Crank WARNS.

Cast sizeof() to (int), as it's being compared against an int, not a size_t.
If i is changed to a size_t, it means the logic must be slightly changed later
in the flow, where --i is checked to be >= 0.  I am not sure I want to make a
logic change to account for clearing up a warning, when an aesthetic one will
keep from modifying the logic.

Other harmless casts, that I think I've made in the right directions.

Make gpbc() an inline function, rather than an obfuscated macro, make its
scratch space local, rather than global.  The previous macro used a dirty
hack (logical AND in place of a conditional) which would lead GCC to throw
a fit (rightly so) as the logical check, as well as the incrementation of
a variable, were not used for anything.

const'ify a few places where gcc3 yells. xstrdup() some global consts in
places where we xstrdup() when not using consts, but tried to assign them
to non-consts before.

Don't use execv(2) if we don't have the kind of arguments it wants.

Reviewed by:    asmodai obrien tjr
Submitted by:   tjr (a gcc3 build log)

usr.bin/m4/Makefile

@@ -8,6 +8,7 @@ PROG=	m4
 CFLAGS+=-DEXTENDED
 
 SRCS=	eval.c expr.c look.c main.c misc.c gnum4.c trace.c
+WARNS?=	2
 MAN=	m4.1
 
 .include <bsd.prog.mk>

usr.bin/m4/eval.c

@@ -593,12 +593,12 @@ dodefine(name, defn)
 			p->type = n & TYPEMASK;
 			if ((n & NOARGS) == 0)
 				p->type |= NEEDARGS;
-			p->defn = null;
+			p->defn = xstrdup(null);
 			return;
 		}
 	}
 	if (!*defn)
-		p->defn = null;
+		p->defn = xstrdup(null);
 	else
 		p->defn = xstrdup(defn);
 	p->type = MACRTYPE;
@@ -615,7 +615,7 @@ dodefn(name)
 	const char *name;
 {
 	ndptr p;
-	char *real;
+	const char *real;
 
 	if ((p = lookup(name)) != nil) {
 		if (p->defn != null) {
@@ -648,7 +648,7 @@ dopushdef(name, defn)
 		    CURRENT_LINE);
 	p = addent(name);
 	if (!*defn)
-		p->defn = null;
+		p->defn = xstrdup(null);
 	else
 		p->defn = xstrdup(defn);
 	p->type = MACRTYPE;
@@ -663,7 +663,7 @@ static void
 dump_one_def(p)
 	ndptr p;
 {
-	char *real;
+	const char *real;
 
 	if (mimic_gnu) {
 		if ((p->type & TYPEMASK) == MACRTYPE)

usr.bin/m4/expr.c

@@ -245,21 +245,19 @@ not()
 static int
 eqrel()
 {
-	int vl, vr, eqrel;
+	int vl, vr, eqrelval;
 
 	vl = shift();
-	while ((eqrel = geteqrel()) != -1) {
+	while ((eqrelval = geteqrel()) != -1) {
 		vr = shift();
 
-		switch (eqrel) {
-
+		switch (eqrelval) {
 		case EQL:
 			vl = (vl == vr);
 			break;
 		case NEQ:
 			vl = (vl != vr);
 			break;
-
 		case LEQ:
 			vl = (vl <= vr);
 			break;
@@ -446,7 +444,7 @@ constant()
 		ungetch();
 		return num();
 	}
-	for (i = 0; i < sizeof(int); i++) {
+	for (i = 0; i < (int)sizeof(int); i++) {
 		if ((c = getch()) == '\'') {
 			ungetch();
 			break;

usr.bin/m4/extern.h

@@ -71,7 +71,7 @@ extern void	remhash(const char *, int);
 /* main.c */
 extern void outputstr(const char *);
 extern int builtin_type(const char *);
-extern char *builtin_realname(int);
+extern const char *builtin_realname(int);
 extern void emitline(void);
 
 /* misc.c */
@@ -148,11 +148,27 @@ extern char *bbase[];		/* buffer base per ilevel */
 extern char ecommt[MAXCCHARS+1];/* end character for comment */
 extern char *ep;		/* first free char in strspace */
 extern char lquote[MAXCCHARS+1];/* left quote character (`) */
-extern char *m4wraps;		/* m4wrap string default. */
-extern char *null;		/* as it says.. just a null. */
+extern const char *m4wraps;	/* m4wrap string default. */
+extern const char *null;	/* as it says.. just a null. */
 extern char rquote[MAXCCHARS+1];/* right quote character (') */
 extern char scommt[MAXCCHARS+1];/* start character for comment */
 extern int synccpp;		/* Line synchronisation for C preprocessor */
-extern int chscratch;		/* Scratch space for gpbc() macro */
 
 extern int mimic_gnu;		/* behaves like gnu-m4 */
+
+/* get a possibly pushed-back-character, increment lineno if need be */
+static __inline int gpbc(void)
+{
+	int chscratch;		/* Scratch space. */
+
+	if (bp > bufbase) {
+		if (*--bp) 
+			return (*bp);
+		else
+			return (EOF);
+	}
+	chscratch = obtain_char(infile+ilevel);
+	if (chscratch == '\n')
+		++inlineno[ilevel];
+	return (chscratch);
+}

usr.bin/m4/gnum4.c

@@ -208,7 +208,7 @@ static void exit_regerror(int, regex_t *);
 static void do_subst(const char *, regex_t *, const char *, regmatch_t *);
 static void do_regexpindex(const char *, regex_t *, regmatch_t *);
 static void do_regexp(const char *, regex_t *, const char *, regmatch_t *);
-static void add_sub(int, const char *, regex_t *, regmatch_t *);
+static void add_sub(size_t, const char *, regex_t *, regmatch_t *);
 static void add_replace(const char *, regex_t *, const char *, regmatch_t *);
 #define addconstantstring(s) addchars((s), sizeof(s)-1)
 
@@ -273,7 +273,7 @@ exit_regerror(er, re)
 
 static void
 add_sub(n, string, re, pm)
-	int n;
+	size_t n;
 	const char *string;
 	regex_t *re;
 	regmatch_t *pm;
@@ -522,18 +522,12 @@ doesyscmd(cmd)
 {
 	int p[2];
 	pid_t pid, cpid;
-	char *argv[4];
 	int cc;
 	int status;
 
 	/* Follow gnu m4 documentation: first flush buffers. */
 	fflush(NULL);
 
-	argv[0] = "sh";
-	argv[1] = "-c";
-	argv[2] = (char *)cmd;
-	argv[3] = NULL;
-
 	/* Just set up standard output, share stderr and stdin with m4 */
 	if (pipe(p) == -1)
 		err(1, "bad pipe");
@@ -545,7 +539,7 @@ doesyscmd(cmd)
 		(void) close(p[0]);
 		(void) dup2(p[1], 1);
 		(void) close(p[1]);
-		execv(_PATH_BSHELL, argv);
+		execl(_PATH_BSHELL, "sh", "-c", cmd, NULL);
 		exit(1);
 	default:
 		/* Read result in two stages, since m4's buffer is

usr.bin/m4/main.c

@@ -80,14 +80,13 @@ int maxout;
 FILE *active;			/* active output file pointer  */
 int ilevel = 0; 		/* input file stack pointer    */
 int oindex = 0; 		/* diversion index..	       */
-char *null = "";                /* as it says.. just a null..  */
-char *m4wraps = "";             /* m4wrap string default..     */
+const char *null = "";          /* as it says.. just a null..  */
+const char *m4wraps = "";       /* m4wrap string default..     */
 char lquote[MAXCCHARS+1] = {LQUOTE};	/* left quote character  (`)   */
 char rquote[MAXCCHARS+1] = {RQUOTE};	/* right quote character (')   */
 char scommt[MAXCCHARS+1] = {SCOMMT};	/* start character for comment */
 char ecommt[MAXCCHARS+1] = {ECOMMT};	/* end character for comment   */
 int synccpp;			/* Line synchronisation for C preprocessor */
-int chscratch;			/* Scratch space for gpbc() macro */
 
