13 files changed, 241 insertions, 147 deletions

diff --git a/src/mds-kbdc/builtin-functions.c b/src/mds-kbdc/builtin-functions.c
index fca6496..4ccc31f 100644
--- a/src/mds-kbdc/builtin-functions.c
+++ b/src/mds-kbdc/builtin-functions.c
@@ -19,6 +19,8 @@
 
 #include "variables.h"
 
+#include <libmdsserver/macros.h>
+
 #include <stdlib.h>
 #include <string.h>
 
@@ -34,8 +36,7 @@
   size_t bn = string_length(b);					\
   size_t i, n = an > bn ? an : bn;				\
   char32_t* restrict rc = malloc((n + 1) * sizeof(char32_t));	\
-  if (rc == NULL)						\
-    return NULL;						\
+  fail_if (rc == NULL);						\
   rc[n] = -1
 
 /**
@@ -45,10 +46,19 @@
   const char32_t* restrict a = *args++;				\
   size_t i, n = string_length(a);				\
   char32_t* restrict rc = malloc((n + 1) * sizeof(char32_t));	\
-  if (rc == NULL)						\
-    return NULL;						\
+  fail_if (rc == NULL);						\
   rc[n] = -1
 
+/**
+ * Return a value, or if there was a failure somewhere, return `NULL`
+ * 
+ * @param  v:void*  The value to return on success
+ */
+#define return(v)				\
+  return v;					\
+ fail:						\
+  return NULL;
+
 
 /**
  * Definition of the built-in function add/2
@@ -61,7 +71,7 @@ static char32_t* builtin_function_add_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] + b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -76,7 +86,7 @@ static char32_t* builtin_function_sub_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] - b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -91,7 +101,7 @@ static char32_t* builtin_function_mul_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] * b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -106,7 +116,7 @@ static char32_t* builtin_function_div_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] / b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -121,7 +131,7 @@ static char32_t* builtin_function_mod_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] % b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -136,7 +146,7 @@ static char32_t* builtin_function_rsh_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] << b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -151,7 +161,7 @@ static char32_t* builtin_function_lsh_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] >> b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -166,7 +176,7 @@ static char32_t* builtin_function_or_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] | b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -181,7 +191,7 @@ static char32_t* builtin_function_and_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] & b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -196,7 +206,7 @@ static char32_t* builtin_function_xor_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] ^ b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -211,7 +221,7 @@ static char32_t* builtin_function_not_1(const char32_t** restrict args)
   define_1;
   for (i = 0; i < n; i++)
     rc[i] = !a[i];
-  return rc;
+  return(rc);
 }
 
 
@@ -226,7 +236,7 @@ static char32_t* builtin_function_equals_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] == b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -241,7 +251,7 @@ static char32_t* builtin_function_greater_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] > b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -256,7 +266,7 @@ static char32_t* builtin_function_less_2(const char32_t** restrict args)
   define_2;
   for (i = 0; i < n; i++)
     rc[i] = a[i % an] < b[i % bn];
-  return rc;
+  return(rc);
 }
 
 
@@ -270,11 +280,13 @@ static char32_t* builtin_function_get_2(const char32_t** restrict args)
 {
   const char32_t* restrict a = *args++;
   const char32_t* restrict b = *args++;
+  char32_t* restrict rc;
   size_t n = (size_t)*b;
   mds_kbdc_tree_t* value = variables_get((size_t)*a);
   while (n--)
     value = value->next;
-  return string_dup(value->compiled_string.string);
+  fail_if (rc = string_dup(value->compiled_string.string), rc == NULL);
+  return(rc);
 }
 
 
@@ -289,20 +301,22 @@ static char32_t* builtin_function_set_3(const char32_t** restrict args)
   const char32_t* restrict a = *args++;
   const char32_t* restrict b = *args++;
   const char32_t* restrict c = *args++;
+  char32_t* restrict rc;
   size_t n = (size_t)*b;
   mds_kbdc_tree_t* value = variables_get((size_t)*a);
   while (n--)
     value = value->next;
   free(value->compiled_string.string);
   value->compiled_string.string = string_dup(c);
-  if (value->compiled_string.string == NULL)
-    return NULL;
-  return string_dup(c);
+  fail_if (value->compiled_string.string == NULL);
+  fail_if (rc = string_dup(c), rc == NULL);
+  return(rc);
 }
 
 
 #undef define_1
 #undef define_2
+#undef return
 
 
 /**
@@ -350,32 +364,33 @@ int builtin_function_defined(const char* restrict name, size_t arg_count)
  */
 char32_t* builtin_function_invoke(const char* restrict name, size_t arg_count, const char32_t** restrict args)
 {
-  if (arg_count == 3)
-    if (!strcmp(name, "set"))
-      return builtin_function_set_3(args);
+#define t(f)  do { fail_if (rc = builtin_function_##f(args), rc == NULL); return rc; } while (0)
+  char32_t* rc;
   
-  if (arg_count == 1)
-    if (!strcmp(name, "not"))
-      return builtin_function_not_1(args);
+  if ((arg_count == 3) && !strcmp(name, "set"))  t (set_3);
+  if ((arg_count == 1) && !strcmp(name, "not"))  t (not_1);
   
   if (arg_count != 2)
     abort();
   
