libbb: better unicode width support. Hopefully fixes bug 839.

Also opens up a possibility to make other unicode stuff smaller
and more correct later. but:

function                                             old     new   delta
static.combining                                       -     516    +516
bb_wcwidth                                             -     328    +328
unicode_cut_nchars                                     -     141    +141
mbstowc_internal                                       -      93     +93
in_table                                               -      78     +78
cal_main                                             899     961     +62
static.combining0x10000                                -      40     +40
unicode_strlen                                         -      31     +31
bb_mbstrlen                                           31       -     -31
bb_mbstowcs                                          173     102     -71
------------------------------------------------------------------------------
(add/remove: 7/1 grow/shrink: 1/1 up/down: 1289/-102)        Total: 1187 bytes

Uses code of Markus Kuhn, which is in public domain:
http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
"Permission to use, copy, modify, and distribute this software
 for any purpose and without fee is hereby granted. The author
 disclaims all warranties with regard to this software."

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 153 insertions, 57 deletions

diff --git a/libbb/unicode.c b/libbb/unicode.c
index 80042957c..844c154e0 100644
--- a/libbb/unicode.c
+++ b/libbb/unicode.c
@@ -9,22 +9,19 @@
 #include "libbb.h"
 #include "unicode.h"
 
-/* If it's not a constant... */
+/* If it's not #defined as a constant in unicode.h... */
 #ifndef unicode_status
 uint8_t unicode_status;
 #endif
 
-size_t FAST_FUNC bb_mbstrlen(const char *string)
-{
-	size_t width = mbstowcs(NULL, string, INT_MAX);
-	if (width == (size_t)-1L)
-		return strlen(string);
-	return width;
-}
+/* This file is compiled only if FEATURE_ASSUME_UNICODE is on.
+ * We check other options and decide whether to use libc support
+ * via locale, or use our own logic:
+ */
 
 #if ENABLE_LOCALE_SUPPORT
 
-/* Unicode support using libc */
+/* Unicode support using libc locale support. */
 
 void FAST_FUNC init_unicode(void)
 {
@@ -34,12 +31,12 @@ void FAST_FUNC init_unicode(void)
 	if (unicode_status != UNICODE_UNKNOWN)
 		return;
 
-	unicode_status = bb_mbstrlen(unicode_0x394) == 1 ? UNICODE_ON : UNICODE_OFF;
+	unicode_status = unicode_strlen(unicode_0x394) == 1 ? UNICODE_ON : UNICODE_OFF;
 }
 
 #else
 
-/* Crude "locale support" which knows only C and Unicode locales */
+/* Homegrown Unicode support. It knows only C and Unicode locales. */
 
 # if ENABLE_FEATURE_CHECK_UNICODE_IN_ENV
 void FAST_FUNC init_unicode(void)
@@ -93,7 +90,6 @@ static size_t wcrtomb_internal(char *s, wchar_t wc)
 	s[0] = wc | (uint8_t)(0x3f00 >> n);
 	return n;
 }
-
 size_t FAST_FUNC wcrtomb(char *s, wchar_t wc, mbstate_t *ps UNUSED_PARAM)
 {
 	if (unicode_status != UNICODE_ON) {
@@ -103,7 +99,6 @@ size_t FAST_FUNC wcrtomb(char *s, wchar_t wc, mbstate_t *ps UNUSED_PARAM)
 
 	return wcrtomb_internal(s, wc);
 }
-
 size_t FAST_FUNC wcstombs(char *dest, const wchar_t *src, size_t n)
 {
 	size_t org_n = n;
@@ -144,6 +139,51 @@ size_t FAST_FUNC wcstombs(char *dest, const wchar_t *src, size_t n)
 	return org_n - n;
 }
 
+static const char *mbstowc_internal(wchar_t *res, const char *src)
+{
+	int bytes;
+	unsigned c = (unsigned char) *src++;
+
+	if (c <= 0x7f) {
+		*res = c;
+		return src;
+	}
+
+	/* 80-7FF -> 110yyyxx 10xxxxxx */
+	/* 800-FFFF -> 1110yyyy 10yyyyxx 10xxxxxx */
+	/* 10000-1FFFFF -> 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx */
+	/* 200000-3FFFFFF -> 111110tt 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx */
+	/* 4000000-FFFFFFFF -> 111111tt 10tttttt 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx */
+	bytes = 0;
+	do {
+		c <<= 1;
+		bytes++;
+	} while ((c & 0x80) && bytes < 6);
+	if (bytes == 1)
+		return NULL;
+	c = (uint8_t)(c) >> bytes;
+
+	while (--bytes) {
+		unsigned ch = (unsigned char) *src++;
+		if ((ch & 0xc0) != 0x80) {
+			return NULL;
+		}
+		c = (c << 6) + (ch & 0x3f);
+	}
+
+	/* TODO */
+	/* Need to check that c isn't produced by overlong encoding */
+	/* Example: 11000000 10000000 converts to NUL */
+	/* 11110000 10000000 10000100 10000000 converts to 0x100 */
+	/* correct encoding: 11000100 10000000 */
+	if (c <= 0x7f) { /* crude check */
+		return NULL;
+		//or maybe 0xfffd; /* replacement character */
+	}
+
+	*res = c;
+	return src;
+}
 size_t FAST_FUNC mbstowcs(wchar_t *dest, const char *src, size_t n)
 {
 	size_t org_n = n;
@@ -162,58 +202,20 @@ size_t FAST_FUNC mbstowcs(wchar_t *dest, const char *src, size_t n)
 	}
 
