init

7 files changed, 293 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..64c75c2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.o
+*_test
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5d2ed5d
--- /dev/null
+++ b/Makefile
@@ -0,0 +1 @@
+unpack_test: unpack_test.o unpack.o common.o
diff --git a/common.c b/common.c
new file mode 100644
index 0000000..106fc7a
--- /dev/null
+++ b/common.c
@@ -0,0 +1,33 @@
+#include <stddef.h>
+
+#include "common.h"
+#include "pack.h"
+
+size_t getsize(char c)
+{
+	switch (c) {
+	case 'b': case 'B':
+	case 'x':
+		return 1;
+	case 'h': case 'H':
+	case 'i': case 'I':
+		return 2;
+	case 'l': case 'L':
+	case 'f':
+		return 4;
+	case 'q': case 'Q':
+	case 'd':
+		return 8;
+	case 's': default: return (size_t)-1;
+	}
+}
+
+const char *pack_strerror(enum pack_status status)
+{
+	switch (status) {
+	case PACK_OK: return "Success";
+	case PACK_FMTINVAL: return "Invalid format parameter";
+	case PACK_TOOSMALL: return "Buffer too small";
+	default: return "Invalid Status";
+	}
+}
diff --git a/common.h b/common.h
new file mode 100644
index 0000000..f5a39c9
--- /dev/null
+++ b/common.h
@@ -0,0 +1,8 @@
+#ifndef PACK_INTERNAL_H
+#define PACK_INTERNAL_H
+
+#include <stddef.h>
+
+size_t getsize(char c);
+
+#endif // !PACK_INTERNAL_H
diff --git a/pack.h b/pack.h
new file mode 100644
index 0000000..7a8fc69
--- /dev/null
+++ b/pack.h
@@ -0,0 +1,16 @@
+#ifndef PACK_H
+#define PACK_H
+
+#include <stddef.h>
+
+enum pack_status {
+	PACK_OK,
+	PACK_FMTINVAL,
+	PACK_TOOSMALL,
+};
+
+enum pack_status unpack(void *buf, size_t size, const char *fmt, ...);
+
+const char *pack_strerror(enum pack_status status);
+
+#endif // !PACK_H
diff --git a/unpack.c b/unpack.c
new file mode 100644
index 0000000..2617e9a
--- /dev/null
+++ b/unpack.c
@@ -0,0 +1,123 @@
+#include <ctype.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <limits.h>
+
+#include <stdio.h>
+
+#include "common.h"
+#include "pack.h"
+
+typedef enum pack_status unpacker(void *buf, size_t size, va_list ap);
+
+enum endian { BIG, LITTLE };
+
+uintmax_t read_val(unsigned char *buf, size_t size, enum endian e)
+{
+	unsigned long long val = 0;
+
+	for (size_t i = 0; i < size; i++)
+		val |= (buf[i] & 0xff) << (e == LITTLE ? i : size - i - 1) * 8;
+
+	return val;
+}
+#define X(M) \
+	M(b, signed   char     ) \
+	M(B, unsigned char     ) \
+	M(h,          short    ) \
+	M(H, unsigned short    ) \
+	M(i,          int      ) \
+	M(I, unsigned          ) \
+	M(l,          long     ) \
+	M(L, unsigned long     ) \
+	M(q,          long long) \
+	M(Q, unsigned long long)
+
+enum pack_status unpack(void *buf_, size_t size, const char *fmt, ...)