-  if (!strcmp(name, "add"))      return builtin_function_add_2(args);
-  if (!strcmp(name, "sub"))      return builtin_function_sub_2(args);
-  if (!strcmp(name, "mul"))      return builtin_function_mul_2(args);
-  if (!strcmp(name, "div"))      return builtin_function_div_2(args);
-  if (!strcmp(name, "mod"))      return builtin_function_mod_2(args);
-  if (!strcmp(name, "rsh"))      return builtin_function_rsh_2(args);
-  if (!strcmp(name, "lsh"))      return builtin_function_lsh_2(args);
-  if (!strcmp(name, "or"))       return builtin_function_or_2(args);
-  if (!strcmp(name, "and"))      return builtin_function_and_2(args);
-  if (!strcmp(name, "xor"))      return builtin_function_xor_2(args);
-  if (!strcmp(name, "equals"))   return builtin_function_equals_2(args);
-  if (!strcmp(name, "greater"))  return builtin_function_greater_2(args);
-  if (!strcmp(name, "less"))     return builtin_function_less_2(args);
-  if (!strcmp(name, "get"))      return builtin_function_get_2(args);
+  if (!strcmp(name, "add"))      t (add_2);
+  if (!strcmp(name, "sub"))      t (sub_2);
+  if (!strcmp(name, "mul"))      t (mul_2);
+  if (!strcmp(name, "div"))      t (div_2);
+  if (!strcmp(name, "mod"))      t (mod_2);
+  if (!strcmp(name, "rsh"))      t (rsh_2);
+  if (!strcmp(name, "lsh"))      t (lsh_2);
+  if (!strcmp(name, "or"))       t (or_2);
+  if (!strcmp(name, "and"))      t (and_2);
+  if (!strcmp(name, "xor"))      t (xor_2);
+  if (!strcmp(name, "equals"))   t (equals_2);
+  if (!strcmp(name, "greater"))  t (greater_2);
+  if (!strcmp(name, "less"))     t (less_2);
+  if (!strcmp(name, "get"))      t (get_2);
   
   abort();
+ fail:
+  return NULL;
+#undef t
 }
 
diff --git a/src/mds-kbdc/compile-layout.c b/src/mds-kbdc/compile-layout.c
index ccf647c..539ade3 100644
--- a/src/mds-kbdc/compile-layout.c
+++ b/src/mds-kbdc/compile-layout.c
@@ -604,6 +604,8 @@ static int check_function_calls_in_literal(const mds_kbdc_tree_t* restrict tree,
 {
   int rc = 0;
   (void) check_function_calls_in_literal_(tree, raw, lineoff, &raw, &rc);
+  fail_if (rc < 0);
+ fail:
   return rc;
 }
 
@@ -669,7 +671,10 @@ static char32_t* parse_escape(mds_kbdc_tree_t* restrict tree, const char* restri
   /* Read escape. */
   if (*escape == 100)
     /* Function call. */
-    return parse_function_call(tree, raw_, lineoff, escape, end);
+    {
+      fail_if (rc = parse_function_call(tree, raw_, lineoff, escape, end), rc == NULL);
+      return rc;
+    }
   /* Octal or hexadecimal representation, or variable dereference. */
   for (; (c = *raw); have = 1, raw++)
     if      (CR( 8, '0', '7'))  numbuf =  8 * numbuf + (c & 15);
@@ -909,7 +914,11 @@ static char32_t* parse_string(mds_kbdc_tree_t* restrict tree, const char* restri
 {
   mds_kbdc_tree_t* old_last_value_statement = last_value_statement;
   char32_t* rc = (strchr("\"\\", *raw) ? parse_quoted_string : parse_unquoted_string)(tree, raw, lineoff);
-  return last_value_statement = old_last_value_statement, rc;
+  last_value_statement = old_last_value_statement;
+  fail_if (rc == NULL);
+  return rc;
+ fail:
+  return NULL;
 }
 
 
@@ -1077,7 +1086,7 @@ static size_t parse_variable(mds_kbdc_tree_t* restrict tree, const char* restric
   memcpy(dotless, raw_, n * sizeof(char)), dotless[n] = '\0';
   var = (size_t)atoll(dotless + 1);
   if (strlen(dotless + 1) != (size_t)snprintf(NULL, 0, "%zu", var))
-    return errno = ERANGE, (size_t)0;
+    fail_if ((errno = ERANGE));
   return var;
  fail:
   return 0;
@@ -1172,7 +1181,10 @@ static int parse_function_argument(mds_kbdc_tree_t* restrict tree, const char* r
 static int set_macro(mds_kbdc_tree_macro_t* restrict macro,
 		     mds_kbdc_include_stack_t* macro_include_stack)
 {
-  return callables_set(macro->name, 0, (mds_kbdc_tree_t*)macro, macro_include_stack);
+  fail_if (callables_set(macro->name, 0, (mds_kbdc_tree_t*)macro, macro_include_stack));
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -1246,7 +1258,10 @@ static int set_function(mds_kbdc_tree_function_t* restrict function,
   
