转载：http://blog.csdn.net/wavemcu/article/details/7202908
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作者：EasyWave 时间：2012.01.15
类别：linux驱动开发 声明：转载，请保留链接
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在嵌入式linux系统中，busybox是最常见的用来构建文件系统的。可是从busybox1.17.0以上之后，对ls命令不做修改是无法显
示中文的。就算是内核设置了支持中文的话，在shell下用ls命令也是无法显示中文的，这是因为busybox1.17.0以后版本对中文的支持进行了
限制。现在就来讲讲如何修改让busybox1.17.0以上版本支持中文，要想让busybox1.17.0以上支持中文，需要修改两个文
件：printable_string.c以及unicode.c
。下面来分析，为什么ls命令无法显示中文。请看printable_string.c未修改过的代码：
const char* FAST_FUNC printable_string(uni_stat_t *stats, const char *str)
{
static char *saved[];
static unsigned cur_saved; /* = 0 */ char *dst;
const char *s; s = str;
while () {
unsigned char c = *s;
if (c == '\0') {
/* 99+% of inputs do not need conversion */
if (stats) {
stats->byte_count = (s - str);
stats->unicode_count = (s - str);
stats->unicode_width = (s - str);
}
return str;
}
if (c < ' ')
break;
if (c >= 0x7f)
break;
s++;
} #if ENABLE_UNICODE_SUPPORT
dst = unicode_conv_to_printable(stats, str);
#else
{
char *d = dst = xstrdup(str);
while () {
unsigned char c = *d;
if (c == '\0')
break;
if (c < ' ' || c >= 0x7f)
*d = '?';
d++;
}
if (stats) {
stats->byte_count = (d - dst);
stats->unicode_count = (d - dst);
stats->unicode_width = (d - dst);
}
}
#endif free(saved[cur_saved]);
saved[cur_saved] = dst;
cur_saved = (cur_saved + ) & (ARRAY_SIZE(saved)-); return dst;
}
从上面代码23和24行以及37和38行可以看出：大于0x7F的字符直接被break掉，或者直接被“？”代替了。所以就算是linux内核设置了支持中文，也是无法显示出来的，被“？”代替了。修改红色加粗的代码如下：
const char* FAST_FUNC printable_string(uni_stat_t *stats, const char *str)
{
static char *saved[];
static unsigned cur_saved; /* = 0 */ char *dst;
const char *s; s = str;
while () {
unsigned char c = *s;
if (c == '\0') {
/* 99+% of inputs do not need conversion */
if (stats) {
stats->byte_count = (s - str);
stats->unicode_count = (s - str);
stats->unicode_width = (s - str);
}
return str;
}
if (c < ' ')
break;
/*
if (c >= 0x7f)
break;
*/
s++;
} #if ENABLE_UNICODE_SUPPORT
dst = unicode_conv_to_printable(stats, str);
#else
{
char *d = dst = xstrdup(str);
while () {
unsigned char c = *d;
if (c == '\0')
break;
if (c < ' ' /*|| c >= 0x7f */)
*d = '?';
d++;
}
if (stats) {
stats->byte_count = (d - dst);
stats->unicode_count = (d - dst);
stats->unicode_width = (d - dst);
}
}
#endif free(saved[cur_saved]);
saved[cur_saved] = dst;
cur_saved = (cur_saved + ) & (ARRAY_SIZE(saved)-); return dst;
}
经过以上的修改之后，同时busybox1.17.0配置的时候没有选中[] Support Unicode的话，那么采用ls命令是可以看到中文的，这个我自己已经亲自测试过的。可是还有一种情况：busybox1.17.0在配置的时候选中了：[*] Support Unicode，见下：
在配置里，有Support Unicode选上的：
Busybox Settings->General Configuration->
│ │[ ] Enable locale support (system needs locale for this to work) │ │
│ │[*] Support Unicode │ │
│ │[*] Support for --long-options │ │
那么这样还需要修改一个文件，这个文件就是：unicode.c。如果不修改这个文件，ls命令也是无法显示出中文的。见下未修改的代码：
static char* FAST_FUNC unicode_conv_to_printable2(uni_stat_t *stats, const char *src, unsigned width, int flags)
{
char *dst;
unsigned dst_len;
unsigned uni_count;
unsigned uni_width; if (unicode_status != UNICODE_ON) {
char *d;
if (flags & UNI_FLAG_PAD) {
d = dst = xmalloc(width + );
while ((int)--width >= ) {
unsigned char c = *src;
if (c == '\0') {
do
*d++ = ' ';
while ((int)--width >= );
break;
}
*d++ = (c >= ' ' && c < 0x7f) ? c : '?';
src++;
}
*d = '\0';
} else {
d = dst = xstrndup(src, width);
while (*d) {
unsigned char c = *d;
if (c < ' ' || c >= 0x7f)
*d = '?';
d++;
}
}
if (stats) {
stats->byte_count = (d - dst);
stats->unicode_count = (d - dst);
stats->unicode_width = (d - dst);
}
return dst;
} dst = NULL;
uni_count = uni_width = ;
dst_len = ;
while () {
int w;
wchar_t wc; #if ENABLE_UNICODE_USING_LOCALE
{
mbstate_t mbst = { };
ssize_t rc = mbsrtowcs(&wc, &src, , &mbst);
/* If invalid sequence is seen: -1 is returned,
* src points to the invalid sequence, errno = EILSEQ.
* Else number of wchars (excluding terminating L'\0')
* written to dest is returned.
* If len (here: 1) non-L'\0' wchars stored at dest,
* src points to the next char to be converted.
* If string is completely converted: src = NULL.