+{
+	enum endian endianness = BIG;
+	unsigned char *buf = buf_;
+	size_t offset = 0;
+	va_list ap;
+
+	va_start(ap, fmt);
+
+	for (int i = 0; fmt[i] != '\0'; i++) {
+		bool sign = islower(fmt[i]);
+		size_t s;
+		union {
+			signed   char      *b;
+			unsigned char      *B;
+			         short     *h;
+			unsigned short     *H;
+			         int       *i;
+			unsigned int       *I;
+			         long      *l;
+			unsigned long      *L;
+			         long long *q;
+			unsigned long long *Q;
+		} arg;
+		/*void *arg;*/
+		union { uintmax_t u; intmax_t s; } val;
+		switch (fmt[i]) {
+		case '>': endianness = BIG; continue;
+		case '<': endianness = LITTLE; continue;
+		case 'b': arg.b = va_arg(ap, signed   char      *);
+		case 'B': arg.B = va_arg(ap, unsigned char      *);
+		case 'h': arg.h = va_arg(ap,          short     *);
+		case 'H': arg.H = va_arg(ap, unsigned short     *);
+		case 'i': arg.i = va_arg(ap,          int       *);
+		case 'I': arg.I = va_arg(ap, unsigned           *);
+		case 'l': arg.l = va_arg(ap,          long      *);
+		case 'L': arg.L = va_arg(ap, unsigned long      *);
+		case 'q': arg.q = va_arg(ap,          long long *);
+		case 'Q': arg.Q = va_arg(ap, unsigned long long *);
+		case 'x': break;
+		return PACK_FMTINVAL;
+		}
+
+		s = getsize(fmt[i]);
+		if (s == (size_t)-1) return PACK_FMTINVAL;
+
+		if (size - offset < s) return PACK_TOOSMALL;
+
+		if (fmt[i] == 'x') goto skip;
+
+		val.u = read_val(buf, s, endianness);
+
+		fprintf(stderr, "%zu, %llu\n", s, val.u);
+
+		if (sign) {
+			intmax_t vals;
+			if (!(val.u & (1llu << (s * 8 - 1)))) {
+				vals = val.u;
+			} else {
+				uintmax_t offt = UINTMAX_MAX >> (sizeof offt * CHAR_BIT - s * 8);
+				vals = val.u - offt - 1;
+			}
+			val.s = vals;
+			fprintf(stderr, "signed %lld\n", val.s);
+		}
+
+		switch (fmt[i]) {
+#define D(t, f) fprintf(stderr, "(%p) "#t " = %" #f "\n", (void *)arg.t, *arg.t)
+		case 'b': *arg.b = val.s; D(b, d); break;
+		case 'B': *arg.B = val.u; D(B, u); break;
+		case 'h': *arg.h = val.s; D(h, d); break;
+		case 'H': *arg.H = val.u; D(H, u); break;
+		case 'i': *arg.i = val.s; D(i, d); break;
+		case 'I': *arg.I = val.u; D(I, u); break;
+		case 'l': *arg.l = val.s; D(l, ld); break;
+		case 'L': *arg.L = val.u; D(L, lu); break;
+		case 'q': *arg.q = val.s; D(q, lld); break;
+		case 'Q': *arg.Q = val.u; D(Q, llu); break;
+		}
+skip:
+		offset += s;
+	}
+
+	va_end(ap);
+
+	return PACK_OK;
+}
diff --git a/unpack_test.c b/unpack_test.c
new file mode 100644
index 0000000..8eee6b3
--- /dev/null
+++ b/unpack_test.c
@@ -0,0 +1,110 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+#include "pack.h"
+
+typedef bool test_func(void);
+
+struct test {
+	test_func *func;
+	char *desc;
+};
+
+#define TEST(name) bool test_##name(void)