   *suffix_start = '\0';
   r = callables_set(suffixless, arg_count, (mds_kbdc_tree_t*)function, function_include_stack);
-  return *suffix_start = '/', r;
+  fail_if (*suffix_start = '/', r);
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -1304,8 +1319,7 @@ static int compile_include(mds_kbdc_tree_include_t* restrict tree)
 {
   void* data;
   int r;
-  if (mds_kbdc_include_stack_push(tree, &data))
-    return -1;
+  fail_if (mds_kbdc_include_stack_push(tree, &data));
   r = compile_subtree(tree->inner);
   mds_kbdc_include_stack_pop(data);
   
@@ -1314,7 +1328,10 @@ static int compile_include(mds_kbdc_tree_include_t* restrict tree)
    * include-stack as its overriding statement. */
   last_value_statement = NULL;
   
-  return r;
+  fail_if (r);
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -1650,7 +1667,7 @@ static int compile_have_range(mds_kbdc_tree_assumption_have_range_t* restrict tr
  */
 static int check_marco_calls(mds_kbdc_tree_t* restrict tree)
 {
-#define t(...)   if (rc |= r = (__VA_ARGS__), r < 0)  return r
+#define t(...)   fail_if (rc |= r = (__VA_ARGS__), r < 0)
   mds_kbdc_tree_macro_t* _macro;
   mds_kbdc_include_stack_t* _macro_include_stack;
   void* data;
@@ -1685,6 +1702,8 @@ static int check_marco_calls(mds_kbdc_tree_t* restrict tree)
   
   tree = tree->next;
   goto again;
+ fail:
+  return -1;
   (void) _macro;
   (void) _macro_include_stack;
 #undef t
@@ -1699,7 +1718,7 @@ static int check_marco_calls(mds_kbdc_tree_t* restrict tree)
  */
 static int check_function_calls_in_for(const mds_kbdc_tree_for_t* restrict tree)
 {
-#define t(...)  if (rc |= r = check_function_calls_in_literal(__VA_ARGS__), r < 0)  return r
+#define t(...)  fail_if (rc |= r = check_function_calls_in_literal(__VA_ARGS__), r < 0)
   size_t lineoff_first;
   size_t lineoff_last;
   char* restrict code = result->source_code->real_lines[tree->loc_line];
@@ -1713,6 +1732,8 @@ static int check_function_calls_in_for(const mds_kbdc_tree_for_t* restrict tree)
   t ((const mds_kbdc_tree_t*)tree, tree->last, lineoff_last);
   
   return rc;
+ fail:
+  return -1;
 #undef t
 }
 
@@ -1727,9 +1748,13 @@ static int check_function_calls_in_if(const mds_kbdc_tree_if_t* restrict tree)
 {
   size_t lineoff;
   char* restrict code = result->source_code->real_lines[tree->loc_line];
+  int r;
   
   for (lineoff = tree->loc_end; code[lineoff] == ' '; lineoff++);
-  return check_function_calls_in_literal((const mds_kbdc_tree_t*)tree, tree->condition, lineoff);
+  r = check_function_calls_in_literal((const mds_kbdc_tree_t*)tree, tree->condition, lineoff);
+  fail_if (r < 0);
+ fail:
+  return r;
 }
 
 
@@ -1741,7 +1766,11 @@ static int check_function_calls_in_if(const mds_kbdc_tree_if_t* restrict tree)
  */
 static int check_function_calls_in_keys(const mds_kbdc_tree_keys_t* restrict tree)
 {
-  return check_function_calls_in_literal((const mds_kbdc_tree_t*)tree, tree->keys, tree->loc_start);
+  int r;
+  r = check_function_calls_in_literal((const mds_kbdc_tree_t*)tree, tree->keys, tree->loc_start);
+  fail_if (r < 0);
+ fail:
+  return r;
 }
 
 
@@ -1753,7 +1782,11 @@ static int check_function_calls_in_keys(const mds_kbdc_tree_keys_t* restrict tre
  */
 static int check_function_calls_in_string(const mds_kbdc_tree_string_t* restrict tree)
 {
-  return check_function_calls_in_literal((const mds_kbdc_tree_t*)tree, tree->string, tree->loc_start);
+  int r;
+  r = check_function_calls_in_literal((const mds_kbdc_tree_t*)tree, tree->string, tree->loc_start);
+  fail_if (r < 0);
+ fail:
+  return r;
 }
 
 
@@ -1765,7 +1798,7 @@ static int check_function_calls_in_string(const mds_kbdc_tree_string_t* restrict
  */
 static int check_function_calls(const mds_kbdc_tree_t* restrict tree)
 {
-#define t(...)   if (rc |= r = (__VA_ARGS__), r < 0)  return r
+#define t(...)   fail_if (rc |= r = (__VA_ARGS__), r < 0)
   void* data;
   int r, rc = 0;
  again:
@@ -1801,6 +1834,8 @@ static int check_function_calls(const mds_kbdc_tree_t* restrict tree)
   
   tree = tree->next;
   goto again;
+ fail:
+  return -1;
 #undef t
 }
 
@@ -2103,12 +2138,13 @@ static int compile_if(mds_kbdc_tree_if_t* restrict tree)
   /* Evaluate whether the evaluted value is true. */
   for (ok = 1, i = 0; data[i] >= 0; i++)
     ok &= !!(data[i]);
-  free(data);
+  free(data), data = NULL;;
   
