utf8.c: add reencode_string_len() that can handle NULs in string

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/precompose_utf8.c

@@ -78,7 +78,7 @@ void precompose_argv(int argc, const char **argv)
 		size_t namelen;
 		oldarg = argv[i];
 		if (has_non_ascii(oldarg, (size_t)-1, &namelen)) {
-			newarg = reencode_string_iconv(oldarg, namelen, ic_precompose);
+			newarg = reencode_string_iconv(oldarg, namelen, ic_precompose, NULL);
 			if (newarg)
 				argv[i] = newarg;
 		}

utf8.c

@@ -468,7 +468,7 @@ int utf8_fprintf(FILE *stream, const char *format, ...)
 #else
 	typedef char * iconv_ibp;
 #endif
-char *reencode_string_iconv(const char *in, size_t insz, iconv_t conv)
+char *reencode_string_iconv(const char *in, size_t insz, iconv_t conv, int *outsz_p)
 {
 	size_t outsz, outalloc;
 	char *out, *outpos;
@@ -502,13 +502,17 @@ char *reencode_string_iconv(const char *in, size_t insz, iconv_t conv)
 		}
 		else {
 			*outpos = '\0';
+			if (outsz_p)
+				*outsz_p = outpos - out;
 			break;
 		}
 	}
 	return out;
 }
 
-char *reencode_string(const char *in, const char *out_encoding, const char *in_encoding)
+char *reencode_string_len(const char *in, int insz,
+			  const char *out_encoding, const char *in_encoding,
+			  int *outsz)
 {
 	iconv_t conv;
 	char *out;
@@ -534,7 +538,7 @@ char *reencode_string(const char *in, const char *out_encoding, const char *in_e
 			return NULL;
 	}
 
-	out = reencode_string_iconv(in, strlen(in), conv);
+	out = reencode_string_iconv(in, insz, conv, outsz);
 	iconv_close(conv);
 	return out;
 }

utf8.h

@@ -17,12 +17,25 @@ void strbuf_add_wrapped_bytes(struct strbuf *buf, const char *data, int len,
 			     int indent, int indent2, int width);
 
 #ifndef NO_ICONV
-char *reencode_string_iconv(const char *in, size_t insz, iconv_t conv);
-char *reencode_string(const char *in, const char *out_encoding, const char *in_encoding);
+char *reencode_string_iconv(const char *in, size_t insz,
+			    iconv_t conv, int *outsz);
+char *reencode_string_len(const char *in, int insz,
+			  const char *out_encoding,
+			  const char *in_encoding,
+			  int *outsz);
 #else
-#define reencode_string(a,b,c) NULL
+#define reencode_string_len(a,b,c,d,e) NULL
 #endif
 
+static inline char *reencode_string(const char *in,
+				    const char *out_encoding,
+				    const char *in_encoding)
+{
+	return reencode_string_len(in, strlen(in),
+				   out_encoding, in_encoding,
+				   NULL);
+}
+
 int mbs_chrlen(const char **text, size_t *remainder_p, const char *encoding);
 
 #endif