pkuuid.h: first-pass + bump version to 0.4.1

1 files changed, 203 insertions, 0 deletions

diff --git a/pkuuid.h b/pkuuid.h
new file mode 100644
index 0000000..7426f79
--- /dev/null
+++ b/pkuuid.h
@@ -0,0 +1,203 @@
+#ifndef PK_UUID_H
+#define PK_UUID_H
+
+#include "stddef.h"
+#include <time.h>
+
+struct pk_uuid {
+	alignas(max_align_t) unsigned char uuid[16];
+};
+
+const struct pk_uuid pk_uuid_zed = { .uuid = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } };
+const struct pk_uuid pk_uuid_max = { .uuid = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF } };
+
+#define pk_uuid_printf_format PK_Q(%.2x%.2x%.2x%.2x-%.2x%.2x-%.2x%.2x-%.2x%.2x-%.2x%.2x%.2x%.2x%.2x%.2x)
+#define pk_uuid_printf_var(id) id.uuid[0], id.uuid[1], id.uuid[2], id.uuid[3], id.uuid[4], id.uuid[5], id.uuid[6], id.uuid[7], id.uuid[8], id.uuid[9], id.uuid[10], id.uuid[11], id.uuid[12], id.uuid[13], id.uuid[14], id.uuid[15]
+
+void pk_uuid_init(time_t srand_seed);
+void pk_uuid_teardown();
+
+struct pk_uuid pk_uuid_new_v7();
+
+#if defined(__cplusplus)
+#include <ostream>
+#include <iomanip>
+std::ostream& operator<<(std::ostream &o, const struct pk_uuid& uuid);
+std::istream& operator>>(std::istream &i, struct pk_uuid& uuid);
+#endif
+
+#endif /* PK_UUID_H */
+
+#ifdef PK_IMPL_UUID
+
+#include <stdatomic.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+// TODO JCB - 2025-03-19
+// This should have platform-specific defines
+#ifndef PK_UUID_CLOCK
+	#ifdef CLOCK_TAI
+		#define PK_UUID_CLOCK CLOCK_TAI
+	#else
+		#define PK_UUID_CLOCK CLOCK_REALTIME
+	#endif
+#endif
+
+void
+pk_uuid_init(time_t srand_seed)
+{
+	// TODO 2025-03-19 - JCB
+	// pk.h should NOT be setting srand.
+	// Replace dependency on rand/srand with a sufficient rand() implementation.
+	// I would prefer if generating a UUID did not advance a global random.
+	// Consider creating a pkrand.h to resolve this.
+	srand(srand_seed);
+}
+
+void
+pk_uuid_teardown()
+{
+}
+
+struct pk_uuid
+pk_uuid_new_v7()
+{
+	const int n = 1;
+	uint32_t r;
+	// https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-7
+	struct pk_uuid ret;
+	struct timespec t;
+	clock_gettime(PK_UUID_CLOCK, &t);
+	uint32_t sec = (uint32_t)t.tv_sec;
+	uint32_t nsec = (uint32_t)t.tv_nsec;
+	// [000-047] (6 bytes) big-endian unix epoch
+	// TODO test this on a big-endian machine, I don't think this is correct.
+	// This `if` determines if we are big or little endian.
+	// A return value of 1 says we are little endian, so swap the bits.
