xref: /src/usr.bin/make/meta.c

/*      $NetBSD: meta.c,v 1.151 2020/11/28 10:25:45 rillig Exp $ */

/*
 * Implement 'meta' mode.
 * Adapted from John Birrell's patches to FreeBSD make.
 * --sjg
 */
/*
 * Copyright (c) 2009-2016, Juniper Networks, Inc.
 * Portions Copyright (c) 2009, John Birrell.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#if defined(USE_META)

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <sys/stat.h>
#include <libgen.h>
#include <errno.h>
#if !defined(HAVE_CONFIG_H) || defined(HAVE_ERR_H)
#include <err.h>
#endif

#include "make.h"
#include "dir.h"
#include "job.h"

#ifdef USE_FILEMON
#include "filemon/filemon.h"
#endif

static BuildMon Mybm;			/* for compat */
static StringList *metaBailiwick;	/* our scope of control */
static char *metaBailiwickStr;		/* string storage for the list */
static StringList *metaIgnorePaths;	/* paths we deliberately ignore */
static char *metaIgnorePathsStr;	/* string storage for the list */

#ifndef MAKE_META_IGNORE_PATHS
#define MAKE_META_IGNORE_PATHS ".MAKE.META.IGNORE_PATHS"
#endif
#ifndef MAKE_META_IGNORE_PATTERNS
#define MAKE_META_IGNORE_PATTERNS ".MAKE.META.IGNORE_PATTERNS"
#endif
#ifndef MAKE_META_IGNORE_FILTER
#define MAKE_META_IGNORE_FILTER ".MAKE.META.IGNORE_FILTER"
#endif

Boolean useMeta = FALSE;
static Boolean useFilemon = FALSE;
static Boolean writeMeta = FALSE;
static Boolean metaMissing = FALSE;	/* oodate if missing */
static Boolean filemonMissing = FALSE;	/* oodate if missing */
static Boolean metaEnv = FALSE;		/* don't save env unless asked */
static Boolean metaVerbose = FALSE;
static Boolean metaIgnoreCMDs = FALSE;	/* ignore CMDs in .meta files */
static Boolean metaIgnorePatterns = FALSE; /* do we need to do pattern matches */
static Boolean metaIgnoreFilter = FALSE; /* do we have more complex filtering? */
static Boolean metaCurdirOk = FALSE;	/* write .meta in .CURDIR Ok? */
static Boolean metaSilent = FALSE;	/* if we have a .meta be SILENT */

extern Boolean forceJobs;
extern char    **environ;

#define	MAKE_META_PREFIX	".MAKE.META.PREFIX"

#ifndef N2U
# define N2U(n, u)   (((n) + ((u) - 1)) / (u))
#endif
#ifndef ROUNDUP
# define ROUNDUP(n, u)   (N2U((n), (u)) * (u))
#endif

#if !defined(HAVE_STRSEP)
# define strsep(s, d) stresep((s), (d), '\0')
#endif

/*
 * Filemon is a kernel module which snoops certain syscalls.
 *
 * C chdir
 * E exec
 * F [v]fork
 * L [sym]link
 * M rename
 * R read
 * W write
 * S stat
 *
 * See meta_oodate below - we mainly care about 'E' and 'R'.
 *
 * We can still use meta mode without filemon, but
 * the benefits are more limited.
 */
#ifdef USE_FILEMON

/*
 * Open the filemon device.
 */
static void
meta_open_filemon(BuildMon *pbm)
{
    int dupfd;

    pbm->mon_fd = -1;
    pbm->filemon = NULL;
    if (!useFilemon || !pbm->mfp)
	return;

    pbm->filemon = filemon_open();
    if (pbm->filemon == NULL) {
	useFilemon = FALSE;
	warn("Could not open filemon %s", filemon_path());
	return;
    }

    /*
     * We use a file outside of '.'
     * to avoid a FreeBSD kernel bug where unlink invalidates
     * cwd causing getcwd to do a lot more work.
     * We only care about the descriptor.
     */
    pbm->mon_fd = mkTempFile("filemon.XXXXXX", NULL);
    if ((dupfd = dup(pbm->mon_fd)) == -1) {
	err(1, "Could not dup filemon output!");
    }
    (void)fcntl(dupfd, F_SETFD, FD_CLOEXEC);
    if (filemon_setfd(pbm->filemon, dupfd) == -1) {
	err(1, "Could not set filemon file descriptor!");
    }
    /* we don't need these once we exec */
    (void)fcntl(pbm->mon_fd, F_SETFD, FD_CLOEXEC);
}

/*
 * Read the build monitor output file and write records to the target's
 * metadata file.
 */
static int
filemon_read(FILE *mfp, int fd)
{
    char buf[BUFSIZ];
    int error;

    /* Check if we're not writing to a meta data file.*/
    if (mfp == NULL) {
	if (fd >= 0)
	    close(fd);			/* not interested */
	return 0;
    }
    /* rewind */
    if (lseek(fd, (off_t)0, SEEK_SET) < 0) {
	error = errno;
	warn("Could not rewind filemon");
	fprintf(mfp, "\n");
    } else {
	ssize_t n;

	error = 0;
	fprintf(mfp, "\n-- filemon acquired metadata --\n");

	while ((n = read(fd, buf, sizeof buf)) > 0) {
	    if ((ssize_t)fwrite(buf, 1, (size_t)n, mfp) < n)
		error = EIO;
	}
    }
    fflush(mfp);
    if (close(fd) < 0)
	error = errno;
    return error;
}
#endif

/*
 * when realpath() fails,
 * we use this, to clean up ./ and ../
 */
static void
eat_dots(char *buf, size_t bufsz, int dots)
{
    char *cp;
    char *cp2;
    const char *eat;
    size_t eatlen;

    switch (dots) {
    case 1:
	eat = "/./";
	eatlen = 2;
	break;
    case 2:
	eat = "/../";
	eatlen = 3;
	break;
    default:
	return;
    }

    do {
	cp = strstr(buf, eat);
	if (cp != NULL) {
	    cp2 = cp + eatlen;
	    if (dots == 2 && cp > buf) {
		do {
		    cp--;
		} while (cp > buf && *cp != '/');
	    }
	    if (*cp == '/') {
		strlcpy(cp, cp2, bufsz - (size_t)(cp - buf));
	    } else {
		return;			/* can't happen? */
	    }
	}
    } while (cp != NULL);
}

static char *
meta_name(char *mname, size_t mnamelen,
	  const char *dname,
	  const char *tname,
	  const char *cwd)
{
    char buf[MAXPATHLEN];
    char *rp;
    char *cp;
    char *tp;
    char *dtp;
    size_t ldname;

