MINOR: vars: Delay variable content freeing in var_set function

When calling var_set on a variable of type string (SMP_T_STR, SMP_T_BIN
or SMP_T_METH), the contents of the variable were freed directly. When
adding conditions to set-var calls we might have cases in which the
contents of an existing variable should be kept unchanged so the freeing
of the internal buffers is delayed in the var_set function (so that we
can bypass it later).

diff --git a/src/vars.c b/src/vars.c
index 27fc23d11d6cc633151a5bff95c4057078d60c29..375b31b79ce782bd2f6693fa712d30bb95beff75 100644 (file)
--- a/src/vars.c
+++ b/src/vars.c
@@ -301,6 +301,25 @@ static int smp_fetch_var(const struct arg *args, struct sample *smp, const char
        return vars_get_by_desc(var_desc, smp, def);
 }
 
+/*
+ * Clear the contents of a variable so that it can be reset directly.
+ * This function is used just before a variable is filled out of a sample's
+ * content.
+ */
+static inline void var_clear_buffer(struct sample *smp, struct vars *vars, struct var *var, int var_type)
+{
+       if (var_type == SMP_T_STR || var_type == SMP_T_BIN) {
+               ha_free(&var->data.u.str.area);
+               var_accounting_diff(vars, smp->sess, smp->strm,
+                                   -var->data.u.str.data);
+       }
+       else if (var_type == SMP_T_METH && var->data.u.meth.meth == HTTP_METH_OTHER) {
+               ha_free(&var->data.u.meth.str.area);
+               var_accounting_diff(vars, smp->sess, smp->strm,
+                                   -var->data.u.meth.str.data);
+       }
+}
+
 /* This function tries to create a variable whose name hash is <name_hash> in
  * scope <scope> and store sample <smp> as its value.
  *
@@ -321,6 +340,7 @@ static int var_set(uint64_t name_hash, enum vars_scope scope, struct sample *smp
        struct vars *vars;
        struct var *var;
        int ret = 0;
+       int previous_type = SMP_T_ANY;
 
        vars = get_vars(smp->sess, smp->strm, scope);
        if (!vars || vars->scope != scope)
@@ -336,19 +356,6 @@ static int var_set(uint64_t name_hash, enum vars_scope scope, struct sample *smp
                        ret = 1;
                        goto unlock;
                }
-
-               /* free its used memory. */
-               if (var->data.type == SMP_T_STR ||
-                   var->data.type == SMP_T_BIN) {
-                       ha_free(&var->data.u.str.area);
-                       var_accounting_diff(vars, smp->sess, smp->strm,
-                                           -var->data.u.str.data);
-               }
-               else if (var->data.type == SMP_T_METH && var->data.u.meth.meth == HTTP_METH_OTHER) {
-                       ha_free(&var->data.u.meth.str.area);
-                       var_accounting_diff(vars, smp->sess, smp->strm,
-                                           -var->data.u.meth.str.data);
-               }
        } else {
                if (flags & VF_UPDATEONLY)
                        goto unlock;
@@ -368,22 +375,27 @@ static int var_set(uint64_t name_hash, enum vars_scope scope, struct sample *smp
        }
 
        /* Set type. */
+       previous_type = var->data.type;
        var->data.type = smp->data.type;
 
        /* Copy data. If the data needs memory, the function can fail. */
        switch (var->data.type) {
        case SMP_T_BOOL:
        case SMP_T_SINT:
+               var_clear_buffer(smp, vars, var, previous_type);
                var->data.u.sint = smp->data.u.sint;
                break;
        case SMP_T_IPV4:
+               var_clear_buffer(smp, vars, var, previous_type);
                var->data.u.ipv4 = smp->data.u.ipv4;
                break;
        case SMP_T_IPV6:
+               var_clear_buffer(smp, vars, var, previous_type);
                var->data.u.ipv6 = smp->data.u.ipv6;
                break;
        case SMP_T_STR:
        case SMP_T_BIN:
+               var_clear_buffer(smp, vars, var, previous_type);
                if (!var_accounting_add(vars, smp->sess, smp->strm, smp->data.u.str.data)) {
                        var->data.type = SMP_T_BOOL; /* This type doesn't use additional memory. */
                        goto unlock;
@@ -401,6 +413,7 @@ static int var_set(uint64_t name_hash, enum vars_scope scope, struct sample *smp
                       var->data.u.str.data);
                break;
        case SMP_T_METH:
+               var_clear_buffer(smp, vars, var, previous_type);
                var->data.u.meth.meth = smp->data.u.meth.meth;
                if (smp->data.u.meth.meth != HTTP_METH_OTHER)
                        break;