+	if (*(char *)&n == 1) {
+		ret.uuid[0] = (uint8_t)((sec  & 0xFF000000) >> 24);
+		ret.uuid[1] = (uint8_t)((sec  & 0x00FF0000) >> 16);
+		ret.uuid[2] = (uint8_t)((sec  & 0x0000FF00) >> 8);
+		ret.uuid[3] = (uint8_t)((sec  & 0x000000FF) >> 0);
+		ret.uuid[4] = (uint8_t)((nsec & 0x0000FF00) >> 8);
+		ret.uuid[5] = (uint8_t)((nsec & 0x000000FF) >> 0);
+	} else {
+		ret.uuid[0] = (uint8_t)((sec  & 0xFF000000) >> 0);
+		ret.uuid[1] = (uint8_t)((sec  & 0x00FF0000) >> 8);
+		ret.uuid[2] = (uint8_t)((sec  & 0x0000FF00) >> 16);
+		ret.uuid[3] = (uint8_t)((sec  & 0x000000FF) >> 24);
+		ret.uuid[4] = (uint8_t)((nsec & 0xFF000000) >> 0);
+		ret.uuid[5] = (uint8_t)((nsec & 0x00FF0000) >> 8);
+	}
+	// [052-127] random
+	r = (uint32_t)rand();
+	if (*(char *)&n == 1) {
+		ret.uuid[8]  = (uint8_t)((r & 0xFF000000) >> 24);
+		ret.uuid[9]  = (uint8_t)((r & 0x00FF0000) >> 16);
+		ret.uuid[10] = (uint8_t)((r & 0x0000FF00) >> 8);
+		ret.uuid[11] = (uint8_t)((r & 0x000000FF) >> 0);
+	} else {
+		ret.uuid[8]  = (uint8_t)((r & 0xFF000000) >> 0);
+		ret.uuid[9]  = (uint8_t)((r & 0x00FF0000) >> 8);
+		ret.uuid[10] = (uint8_t)((r & 0x0000FF00) >> 16);
+		ret.uuid[11] = (uint8_t)((r & 0x000000FF) >> 24);
+	}
+	r = rand();
+	if (*(char *)&n == 1) {
+		ret.uuid[12] = (uint8_t)((r & 0xFF000000) >> 24);
+		ret.uuid[13] = (uint8_t)((r & 0x00FF0000) >> 16);
+		ret.uuid[14] = (uint8_t)((r & 0x0000FF00) >> 8);
+		ret.uuid[15] = (uint8_t)((r & 0x000000FF) >> 0);
+	} else {
+		ret.uuid[12] = (uint8_t)((r & 0xFF000000) >> 0);
+		ret.uuid[13] = (uint8_t)((r & 0x00FF0000) >> 8);
+		ret.uuid[14] = (uint8_t)((r & 0x0000FF00) >> 16);
+		ret.uuid[15] = (uint8_t)((r & 0x000000FF) >> 24);
+	}
+	ret.uuid[6]  = ret.uuid[9]  ^ ret.uuid[12];
+	ret.uuid[7]  = ret.uuid[10] ^ ret.uuid[15];
+
+	// [048-051] v7 nibble
+	// version must be 0x7_
+	// 0x70 is 0b01110000
+	// 0x7F is 0b01111111
+	ret.uuid[6] |= 0x70;
+	ret.uuid[6] &= 0x7F;
+
+	// [064-065] 2-bit variant field
+	// variant must be 0b10
+	// 0x80 is 0b10000000
+	// 0xBF is 0b10111111
+	ret.uuid[8] |= 0x80;
+	ret.uuid[8] &= 0xBF;
+
+	return ret;
+}
+
+#if defined(__cplusplus)
+#include "./pkstn.h" /* deleteme */
+std::ostream&
+operator<<(std::ostream &o, const struct pk_uuid& uuid)
+{
+	int i;
+	o << std::hex;
+	for (i = 0; i < 4; ++i) {
+		o << std::setw(2) << std::setfill('0');
+		o << (uint16_t)uuid.uuid[i];
+	}
+	o << "-";
+	for (i = 4; i < 6; ++i) {
+		o << std::setw(2) << std::setfill('0');
+		o << (uint16_t)uuid.uuid[i];
+	}
+	o << "-";
+	for (i = 6; i < 8; ++i) {
+		o << std::setw(2) << std::setfill('0');
+		o << (uint16_t)uuid.uuid[i];
+	}
+	o << "-";
+	for (i = 8; i < 10; ++i) {
+		o << std::setw(2) << std::setfill('0');
+		o << (uint16_t)uuid.uuid[i];
+	}
+	o << "-";
+	for (i = 10; i < 16; ++i) {
+		o << std::setw(2) << std::setfill('0');
+		o << (uint16_t)uuid.uuid[i];
+	}
+	return o;
+}
+
+std::istream&
+operator>>(std::istream &i, struct pk_uuid& uuid)
+{
+	char c[3];
+	char k = 0;
+	char offset = 0;
+	c[2] = '\0';
+	for (k = 0; k < 20; ++k) {
+		if (k == 4 || k == 7 || k == 10 || k == 13) {
+			offset += 1;
+			c[0] = i.peek();
+			if (c[0] != '-') {
+				goto err_out;
+			}
+			i.get(); // burn
+			continue;
+		}
+		i.get(c[0]);
+		i.get(c[1]);
+		if (pk_stn_uint8_t(&uuid.uuid[k - offset], c, 16) != PK_STN_RES_SUCCESS) {
+			goto err_out;
+		}
+	}
+	return i;
+err_out:
+	i.seekg(-(((k + 1) * 2) + offset), std::ios_base::cur);
+	uuid = pk_uuid_zed;
+	return i;
+}
+#endif
+
+#endif