    /*
     * Weed out relative paths from the target file name.
     * We have to be careful though since if target is a
     * symlink, the result will be unstable.
     * So we use realpath() just to get the dirname, and leave the
     * basename as given to us.
     */
    if ((cp = strrchr(tname, '/'))) {
	if (cached_realpath(tname, buf)) {
	    if ((rp = strrchr(buf, '/'))) {
		rp++;
		cp++;
		if (strcmp(cp, rp) != 0)
		    strlcpy(rp, cp, sizeof buf - (size_t)(rp - buf));
	    }
	    tname = buf;
	} else {
	    /*
	     * We likely have a directory which is about to be made.
	     * We pretend realpath() succeeded, to have a chance
	     * of generating the same meta file name that we will
	     * next time through.
	     */
	    if (tname[0] == '/') {
		strlcpy(buf, tname, sizeof buf);
	    } else {
		snprintf(buf, sizeof buf, "%s/%s", cwd, tname);
	    }
	    eat_dots(buf, sizeof buf, 1);	/* ./ */
	    eat_dots(buf, sizeof buf, 2);	/* ../ */
	    tname = buf;
	}
    }
    /* on some systems dirname may modify its arg */
    tp = bmake_strdup(tname);
    dtp = dirname(tp);
    if (strcmp(dname, dtp) == 0)
	snprintf(mname, mnamelen, "%s.meta", tname);
    else {
	ldname = strlen(dname);
	if (strncmp(dname, dtp, ldname) == 0 && dtp[ldname] == '/')
	    snprintf(mname, mnamelen, "%s/%s.meta", dname, &tname[ldname+1]);
	else
	    snprintf(mname, mnamelen, "%s/%s.meta", dname, tname);

	/*
	 * Replace path separators in the file name after the
	 * current object directory path.
	 */
	cp = mname + strlen(dname) + 1;

	while (*cp != '\0') {
	    if (*cp == '/')
		*cp = '_';
	    cp++;
	}
    }
    free(tp);
    return mname;
}

/*
 * Return true if running ${.MAKE}
 * Bypassed if target is flagged .MAKE
 */
static Boolean
is_submake(const char *cmd, GNode *gn)
{
    static const char *p_make = NULL;
    static size_t p_len;
    char *mp = NULL;
    char *cp;
    char *cp2;
    Boolean rc = FALSE;

    if (p_make == NULL) {
	void *dontFreeIt;
	p_make = Var_Value(".MAKE", gn, &dontFreeIt);
	p_len = strlen(p_make);
    }
    cp = strchr(cmd, '$');
    if ((cp)) {
	(void)Var_Subst(cmd, gn, VARE_WANTRES, &mp);
	/* TODO: handle errors */
	cmd = mp;
    }
    cp2 = strstr(cmd, p_make);
    if (cp2 != NULL) {
	switch (cp2[p_len]) {
	case '\0':
	case ' ':
	case '\t':
	case '\n':
	    rc = TRUE;
	    break;
	}
	if (cp2 > cmd && rc) {
	    switch (cp2[-1]) {
	    case ' ':
	    case '\t':
	    case '\n':
		break;
	    default:
		rc = FALSE;		/* no match */
		break;
	    }
	}
    }
    free(mp);
    return rc;
}

static Boolean
any_is_submake(GNode *gn)
{
    StringListNode *ln;

    for (ln = gn->commands->first; ln != NULL; ln = ln->next)
	if (is_submake(ln->datum, gn))
	    return TRUE;
    return FALSE;
}

static void
printCMD(const char *cmd, FILE *fp, GNode *gn)
{
    char *cmd_freeIt = NULL;

    if (strchr(cmd, '$')) {
	(void)Var_Subst(cmd, gn, VARE_WANTRES, &cmd_freeIt);
	/* TODO: handle errors */
	cmd = cmd_freeIt;
    }
    fprintf(fp, "CMD %s\n", cmd);
    free(cmd_freeIt);
}

static void
printCMDs(GNode *gn, FILE *fp)
{
    GNodeListNode *ln;

    for (ln = gn->commands->first; ln != NULL; ln = ln->next)
	printCMD(ln->datum, fp, gn);
}

/*
 * Certain node types never get a .meta file
 */
#define SKIP_META_TYPE(_type) do { \
    if ((gn->type & __CONCAT(OP_, _type))) { \
	if (verbose) { \
	    debug_printf("Skipping meta for %s: .%s\n", \
		    gn->name, __STRING(_type)); \
	} \
	return FALSE; \
    } \
} while (0)


/*
 * Do we need/want a .meta file ?
 */
static Boolean
meta_needed(GNode *gn, const char *dname, const char *tname,
	     char *objdir, Boolean verbose)
{
    struct cached_stat cst;

    if (verbose)
	verbose = DEBUG(META) != 0;

    /* This may be a phony node which we don't want meta data for... */
    /* Skip .meta for .BEGIN, .END, .ERROR etc as well. */
    /* Or it may be explicitly flagged as .NOMETA */
    SKIP_META_TYPE(NOMETA);
    /* Unless it is explicitly flagged as .META */
    if (!(gn->type & OP_META)) {
	SKIP_META_TYPE(PHONY);
	SKIP_META_TYPE(SPECIAL);
	SKIP_META_TYPE(MAKE);
    }

    /* Check if there are no commands to execute. */
    if (Lst_IsEmpty(gn->commands)) {
	if (verbose)
	    debug_printf("Skipping meta for %s: no commands\n", gn->name);
	return FALSE;
    }
    if ((gn->type & (OP_META|OP_SUBMAKE)) == OP_SUBMAKE) {
	/* OP_SUBMAKE is a bit too aggressive */
	if (any_is_submake(gn)) {
	    DEBUG1(META, "Skipping meta for %s: .SUBMAKE\n", gn->name);
	    return FALSE;
	}
    }

    /* The object directory may not exist. Check it.. */
    if (cached_stat(dname, &cst) != 0) {
	if (verbose)
	    debug_printf("Skipping meta for %s: no .OBJDIR\n", gn->name);
	return FALSE;
    }

    /* make sure these are canonical */
    if (cached_realpath(dname, objdir))
	dname = objdir;

