Filters: generate backward compatible "get field" and "get context" instructions

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c b/src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c
index 34183ed2edf4f79a46ff5624f4ce4e60a593fdfc..d548da749e88ff2279b16b77673d290d4de7c16f 100644 (file)
--- a/src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c
+++ b/src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c
@@ -157,12 +157,158 @@ int visit_node_root(struct filter_parser_ctx *ctx, struct ir_op *node)
        return bytecode_push(&ctx->bytecode, &insn, 1, sizeof(insn));
 }
 
+static
+int append_str(char **s, const char *append)
+{
+       char *old = *s;
+       char *new;
+       size_t oldlen = (old == NULL) ? 0 : strlen(old);
+       size_t appendlen = strlen(append);
+
+       new = calloc(oldlen + appendlen + 1, 1);
+       if (!new) {
+               return -ENOMEM;
+       }
+       if (oldlen) {
+               strcpy(new, old);
+       }
+       strcat(new, append);
+       *s = new;
+       free(old);
+       return 0;
+}
+
+/*
+ * 1: match
+ * 0: no match
+ * < 0: error
+ */
+static
+int load_expression_legacy_match(const struct ir_load_expression *exp,
+               enum filter_op *op_type,
+               char **symbol)
+{
+       const struct ir_load_expression_op *op;
+       bool need_dot = false;
+
+       op = exp->child;
+       switch (op->type) {
+       case IR_LOAD_EXPRESSION_GET_CONTEXT_ROOT:
+               *op_type = FILTER_OP_GET_CONTEXT_REF;
+               if (append_str(symbol, "$ctx.")) {
+                       return -ENOMEM;
+               }
+               need_dot = false;
+               break;
+       case IR_LOAD_EXPRESSION_GET_APP_CONTEXT_ROOT:
+               *op_type = FILTER_OP_GET_CONTEXT_REF;
+               if (append_str(symbol, "$app.")) {
+                       return -ENOMEM;
+               }
+               need_dot = false;
+               break;
+       case IR_LOAD_EXPRESSION_GET_PAYLOAD_ROOT:
+               *op_type = FILTER_OP_LOAD_FIELD_REF;
+               need_dot = false;
+               break;
+
+       case IR_LOAD_EXPRESSION_GET_SYMBOL:
+       case IR_LOAD_EXPRESSION_GET_INDEX:
+       case IR_LOAD_EXPRESSION_LOAD_FIELD:
+       default:
+               return 0;       /* no match */
+       }
+
+       for (;;) {
+               op = op->next;
+               if (!op) {
+                       return 0;       /* no match */
+               }
+               switch (op->type) {
+               case IR_LOAD_EXPRESSION_LOAD_FIELD:
+                       goto end;
+               case IR_LOAD_EXPRESSION_GET_SYMBOL:
+                       if (need_dot && append_str(symbol, ".")) {
+                               return -ENOMEM;
+                       }
+                       if (append_str(symbol, op->u.symbol)) {
+                               return -ENOMEM;
+                       }
+                       break;
+               default:
+                       return 0;        /* no match */
+               }
+               need_dot = true;
+       }
+end:
+       return 1;       /* Legacy match */
+}
+
+/*
+ * 1: legacy match
+ * 0: no legacy match
+ * < 0: error
+ */
+static
+int visit_node_load_expression_legacy(struct filter_parser_ctx *ctx,
+               const struct ir_load_expression *exp,
+               const struct ir_load_expression_op *op)
+{
+       struct load_op *insn = NULL;
+       uint32_t insn_len = sizeof(struct load_op)
+               + sizeof(struct field_ref);
+       struct field_ref ref_offset;
+       uint32_t reloc_offset_u32;
+       uint16_t reloc_offset;
+       enum filter_op op_type;
+       char *symbol = NULL;
+       int ret;
+
+       ret = load_expression_legacy_match(exp, &op_type, &symbol);
+       if (ret <= 0) {
+               goto end;
+       }
+       insn = calloc(insn_len, 1);
+       if (!insn) {
+               ret = -ENOMEM;
+               goto end;
+       }
+       insn->op = op_type;
+       ref_offset.offset = (uint16_t) -1U;
+       memcpy(insn->data, &ref_offset, sizeof(ref_offset));
+       /* reloc_offset points to struct load_op */
+       reloc_offset_u32 = bytecode_get_len(&ctx->bytecode->b);
+       if (reloc_offset_u32 > LTTNG_FILTER_MAX_LEN - 1) {
+               ret = -EINVAL;
+               goto end;
+       }
+       reloc_offset = (uint16_t) reloc_offset_u32;
+       ret = bytecode_push(&ctx->bytecode, insn, 1, insn_len);
+       if (ret) {
+               goto end;
+       }
+       /* append reloc */
+       ret = bytecode_push(&ctx->bytecode_reloc, &reloc_offset,
+                               1, sizeof(reloc_offset));
+       if (ret) {
+               goto end;
+       }
+       ret = bytecode_push(&ctx->bytecode_reloc, symbol,
+                               1, strlen(symbol) + 1);
+       ret = 1;        /* legacy */
+end:
+       free(insn);
+       free(symbol);
+       return ret;
+}
+
 static
 int visit_node_load_expression(struct filter_parser_ctx *ctx,
                const struct ir_op *node)
 {
        struct ir_load_expression *exp;
        struct ir_load_expression_op *op;
+       int ret;
 
        exp = node->u.load.u.expression;
        if (!exp) {
@@ -172,6 +318,15 @@ int visit_node_load_expression(struct filter_parser_ctx *ctx,
        if (!op) {
                return -EINVAL;
        }
+
+       ret = visit_node_load_expression_legacy(ctx, exp, op);
+       if (ret < 0) {
+               return ret;
+       }
+       if (ret > 0) {
+               return 0;       /* legacy */
+       }
+
        for (; op != NULL; op = op->next) {
                switch (op->type) {
                case IR_LOAD_EXPRESSION_GET_CONTEXT_ROOT: