Add POSIX-style support for multibyte characters to od(1): the 'c'

conversion interprets input bytes as multibyte sequences and displays
printable characters in the area corresponding to their first byte.
The remaining bytes are shown as "**".

usr.bin/hexdump/conv.c

@@ -39,15 +39,30 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 
+#include <assert.h>
 #include <stdio.h>
 #include <ctype.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <wchar.h>
+#include <wctype.h>
 #include "hexdump.h"
 
 void
-conv_c(PR *pr, u_char *p)
+conv_c(PR *pr, u_char *p, size_t bufsize)
 {
 	char buf[10];
 	char const *str;
+	wchar_t wc;
+	size_t clen, oclen;
+	int converr, pad, width;
+	char peekbuf[MB_LEN_MAX];
+
+	if (pr->mbleft > 0) {
+		str = "**";
+		pr->mbleft--;
+		goto strpr;
+	}
 
 	switch(*p) {
 	case '\0':
@@ -78,9 +93,53 @@ conv_c(PR *pr, u_char *p)
 	default:
 		break;
 	}
-	if (isprint(*p)) {
-		*pr->cchar = 'c';
-		(void)printf(pr->fmt, *p);
+	/*
+	 * Multibyte characters are disabled for hexdump(1) for backwards
+	 * compatibility and consistency (none of its other output formats
+	 * recognize them correctly).
+	 */
+	converr = 0;
+	if (odmode && MB_CUR_MAX > 1) {
+		oclen = 0;
+retry:
+		clen = mbrtowc(&wc, p, bufsize, &pr->mbstate);
+		if (clen == 0)
+			clen = 1;
+		else if (clen == (size_t)-1 || (clen == (size_t)-2 &&
+		    buf == peekbuf)) {
+			memset(&pr->mbstate, 0, sizeof(pr->mbstate));
+			wc = *p;
+			clen = 1;
+			converr = 1;
+		} else if (clen == (size_t)-2) {
+			/*
+			 * Incomplete character; peek ahead and see if we
+			 * can complete it.
+			 */
+			oclen = bufsize;
+			bufsize = peek(p = peekbuf, MB_CUR_MAX);
+			goto retry;
+		}
+		clen += oclen;
+	} else {
+		wc = *p;
+		clen = 1;
+	}
+	if (!converr && iswprint(wc)) {
+		if (!odmode) {
+			*pr->cchar = 'c';
+			(void)printf(pr->fmt, (int)wc);
+		} else {	
+			*pr->cchar = 'C';
+			assert(strcmp(pr->fmt, "%3C") == 0);
+			width = wcwidth(wc);
+			assert(width > 0);
+			pad = 3 - width;
+			if (pad < 0)
+				pad = 0;
+			(void)printf("%*s%C", pad, "", wc);
+			pr->mbleft = clen - 1;
+		}
 	} else {
 		(void)sprintf(buf, "%03o", (int)*p);
 		str = buf;

usr.bin/hexdump/display.c

@@ -132,7 +132,8 @@ print(PR *pr, u_char *bp)
 		(void)printf(pr->fmt, "");
 		break;
 	case F_C:
-		conv_c(pr, bp);
+		conv_c(pr, bp, eaddress ? eaddress - address :
+		    blocksize - address % blocksize);
 		break;
 	case F_CHAR:
 		(void)printf(pr->fmt, *bp);
@@ -261,6 +262,10 @@ get(void)
 				errx(1, "cannot skip past end of input");
 			if (need == blocksize)
 				return((u_char *)NULL);
+			/*
+			 * XXX bcmp() is not quite right in the presence
+			 * of multibyte characters.
+			 */
 			if (vflag != ALL && 
 			    valid_save && 
 			    bcmp(curp, savp, nread) == 0) {
@@ -284,6 +289,10 @@ get(void)
 		if (length != -1)
 			length -= n;
 		if (!(need -= n)) {
+			/*
+			 * XXX bcmp() is not quite right in the presence
+			 * of multibyte characters.
+			 */
 			if (vflag == ALL || vflag == FIRST ||
 			    valid_save == 0 ||
 			    bcmp(curp, savp, blocksize) != 0) {
@@ -303,6 +312,27 @@ get(void)
 	}
 }
 
+size_t
+peek(u_char *buf, size_t nbytes)
+{
+	size_t n, nread;
+	int c;
+
+	if (length != -1 && nbytes > length)
+		nbytes = length;
+	nread = 0;
+	while (nread < nbytes && (c = getchar()) != EOF) {
+		*buf++ = c;
+		nread++;
+	}
+	n = nread;
+	while (n-- > 0) {
+		c = *--buf;
+		ungetc(c, stdin);
+	}
+	return (nread);
+}
+
 int
 next(char **argv)
 {

usr.bin/hexdump/hexdump.h

@@ -34,6 +34,8 @@
  * $FreeBSD$
  */
 
+#include <wchar.h>
+
 typedef struct _pr {
 	struct _pr *nextpr;		/* next print unit */
 #define	F_ADDRESS	0x001		/* print offset */
@@ -52,6 +54,8 @@ typedef struct _pr {
 	char *cchar;			/* conversion character */
 	char *fmt;			/* printf format */
 	char *nospace;			/* no whitespace version */
+	int mbleft;			/* bytes left of multibyte char. */
+	mbstate_t mbstate;		/* conversion state */
 } PR;
 
 typedef struct _fu {
@@ -88,7 +92,7 @@ void	 badconv(char *);
 void	 badfmt(const char *);
 void	 badsfmt(void);
 void	 bpad(PR *);
-void	 conv_c(PR *, u_char *);
+void	 conv_c(PR *, u_char *, size_t);
 void	 conv_u(PR *, u_char *);
 void	 display(void);
 void	 doskip(const char *, int);
@@ -98,6 +102,7 @@ void	 newsyntax(int, char ***);
 int	 next(char **);
 void	 nomem(void);
 void	 oldsyntax(int, char ***);
+size_t	 peek(u_char *, size_t);
 void	 rewrite(FS *);
 int	 size(FS *);
 void	 usage(void);

usr.bin/hexdump/od.1

@@ -32,7 +32,7 @@
 .\"	@(#)od.1	8.1 (Berkeley) 6/6/93
 .\" $FreeBSD$
 .\"
-.Dd July 3, 2004
+.Dd July 11, 2004
 .Os
 .Dt OD 1
 .Sh NAME
@@ -179,6 +179,10 @@ characters, which are represented as C escapes:
 .It vertical tab
 \ev
 .El
+.Pp
+Multi-byte characters are displayed in the area corresponding to the first
+byte of the character. The remaining bytes are shown as
+.Ql ** .
 .It Xo
 .Sm off
 .Op Cm d | o | u | x
@@ -231,6 +235,15 @@ contain one line for each format.
 If no output format is specified,
 .Fl t Ar oS
 is assumed.
+.Sh ENVIRONMENT
+The
+.Ev LANG , LC_ALL
+and
+.Ev LC_CTYPE
+environment variables affect the execution of
+.Nm
+as described in
+.Xr environ 7 .
 .Sh DIAGNOSTICS
 .Ex -std
 .Sh COMPATIBILITY
@@ -252,7 +265,3 @@ An
 .Nm
 command appeared in
 .At v1 .
-.Sh BUGS
-The
-.Nm
-utility does not recognize multibyte characters.