    /* If we aren't in the object directory, don't create a meta file. */
    if (!metaCurdirOk && strcmp(curdir, dname) == 0) {
	if (verbose)
	    debug_printf("Skipping meta for %s: .OBJDIR == .CURDIR\n",
			 gn->name);
	return FALSE;
    }
    return TRUE;
}


static FILE *
meta_create(BuildMon *pbm, GNode *gn)
{
    FILE *fp;
    char buf[MAXPATHLEN];
    char objdir[MAXPATHLEN];
    char **ptr;
    const char *dname;
    const char *tname;
    char *fname;
    const char *cp;
    void *dname_freeIt;

    fp = NULL;

    dname = Var_Value(".OBJDIR", gn, &dname_freeIt);
    tname = GNode_VarTarget(gn);

    /* if this succeeds objdir is realpath of dname */
    if (!meta_needed(gn, dname, tname, objdir, TRUE))
	goto out;
    dname = objdir;

    if (metaVerbose) {
	char *mp;

	/* Describe the target we are building */
	(void)Var_Subst("${" MAKE_META_PREFIX "}", gn, VARE_WANTRES, &mp);
	/* TODO: handle errors */
	if (mp[0] != '\0')
	    fprintf(stdout, "%s\n", mp);
	free(mp);
    }
    /* Get the basename of the target */
    if ((cp = strrchr(tname, '/')) == NULL) {
	cp = tname;
    } else {
	cp++;
    }

    fflush(stdout);

    if (!writeMeta)
	/* Don't create meta data. */
	goto out;

    fname = meta_name(pbm->meta_fname, sizeof pbm->meta_fname,
		      dname, tname, objdir);

#ifdef DEBUG_META_MODE
    DEBUG1(META, "meta_create: %s\n", fname);
#endif

    if ((fp = fopen(fname, "w")) == NULL)
	err(1, "Could not open meta file '%s'", fname);

    fprintf(fp, "# Meta data file %s\n", fname);

    printCMDs(gn, fp);

    fprintf(fp, "CWD %s\n", getcwd(buf, sizeof buf));
    fprintf(fp, "TARGET %s\n", tname);
    cp = GNode_VarOodate(gn);
    if (cp && *cp) {
	fprintf(fp, "OODATE %s\n", cp);
    }
    if (metaEnv) {
	for (ptr = environ; *ptr != NULL; ptr++)
	    fprintf(fp, "ENV %s\n", *ptr);
    }

    fprintf(fp, "-- command output --\n");
    fflush(fp);

    Var_Append(".MAKE.META.FILES", fname, VAR_GLOBAL);
    Var_Append(".MAKE.META.CREATED", fname, VAR_GLOBAL);

    gn->type |= OP_META;		/* in case anyone wants to know */
    if (metaSilent) {
	    gn->type |= OP_SILENT;
    }
 out:
    bmake_free(dname_freeIt);

    return fp;
}

static Boolean
boolValue(char *s)
{
    switch(*s) {
    case '0':
    case 'N':
    case 'n':
    case 'F':
    case 'f':
	return FALSE;
    }
    return TRUE;
}

/*
 * Initialization we need before reading makefiles.
 */
void
meta_init(void)
{
#ifdef USE_FILEMON
	/* this allows makefiles to test if we have filemon support */
	Var_Set(".MAKE.PATH_FILEMON", filemon_path(), VAR_GLOBAL);
#endif
}


#define get_mode_bf(bf, token) \
    if ((cp = strstr(make_mode, token))) \
	bf = boolValue(cp + sizeof (token) - 1)

/*
 * Initialization we need after reading makefiles.
 */
void
meta_mode_init(const char *make_mode)
{
    static Boolean once = FALSE;
    char *cp;
    void *freeIt;

    useMeta = TRUE;
    useFilemon = TRUE;
    writeMeta = TRUE;

    if (make_mode != NULL) {
	if (strstr(make_mode, "env"))
	    metaEnv = TRUE;
	if (strstr(make_mode, "verb"))
	    metaVerbose = TRUE;
	if (strstr(make_mode, "read"))
	    writeMeta = FALSE;
	if (strstr(make_mode, "nofilemon"))
	    useFilemon = FALSE;
	if (strstr(make_mode, "ignore-cmd"))
	    metaIgnoreCMDs = TRUE;
	if (useFilemon)
	    get_mode_bf(filemonMissing, "missing-filemon=");
	get_mode_bf(metaCurdirOk, "curdirok=");
	get_mode_bf(metaMissing, "missing-meta=");
	get_mode_bf(metaSilent, "silent=");
    }
    if (metaVerbose && !Var_Exists(MAKE_META_PREFIX, VAR_GLOBAL)) {
	/*
	 * The default value for MAKE_META_PREFIX
	 * prints the absolute path of the target.
	 * This works be cause :H will generate '.' if there is no /
	 * and :tA will resolve that to cwd.
	 */
	Var_Set(MAKE_META_PREFIX, "Building ${.TARGET:H:tA}/${.TARGET:T}", VAR_GLOBAL);
    }
    if (once)
	return;
    once = TRUE;
    memset(&Mybm, 0, sizeof Mybm);
    /*
     * We consider ourselves master of all within ${.MAKE.META.BAILIWICK}
     */
    metaBailiwick = Lst_New();
    (void)Var_Subst("${.MAKE.META.BAILIWICK:O:u:tA}",
		    VAR_GLOBAL, VARE_WANTRES, &metaBailiwickStr);
    /* TODO: handle errors */
    str2Lst_Append(metaBailiwick, metaBailiwickStr);
    /*
     * We ignore any paths that start with ${.MAKE.META.IGNORE_PATHS}
     */
    metaIgnorePaths = Lst_New();
    Var_Append(MAKE_META_IGNORE_PATHS,
	       "/dev /etc /proc /tmp /var/run /var/tmp ${TMPDIR}", VAR_GLOBAL);
    (void)Var_Subst("${" MAKE_META_IGNORE_PATHS ":O:u:tA}",
		    VAR_GLOBAL, VARE_WANTRES, &metaIgnorePathsStr);
    /* TODO: handle errors */
    str2Lst_Append(metaIgnorePaths, metaIgnorePathsStr);

    /*
     * We ignore any paths that match ${.MAKE.META.IGNORE_PATTERNS}
     */
    freeIt = NULL;
    if (Var_Value(MAKE_META_IGNORE_PATTERNS, VAR_GLOBAL, &freeIt)) {
	metaIgnorePatterns = TRUE;
	bmake_free(freeIt);
    }
    freeIt = NULL;
    if (Var_Value(MAKE_META_IGNORE_FILTER, VAR_GLOBAL, &freeIt)) {
	metaIgnoreFilter = TRUE;
	bmake_free(freeIt);
    }
}

