Add charset_from_locale(), a best-effort attempt to return the

libcharset CS_* identifier for the character set indicated by the
active locale. Uses code from Markus Kuhn's website.

git-svn-id: svn://svn.tartarus.org/sgt/charset@4115 cda61777-01e9-0310-a592-d414129be87e

diff --git a/Makefile b/Makefile
index da58271..bf937c4 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -57,6 +57,7 @@ LIBCHARSET_OBJS = \
        $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)jisx0208.o \
        $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)jisx0212.o \
        $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)ksx1001.o \
+       $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)locale.o \
        $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)localenc.o \
        $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)macenc.o \
        $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)mimeenc.o \
@@ -123,6 +124,10 @@ $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)ksx1001.o: \
        $(LIBCHARSET_SRCDIR)ksx1001.c
        $(CC) $(CFLAGS) $(MD) -c -o $@ $<
 
+$(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)locale.o: \
+       $(LIBCHARSET_SRCDIR)locale.c
+       $(CC) $(CFLAGS) $(MD) -c -o $@ $<
+
 $(LIBCHARSET_OBJDIR)$(LIBCHARSET_OBJPFX)localenc.o: \
        $(LIBCHARSET_SRCDIR)localenc.c
        $(CC) $(CFLAGS) $(MD) -c -o $@ $<

diff --git a/charset.h b/charset.h
index 3880fbd..883dcfb 100644 (file)
--- a/charset.h
+++ b/charset.h
@@ -207,4 +207,15 @@ int charset_upgrade(int charset);
  */
 int charset_contains_ascii(int charset);
 
+/*
+ * This function tries to deduce the CS_* identifier of the charset
+ * used in the current C locale. It falls back to CS_ASCII if it
+ * can't figure it out at all, so it will always return a valid
+ * charset.
+ * 
+ * (Note that you should have already called setlocale(LC_CTYPE,
+ * "") to guarantee that this function will do the right thing.)
+ */
+int charset_from_locale(void);
+
 #endif /* charset_charset_h */

diff --git a/locale.c b/locale.c
new file mode 100644 (file)
index 0000000..6710d1b
--- /dev/null
+++ b/locale.c
@@ -0,0 +1,93 @@
+/*
+ * locale.c: try very hard to figure out the libcharset charset
+ * identifier corresponding to the current C library locale.
+ * 
+ * This function works by calling nl_langinfo(CODESET) if
+ * available; failing that, it will try to figure it out manually
+ * by examining the locale environment variables. Code for the
+ * latter is adapted from Markus Kuhn's public-domain
+ * implementation of nl_langinfo(CODESET), available at
+ * 
+ *   http://www.cl.cam.ac.uk/~mgk25/ucs/langinfo.c
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "charset.h"
+
+#ifdef HAS_LANGINFO_CODESET
+#include "langinfo.h"
+#endif
+
+int charset_from_locale(void)
+{
+    char *l, *p;
+
+#ifdef HAS_LANGINFO_CODESET
+    int charset;
+    char const *csname;
+
+    csname = nl_langinfo(CODESET);
+    if (csname &&
+       (charset = charset_from_localenc(csname)) != CS_NONE)
+       return charset;
+#endif
+
+    if (((l = getenv("LC_ALL"))   && *l) ||
+       ((l = getenv("LC_CTYPE")) && *l) ||
+       ((l = getenv("LANG"))     && *l)) {
+       /* check standardized locales */
+       if (!strcmp(l, "C") || !strcmp(l, "POSIX"))
+           return CS_ASCII;
+       /* check for encoding name fragment */
+       if (strstr(l, "UTF") || strstr(l, "utf"))
+           return CS_UTF8;
+       if ((p = strstr(l, "8859-"))) {
+           char buf[16];
+           int charset;
+
+           memcpy(buf, "ISO-8859-\0\0", 12);
+           p += 5;
+           if ((*p) >= '0' && (*p) <= '9') {
+               buf[9] = *p++;
+               if ((*p) >= '0' && (*p) <= '9') buf[10] = *p++;
+               if ((charset = charset_from_localenc(buf)) != CS_NONE)
+                   return charset;
+           }
+       }
+       if (strstr(l, "KOI8-RU")) return CS_KOI8_RU;
+       if (strstr(l, "KOI8-R")) return CS_KOI8_R;
+       if (strstr(l, "KOI8-U")) return CS_KOI8_U;
+       /* if (strstr(l, "620")) return "TIS-620"; */
+       if (strstr(l, "2312")) return CS_EUC_CN;
+       /* if (strstr(l, "HKSCS")) return "Big5HKSCS"; */
+       if (strstr(l, "Big5") || strstr(l, "BIG5")) return CS_BIG5;
+       /* if (strstr(l, "GBK")) return "GBK"; */
+       /* if (strstr(l, "18030")) return "GB18030"; */
+       if (strstr(l, "Shift_JIS") || strstr(l, "SJIS")) return CS_SHIFT_JIS;
+       /* check for conclusive modifier */
+       if (strstr(l, "euro")) return CS_ISO8859_15;
+       /* check for language (and perhaps country) codes */
+       if (strstr(l, "zh_TW")) return CS_BIG5;
+       /* if (strstr(l, "zh_HK")) return "Big5HKSCS"; */
+       if (strstr(l, "zh")) return CS_EUC_CN;
+       if (strstr(l, "ja")) return CS_EUC_JP;
+       if (strstr(l, "ko")) return CS_EUC_KR;
+       if (strstr(l, "ru")) return CS_KOI8_R;
+       if (strstr(l, "uk")) return CS_KOI8_U;
+       if (strstr(l, "pl") || strstr(l, "hr") ||
+           strstr(l, "hu") || strstr(l, "cs") ||
+           strstr(l, "sk") || strstr(l, "sl")) return CS_ISO8859_2;
+       if (strstr(l, "eo") || strstr(l, "mt")) return CS_ISO8859_3;
+       if (strstr(l, "el")) return CS_ISO8859_7;
+       if (strstr(l, "he")) return CS_ISO8859_8;
+       if (strstr(l, "tr")) return CS_ISO8859_9;
+       /* if (strstr(l, "th")) return "TIS-620"; */
+       if (strstr(l, "lt")) return CS_ISO8859_13;
+       if (strstr(l, "cy")) return CS_ISO8859_14;
+       if (strstr(l, "ro")) return CS_ISO8859_2;   /* or ISO-8859-16 */
+       if (strstr(l, "am") || strstr(l, "vi")) return CS_UTF8;
+       return CS_ISO8859_1;
+    }
+    return CS_ASCII;
+}