*/
if (rc == ) /* end-of-string */
break;
if (rc < ) { /* error */
src++;
goto subst;
}
if (!iswprint(wc))
goto subst;
}
#else
src = mbstowc_internal(&wc, src);
/* src is advanced to next mb char
* wc == ERROR_WCHAR: invalid sequence is seen
* else: wc is set
*/
if (wc == ERROR_WCHAR) /* error */
goto subst;
if (wc == ) /* end-of-string */
break;
#endif
if (CONFIG_LAST_SUPPORTED_WCHAR && wc > CONFIG_LAST_SUPPORTED_WCHAR)
goto subst;
w = wcwidth(wc);
if ((ENABLE_UNICODE_COMBINING_WCHARS && w < ) /* non-printable wchar */
|| (!ENABLE_UNICODE_COMBINING_WCHARS && w <= )
|| (!ENABLE_UNICODE_WIDE_WCHARS && w > )
) {
subst:
wc = CONFIG_SUBST_WCHAR;
w = ;
}
width -= w;
/* Note: if width == 0, we still may add more chars,
* they may be zero-width or combining ones */
if ((int)width < ) {
/* can't add this wc, string would become longer than width */
width += w;
break;
} uni_count++;
uni_width += w;
dst = xrealloc(dst, dst_len + MB_CUR_MAX);
#if ENABLE_UNICODE_USING_LOCALE
{
mbstate_t mbst = { };
dst_len += wcrtomb(&dst[dst_len], wc, &mbst);
}
#else
dst_len += wcrtomb_internal(&dst[dst_len], wc);
#endif
} /* Pad to remaining width */
if (flags & UNI_FLAG_PAD) {
dst = xrealloc(dst, dst_len + width + );
uni_count += width;
uni_width += width;
while ((int)--width >= ) {
dst[dst_len++] = ' ';
}
}
dst[dst_len] = '\0';
if (stats) {
stats->byte_count = dst_len;
stats->unicode_count = uni_count;
stats->unicode_width = uni_width;
} return dst;
}
见上面20行和28行，需要修改一下，修改后的代码见下：
static char* FAST_FUNC unicode_conv_to_printable2(uni_stat_t *stats, const char *src, unsigned width, int flags)
{
char *dst;
unsigned dst_len;
unsigned uni_count;
unsigned uni_width; if (unicode_status != UNICODE_ON) {
char *d;
if (flags & UNI_FLAG_PAD) {
d = dst = xmalloc(width + );
while ((int)--width >= ) {
unsigned char c = *src;
if (c == '\0') {
do
*d++ = ' ';
while ((int)--width >= );
break;
}
*d++ = (c >= ' '/* && c < 0x7f */) ? c : '?';
src++;
}
*d = '\0';
} else {
d = dst = xstrndup(src, width);
while (*d) {
unsigned char c = *d;
if (c < ' '/* || c >= 0x7f */)
*d = '?';
d++;
}
}
if (stats) {
stats->byte_count = (d - dst);
stats->unicode_count = (d - dst);
stats->unicode_width = (d - dst);
}
return dst;
} dst = NULL;
uni_count = uni_width = ;
dst_len = ;
while () {
int w;
wchar_t wc; #if ENABLE_UNICODE_USING_LOCALE
{
mbstate_t mbst = { };
ssize_t rc = mbsrtowcs(&wc, &src, , &mbst);
/* If invalid sequence is seen: -1 is returned,
* src points to the invalid sequence, errno = EILSEQ.
* Else number of wchars (excluding terminating L'\0')
* written to dest is returned.
* If len (here: 1) non-L'\0' wchars stored at dest,
* src points to the next char to be converted.
* If string is completely converted: src = NULL.
*/
if (rc == ) /* end-of-string */
break;
if (rc < ) { /* error */
src++;
goto subst;
}
if (!iswprint(wc))
goto subst;
}
#else
src = mbstowc_internal(&wc, src);
/* src is advanced to next mb char
* wc == ERROR_WCHAR: invalid sequence is seen
* else: wc is set
*/
if (wc == ERROR_WCHAR) /* error */
goto subst;
if (wc == ) /* end-of-string */
break;
#endif
if (CONFIG_LAST_SUPPORTED_WCHAR && wc > CONFIG_LAST_SUPPORTED_WCHAR)
goto subst;
w = wcwidth(wc);
if ((ENABLE_UNICODE_COMBINING_WCHARS && w < ) /* non-printable wchar */
|| (!ENABLE_UNICODE_COMBINING_WCHARS && w <= )
|| (!ENABLE_UNICODE_WIDE_WCHARS && w > )
) {
subst:
wc = CONFIG_SUBST_WCHAR;
w = ;
}
width -= w;
/* Note: if width == 0, we still may add more chars,
* they may be zero-width or combining ones */
if ((int)width < ) {
/* can't add this wc, string would become longer than width */
width += w;
break;
} uni_count++;
uni_width += w;
dst = xrealloc(dst, dst_len + MB_CUR_MAX);
#if ENABLE_UNICODE_USING_LOCALE
{
mbstate_t mbst = { };
dst_len += wcrtomb(&dst[dst_len], wc, &mbst);
}
#else
dst_len += wcrtomb_internal(&dst[dst_len], wc);
#endif
} /* Pad to remaining width */
if (flags & UNI_FLAG_PAD) {
dst = xrealloc(dst, dst_len + width + );
uni_count += width;
uni_width += width;
while ((int)--width >= ) {
dst[dst_len++] = ' ';
}
}
dst[dst_len] = '\0';
if (stats) {
stats->byte_count = dst_len;
stats->unicode_count = uni_count;
stats->unicode_width = uni_width;
} return dst;
}
经过以上修改之后，就算配置支持Unicode，ls命令也是可以支持中文的。同时也可以进入中文目录可以文件夹。