/*
 * In each case below we allow for job==NULL
 */
void
meta_job_start(Job *job, GNode *gn)
{
    BuildMon *pbm;

    if (job != NULL) {
	pbm = &job->bm;
    } else {
	pbm = &Mybm;
    }
    pbm->mfp = meta_create(pbm, gn);
#ifdef USE_FILEMON_ONCE
    /* compat mode we open the filemon dev once per command */
    if (job == NULL)
	return;
#endif
#ifdef USE_FILEMON
    if (pbm->mfp != NULL && useFilemon) {
	meta_open_filemon(pbm);
    } else {
	pbm->mon_fd = -1;
	pbm->filemon = NULL;
    }
#endif
}

/*
 * The child calls this before doing anything.
 * It does not disturb our state.
 */
void
meta_job_child(Job *job)
{
#ifdef USE_FILEMON
    BuildMon *pbm;

    if (job != NULL) {
	pbm = &job->bm;
    } else {
	pbm = &Mybm;
    }
    if (pbm->mfp != NULL) {
	close(fileno(pbm->mfp));
	if (useFilemon && pbm->filemon) {
	    pid_t pid;

	    pid = getpid();
	    if (filemon_setpid_child(pbm->filemon, pid) == -1) {
		err(1, "Could not set filemon pid!");
	    }
	}
    }
#endif
}

void
meta_job_parent(Job *job, pid_t pid)
{
#if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
    BuildMon *pbm;

    if (job != NULL) {
	pbm = &job->bm;
    } else {
	pbm = &Mybm;
    }
    if (useFilemon && pbm->filemon) {
	filemon_setpid_parent(pbm->filemon, pid);
    }
#endif
}

int
meta_job_fd(Job *job)
{
#if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
    BuildMon *pbm;

    if (job != NULL) {
	pbm = &job->bm;
    } else {
	pbm = &Mybm;
    }
    if (useFilemon && pbm->filemon) {
	return filemon_readfd(pbm->filemon);
    }
#endif
    return -1;
}

int
meta_job_event(Job *job)
{
#if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
    BuildMon *pbm;

    if (job != NULL) {
	pbm = &job->bm;
    } else {
	pbm = &Mybm;
    }
    if (useFilemon && pbm->filemon) {
	return filemon_process(pbm->filemon);
    }
#endif
    return 0;
}

void
meta_job_error(Job *job, GNode *gn, int flags, int status)
{
    char cwd[MAXPATHLEN];
    BuildMon *pbm;

    if (job != NULL) {
	pbm = &job->bm;
	if (gn == NULL)
	    gn = job->node;
    } else {
	pbm = &Mybm;
    }
    if (pbm->mfp != NULL) {
	fprintf(pbm->mfp, "\n*** Error code %d%s\n",
		status,
		(flags & JOB_IGNERR) ?
		"(ignored)" : "");
    }
    if (gn != NULL) {
	Var_Set(".ERROR_TARGET", GNode_Path(gn), VAR_GLOBAL);
    }
    getcwd(cwd, sizeof cwd);
    Var_Set(".ERROR_CWD", cwd, VAR_GLOBAL);
    if (pbm->meta_fname[0] != '\0') {
	Var_Set(".ERROR_META_FILE", pbm->meta_fname, VAR_GLOBAL);
    }
    meta_job_finish(job);
}

void
meta_job_output(Job *job, char *cp, const char *nl)
{
    BuildMon *pbm;

    if (job != NULL) {
	pbm = &job->bm;
    } else {
	pbm = &Mybm;
    }
    if (pbm->mfp != NULL) {
	if (metaVerbose) {
	    static char *meta_prefix = NULL;
	    static size_t meta_prefix_len;

	    if (meta_prefix == NULL) {
		char *cp2;

		(void)Var_Subst("${" MAKE_META_PREFIX "}",
				VAR_GLOBAL, VARE_WANTRES, &meta_prefix);
		/* TODO: handle errors */
		if ((cp2 = strchr(meta_prefix, '$')))
		    meta_prefix_len = (size_t)(cp2 - meta_prefix);
		else
		    meta_prefix_len = strlen(meta_prefix);
	    }
	    if (strncmp(cp, meta_prefix, meta_prefix_len) == 0) {
		cp = strchr(cp+1, '\n');
		if (!cp++)
		    return;
	    }
	}
	fprintf(pbm->mfp, "%s%s", cp, nl);
    }
}

int
meta_cmd_finish(void *pbmp)
{
    int error = 0;
    BuildMon *pbm = pbmp;
#ifdef USE_FILEMON
    int x;
#endif

    if (pbm == NULL)
	pbm = &Mybm;

#ifdef USE_FILEMON
    if (pbm->filemon) {
	while (filemon_process(pbm->filemon) > 0)
	    continue;
	if (filemon_close(pbm->filemon) == -1)
	    error = errno;
	x = filemon_read(pbm->mfp, pbm->mon_fd);
	if (error == 0 && x != 0)
	    error = x;
	pbm->mon_fd = -1;
	pbm->filemon = NULL;
	return error;
    }
#endif

    fprintf(pbm->mfp, "\n");	/* ensure end with newline */
    return error;
}

int
meta_job_finish(Job *job)
{
    BuildMon *pbm;
    int error = 0;
    int x;

    if (job != NULL) {
	pbm = &job->bm;
    } else {
	pbm = &Mybm;
    }
    if (pbm->mfp != NULL) {
	error = meta_cmd_finish(pbm);
	x = fclose(pbm->mfp);
	if (error == 0 && x != 0)
	    error = errno;
	pbm->mfp = NULL;
	pbm->meta_fname[0] = '\0';
    }
    return error;
}

void
meta_finish(void)
{
    if (metaBailiwick != NULL)
	Lst_Free(metaBailiwick);
    free(metaBailiwickStr);
    if (metaIgnorePaths != NULL)
	Lst_Free(metaIgnorePaths);
    free(metaIgnorePathsStr);
}

