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A set of big related changes. okay millert@, tested further by kettenis@
and matthieu@

This all revolves around putting ALL global variables into one single big
hash, and using flags. This removes some impossible to understand stuff,
like old varfind, and allows for some nice stuff.
- each time we reference a global variable, we create it, possibly as a dummy
variable.
- each time we go to the environment, we remember it, thus we no longer go
back to it.

Lists of dependant changes:
- isolate changes to oldVars and checkEnvFirst.
- remove VAR_CMD and VAR_GLOBAL contexts. The only distinction is in parsevar.
Split Parse_DoVar into Parse_DoVar and Parse_CmdlineVar
- rework var modules around obtain_global_var, observe flags in various
functions like Var_Value and Var_Seti.
- Var_Seti/Var_Appendi are almost the same code, use that internally.
- add magic to handle the very special SHELL variable.
- introduce Var_Definedi for the cases where we don't want the actual
value, to simplify tests.
- add keyword .poison, parse it and set global flags accordingly.
- do poison_checks where needed.
- document poison.
- in for loops, set variable temporarily, so that Var_SubstVar will also
substitute it in varmodifiers expressions.

/*	$OpenPackages$ */
/*	$OpenBSD: main.c,v 1.70 2007/07/08 17:44:20 espie Exp $ */
/*	$NetBSD: main.c,v 1.34 1997/03/24 20:56:36 gwr Exp $	*/

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifndef MAKE_BOOTSTRAP
#include <sys/utsname.h>
#endif
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "config.h"
#include "defines.h"
#include "var.h"
#include "parse.h"
#include "parsevar.h"
#include "dir.h"
#include "error.h"
#include "pathnames.h"
#include "init.h"
#include "job.h"
#include "compat.h"
#include "targ.h"
#include "suff.h"
#include "str.h"
#include "main.h"
#include "lst.h"
#include "memory.h"
#include "make.h"

#ifndef PATH_MAX
# ifdef MAXPATHLEN
#  define PATH_MAX (MAXPATHLEN+1)
# else
#  define PATH_MAX	1024
# endif
#endif

#ifndef DEFMAXLOCAL
#define DEFMAXLOCAL DEFMAXJOBS
#endif	/* DEFMAXLOCAL */

#define MAKEFLAGS	".MAKEFLAGS"

static LIST		to_create; 	/* Targets to be made */
Lst create = &to_create;
GNode			*DEFAULT;	/* .DEFAULT node */
bool 		allPrecious;	/* .PRECIOUS given on line by itself */

static bool		noBuiltins;	/* -r flag */
static LIST		makefiles;	/* ordered list of makefiles to read */
static LIST		varstoprint;	/* list of variables to print */
int			maxJobs;	/* -j argument */
static int		maxLocal;	/* -L argument */
bool 		compatMake;	/* -B argument */
int 		debug;		/* -d flag */
bool 		noExecute;	/* -n flag */
bool 		keepgoing;	/* -k flag */
bool 		queryFlag;	/* -q flag */
bool 		touchFlag;	/* -t flag */
bool 		usePipes;	/* !-P flag */
bool 		ignoreErrors;	/* -i flag */
bool 		beSilent;	/* -s flag */

static void		MainParseArgs(int, char **);
static char *		chdir_verify_path(const char *);
static int		ReadMakefile(void *, void *);
static void		add_dirpath(Lst, const char *);
static void		usage(void);
static void		posixParseOptLetter(int);
static void		record_option(int, const char *);

static char *curdir;			/* startup directory */
static char *objdir;			/* where we chdir'ed to */


static void record_option(int c, const char *arg)
{
    char opt[3];

    opt[0] = '-';
    opt[1] = c;
    opt[2] = '\0';
    Var_Append(MAKEFLAGS, opt, VAR_GLOBAL);
    if (arg != NULL)
    	Var_Append(MAKEFLAGS, arg, VAR_GLOBAL);
}

static void
posixParseOptLetter(int c)
{
	switch(c) {
	case 'B':
		compatMake = true;
		return;	/* XXX don't pass to submakes. */
	case 'P':
		usePipes = false;
		break;
	case 'S':
		keepgoing = false;
		break;
	case 'e':
		Var_setCheckEnvFirst(true);
		break;
	case 'i':
		ignoreErrors = true;
		break;
	case 'k':
		keepgoing = true;
		break;
	case 'n':
		noExecute = true;
		break;
	case 'q':
		queryFlag = true;
		/* Kind of nonsensical, wot? */
		break;
	case 'r':
		noBuiltins = true;
		break;
	case 's':
		beSilent = true;
		break;
	case 't':
		touchFlag = true;
		break;
	default:
	case '?':
		usage();
	}
	record_option(c, NULL);
}