 	while (n) {
-		int bytes;
-		unsigned c = (unsigned char) *src++;
-
-		if (c <= 0x7f) {
-			if (dest)
-				*dest++ = c;
-			if (c == '\0')
-				break;
-			n--;
-			continue;
-		}
-
-		/* 80-7FF -> 110yyyxx 10xxxxxx */
-		/* 800-FFFF -> 1110yyyy 10yyyyxx 10xxxxxx */
-		/* 10000-1FFFFF -> 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx */
-		/* 200000-3FFFFFF -> 111110tt 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx */
-		/* 4000000-FFFFFFFF -> 111111tt 10tttttt 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx */
-		bytes = 0;
-		do {
-			c <<= 1;
-			bytes++;
-		} while ((c & 0x80) && bytes < 6);
-		if (bytes == 1)
+		wchar_t wc;
+		const char *rc = mbstowc_internal(dest ? dest : &wc, src);
+		if (rc == NULL) /* error */
 			return (size_t) -1L;
-		c = (uint8_t)(c) >> bytes;
-
-		while (--bytes) {
-			unsigned ch = (unsigned char) *src++;
-			if ((ch & 0xc0) != 0x80) {
-				return (size_t) -1L;
-			}
-			c = (c << 6) + (ch & 0x3f);
-		}
-
-		/* TODO */
-		/* Need to check that c isn't produced by overlong encoding */
-		/* Example: 11000000 10000000 converts to NUL */
-		/* 11110000 10000000 10000100 10000000 converts to 0x100 */
-		/* correct encoding: 11000100 10000000 */
-		if (c <= 0x7f) { /* crude check */
-			return (size_t) -1L;
-			//or maybe: c = 0xfffd; /* replacement character */
-		}
-
 		if (dest)
-			*dest++ = c;
+			dest++;
 		n--;
 	}
 
 	return org_n - n;
 }
 
+#include "unicode_wcwidth.c"
+
 int FAST_FUNC iswspace(wint_t wc)
 {
 	return (unsigned)wc <= 0x7f && isspace(wc);
@@ -229,4 +231,98 @@ int FAST_FUNC iswpunct(wint_t wc)
 	return (unsigned)wc <= 0x7f && ispunct(wc);
 }
 
+#endif /* Homegrown Unicode support */
+
+
+/* The rest is mostly same for libc and for "homegrown" support */
+
+size_t FAST_FUNC unicode_strlen(const char *string)
+{
+	size_t width = mbstowcs(NULL, string, INT_MAX);
+	if (width == (size_t)-1L)
+		return strlen(string);
+	return width;
+}
+
+char* FAST_FUNC unicode_cut_nchars(unsigned width, const char *src)
+{
+	char *dst;
+	unsigned dst_len;
+
+	if (unicode_status != UNICODE_ON)
+		return xasprintf("%-*.*s", width, width, src);
+
+	dst = NULL;
+	dst_len = 0;
+	while (1) {
+		int w;
+		wchar_t wc;
+
+		dst = xrealloc(dst, dst_len + 2 * MB_CUR_MAX);
+#if ENABLE_LOCALE_SUPPORT
+		{
+			mbstate_t mbst = { 0 };
+			ssize_t rc = mbsrtowcs(&wc, &src, 1, &mbst);
+			if (rc <= 0) /* error, or end-of-string */
+				break;
+		}
+#else
+		src = mbstowc_internal(&wc, src);
+		if (!src || wc == 0) /* error, or end-of-string */
+			break;
 #endif
+		w = wcwidth(wc);
+		if (w < 0) /* non-printable wchar */
+			break;
+		width -= w;
+		if ((int)width < 0) { /* string is longer than width */
+			width += w;
+			while (width) {
+				dst[dst_len++] = ' ';
+				width--;
+			}
+			break;
+		}
+#if ENABLE_LOCALE_SUPPORT
+		{
+			mbstate_t mbst = { 0 };
+			dst_len += wcrtomb(&dst[dst_len], wc, &mbst);
+		}
+#else
+		dst_len += wcrtomb_internal(&dst[dst_len], wc);
+#endif
+	}
+	dst[dst_len] = '\0';
+	return dst;
+}
+
+unsigned FAST_FUNC unicode_padding_to_width(unsigned width, const char *src)
+{
+	if (unicode_status != UNICODE_ON) {
+		return width - strnlen(src, width);
+	}
+
+	while (1) {
+		int w;
+		wchar_t wc;
+
+#if ENABLE_LOCALE_SUPPORT
+		{
+			mbstate_t mbst = { 0 };
+			ssize_t rc = mbsrtowcs(&wc, &src, 1, &mbst);
+			if (rc <= 0) /* error, or end-of-string */
+				return width;
+		}
+#else
+		src = mbstowc_internal(&wc, src);
+		if (!src || wc == 0) /* error, or end-of-string */
+			return width;
+#endif
+		w = wcwidth(wc);
+		if (w < 0) /* non-printable wchar */
+			return width;
+		width -= w;
+		if ((int)width <= 0) /* string is longer than width */
+			return 0;
+	}
+}