Non-portable implementation

git-svn-id: file:///svn/tokudb@239 c7de825b-a66e-492c-adef-691d508d4ae1

buildheader/Makefile

+CFLAGS = -Wall -W -O2 -Werror -g
+make_db_h:
+run: make_db_h
+	./make_db_h

buildheader/make_db_h.c

+/* Make a db.h that will be link-time compatible with Sleepycat's Berkeley DB. */
+
+#include <db.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+
+void print_dbtype(void) {
+    /* DBTYPE is mentioned by db_open.html */
+    printf("typedef enum {\n");
+    printf(" DB_BTREE=%d\n", DB_BTREE);
+    printf("} DBTYPE;\n");
+}
+
+
+DB db_dummy;
+
+#define DECL_LIMIT 100
+#define FIELD_LIMIT 100
+struct fieldinfo {
+    char decl[DECL_LIMIT];
+    unsigned int off;
+    unsigned int size;
+} db_fields[FIELD_LIMIT];
+int db_field_counter=0;
+
+
+int compare_fields (const void *av, const void *bv) {
+    const struct fieldinfo *a = av;
+    const struct fieldinfo *b = bv;
+    if (a->off < b->off) return -1;
+    if (a->off > b->off) return 1;
+    return 0;
+}				      
+
+#define DB_STRUCT_SETUP(name, fstring) ({ snprintf(db_fields[db_field_counter].decl, DECL_LIMIT, fstring, #name); \
+	    db_fields[db_field_counter].off = offsetof(DB, name); \
+	    db_fields[db_field_counter].size = sizeof(db_dummy.name); \
+	    db_field_counter++; })
+
+void print_db_struct (void) {
+    int i;
+    unsigned int current_offset=0;
+    int dummy_counter=0;
+    int did_toku_internal=0;
+    /* Do these in alphabetical order. */
+    DB_STRUCT_SETUP(app_private,    "void *%s");
+    DB_STRUCT_SETUP(close,          "int (*%s) (DB*, u_int32_t)");
+    DB_STRUCT_SETUP(cursor,         "int (*%s) (DB *, DB_TXN *, DBC **, u_int32_t)");
+    DB_STRUCT_SETUP(del,            "int (*%s) (DB *, DB_TXN *, DBT *, u_int32_t)");
+    DB_STRUCT_SETUP(get,            "int (*%s) (DB *, DB_TXN *, DBT *, DBT *, u_int32_t)");
+    DB_STRUCT_SETUP(key_range,      "int (*%s) (DB *, DB_TXN *, DBT *, DB_KEY_RANGE *, u_int32_t)");
+    DB_STRUCT_SETUP(open,           "int (*%s) (DB *, DB_TXN *, const char *, const char *, DBTYPE, u_int32_t, int)");
+    DB_STRUCT_SETUP(put,            "int (*%s) (DB *, DB_TXN *, DBT *, DBT *, u_int32_t)");
+    DB_STRUCT_SETUP(remove,         "int (*%s) (DB *, const char *, const char *, u_int32_t)");
+    DB_STRUCT_SETUP(rename,         "int (*%s) (DB *, const char *, const char *, const char *, u_int32_t)");
+    DB_STRUCT_SETUP(set_bt_compare, "int (*%s) (DB *, int (*)(DB *, const DBT *, const DBT *))");
+    DB_STRUCT_SETUP(set_flags,      "int (*%s) (DB *, u_int32_t)");
+    DB_STRUCT_SETUP(stat,           "int (*%s) (DB *, void *, u_int32_t)");
+    qsort(db_fields, db_field_counter, sizeof(db_fields[0]), compare_fields);
+    printf("struct __toku_db {\n");
+    for (i=0; i<db_field_counter; i++) {
+	unsigned int this_offset = db_fields[i].off;
+	if (!did_toku_internal && this_offset+sizeof(void*)>current_offset) {
+	    printf("  struct __tokudb_internal *i;\n");
+	    current_offset+=sizeof(void*);
+	    did_toku_internal=1;
+	}
+	if (this_offset>current_offset) {
+	    printf("  char dummy%d[%d];\n", dummy_counter++, this_offset-current_offset);
+	    current_offset=this_offset;
+	}
+	if (this_offset<current_offset) {
+	    printf("Whoops\n");
+	}
+	printf("  %s; /* offset=%d size=%d */\n", db_fields[i].decl, db_fields[i].off, db_fields[i].size);
+	current_offset+=db_fields[i].size;
+    }
+    printf("}\n");
+}
+int main (int argc __attribute__((__unused__)), char *argv[] __attribute__((__unused__))) {
+    printf("#ifndef _DB_H\n");
+    printf("#define _DB_H\n");
+    printf("/* This code generated by make_db_h.   Copyright (c) 2007 Tokutek */\n");
+    printf("#if defined(__cplusplus)\nextern \"C\" {\n#endif\n");
+    printf("#if defined(__cplusplus)\n}\n#endif\n");
+    printf("typedef struct __toku_db DB;\n");
+    print_dbtype();
+    print_db_struct();
+    printf("#endif\n");
+    return 0;
+}