/*
 * Fetch a full line from fp - growing bufp if needed
 * Return length in bufp.
 */
static int
fgetLine(char **bufp, size_t *szp, int o, FILE *fp)
{
    char *buf = *bufp;
    size_t bufsz = *szp;
    struct stat fs;
    int x;

    if (fgets(&buf[o], (int)bufsz - o, fp) != NULL) {
    check_newline:
	x = o + (int)strlen(&buf[o]);
	if (buf[x - 1] == '\n')
	    return x;
	/*
	 * We need to grow the buffer.
	 * The meta file can give us a clue.
	 */
	if (fstat(fileno(fp), &fs) == 0) {
	    size_t newsz;
	    char *p;

	    newsz = ROUNDUP(((size_t)fs.st_size / 2), BUFSIZ);
	    if (newsz <= bufsz)
		newsz = ROUNDUP((size_t)fs.st_size, BUFSIZ);
	    if (newsz <= bufsz)
		return x;		/* truncated */
	    DEBUG2(META, "growing buffer %zu -> %zu\n", bufsz, newsz);
	    p = bmake_realloc(buf, newsz);
	    *bufp = buf = p;
	    *szp = bufsz = newsz;
	    /* fetch the rest */
	    if (fgets(&buf[x], (int)bufsz - x, fp) == NULL)
		return x;		/* truncated! */
	    goto check_newline;
	}
    }
    return 0;
}

static Boolean
prefix_match(const char *prefix, const char *path)
{
    size_t n = strlen(prefix);

    return strncmp(path, prefix, n) == 0;
}

static Boolean
has_any_prefix(const char *path, StringList *prefixes)
{
    StringListNode *ln;

    for (ln = prefixes->first; ln != NULL; ln = ln->next)
	if (prefix_match(ln->datum, path))
	    return TRUE;
    return FALSE;
}

/* See if the path equals prefix or starts with "prefix/". */
static Boolean
path_starts_with(const char *path, const char *prefix)
{
    size_t n = strlen(prefix);

    if (strncmp(path, prefix, n) != 0)
	return FALSE;
    return path[n] == '\0' || path[n] == '/';
}

static int
meta_ignore(GNode *gn, const char *p)
{
    char fname[MAXPATHLEN];

    if (p == NULL)
	return TRUE;

    if (*p == '/') {
	cached_realpath(p, fname); /* clean it up */
	if (has_any_prefix(fname, metaIgnorePaths)) {
#ifdef DEBUG_META_MODE
	    DEBUG1(META, "meta_oodate: ignoring path: %s\n", p);
#endif
	    return TRUE;
	}
    }

    if (metaIgnorePatterns) {
	const char *expr;
	char *pm;

	Var_Set(".p.", p, gn);
	expr = "${" MAKE_META_IGNORE_PATTERNS ":@m@${.p.:M$m}@}";
	(void)Var_Subst(expr, gn, VARE_WANTRES, &pm);
	/* TODO: handle errors */
	if (pm[0] != '\0') {
#ifdef DEBUG_META_MODE
	    DEBUG1(META, "meta_oodate: ignoring pattern: %s\n", p);
#endif
	    free(pm);
	    return TRUE;
	}
	free(pm);
    }

    if (metaIgnoreFilter) {
	char *fm;

	/* skip if filter result is empty */
	snprintf(fname, sizeof fname,
		 "${%s:L:${%s:ts:}}",
		 p, MAKE_META_IGNORE_FILTER);
	(void)Var_Subst(fname, gn, VARE_WANTRES, &fm);
	/* TODO: handle errors */
	if (*fm == '\0') {
#ifdef DEBUG_META_MODE
	    DEBUG1(META, "meta_oodate: ignoring filtered: %s\n", p);
#endif
	    free(fm);
	    return TRUE;
	}
	free(fm);
    }
    return FALSE;
}

/*
 * When running with 'meta' functionality, a target can be out-of-date
 * if any of the references in its meta data file is more recent.
 * We have to track the latestdir on a per-process basis.
 */
#define LCWD_VNAME_FMT ".meta.%d.lcwd"
#define LDIR_VNAME_FMT ".meta.%d.ldir"

/*
 * It is possible that a .meta file is corrupted,
 * if we detect this we want to reproduce it.
 * Setting oodate TRUE will have that effect.
 */
#define CHECK_VALID_META(p) if (!(p && *p)) { \
    warnx("%s: %d: malformed", fname, lineno); \
    oodate = TRUE; \
    continue; \
    }

#define DEQUOTE(p) if (*p == '\'') {	\
    char *ep; \
    p++; \
    if ((ep = strchr(p, '\''))) \
	*ep = '\0'; \
    }

static void
append_if_new(StringList *list, const char *str)
{
    StringListNode *ln;

    for (ln = list->first; ln != NULL; ln = ln->next)
	if (strcmp(ln->datum, str) == 0)
	    return;
    Lst_Append(list, bmake_strdup(str));
}

Boolean
meta_oodate(GNode *gn, Boolean oodate)
{
    static char *tmpdir = NULL;
    static char cwd[MAXPATHLEN];
    char lcwd_vname[64];
    char ldir_vname[64];
    char lcwd[MAXPATHLEN];
    char latestdir[MAXPATHLEN];
    char fname[MAXPATHLEN];
    char fname1[MAXPATHLEN];
    char fname2[MAXPATHLEN];
    char fname3[MAXPATHLEN];
    const char *dname;
    const char *tname;
    char *p;
    char *cp;
    char *link_src;
    char *move_target;
    static size_t cwdlen = 0;
    static size_t tmplen = 0;
    FILE *fp;
    Boolean needOODATE = FALSE;
    StringList *missingFiles;
    Boolean have_filemon = FALSE;
    void *objdir_freeIt;

    if (oodate)
	return oodate;		/* we're done */

    dname = Var_Value(".OBJDIR", gn, &objdir_freeIt);
    tname = GNode_VarTarget(gn);

    /* if this succeeds fname3 is realpath of dname */
    if (!meta_needed(gn, dname, tname, fname3, FALSE))
	goto oodate_out;
    dname = fname3;

    missingFiles = Lst_New();

    /*
     * We need to check if the target is out-of-date. This includes
     * checking if the expanded command has changed. This in turn
     * requires that all variables are set in the same way that they
     * would be if the target needs to be re-built.
     */
    Make_DoAllVar(gn);

    meta_name(fname, sizeof fname, dname, tname, dname);