   /* Compile the appropriate clause. */
   ok = compile_subtree(ok ? tree->inner : tree->otherwise);
   last_value_statement = NULL;
-  return ok;
+  fail_if (ok < 0);
+  return 0;
   FAIL_BEGIN;
   free(data);
   FAIL_END;
@@ -2200,7 +2236,10 @@ static int evaluate_element(mds_kbdc_tree_t* restrict node)
  */
 static int compile_keys(mds_kbdc_tree_keys_t* restrict tree)
 {
-  return evaluate_element((mds_kbdc_tree_t*)tree) < 0 ? -1 : 0;
+  fail_if (evaluate_element((mds_kbdc_tree_t*)tree));
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -2212,7 +2251,10 @@ static int compile_keys(mds_kbdc_tree_keys_t* restrict tree)
  */
 static int compile_string(mds_kbdc_tree_string_t* restrict tree)
 {
-  return evaluate_element((mds_kbdc_tree_t*)tree) < 0 ? -1 : 0;
+  fail_if (evaluate_element((mds_kbdc_tree_t*)tree));
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -2225,11 +2267,12 @@ static int compile_string(mds_kbdc_tree_string_t* restrict tree)
 static int compile_array(mds_kbdc_tree_array_t* restrict tree)
 {
   int r = evaluate_element(tree->elements);
-  if (r < 0)
-    return -1;
+  fail_if (r < 0);
   if (r)
     tree->processed = PROCESS_LEVEL;
   return 0;
+ fail:
+  return -1;
 }
 
 
@@ -2261,7 +2304,7 @@ static int check_nonnul(mds_kbdc_tree_t* restrict tree)
   tree = tree->next;
   goto again;
  fail:
-   return -1;
+  return -1;
 }
 
 
@@ -2533,7 +2576,10 @@ int compile_layout(mds_kbdc_parsed_t* restrict result_)
   variables_terminate();
   callables_terminate();
   errno = saved_errno;
-  return r;
+  fail_if (r);
+  return 0;
+ fail:
+  return -1;
 }
 
 
diff --git a/src/mds-kbdc/eliminate-dead-code.c b/src/mds-kbdc/eliminate-dead-code.c
index 4916fa4..5628a91 100644
--- a/src/mds-kbdc/eliminate-dead-code.c
+++ b/src/mds-kbdc/eliminate-dead-code.c
@@ -82,11 +82,13 @@ static int eliminate_include(mds_kbdc_tree_include_t* restrict tree)
 {
   void* data;
   int r;
-  if (mds_kbdc_include_stack_push(tree, &data))
-    return -1;
+  fail_if (mds_kbdc_include_stack_push(tree, &data));
   r = eliminate_subtree(tree->inner);
   mds_kbdc_include_stack_pop(data);
-  return r;
+  fail_if (r);
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -118,9 +120,8 @@ static int eliminate_if(mds_kbdc_tree_if_t* restrict tree)
  */
 static int eliminate_subtree(mds_kbdc_tree_t* restrict tree)
 {
-#define e(type)  if ((r = eliminate_##type(&(tree->type))))     return r
-#define E(type)  if ((r = eliminate_##type(&(tree->type##_))))  return r
-  int r;
+#define e(type)  fail_if (eliminate_##type(&(tree->type)))
+#define E(type)  fail_if (eliminate_##type(&(tree->type##_)))
  again:
   if (tree == NULL)
     return 0;
@@ -134,8 +135,7 @@ static int eliminate_subtree(mds_kbdc_tree_t* restrict tree)
     case C(MACRO):
     case C(ASSUMPTION):
     case C(FOR):
-      if ((r = eliminate_subtree(tree->information.inner)))
-	return r;
+      fail_if (eliminate_subtree(tree->information.inner));
       if ((tree->type == C(FUNCTION)) || (tree->type == C(MACRO)))  elimination_level = 0;
       else if ((tree->type == C(FOR)) && (elimination_level == 1))  elimination_level = 0;
       break;
@@ -174,7 +174,11 @@ int eliminate_dead_code(mds_kbdc_parsed_t* restrict result_)
   int r;
   mds_kbdc_include_stack_begin(result = result_);
   r = eliminate_subtree(result_->tree);
-  return mds_kbdc_include_stack_end(), r;
+  mds_kbdc_include_stack_end();
+  fail_if (r);
+  return 0;
+ fail:
+  return -1;
 }
 
 
diff --git a/src/mds-kbdc/include-stack.c b/src/mds-kbdc/include-stack.c
index bec1425..d8c4547 100644
--- a/src/mds-kbdc/include-stack.c
+++ b/src/mds-kbdc/include-stack.c
@@ -190,9 +190,7 @@ mds_kbdc_include_stack_t* mds_kbdc_include_stack_save(void)
       return latest_save;
     }
   