+#define TEST_ENTRY(name, description) { test_##name, description }
+#define TEST_ENTRY_END { NULL, NULL }
+#define DATA(...) (unsigned char []){ __VA_ARGS__ }, sizeof (unsigned char []){ __VA_ARGS__ }
+#define CHECK(test) if (!(test)) { puts("! " #test); return false; }
+
+#define CHECK_UNPACK(data, fmt, ...) do { \
+	enum pack_status s = unpack(data, fmt, __VA_ARGS__); \
+	if (s != PACK_OK) { \
+		printf(__FILE__ ":%d unpack(" #data ", " #fmt ", ...) -> %s (%d)\n", __LINE__, pack_strerror(s), s); \
+		return false; \
+	} \
+} while (0)
+#define CHECK_EQUAL(a, b) if (a != b) { printf(__FILE__ ":%d %d != %d\n", __LINE__, a, b); return false; }
+
+TEST(schar)
+{
+	signed char c = __LINE__;
+	fprintf(stderr, "Address of c: %p\n", (void *)&c);
+	CHECK_UNPACK(DATA(0), "b", &c);
+	CHECK_EQUAL(c, 0);
+	CHECK_UNPACK(DATA(1), "b", &c);
+	CHECK_EQUAL(c, 1);
+	CHECK_UNPACK(DATA(127), "b", &c);
+	CHECK_EQUAL(c, 127);
+	CHECK_UNPACK(DATA(255), "b", &c);
+	CHECK_EQUAL(c, -1);
+	CHECK_UNPACK(DATA(128), "b", &c);
+	CHECK_EQUAL(c, -128);
+	return true;
+}
+
+TEST(uchar)
+{
+	unsigned char c = __LINE__;
+	fprintf(stderr, "Address of c: %p\n", (void *)&c);
+	CHECK_UNPACK(DATA(0), "B", &c);
+	CHECK_EQUAL(c, 0);
+	CHECK_UNPACK(DATA(1), "B", &c);
+	CHECK_EQUAL(c, 1);
+	CHECK_UNPACK(DATA(255), "B", &c);
+	CHECK_EQUAL(c, 255);
+	return true;
+}
+
+TEST(sshort)
+{
+	short s = __LINE__;
+	fprintf(stderr, "Address of s: %p\n", (void *)&s);
+	CHECK_UNPACK(DATA(0, 0), "h", &s);
+	CHECK_EQUAL(s, 0);
+	CHECK_UNPACK(DATA(0, 0), ">h", &s);
+	CHECK_EQUAL(s, 0);
+	CHECK_UNPACK(DATA(0, 0), "<h", &s);
+	CHECK_EQUAL(s, 0);
+	CHECK_UNPACK(DATA(0, 1), "h", &s);
+	CHECK_EQUAL(s, 1);
+	CHECK_UNPACK(DATA(0, 1), ">h", &s);
+	CHECK_EQUAL(s, 1);
+	CHECK_UNPACK(DATA(1, 0), "<h", &s);
+	CHECK_EQUAL(s, 1);
+	CHECK_UNPACK(DATA(0x7f, 0xff), "h", &s);
+	CHECK_EQUAL(s, 32767);
+	CHECK_UNPACK(DATA(0x7f, 0xff), ">h", &s);
+	CHECK_EQUAL(s, 32767);
+	CHECK_UNPACK(DATA(0xff, 0x7f), "<h", &s);
+	CHECK_EQUAL(s, 32767);
+	CHECK_UNPACK(DATA(0xff, 0xff), "h", &s);
+	CHECK_EQUAL(s, -1);
+	CHECK_UNPACK(DATA(0xff, 0xff), ">h", &s);
+	CHECK_EQUAL(s, -1);
+	CHECK_UNPACK(DATA(0xff, 0xff), "<h", &s);
+	CHECK_EQUAL(s, -1);
+	CHECK_UNPACK(DATA(0x80, 0x00), "h", &s);
+	CHECK_EQUAL(s, -32768);
+	CHECK_UNPACK(DATA(0x80, 0x00), ">h", &s);
+	CHECK_EQUAL(s, -32768);
+	CHECK_UNPACK(DATA(0x00, 0x80), "<h", &s);
+	CHECK_EQUAL(s, -32768);
+}
+
+TEST(ushort)
+{
+	unsigned short s;
+}
+
+int main(void)
+{
+	struct test tests[] = {
+		TEST_ENTRY(schar, "schar unpacking"),
+		TEST_ENTRY(uchar, "uchar unpacking"),
+		TEST_ENTRY(sshort, "sshort unpacking"),
+		TEST_ENTRY_END
+	};
+
+	for (int i = 0; tests[i].func != NULL; i++)
+		printf("%s %s\n", tests[i].func() ? " OK " : "FAIL", tests[i].desc);
+}