#ifdef DEBUG_META_MODE
    DEBUG1(META, "meta_oodate: %s\n", fname);
#endif

    if ((fp = fopen(fname, "r")) != NULL) {
	static char *buf = NULL;
	static size_t bufsz;
	int lineno = 0;
	int lastpid = 0;
	int pid;
	int x;
	StringListNode *cmdNode;
	struct cached_stat cst;

	if (buf == NULL) {
	    bufsz = 8 * BUFSIZ;
	    buf = bmake_malloc(bufsz);
	}

	if (cwdlen == 0) {
	    if (getcwd(cwd, sizeof cwd) == NULL)
		err(1, "Could not get current working directory");
	    cwdlen = strlen(cwd);
	}
	strlcpy(lcwd, cwd, sizeof lcwd);
	strlcpy(latestdir, cwd, sizeof latestdir);

	if (tmpdir == NULL) {
	    tmpdir = getTmpdir();
	    tmplen = strlen(tmpdir);
	}

	/* we want to track all the .meta we read */
	Var_Append(".MAKE.META.FILES", fname, VAR_GLOBAL);

	cmdNode = gn->commands->first;
	while (!oodate && (x = fgetLine(&buf, &bufsz, 0, fp)) > 0) {
	    lineno++;
	    if (buf[x - 1] == '\n')
		buf[x - 1] = '\0';
	    else {
		warnx("%s: %d: line truncated at %u", fname, lineno, x);
		oodate = TRUE;
		break;
	    }
	    link_src = NULL;
	    move_target = NULL;
	    /* Find the start of the build monitor section. */
	    if (!have_filemon) {
		if (strncmp(buf, "-- filemon", 10) == 0) {
		    have_filemon = TRUE;
		    continue;
		}
		if (strncmp(buf, "# buildmon", 10) == 0) {
		    have_filemon = TRUE;
		    continue;
		}
	    }

	    /* Delimit the record type. */
	    p = buf;
#ifdef DEBUG_META_MODE
	    DEBUG3(META, "%s: %d: %s\n", fname, lineno, buf);
#endif
	    strsep(&p, " ");
	    if (have_filemon) {
		/*
		 * We are in the 'filemon' output section.
		 * Each record from filemon follows the general form:
		 *
		 * <key> <pid> <data>
		 *
		 * Where:
		 * <key> is a single letter, denoting the syscall.
		 * <pid> is the process that made the syscall.
		 * <data> is the arguments (of interest).
		 */
		switch(buf[0]) {
		case '#':		/* comment */
		case 'V':		/* version */
		    break;
		default:
		    /*
		     * We need to track pathnames per-process.
		     *
		     * Each process run by make, starts off in the 'CWD'
		     * recorded in the .meta file, if it chdirs ('C')
		     * elsewhere we need to track that - but only for
		     * that process.  If it forks ('F'), we initialize
		     * the child to have the same cwd as its parent.
		     *
		     * We also need to track the 'latestdir' of
		     * interest.  This is usually the same as cwd, but
		     * not if a process is reading directories.
		     *
		     * Each time we spot a different process ('pid')
		     * we save the current value of 'latestdir' in a
		     * variable qualified by 'lastpid', and
		     * re-initialize 'latestdir' to any pre-saved
		     * value for the current 'pid' and 'CWD' if none.
		     */
		    CHECK_VALID_META(p);
		    pid = atoi(p);
		    if (pid > 0 && pid != lastpid) {
			const char *ldir;
			void *tp;

			if (lastpid > 0) {
			    /* We need to remember these. */
			    Var_Set(lcwd_vname, lcwd, VAR_GLOBAL);
			    Var_Set(ldir_vname, latestdir, VAR_GLOBAL);
			}
			snprintf(lcwd_vname, sizeof lcwd_vname, LCWD_VNAME_FMT, pid);
			snprintf(ldir_vname, sizeof ldir_vname, LDIR_VNAME_FMT, pid);
			lastpid = pid;
			ldir = Var_Value(ldir_vname, VAR_GLOBAL, &tp);
			if (ldir != NULL) {
			    strlcpy(latestdir, ldir, sizeof latestdir);
			    bmake_free(tp);
			}
			ldir = Var_Value(lcwd_vname, VAR_GLOBAL, &tp);
			if (ldir != NULL) {
			    strlcpy(lcwd, ldir, sizeof lcwd);
			    bmake_free(tp);
			}
		    }
		    /* Skip past the pid. */
		    if (strsep(&p, " ") == NULL)
			continue;
#ifdef DEBUG_META_MODE
		    if (DEBUG(META))
			debug_printf("%s: %d: %d: %c: cwd=%s lcwd=%s ldir=%s\n",
				     fname, lineno,
				     pid, buf[0], cwd, lcwd, latestdir);
#endif
		    break;
		}

		CHECK_VALID_META(p);

		/* Process according to record type. */
		switch (buf[0]) {
		case 'X':		/* eXit */
		    Var_Delete(lcwd_vname, VAR_GLOBAL);
		    Var_Delete(ldir_vname, VAR_GLOBAL);
		    lastpid = 0;	/* no need to save ldir_vname */
		    break;

		case 'F':		/* [v]Fork */
		    {
			char cldir[64];
			int child;

			child = atoi(p);
			if (child > 0) {
			    snprintf(cldir, sizeof cldir, LCWD_VNAME_FMT, child);
			    Var_Set(cldir, lcwd, VAR_GLOBAL);
			    snprintf(cldir, sizeof cldir, LDIR_VNAME_FMT, child);
			    Var_Set(cldir, latestdir, VAR_GLOBAL);
#ifdef DEBUG_META_MODE
			    if (DEBUG(META))
				debug_printf(
					"%s: %d: %d: cwd=%s lcwd=%s ldir=%s\n",
					fname, lineno,
					child, cwd, lcwd, latestdir);
#endif
			}
		    }
		    break;

		case 'C':		/* Chdir */
		    /* Update lcwd and latest directory. */
		    strlcpy(latestdir, p, sizeof latestdir);
		    strlcpy(lcwd, p, sizeof lcwd);
		    Var_Set(lcwd_vname, lcwd, VAR_GLOBAL);
		    Var_Set(ldir_vname, lcwd, VAR_GLOBAL);
#ifdef DEBUG_META_MODE
		    DEBUG4(META, "%s: %d: cwd=%s ldir=%s\n",
			   fname, lineno, cwd, lcwd);
#endif
		    break;