-  latest_save = malloc(sizeof(mds_kbdc_include_stack_t));
-  if (latest_save == NULL)
-    return NULL;
+  fail_if (xmalloc(latest_save, 1, mds_kbdc_include_stack_t));
   
   latest_save->stack = NULL;
   latest_save->ptr = includes_ptr;
@@ -207,8 +205,8 @@ mds_kbdc_include_stack_t* mds_kbdc_include_stack_save(void)
   return latest_save;
  fail:
   saved_errno = errno;
-  free(latest_save->stack);
-  latest_save = NULL;
+  if (latest_save)
+    free(latest_save->stack), latest_save = NULL;
   errno = saved_errno;
   return NULL;
 }
@@ -229,8 +227,7 @@ int mds_kbdc_include_stack_restore(mds_kbdc_include_stack_t* restrict stack)
   if (stack->ptr > includes_size)
     {
       new = realloc(includes, stack->ptr * sizeof(const mds_kbdc_tree_include_t*));
-      if (new == NULL)
-	return -1;
+      fail_if (new == NULL);
       includes = new;
       includes_size = stack->ptr;
     }
@@ -238,6 +235,8 @@ int mds_kbdc_include_stack_restore(mds_kbdc_include_stack_t* restrict stack)
   memcpy(includes, stack->stack, stack->ptr * sizeof(const mds_kbdc_tree_include_t*));
   includes_ptr = stack->ptr;
   return 0;
+ fail:
+  return -1;
 }
 
 
diff --git a/src/mds-kbdc/make-tree.c b/src/mds-kbdc/make-tree.c
index 8a7bb1e..77155b2 100644
--- a/src/mds-kbdc/make-tree.c
+++ b/src/mds-kbdc/make-tree.c
@@ -425,7 +425,7 @@ static int too_few;
  * Get the pathname name of the parsed file
  * 
  * @param   filename  The filename of the parsed file
- * @return            The value the caller should return, or 1 if the caller should not return
+ * @return            The value the caller should return, or 1 if the caller should not return, -1 on error
  */
 static int get_pathname(const char* restrict filename)
 {
@@ -769,9 +769,10 @@ static int have_more_parameters(void)
  */
 static int test_for_keyword(const char* restrict keyword)
 {
-  int r, ok;
-  if (r = have_more_parameters(), r <= 0)
-    return r;
+  int ok, r = have_more_parameters();
+  fail_if (r < 0);
+  if (r == 0)
+    return 0;
   
   ok = (strstr(line, keyword) == line);
   line += strlen(keyword);
@@ -807,8 +808,10 @@ static int keys(mds_kbdc_tree_t** restrict var)
   char* arg_end;
   char* call_end;
   int r, escape = 0, quote = 0, triangle;
-  if (r = have_more_parameters(), r <= 0)
-    return r;
+  r = have_more_parameters();
+  fail_if (r < 0);
+  if (r == 0)
+    return 0;
   
   arg_end = line;
   call_end = arg_end;
@@ -863,8 +866,10 @@ static int pure_keys(char** restrict var)
   char* arg_end;
   char* call_end;
   int r, escape = 0, quote = 0, triangle;
-  if (r = have_more_parameters(), r <= 0)
-    return r;
+  r = have_more_parameters();
+  fail_if (r < 0);
+  if (r == 0)
+    return 0;
   
   arg_end = line;
   call_end = arg_end;
@@ -1408,8 +1413,10 @@ int parse_to_tree(const char* restrict filename, mds_kbdc_parsed_t* restrict res
   fail_if (xmalloc(result->source_code, 1, mds_kbdc_source_code_t));
   mds_kbdc_source_code_initialise(result->source_code);
   
-  if (r = get_pathname(filename), r <= 0)
-    return r;
+  r = get_pathname(filename);
+  fail_if (r < 0);
+  if (r == 0)
+    return 0;
   
   fail_if (read_source_code());
   fail_if (allocate_stacks());
diff --git a/src/mds-kbdc/paths.c b/src/mds-kbdc/paths.c
index a14681e..e294020 100644
--- a/src/mds-kbdc/paths.c
+++ b/src/mds-kbdc/paths.c
@@ -73,7 +73,10 @@ char* abspath(const char* path)
   size_t size, p;
   
   if (*path == '/')
-    return strdup(path);
+    {
+      fail_if (buf = strdup(path), buf == NULL);
+      return buf;
+    }
   
   fail_if (cwd = curpath(), cwd == NULL);
   size = (p = strlen(cwd)) + strlen(path) + 2;
diff --git a/src/mds-kbdc/process-includes.c b/src/mds-kbdc/process-includes.c
index 57e0502..2faaf3f 100644
--- a/src/mds-kbdc/process-includes.c
+++ b/src/mds-kbdc/process-includes.c
@@ -242,8 +242,7 @@ static int process_include(mds_kbdc_tree_include_t* restrict tree)
  */
 static int process_includes_in_tree(mds_kbdc_tree_t* restrict tree)
 {
-#define p(expr)  if ((r = process_includes_in_tree(tree->expr)))  return r
-  int r;
+#define p(expr)  fail_if (process_includes_in_tree(tree->expr))
  again:
   if (tree == NULL)
     return 0;
@@ -257,8 +256,7 @@ static int process_includes_in_tree(mds_kbdc_tree_t* restrict tree)
     case C(FOR):          p (for_.inner);         break;
     case C(IF):           p (if_.inner);          p (if_.otherwise);  break;
     case C(INCLUDE):
-      if ((r = process_include(&(tree->include))))
-	return r;
+      fail_if (process_include(&(tree->include)));
       break;
     default:
       break;
@@ -266,6 +264,8 @@ static int process_includes_in_tree(mds_kbdc_tree_t* restrict tree)
   