/*-
 * MainParseArgs --
 *	Parse a given argument vector. Called from main() and from
 *	Main_ParseArgLine() when the .MAKEFLAGS target is used.
 *
 *	XXX: Deal with command line overriding .MAKEFLAGS in makefile
 *
 * Side Effects:
 *	Various global and local flags will be set depending on the flags
 *	given
 */
static void
MainParseArgs(int argc, char **argv)
{
	int c, optend;
	int forceJobs = 0;

#define OPTFLAGS "BD:I:PSV:d:ef:ij:km:nqrst"
#define OPTLETTERS "BPSiknqrst"

	optind = 1;	/* since we're called more than once */
	optreset = 1;
	optend = 0;
	while (optind < argc) {
		if (!optend && argv[optind][0] == '-') {
			if (argv[optind][1] == '\0')
				optind++;	/* ignore "-" */
			else if (argv[optind][1] == '-' &&
			    argv[optind][2] == '\0') {
				optind++;	/* ignore "--" */
				optend++;	/* "--" denotes end of flags */
			}
		}
		c = optend ? -1 : getopt(argc, argv, OPTFLAGS);
		switch (c) {
		case 'D':
			Var_Set(optarg, "1", VAR_GLOBAL);
			record_option(c, optarg);
			break;
		case 'I':
			Parse_AddIncludeDir(optarg);
			record_option(c, optarg);
			break;
		case 'V':
			Lst_AtEnd(&varstoprint, optarg);
			record_option(c, optarg);
			break;
		case 'd': {
			char *modules = optarg;

			for (; *modules; ++modules)
				switch (*modules) {
				case 'A':
					debug = ~0;
					break;
				case 'a':
					debug |= DEBUG_ARCH;
					break;
				case 'c':
					debug |= DEBUG_COND;
					break;
				case 'd':
					debug |= DEBUG_DIR;
					break;
				case 'f':
					debug |= DEBUG_FOR;
					break;
				case 'g':
					if (modules[1] == '1') {
						debug |= DEBUG_GRAPH1;
						++modules;
					}
					else if (modules[1] == '2') {
						debug |= DEBUG_GRAPH2;
						++modules;
					}
					break;
				case 'j':
					debug |= DEBUG_JOB;
					break;
				case 'l':
					debug |= DEBUG_LOUD;
					break;
				case 'm':
					debug |= DEBUG_MAKE;
					break;
				case 's':
					debug |= DEBUG_SUFF;
					break;
				case 't':
					debug |= DEBUG_TARG;
					break;
				case 'v':
					debug |= DEBUG_VAR;
					break;
				default:
					(void)fprintf(stderr,
				"make: illegal argument to -d option -- %c\n",
					    *modules);
					usage();
				}
			record_option(c, optarg);
			break;
		}
		case 'f':
			Lst_AtEnd(&makefiles, optarg);
			break;
		case 'j': {
		   char *endptr;

			forceJobs = true;
			maxJobs = strtol(optarg, &endptr, 0);
			if (endptr == optarg) {
				fprintf(stderr,
					"make: illegal argument to -j option -- %s -- not a number\n",
					optarg);
				usage();
			}
			maxLocal = maxJobs;
			record_option(c, optarg);
			break;
		}
		case 'm':
			Dir_AddDir(sysIncPath, optarg);
			record_option(c, optarg);
			break;
		case -1:
			/* Check for variable assignments and targets. */
			if (argv[optind] != NULL &&
			    !Parse_CmdlineVar(argv[optind])) {
				if (!*argv[optind])
					Punt("illegal (null) argument.");
				Lst_AtEnd(create, estrdup(argv[optind]));
			}
			optind++;	/* skip over non-option */
			break;
		default:
			posixParseOptLetter(c);
		}
	}