		case 'M':		/* renaMe */
		    /*
		     * For 'M'oves we want to check
		     * the src as for 'R'ead
		     * and the target as for 'W'rite.
		     */
		    cp = p;		/* save this for a second */
		    /* now get target */
		    if (strsep(&p, " ") == NULL)
			continue;
		    CHECK_VALID_META(p);
		    move_target = p;
		    p = cp;
		    /* 'L' and 'M' put single quotes around the args */
		    DEQUOTE(p);
		    DEQUOTE(move_target);
		    /* FALLTHROUGH */
		case 'D':		/* unlink */
		    if (*p == '/') {
			/* remove any missingFiles entries that match p */
			StringListNode *ln = missingFiles->first;
			while (ln != NULL) {
			    StringListNode *next = ln->next;
			    if (path_starts_with(ln->datum, p)) {
				free(ln->datum);
				Lst_Remove(missingFiles, ln);
			    }
			    ln = next;
			}
		    }
		    if (buf[0] == 'M') {
			/* the target of the mv is a file 'W'ritten */
#ifdef DEBUG_META_MODE
			DEBUG2(META, "meta_oodate: M %s -> %s\n",
			       p, move_target);
#endif
			p = move_target;
			goto check_write;
		    }
		    break;
		case 'L':		/* Link */
		    /*
		     * For 'L'inks check
		     * the src as for 'R'ead
		     * and the target as for 'W'rite.
		     */
		    link_src = p;
		    /* now get target */
		    if (strsep(&p, " ") == NULL)
			continue;
		    CHECK_VALID_META(p);
		    /* 'L' and 'M' put single quotes around the args */
		    DEQUOTE(p);
		    DEQUOTE(link_src);
#ifdef DEBUG_META_MODE
		    DEBUG2(META, "meta_oodate: L %s -> %s\n", link_src, p);
#endif
		    /* FALLTHROUGH */
		case 'W':		/* Write */
		check_write:
		    /*
		     * If a file we generated within our bailiwick
		     * but outside of .OBJDIR is missing,
		     * we need to do it again.
		     */
		    /* ignore non-absolute paths */
		    if (*p != '/')
			break;

		    if (Lst_IsEmpty(metaBailiwick))
			break;

		    /* ignore cwd - normal dependencies handle those */
		    if (strncmp(p, cwd, cwdlen) == 0)
			break;

		    if (!has_any_prefix(p, metaBailiwick))
			break;

		    /* tmpdir might be within */
		    if (tmplen > 0 && strncmp(p, tmpdir, tmplen) == 0)
			break;

		    /* ignore anything containing the string "tmp" */
		    /* XXX: The arguments to strstr must be swapped. */
		    if ((strstr("tmp", p)))
			break;

		    if ((link_src != NULL && cached_lstat(p, &cst) < 0) ||
			(link_src == NULL && cached_stat(p, &cst) < 0)) {
			if (!meta_ignore(gn, p))
			    append_if_new(missingFiles, p);
		    }
		    break;
		check_link_src:
		    p = link_src;
		    link_src = NULL;
#ifdef DEBUG_META_MODE
		    DEBUG1(META, "meta_oodate: L src %s\n", p);
#endif
		    /* FALLTHROUGH */
		case 'R':		/* Read */
		case 'E':		/* Exec */
		    /*
		     * Check for runtime files that can't
		     * be part of the dependencies because
		     * they are _expected_ to change.
		     */
		    if (meta_ignore(gn, p))
			break;

		    /*
		     * The rest of the record is the file name.
		     * Check if it's not an absolute path.
		     */
		    {
			char *sdirs[4];
			char **sdp;
			int sdx = 0;
			Boolean found = FALSE;

			if (*p == '/') {
			    sdirs[sdx++] = p; /* done */
			} else {
			    if (strcmp(".", p) == 0)
				continue; /* no point */

			    /* Check vs latestdir */
			    snprintf(fname1, sizeof fname1, "%s/%s", latestdir, p);
			    sdirs[sdx++] = fname1;

			    if (strcmp(latestdir, lcwd) != 0) {
				/* Check vs lcwd */
				snprintf(fname2, sizeof fname2, "%s/%s", lcwd, p);
				sdirs[sdx++] = fname2;
			    }
			    if (strcmp(lcwd, cwd) != 0) {
				/* Check vs cwd */
				snprintf(fname3, sizeof fname3, "%s/%s", cwd, p);
				sdirs[sdx++] = fname3;
			    }
			}
			sdirs[sdx++] = NULL;

			for (sdp = sdirs; *sdp && !found; sdp++) {
#ifdef DEBUG_META_MODE
			    DEBUG3(META, "%s: %d: looking for: %s\n",
				   fname, lineno, *sdp);
#endif
			    if (cached_stat(*sdp, &cst) == 0) {
				found = TRUE;
				p = *sdp;
			    }
			}
			if (found) {
#ifdef DEBUG_META_MODE
			    DEBUG3(META, "%s: %d: found: %s\n",
				   fname, lineno, p);
#endif
			    if (!S_ISDIR(cst.cst_mode) &&
				cst.cst_mtime > gn->mtime) {
				DEBUG3(META, "%s: %d: file '%s' is newer than the target...\n",
				       fname, lineno, p);
				oodate = TRUE;
			    } else if (S_ISDIR(cst.cst_mode)) {
				/* Update the latest directory. */
				cached_realpath(p, latestdir);
			    }
			} else if (errno == ENOENT && *p == '/' &&
				   strncmp(p, cwd, cwdlen) != 0) {
			    /*
			     * A referenced file outside of CWD is missing.
			     * We cannot catch every eventuality here...
			     */
			    append_if_new(missingFiles, p);
			}
		    }
		    if (buf[0] == 'E') {
			/* previous latestdir is no longer relevant */
			strlcpy(latestdir, lcwd, sizeof latestdir);
		    }
		    break;
		default:
		    break;
		}
		if (!oodate && buf[0] == 'L' && link_src != NULL)
		    goto check_link_src;
	    } else if (strcmp(buf, "CMD") == 0) {
		/*
		 * Compare the current command with the one in the
		 * meta data file.
		 */
		if (cmdNode == NULL) {
		    DEBUG2(META, "%s: %d: there were more build commands in the meta data file than there are now...\n",
			   fname, lineno);
		    oodate = TRUE;
		} else {
		    char *cmd = cmdNode->datum;
		    Boolean hasOODATE = FALSE;

		    if (strstr(cmd, "$?"))
			hasOODATE = TRUE;
		    else if ((cp = strstr(cmd, ".OODATE"))) {
			/* check for $[{(].OODATE[:)}] */
			if (cp > cmd + 2 && cp[-2] == '$')
			    hasOODATE = TRUE;
		    }
		    if (hasOODATE) {
			needOODATE = TRUE;
			DEBUG2(META, "%s: %d: cannot compare command using .OODATE\n",
			       fname, lineno);
		    }
		    (void)Var_Subst(cmd, gn, VARE_WANTRES|VARE_UNDEFERR, &cmd);
		    /* TODO: handle errors */

		    if ((cp = strchr(cmd, '\n'))) {
			int n;

