p);
1468 #endif
1469 			    if (!S_ISDIR(cst.cst_mode) &&
1470 				cst.cst_mtime > gn->mtime) {
1471 				DEBUG3(META, "%s: %d: file '%s' is newer than the target...\n",
1472 				       fname, lineno, p);
1473 				oodate = true;
1474 			    } else if (S_ISDIR(cst.cst_mode)) {
1475 				/* Update the latest directory. */
1476 				cached_realpath(p, latestdir);
1477 			    }
1478 			} else if (errno == ENOENT && *p == '/' &&
1479 				   strncmp(p, cwd, cwdlen) != 0) {
1480 			    /*
1481 			     * A referenced file outside of CWD is missing.
1482 			     * We cannot catch every eventuality here...
1483 			     */
1484 			    append_if_new(&missingFiles, p);
1485 			}
1486 		    }
1487 		    if (buf[0] == 'E') {
1488 			/* previous latestdir is no longer relevant */
1489 			strlcpy(latestdir, lcwd, sizeof latestdir);
1490 		    }
1491 		    break;
1492 		default:
1493 		    break;
1494 		}
1495 		if (!oodate && buf[0] == 'L' && link_src != NULL)
1496 		    goto check_link_src;
1497 	    } else if (strcmp(buf, "CMD") == 0) {
1498 		/*
1499 		 * Compare the current command with the one in the
1500 		 * meta data file.
1501 		 */
1502 		if (cmdNode == NULL) {
1503 		    DEBUG2(META, "%s: %d: there were more build commands in the meta data file than there are now...\n",
1504 			   fname, lineno);
1505 		    oodate = true;
1506 		} else {
1507 		    const char *cp;
1508 		    char *cmd = cmdNode->datum;
1509 		    bool hasOODATE = false;
1510 
1511 		    if (strstr(cmd, "$?") != NULL)
1512 			hasOODATE = true;
1513 		    else if ((cp = strstr(cmd, ".OODATE")) != NULL) {
1514 			/* check for $[{(].OODATE[:)}] */
1515 			if (cp > cmd + 2 && cp[-2] == '$')
1516 			    hasOODATE = true;
1517 		    }
1518 		    if (hasOODATE) {
1519 			needOODATE = true;
1520 			DEBUG2(META, "%s: %d: cannot compare command using .OODATE\n",
1521 			       fname, lineno);
1522 		    }
1523 		    (void)Var_Subst(cmd, gn, VARE_UNDEFERR, &cmd);
1524 		    /* TODO: handle errors */
1525 
1526 		    if ((cp = strchr(cmd, '\n')) != NULL) {
1527 			int n;
1528 
1529 			/*
1530 			 * This command contains newlines, we need to
1531 			 * fetch more from the .meta file before we
1532 			 * attempt a comparison.
1533 			 */
1534 			/* first put the newline back at buf[x - 1] */
1535 			buf[x - 1] = '\n';
1536 			do {
1537 			    /* now fetch the next line */
1538 			    if ((n = fgetLine(&buf, &bufsz, x, fp)) <= 0)
1539 				break;
1540 			    x = n;
1541 			    lineno++;
1542 			    if (buf[x - 1] != '\n') {
1543 				warnx("%s: %d: line truncated at %u", fname, lineno, x);
1544 				break;
1545 			    }
1546 			    cp = strchr(cp + 1, '\n');
1547 			} while (cp != NULL);
1548 			if (buf[x - 1] == '\n')
1549 			    buf[x - 1] = '\0';
1550 		    }
1551 		    if (p != NULL &&
1552 			!hasOODATE &&
1553 			!(gn->type & OP_NOMETA_CMP) &&
1554 			(strcmp(p, cmd) != 0)) {
1555 			DEBUG4(META, "%s: %d: a build command has changed\n%s\nvs\n%s\n",
1556 			       fname, lineno, p, cmd);
1557 			if (!metaIgnoreCMDs)
1558 			    oodate = true;
1559 		    }
1560 		    free(cmd);
1561 		    cmdNode = cmdNode->next;
1562 		}
1563 	    } else if (strcmp(buf, "CWD") == 0) {
1564 		/*
1565 		 * Check if there are extra commands now
1566 		 * that weren't in the meta data file.