	/*
	 * Be compatible if user did not specify -j and did not explicitly
	 * turn compatibility on
	 */
	if (!compatMake && !forceJobs)
		compatMake = true;
}

/*-
 * Main_ParseArgLine --
 *	Used by the parse module when a .MFLAGS or .MAKEFLAGS target
 *	is encountered and by main() when reading the .MAKEFLAGS envariable.
 *	Takes a line of arguments and breaks it into its
 *	component words and passes those words and the number of them to the
 *	MainParseArgs function.
 *	The line should have all its leading whitespace removed.
 *
 * Side Effects:
 *	Only those that come from the various arguments.
 */
void
Main_ParseArgLine(const char *line) 	/* Line to fracture */
{
	char **argv;			/* Manufactured argument vector */
	int argc;			/* Number of arguments in argv */
	char *args;			/* Space used by the args */
	char *buf;
	char *argv0;
	const char *s;
	size_t len;


	if (line == NULL)
		return;
	for (; *line == ' '; ++line)
		continue;
	if (!*line)
		return;

	/* POSIX rule: MAKEFLAGS can hold a set of option letters without
	 * any blanks or dashes. */
	for (s = line;; s++) {
		if (*s == '\0') {
			while (line != s)
				posixParseOptLetter(*line++);
			return;
		}
		if (strchr(OPTLETTERS, *s) == NULL)
			break;
	}
	argv0 = Var_Value(".MAKE");
	len = strlen(line) + strlen(argv0) + 2;
	buf = emalloc(len);
	(void)snprintf(buf, len, "%s %s", argv0, line);

	argv = brk_string(buf, &argc, &args);
	free(buf);
	MainParseArgs(argc, argv);

	free(args);
	free(argv);
}

char *
chdir_verify_path(const char *path)
{
    struct stat sb;

    if (stat(path, &sb) == 0 && S_ISDIR(sb.st_mode)) {
	if (chdir(path)) {
	    (void)fprintf(stderr, "make warning: %s: %s.\n",
		  path, strerror(errno));
	    return NULL;
	} else {
	    if (path[0] != '/')
	    	return Str_concat(curdir, path, '/');
	    else
		return estrdup(path);
	}
    }

    return NULL;
}


/* Add a :-separated path to a Lst of directories.  */
static void
add_dirpath(Lst l, const char *n)
{
    const char *start;
    const char *cp;

    for (start = n;;) {
	for (cp = start; *cp != '\0' && *cp != ':';)
	    cp++;
	Dir_AddDiri(l, start, cp);
	if (*cp == '\0')
	    break;
	else
	    start= cp+1;
    }
}

int main(int, char **);
/*-
 * main --
 *	The main function, for obvious reasons. Initializes variables
 *	and a few modules, then parses the arguments give it in the
 *	environment and on the command line. Reads the system makefile
 *	followed by either Makefile, makefile or the file given by the
 *	-f argument. Sets the .MAKEFLAGS PMake variable based on all the
 *	flags it has received by then uses either the Make or the Compat
 *	module to create the initial list of targets.
 *
 * Results:
 *	If -q was given, exits -1 if anything was out-of-date. Else it exits
 *	0.
 *
 * Side Effects:
 *	The program exits when done. Targets are created. etc. etc. etc.
 */
int
main(int argc, char **argv)
{
	static LIST targs;	/* target nodes to create */
	bool outOfDate = true;	/* false if all targets up to date */
	struct stat sb, sa;
	char *p, *path, *pathp, *pwd;
	char *mdpath;
	char *machine = getenv("MACHINE");
	char *machine_arch = getenv("MACHINE_ARCH");
	const char *syspath = _PATH_DEFSYSPATH;

