Add utf8conv function to decode/strip prefixes from database strings

Makefile

@@ -1,24 +1,20 @@
-
-MAKE=make
-
-CFLAGS=-g
+CFLAGS=-g -fPIC
 DEFS=-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_REENTRANT -D_THREAD_SAFE -D_GNU_SOURCE
-#WARN=-Wall -Wunused
+WARN=-Wall -Wunused
 
-all: lib
+LIBFILE=xconv.so
 
-lib:
-	gcc ${CFLAGS} ${DEFS} -shared -ldl -lpthread -fPIC xconv.c -o libxconv.so -lxconv
+.PHONY: all clean install
+
+all: $(LIBFILE)
+
+$(LIBFILE): xconv.c
+	@echo "	$<"
+	@$(CC) $(CFLAGS) $(WARN) $(DEFS) -shared -ldl -lpthread -lxconv -o $@ $<
 
 clean:
-	rm -f core *.o *.so
+	rm -f *.so
 
 install: all
-	strip libxconv.so
 	mkdir -p /mod/lib/sql
-	cp libxconv.so /mod/lib/sql/xconv.so
-
-.c.o:
-	@echo "	$<"
-	@$(CC) $(CFLAGS) ${WARN} ${DEFS} ${INCS} -c $< -o $@
-
+	strip $(LIBFILE) -o /mod/lib/sql/$(LIBFILE)

test

@@ -7,7 +7,7 @@ set s "home made p\303at\302e"
 hexdump $s
 
 set db [sqlite3.open ":memory:"]
-$db extension /mod/lib/sql/libqxconv.so
+$db extension /mod/lib/sql/xconv.so
 set ret [$db query {select xconv('%s') as xconv} $s]
 lassign [lindex $ret 0] x t
 

xconv.c

@@ -2,7 +2,6 @@
   * xconv.c -- An SQLite3 C extension that uses libxconv to convert from
   * ISO 6937 to UTF-8.
   */
-#include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sqlite3ext.h>
@@ -22,28 +21,79 @@ sqlite_xconv(sqlite3_context *c, int argc, sqlite3_value **argv)
 		return;
 	}
 
-	dlen = strlen(src) + 20;
+	dlen = strlen(src) * 2 + 14;
 	if (!(dst = (char *)malloc(dlen)))
 	{
 		sqlite3_result_error(c, "malloc() failed", -1);
 		return;
 	}
-	
+
 	if (!xconv(src, dst, dlen))
 	{
 		free(dst);
 		dst = strdup(src);
 	}
+
+	sqlite3_result_text(c, dst, -1, free);
+}
+
+void
+sqlite_utf8conv(sqlite3_context *c, int argc, sqlite3_value **argv)
+{
+	char *src, *dst;
+
+	if (argc != 1 || !(src = (char *)sqlite3_value_text(argv[0])))
+	{
+		sqlite3_result_error(c, "utf8conv requires 1 parameter", -1);
+		return;
+	}
+
+	if (src[0] == 0x10)
+	{
+		if (src[1] == 'i' && src[2] == '7')
+		{
+			size_t dlen;
+
+			src += 3;
+			dlen = strlen(src) * 2 + 14;
+			if (!(dst = (char *)malloc(dlen)))
+			{
+				sqlite3_result_error(c, "malloc() failed", -1);
+				return;
+			}
+
+			if (!xconv(src, dst, dlen))
+			{
+				free(dst);
+				dst = strdup(src);
+			}
+		}
+		else
+			dst = strdup("");
+	}
+	else
+	{
+		if (*src < 0x20)
+			src += *src == 0x1F ? 2 : 1;
+
+		dst = strdup(src);
+	}
+
 	sqlite3_result_text(c, dst, -1, free);
 }
 
 int sqlite3_xconv_init(sqlite3 *db, char **err,
     const sqlite3_api_routines *api)
 {
-	SQLITE_EXTENSION_INIT2(api);
+	int rc1, rc2;
 
-	return sqlite3_create_function(db, "xconv", 1,
+	SQLITE_EXTENSION_INIT2(api);
+	rc1 = sqlite3_create_function(db, "xconv", 1,
 	    SQLITE_UTF8 | SQLITE_DETERMINISTIC, NULL,
 	    sqlite_xconv, NULL, NULL);
+	rc2 = sqlite3_create_function(db, "utf8conv", 1,
+	    SQLITE_UTF8 | SQLITE_DETERMINISTIC, NULL,
+	    sqlite_utf8conv, NULL, NULL);
+	return rc1 != SQLITE_OK && rc2 != SQLITE_OK ? rc1 : SQLITE_OK;
 }