1567 		 */
1568 		if (!oodate && cmdNode != NULL) {
1569 		    DEBUG2(META, "%s: %d: there are extra build commands now that weren't in the meta data file\n",
1570 			   fname, lineno);
1571 		    oodate = true;
1572 		}
1573 		CHECK_VALID_META(p);
1574 		if (strcmp(p, cwd) != 0) {
1575 		    DEBUG4(META, "%s: %d: the current working directory has changed from '%s' to '%s'\n",
1576 			   fname, lineno, p, curdir);
1577 		    oodate = true;
1578 		}
1579 	    }
1580 	}
1581 
1582 	fclose(fp);
1583 	if (!Lst_IsEmpty(&missingFiles)) {
1584 	    DEBUG2(META, "%s: missing files: %s...\n",
1585 		   fname, (char *)missingFiles.first->datum);
1586 	    oodate = true;
1587 	}
1588 	if (!oodate && !have_filemon && filemonMissing) {
1589 	    DEBUG1(META, "%s: missing filemon data\n", fname);
1590 	    oodate = true;
1591 	}
1592     } else {
1593 	if (writeMeta && (metaMissing || (gn->type & OP_META))) {
1594 	    const char *cp = NULL;
1595 
1596 	    /* if target is in .CURDIR we do not need a meta file */
1597 	    if (gn->path != NULL && (cp = strrchr(gn->path, '/')) != NULL &&
1598 		(cp > gn->path)) {
1599 		if (strncmp(curdir, gn->path, (size_t)(cp - gn->path)) != 0) {
1600 		    cp = NULL;		/* not in .CURDIR */
1601 		}
1602 	    }
1603 	    if (cp == NULL) {
1604 		DEBUG1(META, "%s: required but missing\n", fname);
1605 		oodate = true;
1606 		needOODATE = true;	/* assume the worst */
1607 	    }
1608 	}
1609     }
1610 
1611     Lst_DoneCall(&missingFiles, free);
1612 
1613     if (oodate && needOODATE) {
1614 	/*
1615 	 * Target uses .OODATE which is empty; or we wouldn't be here.
1616 	 * We have decided it is oodate, so .OODATE needs to be set.
1617 	 * All we can sanely do is set it to .ALLSRC.
1618 	 */
1619 	Var_Delete(gn, OODATE);
1620 	Var_Set(gn, OODATE, GNode_VarAllsrc(gn));
1621     }
1622 
1623  oodate_out:
1624     FStr_Done(&dname);
1625     return oodate;
1626 }
1627 
1628 /* support for compat mode */
1629 
1630 static int childPipe[2];
1631 
1632 void
1633 meta_compat_start(void)
1634 {
1635 #ifdef USE_FILEMON_ONCE
1636     /*
1637      * We need to re-open filemon for each cmd.
1638      */
1639     BuildMon *pbm = &Mybm;
1640 
1641     if (pbm->mfp != NULL && useFilemon) {
1642 	meta_open_filemon(pbm);
1643     } else {
1644 	pbm->mon_fd = -1;
1645 	pbm->filemon = NULL;
1646     }
1647 #endif
1648     if (pipe(childPipe) < 0)
1649 	Punt("Cannot create pipe: %s", strerror(errno));
1650     /* Set close-on-exec flag for both */
1651     (void)fcntl(childPipe[0], F_SETFD, FD_CLOEXEC);
1652     (void)fcntl(childPipe[1], F_SETFD, FD_CLOEXEC);
1653 }
1654 
1655 void
1656 meta_compat_child(void)
1657 {
1658     meta_job_child(NULL);
1659     if (dup2(childPipe[1], 1) < 0 || dup2(1, 2) < 0)
1660 	execDie("dup2", "pipe");
1661 }
1662 
1663 void
1664 meta_compat_parent(pid_t child)
1665 {
1666     int outfd, metafd, maxfd, nfds;
1667     char buf[BUFSIZ+1];
1668     fd_set readfds;
1669 
1670     meta_job_parent(NULL, child);
1671     close(childPipe[1]);			/* child side */
1672     outfd = childPipe[0];
1673 #ifdef USE_FILEMON
1674     metafd = Mybm.filemon != NULL ? filemon_readfd(Mybm.filemon) : -1;
1675 #else
1676     metafd = -1;
1677 #endif
1678     maxfd = -1;
1679     if (outfd > maxfd)
1680 	    maxfd = outfd;
1681     if (metafd > maxfd)
1682 	    maxfd = metafd;
1683 
1684     while (outfd != -1 || metafd != -1) {
1685 	FD_ZERO(&readfds);
1686 	if (outfd != -1) {
1687 	    FD_SET(outfd, &readfds);
1688 	}
1689 	if (metafd != -1) {
1690 	    FD_SET(metafd, &readfds);
1691 	}
1692 	nfds = select(maxfd + 1, &readfds, NULL, NULL, NULL);
1693 	if (nfds == -1) {
1694 	    if (errno == EINTR)
1695 		continue;
1696 	    err(1, "select");
1697 	}
1698 
1699 	if (outfd != -1 && FD_ISSET(outfd, &readfds) != 0) do {
1700 	    /* XXX this is not line-buffered */
1701 	    ssize_t nread = read(outfd, buf, sizeof buf - 1);
1702 	    if (nread == -1)
1703 		err(1, "read");
1704 	    if (nread == 0) {
1705 		close(outfd);
1706 		outfd = -1;
1707 		break;
1708 	    }
1709 	    fwrite(buf, 1, (size_t)nread, stdout);
1710 	    fflush(stdout);
1711 	    buf[nread] = '\0';
1712 	    meta_job_output(NULL, buf, "");
1713 	} while (/*CONSTCOND*/false);
1714 	if (metafd != -1 && FD_ISSET(metafd, &readfds) != 0) {
1715 	    if (meta_job_event(NULL) <= 0)
1716 		metafd = -1;
1717 	}
1718     }
1719 }
1720 
1721 #endif /* USE_META */
1722