#ifdef RLIMIT_NOFILE
	/*
	 * get rid of resource limit on file descriptors
	 */
	{
		struct rlimit rl;
		if (getrlimit(RLIMIT_NOFILE, &rl) != -1 &&
		    rl.rlim_cur != rl.rlim_max) {
			rl.rlim_cur = rl.rlim_max;
			(void)setrlimit(RLIMIT_NOFILE, &rl);
		}
	}
#endif
	/*
	 * Find where we are and take care of PWD for the automounter...
	 * All this code is so that we know where we are when we start up
	 * on a different machine with pmake.
	 */
	if ((curdir = dogetcwd()) == NULL) {
		(void)fprintf(stderr, "make: %s.\n", strerror(errno));
		exit(2);
	}

	if (stat(curdir, &sa) == -1) {
	    (void)fprintf(stderr, "make: %s: %s.\n",
			  curdir, strerror(errno));
	    exit(2);
	}

	if ((pwd = getenv("PWD")) != NULL) {
	    if (stat(pwd, &sb) == 0 && sa.st_ino == sb.st_ino &&
		sa.st_dev == sb.st_dev) {
		    free(curdir);
		    curdir = estrdup(pwd);
	    }
	}

	/*
	 * Get the name of this type of MACHINE from utsname
	 * so we can share an executable for similar machines.
	 * (i.e. m68k: amiga hp300, mac68k, sun3, ...)
	 *
	 * Note that both MACHINE and MACHINE_ARCH are decided at
	 * run-time.
	 */
	if (!machine) {
#ifndef MAKE_BOOTSTRAP
	    struct utsname utsname;

	    if (uname(&utsname) == -1) {
		    perror("make: uname");
		    exit(2);
	    }
	    machine = utsname.machine;
#else
	    machine = MACHINE;
#endif
	}

	if (!machine_arch) {
#ifndef MACHINE_ARCH
	    machine_arch = "unknown";	/* XXX: no uname -p yet */
#else
	    machine_arch = MACHINE_ARCH;
#endif
	}

	/*
	 * If the MAKEOBJDIR (or by default, the _PATH_OBJDIR) directory
	 * exists, change into it and build there.  (If a .${MACHINE} suffix
	 * exists, use that directory instead).
	 * Otherwise check MAKEOBJDIRPREFIX`cwd` (or by default,
	 * _PATH_OBJDIRPREFIX`cwd`) and build there if it exists.
	 * If all fails, use the current directory to build.
	 *
	 * Once things are initted,
	 * have to add the original directory to the search path,
	 * and modify the paths for the Makefiles appropriately.  The
	 * current directory is also placed as a variable for make scripts.
	 */
	mdpath = NULL;
	if (!(pathp = getenv("MAKEOBJDIRPREFIX"))) {
		if (!(path = getenv("MAKEOBJDIR"))) {
			path = _PATH_OBJDIR;
			pathp = _PATH_OBJDIRPREFIX;
			mdpath = Str_concat(path, machine, '.');
			if (!(objdir = chdir_verify_path(mdpath)))
				if (!(objdir=chdir_verify_path(path))) {
					free(mdpath);
					mdpath = Str_concat(pathp, curdir, 0);
					if (!(objdir=chdir_verify_path(mdpath)))
						objdir = curdir;
				}
		}
		else if (!(objdir = chdir_verify_path(path)))
			objdir = curdir;
	}
	else {
		mdpath = Str_concat(pathp, curdir, 0);
		if (!(objdir = chdir_verify_path(mdpath)))
			objdir = curdir;
	}
	free(mdpath);

	esetenv("PWD", objdir);
	unsetenv("CDPATH");

	Static_Lst_Init(create);
	Static_Lst_Init(&makefiles);
	Static_Lst_Init(&varstoprint);
	Static_Lst_Init(&targs);

	beSilent = false;		/* Print commands as executed */
	ignoreErrors = false;		/* Pay attention to non-zero returns */
	noExecute = false;		/* Execute all commands */
	keepgoing = false;		/* Stop on error */
	allPrecious = false;		/* Remove targets when interrupted */
	queryFlag = false;		/* This is not just a check-run */
	noBuiltins = false;		/* Read the built-in rules */
	touchFlag = false;		/* Actually update targets */
	usePipes = true;		/* Catch child output in pipes */
	debug = 0;			/* No debug verbosity, please. */

	maxLocal = DEFMAXLOCAL; 	/* Set default local max concurrency */
	maxJobs = maxLocal;
	compatMake = false;		/* No compat mode */