   tree = tree->next;
   goto again;
+ fail:
+  return -1;
 #undef p
 }
 
@@ -290,7 +290,7 @@ int process_includes(mds_kbdc_parsed_t* restrict result_)
     {
       struct stat* old;
       if (xxrealloc(old, included, included_size += 4, struct stat))
-	return included = old, -1;
+	fail_if (included = old, 1);
     }
   
   for (i = 0; i < included_ptr; i++)
diff --git a/src/mds-kbdc/raw-data.c b/src/mds-kbdc/raw-data.c
index 359abe8..83e8b48 100644
--- a/src/mds-kbdc/raw-data.c
+++ b/src/mds-kbdc/raw-data.c
@@ -456,14 +456,15 @@ static char* encode_utf8(char* buffer, char32_t character)
   text[0] = character;
   text[1] = -1;
   
-  if (str_ = str = string_encode(text), str == NULL)
-    return NULL;
+  fail_if (str_ = str = string_encode(text), str == NULL);
   
   while (*str)
     *buffer++ = *str++;
   
   free(str_);
   return buffer;
+ fail:
+  return NULL;
 }
 
 
@@ -489,8 +490,7 @@ char* parse_raw_string(const char* restrict string)
    * is not code point whose UTF-8 encoding is longer than its
    * hexadecimal representation. */
   p = rc = malloc(strlen(string) * sizeof(char));
-  if (rc == NULL)
-    return NULL;
+  fail_if (rc == NULL);
   
   while ((c = *string++))
     if      (r(escape ==  8, '0', '7'))  buf = (buf << 3) | (c & 15);
diff --git a/src/mds-kbdc/simplify-tree.c b/src/mds-kbdc/simplify-tree.c
index c46649e..d24569d 100644
--- a/src/mds-kbdc/simplify-tree.c
+++ b/src/mds-kbdc/simplify-tree.c
@@ -161,6 +161,7 @@ static int eliminate_alternation(mds_kbdc_tree_t* tree, mds_kbdc_tree_t* argumen
   mds_kbdc_tree_t* next_alternative;
   mds_kbdc_tree_t* new_argument;
   size_t i;
+  int saved_errno;
   
   /* Detach next statement, we do not want to duplicate all following statements. */
   next_statement = tree->next, tree->next = NULL;
@@ -171,13 +172,7 @@ static int eliminate_alternation(mds_kbdc_tree_t* tree, mds_kbdc_tree_t* argumen
   for (first = last = NULL; alternative; alternative = next_alternative)
     {
       /* Duplicate statement. */
-      if (new_tree = mds_kbdc_tree_dup(tree), new_tree == NULL)
-	{
-	  int saved_errno = errno;
-	  argument->alternation.inner = alternative;
-	  tree->next = next_statement;
-	  return errno = saved_errno, -1;
-	}
+      fail_if (new_tree = mds_kbdc_tree_dup(tree), new_tree == NULL);
       /* Join trees. */
       if (last)
 	last->next = new_tree;
@@ -204,6 +199,11 @@ static int eliminate_alternation(mds_kbdc_tree_t* tree, mds_kbdc_tree_t* argumen
   /* Reattach the statement that followed to the last generated statement. */
   last->next = next_statement;
   return 0;
+ fail:
+  saved_errno = errno;
+  argument->alternation.inner = alternative;
+  tree->next = next_statement;
+  return errno = saved_errno, -1;
 }
 
 
@@ -567,7 +567,8 @@ static int simplify_alternation(mds_kbdc_tree_alternation_t* restrict tree)
       NEW_ERROR(tree, WARNING, "singleton alternation");
       memcpy(tree, temp, sizeof(mds_kbdc_tree_t));
       free(temp);
-      return simplify((mds_kbdc_tree_t*)tree);
+      fail_if (simplify((mds_kbdc_tree_t*)tree));
+      return 0;
     }
   
   /* Simplify. */
@@ -625,11 +626,10 @@ static mds_kbdc_tree_t* create_permutations(mds_kbdc_tree_t* elements)
   mds_kbdc_tree_t* subperms = NULL;
   mds_kbdc_tree_t* perm;
   mds_kbdc_tree_t ordered;
-  int saved_errno, no_perms;
+  int saved_errno, no_perms, stage = 0;
   
   /* Error case. */
-  if (elements == NULL)
-    return NULL;
+  fail_if (elements == NULL);
   
   /* Base case. */
   if (elements->next == NULL)
@@ -639,6 +639,7 @@ static mds_kbdc_tree_t* create_permutations(mds_kbdc_tree_t* elements)
       return first;
     }
   