			/*
			 * This command contains newlines, we need to
			 * fetch more from the .meta file before we
			 * attempt a comparison.
			 */
			/* first put the newline back at buf[x - 1] */
			buf[x - 1] = '\n';
			do {
			    /* now fetch the next line */
			    if ((n = fgetLine(&buf, &bufsz, x, fp)) <= 0)
				break;
			    x = n;
			    lineno++;
			    if (buf[x - 1] != '\n') {
				warnx("%s: %d: line truncated at %u", fname, lineno, x);
				break;
			    }
			    cp = strchr(++cp, '\n');
			} while (cp != NULL);
			if (buf[x - 1] == '\n')
			    buf[x - 1] = '\0';
		    }
		    if (p != NULL &&
			!hasOODATE &&
			!(gn->type & OP_NOMETA_CMP) &&
			(strcmp(p, cmd) != 0)) {
			DEBUG4(META, "%s: %d: a build command has changed\n%s\nvs\n%s\n",
			       fname, lineno, p, cmd);
			if (!metaIgnoreCMDs)
			    oodate = TRUE;
		    }
		    free(cmd);
		    cmdNode = cmdNode->next;
		}
	    } else if (strcmp(buf, "CWD") == 0) {
		/*
		 * Check if there are extra commands now
		 * that weren't in the meta data file.
		 */
		if (!oodate && cmdNode != NULL) {
		    DEBUG2(META, "%s: %d: there are extra build commands now that weren't in the meta data file\n",
			   fname, lineno);
		    oodate = TRUE;
		}
		CHECK_VALID_META(p);
		if (strcmp(p, cwd) != 0) {
		    DEBUG4(META, "%s: %d: the current working directory has changed from '%s' to '%s'\n",
			   fname, lineno, p, curdir);
		    oodate = TRUE;
		}
	    }
	}

	fclose(fp);
	if (!Lst_IsEmpty(missingFiles)) {
	    DEBUG2(META, "%s: missing files: %s...\n",
		   fname, (char *)missingFiles->first->datum);
	    oodate = TRUE;
	}
	if (!oodate && !have_filemon && filemonMissing) {
	    DEBUG1(META, "%s: missing filemon data\n", fname);
	    oodate = TRUE;
	}
    } else {
	if (writeMeta && (metaMissing || (gn->type & OP_META))) {
	    cp = NULL;

	    /* if target is in .CURDIR we do not need a meta file */
	    if (gn->path && (cp = strrchr(gn->path, '/')) && cp > gn->path) {
		if (strncmp(curdir, gn->path, (size_t)(cp - gn->path)) != 0) {
		    cp = NULL;		/* not in .CURDIR */
		}
	    }
	    if (cp == NULL) {
		DEBUG1(META, "%s: required but missing\n", fname);
		oodate = TRUE;
		needOODATE = TRUE;	/* assume the worst */
	    }
	}
    }

    Lst_Destroy(missingFiles, free);

    if (oodate && needOODATE) {
	/*
	 * Target uses .OODATE which is empty; or we wouldn't be here.
	 * We have decided it is oodate, so .OODATE needs to be set.
	 * All we can sanely do is set it to .ALLSRC.
	 */
	Var_Delete(OODATE, gn);
	Var_Set(OODATE, GNode_VarAllsrc(gn), gn);
    }

 oodate_out:
    bmake_free(objdir_freeIt);
    return oodate;
}

/* support for compat mode */

static int childPipe[2];

void
meta_compat_start(void)
{
#ifdef USE_FILEMON_ONCE
    /*
     * We need to re-open filemon for each cmd.
     */
    BuildMon *pbm = &Mybm;

    if (pbm->mfp != NULL && useFilemon) {
	meta_open_filemon(pbm);
    } else {
	pbm->mon_fd = -1;
	pbm->filemon = NULL;
    }
#endif
    if (pipe(childPipe) < 0)
	Punt("Cannot create pipe: %s", strerror(errno));
    /* Set close-on-exec flag for both */
    (void)fcntl(childPipe[0], F_SETFD, FD_CLOEXEC);
    (void)fcntl(childPipe[1], F_SETFD, FD_CLOEXEC);
}

void
meta_compat_child(void)
{
    meta_job_child(NULL);
    if (dup2(childPipe[1], 1) < 0 || dup2(1, 2) < 0)
	execDie("dup2", "pipe");
}

void
meta_compat_parent(pid_t child)
{
    int outfd, metafd, maxfd, nfds;
    char buf[BUFSIZ+1];
    fd_set readfds;

    meta_job_parent(NULL, child);
    close(childPipe[1]);			/* child side */
    outfd = childPipe[0];
#ifdef USE_FILEMON
    metafd = Mybm.filemon ? filemon_readfd(Mybm.filemon) : -1;
#else
    metafd = -1;
#endif
    maxfd = -1;
    if (outfd > maxfd)
	    maxfd = outfd;
    if (metafd > maxfd)
	    maxfd = metafd;

    while (outfd != -1 || metafd != -1) {
	FD_ZERO(&readfds);
	if (outfd != -1) {
	    FD_SET(outfd, &readfds);
	}
	if (metafd != -1) {
	    FD_SET(metafd, &readfds);
	}
	nfds = select(maxfd + 1, &readfds, NULL, NULL, NULL);
	if (nfds == -1) {
	    if (errno == EINTR)
		continue;
	    err(1, "select");
	}

	if (outfd != -1 && FD_ISSET(outfd, &readfds)) do {
	    /* XXX this is not line-buffered */
	    ssize_t nread = read(outfd, buf, sizeof buf - 1);
	    if (nread == -1)
		err(1, "read");
	    if (nread == 0) {
		close(outfd);
		outfd = -1;
		break;
	    }
	    fwrite(buf, 1, (size_t)nread, stdout);
	    fflush(stdout);
	    buf[nread] = '\0';
	    meta_job_output(NULL, buf, "");
	} while (0);
	if (metafd != -1 && FD_ISSET(metafd, &readfds)) {
	    if (meta_job_event(NULL) <= 0)
		metafd = -1;
	}
    }
}

#endif	/* USE_META */