feat: implement archive reader/writer with round-trip test

test/test.c

@@ -0,0 +1,71 @@
+#include <fpk.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define CHECK(cond, msg)                                                     \
+	do {                                                                  \
+		if (!(cond)) {                                                \
+			fprintf(stderr, "FAIL: %s\n", msg);                  \
+			return EXIT_FAILURE;                                  \
+		}                                                             \
+	} while (0)
+
+static const char *PAK_PATH = "roundtrip.fpk";
+
+int main(void)
+{
+	struct fpk_writer *w;
+	struct fpk *r;
+	fpk_entry_t *entry;
+	void *data;
+	size_t out_size;
+
+	static const char hello[] = "hello, fpk";
+	static const char world[] = "world";
+
+	w = fpk_writer_open(PAK_PATH);
+	CHECK(w != NULL, "fpk_writer_open failed");
+	CHECK(fpk_writer_add(w, "a/hello.txt", hello, sizeof(hello)) == 0,
+	      "fpk_writer_add(hello) failed");
+	CHECK(fpk_writer_add(w, "b/world.txt", world, sizeof(world)) == 0,
+	      "fpk_writer_add(world) failed");
+	CHECK(fpk_writer_add(w, "c/empty.bin", NULL, 0) == 0,
+	      "fpk_writer_add(empty) failed");
+	CHECK(fpk_writer_finalize(w) == 0, "fpk_writer_finalize failed");
+	fpk_writer_close(w);
+
+	r = fpk_open(PAK_PATH);
+	CHECK(r != NULL, "fpk_open failed");
+	CHECK(fpk_entry_count(r) == 3, "unexpected entry_count");
+
+	entry = fpk_find(r, "a/hello.txt");
+	CHECK(entry != NULL, "fpk_find(hello) failed");
+	CHECK(entry->data_size == sizeof(hello), "hello size mismatch");
+	data = fpk_read(r, entry, &out_size);
+	CHECK(data != NULL, "fpk_read(hello) failed");
+	CHECK(out_size == sizeof(hello), "hello read size mismatch");
+	CHECK(memcmp(data, hello, sizeof(hello)) == 0, "hello content mismatch");
+	free(data);
+
+	entry = fpk_find(r, "b/world.txt");
+	CHECK(entry != NULL, "fpk_find(world) failed");
+	data = fpk_read(r, entry, &out_size);
+	CHECK(data != NULL, "fpk_read(world) failed");
+	CHECK(out_size == sizeof(world), "world read size mismatch");
+	CHECK(memcmp(data, world, sizeof(world)) == 0, "world content mismatch");
+	free(data);
+
+	entry = fpk_find(r, "c/empty.bin");
+	CHECK(entry != NULL, "fpk_find(empty) failed");
+	CHECK(entry->data_size == 0, "empty size mismatch");
+
+	CHECK(fpk_find(r, "does/not/exist") == NULL,
+	      "fpk_find(missing) should return NULL");
+
+	fpk_close(r);
+	remove(PAK_PATH);
+
+	printf("PASS\n");
+	return EXIT_SUCCESS;
+}