+  stage++;
   for (previous_next = &elements; (argument = *previous_next); previous_next = &((*previous_next)->next))
     {
       /* Created ordered alternative for a permutation prototype. */
@@ -682,7 +683,8 @@ static mds_kbdc_tree_t* create_permutations(mds_kbdc_tree_t* elements)
   saved_errno = errno;
   mds_kbdc_tree_free(first);
   mds_kbdc_tree_free(subperms);
-  mds_kbdc_tree_destroy(&ordered);
+  if (stage > 0)
+    mds_kbdc_tree_destroy(&ordered);
   errno = saved_errno;
   return NULL;
 }
@@ -730,7 +732,8 @@ static int simplify_unordered(mds_kbdc_tree_unordered_t* restrict tree)
       NEW_ERROR(tree, WARNING, "singleton unordered subsequence");
       memcpy(tree, temp, sizeof(mds_kbdc_tree_t));
       free(temp);
-      return simplify((mds_kbdc_tree_t*)tree);
+      fail_if (simplify((mds_kbdc_tree_t*)tree));
+      return -1;
     }
   
   /* Remove ‘.’:s. */
@@ -783,9 +786,9 @@ static int simplify_unordered(mds_kbdc_tree_unordered_t* restrict tree)
 	   * if it does not list any permutations. */
 	  NEW_ERROR_(result, INTERNAL_ERROR, 0, 0, 0, 0, 1,
 		     "Fail to create permutations of an unordered sequence");
-	  errno = 0;
+	  return 0;
 	}
-      return tree->inner = arguments, -1;
+      fail_if (tree->inner = arguments, 1);
     }
   mds_kbdc_tree_free(arguments);
   
@@ -803,9 +806,8 @@ static int simplify_unordered(mds_kbdc_tree_unordered_t* restrict tree)
  */
 static int simplify(mds_kbdc_tree_t* restrict tree)
 {
-#define s(expr)  if ((r = simplify(tree->expr)))  return r
-#define S(type)  if ((r = simplify_##type(&(tree->type))))  return r
-  int r;
+#define s(expr)  fail_if (simplify(tree->expr))
+#define S(type)  fail_if (simplify_##type(&(tree->type)))
  again:
   if (tree == NULL)
     return 0;
@@ -828,6 +830,8 @@ static int simplify(mds_kbdc_tree_t* restrict tree)
   
   tree = tree->next;
   goto again;
+ fail:
+  return -1;
 #undef s
 #undef S
 }
diff --git a/src/mds-kbdc/string.c b/src/mds-kbdc/string.c
index 062aed3..6ecf757 100644
--- a/src/mds-kbdc/string.c
+++ b/src/mds-kbdc/string.c
@@ -56,8 +56,7 @@ char32_t* string_decode(const char* restrict string)
       length++;
   
   /* Allocated UTF-32 string. */
-  if (xmalloc(rc, length + 1, char32_t))
-    return NULL;
+  fail_if (xmalloc(rc, length + 1, char32_t));
   
   /* Convert to UTF-32. */
   for (i = j = n = 0; string[i]; i++)
@@ -81,6 +80,8 @@ char32_t* string_decode(const char* restrict string)
   
   /* -1-terminate and return. */
   return rc[length] = -1, rc;
+ fail:
+  return NULL;
 }
 
 
@@ -98,8 +99,7 @@ char* string_encode(const char32_t* restrict string)
   char* restrict rc;
   
   /* Allocated Modified UTF-8 string. */
-  if (xmalloc(rc, 7 * n + 1, char))
-    return NULL;
+  fail_if (xmalloc(rc, 7 * n + 1, char));
   
   /* Convert to Modified UTF-8. */
   for (i = j = 0; i < n; i++)
@@ -127,6 +127,8 @@ char* string_encode(const char32_t* restrict string)
   
   /* NUL-terminate and return. */
   return rc[j] = '\0', rc;
+ fail:
+  return NULL;
 }
 
 
@@ -143,9 +145,10 @@ char32_t* string_dup(const char32_t* restrict string)
   if (string == NULL)
     return NULL;
   n = string_length(string) + 1;
-  if (xmalloc(rc, n, char32_t))
-    return NULL;
+  fail_if (xmalloc(rc, n, char32_t));
   memcpy(rc, string, n * sizeof(char32_t));
   return rc;
+ fail:
+  return NULL;
 }
 
diff --git a/src/mds-kbdc/tree.c b/src/mds-kbdc/tree.c
index ac9de2b..b32c503 100644
--- a/src/mds-kbdc/tree.c
+++ b/src/mds-kbdc/tree.c
@@ -60,11 +60,12 @@ void mds_kbdc_tree_initialise(mds_kbdc_tree_t* restrict this, int type)
  */
 mds_kbdc_tree_t* mds_kbdc_tree_create(int type)
 {
-  mds_kbdc_tree_t* this = malloc(sizeof(mds_kbdc_tree_t));
-  if (this == NULL)
-    return NULL;
+  mds_kbdc_tree_t* this;
+  fail_if (xmalloc(this, 1, mds_kbdc_tree_t));
   mds_kbdc_tree_initialise(this, type);
   return this;
+ fail:
+  return NULL;
 }
 
