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[4]; static unsigned cur_saved; /* = 0 */ char *dst; const char *s; s = str; while (1) { unsigned char c = *s; if (c == ' ') { /* 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 (1) { unsigned char c = *d; if (c == ' ') 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 + 1) & (ARRAY_SIZE(saved)-1); 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[4]; static unsigned cur_saved; /* = 0 */ char *dst; const char *s; s = str; while (1) { unsigned char c = *s; if (c == ' ') { /* 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 (1) { unsigned char c = *d; if (c == ' ') 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 + 1) & (ARRAY_SIZE(saved)-1); 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 + 1); while ((int)--width >= 0) { unsigned char c = *src; if (c == ' ') { do *d++ = ' '; while ((int)--width >= 0); break; } *d++ = (c >= ' ' && c < 0x7f) ? c : '?'; src++; } *d = ' '; } 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 = 0; dst_len = 0; while (1) { int w; wchar_t wc; #if ENABLE_UNICODE_USING_LOCALE { mbstate_t mbst = { 0 }; ssize_t rc = mbsrtowcs(&wc, &src, 1, &mbst); /* If invalid sequence is seen: -1 is returned, * src points to the invalid sequence, errno = EILSEQ. * Else number of wchars (excluding terminating L' ') * written to dest is returned. * If len (here: 1) non-L' ' wchars stored at dest, * src points to the next char to be converted. * If string is completely converted: src = NULL. */ if (rc == 0) /* end-of-string */ break; if (rc < 0) { /* 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 == 0) /* 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 < 0) /* non-printable wchar */ || (!ENABLE_UNICODE_COMBINING_WCHARS && w <= 0) || (!ENABLE_UNICODE_WIDE_WCHARS && w > 1) ) { subst: wc = CONFIG_SUBST_WCHAR; w = 1; } width -= w; /* Note: if width == 0, we still may add more chars, * they may be zero-width or combining ones */ if ((int)width < 0) { /* 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 = { 0 }; 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 + 1); uni_count += width; uni_width += width; while ((int)--width >= 0) { dst[dst_len++] = ' '; } } dst[dst_len] = ' '; 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 + 1); while ((int)--width >= 0) { unsigned char c = *src; if (c == ' ') { do *d++ = ' '; while ((int)--width >= 0); break; } *d++ = (c >= ' '/* && c < 0x7f */) ? c : '?'; src++; } *d = ' '; } 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 = 0; dst_len = 0; while (1) { int w; wchar_t wc; #if ENABLE_UNICODE_USING_LOCALE { mbstate_t mbst = { 0 }; ssize_t rc = mbsrtowcs(&wc, &src, 1, &mbst); /* If invalid sequence is seen: -1 is returned, * src points to the invalid sequence, errno = EILSEQ. * Else number of wchars (excluding terminating L' ') * written to dest is returned. * If len (here: 1) non-L' ' wchars stored at dest, * src points to the next char to be converted. * If string is completely converted: src = NULL. */ if (rc == 0) /* end-of-string */ break; if (rc < 0) { /* 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 == 0) /* 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 < 0) /* non-printable wchar */ || (!ENABLE_UNICODE_COMBINING_WCHARS && w <= 0) || (!ENABLE_UNICODE_WIDE_WCHARS && w > 1) ) { subst: wc = CONFIG_SUBST_WCHAR; w = 1; } width -= w; /* Note: if width == 0, we still may add more chars, * they may be zero-width or combining ones */ if ((int)width < 0) { /* 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 = { 0 }; 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 + 1); uni_count += width; uni_width += width; while ((int)--width >= 0) { dst[dst_len++] = ' '; } } dst[dst_len] = ' '; 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。