This is not the most useful way of substring.

src/lorem.c

@@ -17,15 +17,23 @@
 static struct {
 	size_t capacity, size; /* Lead block. */
 	struct block_array blocks;
-} lorem;
+} buffer;
+
+struct lorem lorem(const char *const a, const char *const b) {
+	struct lorem l;
+	assert(a && a <= b);
+	l.sub = a;
+	l.size = (size_t)(b - a);
+	return l;
+}
 
 const char *lorem_dup(const struct lorem sub) {
 	char *string;
 	size_t size;
 	if(!sub.sub) { errno = EDOM; return 0; } /* Null substring. */
 	if(sub.size == ~(size_t)0) { errno = ERANGE; return 0; } /* Unlikely. */
-	if((size = sub.size + 1) > lorem.capacity - lorem.size) {
-		size_t c0 = lorem.capacity < 8 ? 8 : lorem.capacity;
+	if((size = sub.size + 1) > buffer.capacity - buffer.size) {
+		size_t c0 = buffer.capacity < 8 ? 8 : buffer.capacity;
 		char *block = 0, **record = 0;
 		while(c0 < size) { /* Grow. */
 			size_t c1 = c0 + (c0 >> 1) + (c0 >> 3);
@@ -33,31 +41,31 @@ const char *lorem_dup(const struct lorem sub) {
 			c0 = c1;
 		}
 		if(!(block = malloc(c0))
-			|| !(record = block_array_new(&lorem.blocks))) { /* Error. */
+			|| !(record = block_array_new(&buffer.blocks))) { /* Error. */
 			free(block);
 			if(!errno) errno = ERANGE;
 			return 0;
 		}
 		*record = block;
-		lorem.capacity = c0;
-		lorem.size = 0;
+		buffer.capacity = c0;
+		buffer.size = 0;
 		/*printf("%s size %zu\n", orcify(block), c0);*/
 	}
-	assert(lorem.blocks.size);
-	string = lorem.blocks.data[lorem.blocks.size - 1] + lorem.size;
+	assert(buffer.blocks.size);
+	string = buffer.blocks.data[buffer.blocks.size - 1] + buffer.size;
 	memcpy(string, sub.sub, sub.size);
 	string[sub.size] = '\0';
-	lorem.size += size;
+	buffer.size += size;
 	return string;
 }
 
 void lorem_(void) {
 	size_t i;
-	for(i = 0; i < lorem.blocks.size; i++) {
-		char *block = lorem.blocks.data[i];
+	for(i = 0; i < buffer.blocks.size; i++) {
+		char *block = buffer.blocks.data[i];
 		/*printf("free %s\n", orcify(block));*/
 		free(block);
 	}
-	lorem.capacity = lorem.size = 0;
-	block_array_(&lorem.blocks);
+	buffer.capacity = buffer.size = 0;
+	block_array_(&buffer.blocks);
 }

src/lorem.h

@@ -2,5 +2,6 @@
 
 struct lorem { const char *sub; size_t size; };
 
+struct lorem lorem(const char *const a, const char *const b);
 const char *lorem_dup(const struct lorem);
 void lorem_(void);

src/source.re.c

@@ -9,6 +9,12 @@
 #include <stdlib.h>
 #include <assert.h>
 
+/* Temporary buffer to lookup. */
+#define ARRAY_NAME char
+#define ARRAY_TYPE char
+#include "array.h"
+/* ...wait, why would you copy? modify the table to use substring. */
+
 /* This is a lookup table for source strings ("2000glider") to substring the
  first description ("Glider pilot log book"). */
 static int lookup_is_equal(const char *const x, const char *const y)
@@ -26,13 +32,13 @@ static struct lorem lookup_default = { 0, 0 };
 #include "../src/table.h"
 
 
-static void source_to_string(const union line64 line, const struct lorem *u,
+static void source_to_string(const union line64 line, char *const*const u,
 	char (*const a)[12]) { (void)u; date32_to_string(line.date, a); }
 static int source_compare(const union line64 a, const union line64 b)
 	{ return a.u64 > b.u64; }
 #define TREE_NAME source
 #define TREE_KEY union line64
-#define TREE_VALUE struct lorem
+#define TREE_VALUE char *
 #define TREE_COMPARE
 #define TREE_TO_STRING
 #include "../src/tree.h"
@@ -78,6 +84,8 @@ static int scan(union date32 date, const char *const buffer,
 
 		<source> * { why = "default source unrecognized"; goto catch; }
 		<source> @s0 keyword @s1 / "\n" => skip {
+			struct lorem lor = lorem(s0, s1);
+			const char *label;
 			printf("extracted <%.*s>\n", (int)(s1 - s0), s0);
 			continue;
 		}
@@ -115,5 +123,6 @@ struct sources sources(struct journal *const j) {
 catch:
 	sources_(&s);
 finally:
+	char_array_(&temp); /* Erase the temporary buffer. */
 	return s;
 }

test/test_source.c

@@ -17,5 +17,6 @@ catch:
 finally:
 	sources_(&s);
 	journal_(&j);
+	lorem_();
 	return success;
 }