 
diff --git a/src/mds-kbdc/validate-tree.c b/src/mds-kbdc/validate-tree.c
index eeb5735..466f138 100644
--- a/src/mds-kbdc/validate-tree.c
+++ b/src/mds-kbdc/validate-tree.c
@@ -106,11 +106,13 @@ static int validate_include(mds_kbdc_tree_include_t* restrict tree)
 {
   void* data;
   int r;
-  if (mds_kbdc_include_stack_push(tree, &data))
-    return -1;
+  fail_if (mds_kbdc_include_stack_push(tree, &data));
   r = validate_subtree(tree->inner);
   mds_kbdc_include_stack_pop(data);
-  return r;
+  fail_if (r);
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -339,9 +341,11 @@ static int validate_macro_call(mds_kbdc_tree_macro_call_t* restrict tree)
 static int validate_for(mds_kbdc_tree_for_t* restrict tree)
 {
   int r;
-  fors++;
-  r = validate_subtree(tree->inner);
-  return fors--, r;
+  fors++, r = validate_subtree(tree->inner), fors--;
+  fail_if (r);
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -353,8 +357,10 @@ static int validate_for(mds_kbdc_tree_for_t* restrict tree)
  */
 static int validate_if(mds_kbdc_tree_if_t* restrict tree)
 {
-  return -(validate_subtree(tree->inner) ||
-	   validate_subtree(tree->otherwise));
+  fail_if ((validate_subtree(tree->inner) || validate_subtree(tree->otherwise)));
+  return 0;
+ fail:
+  return -1;
 }
 
 
@@ -446,9 +452,8 @@ static int validate_information_data(mds_kbdc_tree_t* restrict tree)
  */
 static int validate_subtree(mds_kbdc_tree_t* restrict tree)
 {
-#define v(type)  if ((r = validate_##type(&(tree->type))))     return r
-#define V(type)  if ((r = validate_##type(&(tree->type##_))))  return r
-  int r;
+#define v(type)  fail_if (validate_##type(&(tree->type)))
+#define V(type)  fail_if (validate_##type(&(tree->type##_)))
  again:
   if (tree == NULL)
     return 0;
@@ -470,14 +475,12 @@ static int validate_subtree(mds_kbdc_tree_t* restrict tree)
     case C(INFORMATION_LANGUAGE):
     case C(INFORMATION_COUNTRY):
     case C(INFORMATION_VARIANT):
-      if ((r = validate_information_data(tree)))
-	return r;
+      fail_if (validate_information_data(tree));
       break;
     case C(ASSUMPTION_HAVE):
     case C(ASSUMPTION_HAVE_CHARS):
     case C(ASSUMPTION_HAVE_RANGE):
-      if ((r = validate_assumption_data(tree)))
-	return r;
+      fail_if (validate_assumption_data(tree));
       break;
     default:
       break;
@@ -485,6 +488,8 @@ static int validate_subtree(mds_kbdc_tree_t* restrict tree)
   
   tree = tree->next;
   goto again;
+ fail:
+  return -1;
 #undef V
 #undef v
 }
@@ -502,7 +507,11 @@ int validate_tree(mds_kbdc_parsed_t* restrict result_)
   mds_kbdc_include_stack_begin(result = result_);
   r = validate_subtree(result_->tree);
   fors = 0;
-  return mds_kbdc_include_stack_end(), r;
+  mds_kbdc_include_stack_end();
+  fail_if (r);
+  return 0;
+ fail:
+  return -1;
 }
 
 
diff --git a/src/mds-kbdc/variables.c b/src/mds-kbdc/variables.c
index 55bae76..7431767 100644
--- a/src/mds-kbdc/variables.c
+++ b/src/mds-kbdc/variables.c
@@ -17,6 +17,8 @@
  */
 #include "variables.h"
 
+#include <libmdsserver/macros.h>
+
 #include <stdlib.h>
 #include <string.h>
 
@@ -149,9 +151,8 @@ int variables_let(size_t variable, mds_kbdc_tree_t* restrict value)
   /* Grow the table if necessary to fit the variable. */
   if (variable >= variable_count)
     {
-      new = realloc(variables, (variable + 1) * sizeof(variable_t*));
-      if (new == NULL)
-	return -1;
+      new = variables;
+      fail_if (xrealloc(new, variable + 1, variable_t*));
       variables = new;
       memset(variables + variable_count, 0, (variable + 1 - variable_count) * sizeof(variable_t*));
       variable_count = variable + 1;
@@ -169,13 +170,15 @@ int variables_let(size_t variable, mds_kbdc_tree_t* restrict value)
       previous = variables[variable];
       variables[variable] = malloc(sizeof(variable_t));
       if (variables[variable] == NULL)
-	return variables[variable] = previous, -1;
+	fail_if (variables[variable] = previous, 1);
       variables[variable]->value = value;
       variables[variable]->previous = previous;
       variables[variable]->scope = current_scope;
     }
   
   return 0;
+ fail:
+  return -1;
 }