	/*
	 * Initialize all external modules.
	 */
	Init();

	if (objdir != curdir)
		Dir_AddDir(dirSearchPath, curdir);
	Var_Set(".CURDIR", curdir, VAR_GLOBAL);
	Var_Set(".OBJDIR", objdir, VAR_GLOBAL);

	/*
	 * Initialize various variables.
	 *	MAKE also gets this name, for compatibility
	 *	.MAKEFLAGS gets set to the empty string just in case.
	 *	MFLAGS also gets initialized empty, for compatibility.
	 */
	Var_Set("MAKE", argv[0], VAR_GLOBAL);
	Var_Set(".MAKE", argv[0], VAR_GLOBAL);
	Var_Set(MAKEFLAGS, "", VAR_GLOBAL);
	Var_Set("MFLAGS", "", VAR_GLOBAL);
	Var_Set("MACHINE", machine, VAR_GLOBAL);
	Var_Set("MACHINE_ARCH", machine_arch, VAR_GLOBAL);

	/*
	 * First snag any flags out of the MAKEFLAGS environment variable.
	 */
	Main_ParseArgLine(getenv("MAKEFLAGS"));

	MainParseArgs(argc, argv);

	/* And set up everything for sub-makes */
	Var_AddCmdline(MAKEFLAGS);


	DEFAULT = NULL;

	/*
	 * Set up the .TARGETS variable to contain the list of targets to be
	 * created. If none specified, make the variable empty -- the parser
	 * will fill the thing in with the default or .MAIN target.
	 */
	if (!Lst_IsEmpty(create)) {
		LstNode ln;

		for (ln = Lst_First(create); ln != NULL; ln = Lst_Adv(ln)) {
			char *name = (char *)Lst_Datum(ln);

			Var_Append(".TARGETS", name, VAR_GLOBAL);
		}
	} else
		Var_Set(".TARGETS", "", VAR_GLOBAL);


	/*
	 * If no user-supplied system path was given (through the -m option)
	 * add the directories from the DEFSYSPATH (more than one may be given
	 * as dir1:...:dirn) to the system include path.
	 */
	if (Lst_IsEmpty(sysIncPath))
	    add_dirpath(sysIncPath, syspath);

	/*
	 * Read in the built-in rules first, followed by the specified
	 * makefile(s), or the default BSDmakefile, Makefile or
	 * makefile, in that order.
	 */
	if (!noBuiltins) {
		LstNode ln;
		LIST sysMkPath; 		/* Path of sys.mk */

		Lst_Init(&sysMkPath);
		Dir_Expand(_PATH_DEFSYSMK, sysIncPath, &sysMkPath);
		if (Lst_IsEmpty(&sysMkPath))
			Fatal("make: no system rules (%s).", _PATH_DEFSYSMK);
		ln = Lst_Find(&sysMkPath, ReadMakefile, NULL);
		if (ln != NULL)
			Fatal("make: cannot open %s.", (char *)Lst_Datum(ln));
#ifdef CLEANUP
		Lst_Destroy(&sysMkPath, (SimpleProc)free);
#endif
	}

	if (!Lst_IsEmpty(&makefiles)) {
		LstNode ln;

		ln = Lst_Find(&makefiles, ReadMakefile, NULL);
		if (ln != NULL)
			Fatal("make: cannot open %s.", (char *)Lst_Datum(ln));
	} else if (!ReadMakefile("BSDmakefile", NULL))
		if (!ReadMakefile("makefile", NULL))
			(void)ReadMakefile("Makefile", NULL);

	/* Always read a .depend file, if it exists. */
	(void)ReadMakefile(".depend", NULL);

	Var_Append("MFLAGS", Var_Value(MAKEFLAGS),
	    VAR_GLOBAL);

	/* Install all the flags into the MAKEFLAGS env variable. */
	if (((p = Var_Value(MAKEFLAGS)) != NULL) && *p)
		esetenv("MAKEFLAGS", p);

	/*
	 * For compatibility, look at the directories in the VPATH variable
	 * and add them to the search path, if the variable is defined. The
	 * variable's value is in the same format as the PATH envariable, i.e.
	 * <directory>:<directory>:<directory>...
	 */
	if (Var_Value("VPATH") != NULL) {
	    char *vpath;

	    vpath = Var_Subst("${VPATH}", NULL, false);
	    add_dirpath(dirSearchPath, vpath);
	    (void)free(vpath);
	}

