t4030: demonstrate behavior of show with textconv

diff --git a/utf8.c b/utf8.c
index a4ee6650ef6c4c487c083aabf0a950b8ec317b09..7f648574a550432e3160fcef178f894faf0bdd54 100644 (file)
--- a/utf8.c
+++ b/utf8.c
@@ -429,6 +429,27 @@ int same_encoding(const char *src, const char *dst)
        return !strcasecmp(src, dst);
 }
 
+/*
+ * Wrapper for fprintf and returns the total number of columns required
+ * for the printed string, assuming that the string is utf8.
+ */
+int utf8_fprintf(FILE *stream, const char *format, ...)
+{
+       struct strbuf buf = STRBUF_INIT;
+       va_list arg;
+       int columns;
+
+       va_start(arg, format);
+       strbuf_vaddf(&buf, format, arg);
+       va_end(arg);
+
+       columns = fputs(buf.buf, stream);
+       if (0 <= columns) /* keep the error from the I/O */
+               columns = utf8_strwidth(buf.buf);
+       strbuf_release(&buf);
+       return columns;
+}
+
 /*
  * Given a buffer and its encoding, return it re-encoded
  * with iconv.  If the conversion fails, returns NULL.
@@ -486,11 +507,66 @@ char *reencode_string(const char *in, const char *out_encoding, const char *in_e
 
        if (!in_encoding)
                return NULL;
+
        conv = iconv_open(out_encoding, in_encoding);
-       if (conv == (iconv_t) -1)
-               return NULL;
+       if (conv == (iconv_t) -1) {
+               /*
+                * Some platforms do not have the variously spelled variants of
+                * UTF-8, so let's fall back to trying the most official
+                * spelling. We do so only as a fallback in case the platform
+                * does understand the user's spelling, but not our official
+                * one.
+                */
+               if (is_encoding_utf8(in_encoding))
+                       in_encoding = "UTF-8";
+               if (is_encoding_utf8(out_encoding))
+                       out_encoding = "UTF-8";
+               conv = iconv_open(out_encoding, in_encoding);
+               if (conv == (iconv_t) -1)
+                       return NULL;
+       }
+
        out = reencode_string_iconv(in, strlen(in), conv);
        iconv_close(conv);
        return out;
 }
 #endif
+
+/*
+ * Returns first character length in bytes for multi-byte `text` according to
+ * `encoding`.
+ *
+ * - The `text` pointer is updated to point at the next character.
+ * - When `remainder_p` is not NULL, on entry `*remainder_p` is how much bytes
+ *   we can consume from text, and on exit `*remainder_p` is reduced by returned
+ *   character length. Otherwise `text` is treated as limited by NUL.
+ */
+int mbs_chrlen(const char **text, size_t *remainder_p, const char *encoding)
+{
+       int chrlen;
+       const char *p = *text;
+       size_t r = (remainder_p ? *remainder_p : SIZE_MAX);
+
+       if (r < 1)
+               return 0;
+
+       if (is_encoding_utf8(encoding)) {
+               pick_one_utf8_char(&p, &r);
+
+               chrlen = p ? (p - *text)
+                          : 1 /* not valid UTF-8 -> raw byte sequence */;
+       }
+       else {
+               /*
+                * TODO use iconv to decode one char and obtain its chrlen
+                * for now, let's treat encodings != UTF-8 as one-byte
+                */
+               chrlen = 1;
+       }
+
+       *text += chrlen;
+       if (remainder_p)
+               *remainder_p -= chrlen;
+
+       return chrlen;
+}