Implement iconv(3) wrapper

Author: tsudoko

Makefile

@@ -3,10 +3,20 @@
 #TARG = iconv.a
 OFILES = iconv.o
 
+# uncomment if you want to use iconv_wrapped
+#OFILES += iconv_wrapped.o
+
 all: $(OFILES)
 iconv.c: _cp932tab.c
 _cp932tab.c: cp932tab.awk CP932.TXT
 	awk -f cp932tab.awk -F'	' CP932.TXT > $@
 
+iconv_wrapped.c: _iconv_wrapped.c
+_iconv_wrapped.c: iconv.c
+	sed -e 's/^#include "iconv.h"//' \
+		-e 's/iconv_t/struct sjconv_state */g' \
+		-e 's/^iconv/sjc_&/' \
+		-e 's/struct sjconv_state/struct sjc_sjconv_state/' $< > $@
+
 clean:
-	rm -f $(TARG) $(OFILES) _cp932tab.c
+	rm -f $(TARG) $(OFILES) _cp932tab.c _iconv_wrapped.c

iconv_wrapped.c

@@ -0,0 +1,78 @@
+#include <stdbool.h>
+
+#include <iconv.h>
+
+#include "_iconv_wrapped.c"
+
+/* iconv_wrapped.c - wrapper around system iconv(3) calls
+ *
+ * Use this if you want to add cp932 support to your existing iconv(3)
+ * implementation.
+ *
+ * To be able to use this, your linker needs to support the --wrap option.
+ * Example usage (gcc):
+ *     gcc someprogramobj1.o someprogramobj2.o iconv_wrapped.o \
+ *          -Wl,--wrap=iconv -Wl,--wrap=iconv_open -Wl,--wrap=iconv_close \
+ *          -o someprogram
+ */
+
+size_t __real_iconv(iconv_t cd, char **restrict inbuf, size_t *restrict inleft, char **restrict outbuf, size_t *restrict outleft);
+iconv_t __real_iconv_open(const char *to, const char *from);
+int __real_iconv_close(iconv_t cd);
+
+struct sjconv_state {
+	union {
+		struct sjc_sjconv_state *sjc;
+		iconv_t real;
+	} cd;
+	bool is_sjconv;
+};
+
+size_t
+__wrap_iconv(struct sjconv_state *s, char **restrict inbuf, size_t *restrict inleft, char **restrict outbuf, size_t *restrict outleft)
+{
+	if(s->is_sjconv)
+		return sjc_iconv(s->cd.sjc, inbuf, inleft, outbuf, outleft);
+	else
+		return __real_iconv(s->cd.real, inbuf, inleft, outbuf, outleft);
+}
+
+iconv_t
+__wrap_iconv_open(const char *to, const char *from)
+{
+
+	struct sjconv_state *s = malloc(sizeof *s);
+	iconv_t cd = __real_iconv_open(to, from);
+	if(cd != (iconv_t)-1) {
+		s->is_sjconv = false;
+		s->cd.real = cd;
+		return s;
+	}
+
+	/* TODO: try converting to utf-8 and then to the target encoding for wider support? */
+	struct sjc_sjconv_state *scd = sjc_iconv_open(to, from);
+	if(scd != (struct sjc_sjconv_state *)-1) {
+		s->is_sjconv = true;
+		s->cd.sjc = scd;
+		return s;
+	}
+
+	free(s);
+	return (iconv_t)-1;
+}
+
+int
+__wrap_iconv_close(struct sjconv_state *s)
+{
+	int ret;
+	if(s->is_sjconv) {
+		if((ret = sjc_iconv_close(s->cd.sjc)) != 0)
+			return ret;
+	} else {
+		if((ret = __real_iconv_close(s->cd.real)) != 0)
+			return ret;
+	}
+
+	free(s);
+	return 0;
+}