	/* Now that all search paths have been read for suffixes et al, it's
	 * time to add the default search path to their lists...  */
	Suff_DoPaths();

	/* Print the initial graph, if the user requested it.  */
	if (DEBUG(GRAPH1))
		Targ_PrintGraph(1);

	/* Print the values of any variables requested by the user.  */
	if (!Lst_IsEmpty(&varstoprint)) {
	    LstNode ln;

	    for (ln = Lst_First(&varstoprint); ln != NULL; ln = Lst_Adv(ln)) {
		    char *value = Var_Value((char *)Lst_Datum(ln));

		    printf("%s\n", value ? value : "");
	    }
	} else {
	    /* Have now read the entire graph and need to make a list of targets
	     * to create. If none was given on the command line, we consult the
	     * parsing module to find the main target(s) to create.  */
	    if (Lst_IsEmpty(create))
		Parse_MainName(&targs);
	    else
		Targ_FindList(&targs, create);

	    if (compatMake)
		/* Compat_Init will take care of creating all the targets as
		 * well as initializing the module.  */
	    	Compat_Run(&targs);
	    else {
		/* Initialize job module before traversing the graph, now that
		 * any .BEGIN and .END targets have been read.	This is done
		 * only if the -q flag wasn't given (to prevent the .BEGIN from
		 * being executed should it exist).  */
		if (!queryFlag) {
			if (maxLocal == -1)
				maxLocal = maxJobs;
			Job_Init(maxJobs, maxLocal);
		}

		/* Traverse the graph, checking on all the targets.  */
		outOfDate = Make_Run(&targs);
	    }
	}

#ifdef CLEANUP
	Lst_Destroy(&targs, NOFREE);
	Lst_Destroy(&varstoprint, NOFREE);
	Lst_Destroy(&makefiles, NOFREE);
	Lst_Destroy(create, (SimpleProc)free);
#endif

	/* print the graph now it's been processed if the user requested it */
	if (DEBUG(GRAPH2))
		Targ_PrintGraph(2);

#ifdef CLEANUP
	if (objdir != curdir)
	    free(objdir);
	free(curdir);
	End();
#endif
	if (queryFlag && outOfDate)
		return 1;
	else
		return 0;
}

/*-
 * ReadMakefile  --
 *	Open and parse the given makefile.
 *
 * Results:
 *	true if ok. false if couldn't open file.
 *
 * Side Effects:
 *	lots
 */
static bool
ReadMakefile(void *p, void *q UNUSED)
{
	char *fname = (char *)p;	/* makefile to read */
	FILE *stream;
	char *name;

	if (!strcmp(fname, "-")) {
		Var_Set("MAKEFILE", "", VAR_GLOBAL);
		Parse_File(estrdup("(stdin)"), stdin);
	} else {
		if ((stream = fopen(fname, "r")) != NULL)
			goto found;
		/* if we've chdir'd, rebuild the path name */
		if (curdir != objdir && *fname != '/') {
			char *path;

			path = Str_concat(curdir, fname, '/');
			if ((stream = fopen(path, "r")) == NULL)
			    free(path);
			else {
			    fname = path;
			    goto found;
			}
		}
		/* look in -I and system include directories. */
		name = Dir_FindFile(fname, parseIncPath);
		if (!name)
			name = Dir_FindFile(fname, sysIncPath);
		if (!name || !(stream = fopen(name, "r")))
			return false;
		fname = name;
		/*
		 * set the MAKEFILE variable desired by System V fans -- the
		 * placement of the setting here means it gets set to the last
		 * makefile specified, as it is set by SysV make.
		 */
found:		Var_Set("MAKEFILE", fname, VAR_GLOBAL);
		Parse_File(fname, stream);
	}
	return true;
}


/*
 * usage --
 *	exit with usage message
 */
static void
usage()
{
	(void)fprintf(stderr,
"usage: make [-BeiknPqrSst] [-D variable] [-d flags] [-f makefile]\n\
	    [-I directory] [-j max_jobs] [-m directory] [-V variable]\n\
	    [NAME=value] [target ...]\n");
	exit(2);
}