 struct keyblk keywrds[] = {	/* m4 keywords to be installed */
 	{ "include",      INCLTYPE },
@@ -476,14 +475,14 @@ macro()
 
 		default:
 			if (LOOK_AHEAD(t, scommt)) {
-				char *p;
-				for (p = scommt; *p; p++)
-					chrsave(*p);
+				char *pc;
+				for (pc = scommt; *pc; pc++)
+					chrsave(*pc);
 				for(;;) {
 					t = gpbc();
 					if (LOOK_AHEAD(t, ecommt)) {
-						for (p = ecommt; *p; p++)
-							chrsave(*p);
+						for (pc = ecommt; *pc; pc++)
+							chrsave(*pc);
 						break;
 					}
 					if (t == EOF)
@@ -574,7 +573,7 @@ initkwds()
 		p->nxtptr = hashtab[h % HASHSIZE];
 		hashtab[h % HASHSIZE] = p;
 		p->name = xstrdup(keywrds[i].knam);
-		p->defn = null;
+		p->defn = xstrdup(null);
 		p->hv = h;
 		p->type = keywrds[i].ktyp & TYPEMASK;
 		if ((keywrds[i].ktyp & NOARGS) == 0)
@@ -595,7 +594,7 @@ builtin_type(key)
 	return -1;
 }
 
-char *
+const char *
 builtin_realname(n)
 	int n;
 {

usr.bin/m4/mdef.h

@@ -145,7 +145,7 @@ struct ndblock {		/* hastable structure         */
 #define nil     ((ndptr) 0)
  
 struct keyblk {
-        char    *knam;          /* keyword name */
+        const char    *knam;    /* keyword name */
         int     ktyp;           /* keyword type */
 };
 
@@ -166,13 +166,9 @@ struct input_file {
 /*
  * macros for readibility and/or speed
  *
- *      gpbc()  - get a possibly pushed-back character
  *      pushf() - push a call frame entry onto stack
  *      pushs() - push a string pointer onto stack
  */
-#define gpbc()   (bp > bufbase) ? (*--bp ? (*bp & 0xFF) : EOF) : \
-	((chscratch = obtain_char(infile+ilevel)) == '\n' && \
-	++inlineno[ilevel], chscratch)
 #define pushf(x) 			\
 	do {				\
 		if (++sp == STACKMAX) 	\

usr.bin/m4/misc.c

@@ -111,7 +111,7 @@ pbstr(s)
 	size_t n;
 
 	n = strlen(s);
-	while (endpbb - bp <= n)
+	while ((size_t)(endpbb - bp) <= n)
 		enlarge_bufspace();
 	while (n > 0)
 		*bp++ = s[--n];
@@ -236,7 +236,7 @@ getdiv(n)
 
 void
 onintr(signo)
-	int signo;
+	int signo __unused;
 {
 #define intrmessage	"m4: interrupted.\n"
 	write(STDERR_FILENO, intrmessage, sizeof(intrmessage)-1);
@@ -375,6 +375,6 @@ dump_buffer(f, m)
 {
 	char *s;
 
-	for (s = bp; s-buf > m;)
+	for (s = bp; s - buf > (int)m;)
 		fputc(*--s, f);
 }

usr.bin/m4/trace.c

@@ -32,6 +32,7 @@ __FBSDID("$FreeBSD$");
 #include <stdio.h>
 #include <err.h>
 #include <stdlib.h>
+#include <string.h>
 #include "mdef.h"
 #include "stdd.h"
 #include "extern.h"