Add support for a few DWARF expressions

expressions.c

@@ -0,0 +1,31 @@
+#include <dwarf.h>
+#include <dwarfw.h>
+#include "leb128.h"
+#include "write.h"
+
+size_t dwarfw_op_write_deref(FILE *f) {
+	return write_u8(DW_OP_deref, f);
+}
+
+size_t dwarfw_op_write_bregx(uint64_t reg, long long int offset, FILE *f) {
+	size_t n, written = 0;
+
+	if (reg < 32) {
+		if (!(n = write_u8(DW_OP_breg0 + reg, f))) {
+			return 0;
+		}
+		written += n;
+	} else {
+		if (!(n = leb128_write_u64(reg, f, 0))) {
+			return 0;
+		}
+		written += n;
+	}
+
+	if (!(n = leb128_write_s64(offset, f, 0))) {
+		return 0;
+	}
+	written += n;
+
+	return written;
+}

include/dwarfw.h

@@ -61,9 +61,17 @@ size_t dwarfw_cie_write_def_cfa_register(struct dwarfw_cie *cie, uint64_t reg,
 	FILE *f);
 size_t dwarfw_cie_write_def_cfa_offset(struct dwarfw_cie *cie,
 	long long int offset, FILE *f);
+size_t dwarfw_cie_write_def_cfa_expression(struct dwarfw_cie *cie,
+	const char *expr, size_t expr_len, FILE *f);
+size_t dwarfw_cie_write_expression(struct dwarfw_cie *cie,
+	uint64_t reg, const char *expr, size_t expr_len, FILE *f);
 size_t dwarfw_cie_write_val_offset(struct dwarfw_cie *cie, uint64_t reg,
 	long long int offset, FILE *f);
 
 size_t dwarfw_cie_pad(struct dwarfw_cie *cie, size_t length, FILE *f);
 
+// Call Frame Expressions
+size_t dwarfw_op_write_deref(FILE *f);
+size_t dwarfw_op_write_bregx(uint64_t reg, long long int offset, FILE *f);
+
 #endif

include/write.h

@@ -0,0 +1,11 @@
+#ifndef WRITE_H
+#define WRITE_H
+
+#include <stdint.h>
+#include <stdio.h>
+
+size_t write_u8(uint8_t b, FILE *f);
+size_t write_u16(uint16_t b, FILE *f);
+size_t write_u32(uint32_t b, FILE *f);
+
+#endif

instructions.c

@@ -4,19 +4,7 @@
 #include <stdbool.h>
 #include "leb128.h"
 #include "pointer.h"
-
-static size_t write_u8(uint8_t b, FILE *f) {
-	return fwrite(&b, 1, sizeof(b), f);
-}
-
-static size_t write_u16(uint16_t b, FILE *f) {
-	return fwrite(&b, 1, sizeof(b), f);
-}
-
-static size_t write_u32(uint32_t b, FILE *f) {
-	return fwrite(&b, 1, sizeof(b), f);
-}
-
+#include "write.h"
 
 #define OPCODE_LOW_MASK 0x3F
 
@@ -301,6 +289,61 @@ size_t dwarfw_cie_write_def_cfa_offset(struct dwarfw_cie *cie,
 	return written;
 }
 
+static size_t write_block(const char *buf, size_t buf_len, FILE *f) {
+	size_t n, written = 0;
+
+	if (!(n = leb128_write_u64(buf_len, f, 0))) {
+		return 0;
+	}
+	written += n;
+
+	if (!(n = fwrite(buf, 1, buf_len, f))) {
+		return 0;
+	}
+	written += n;
+
+	return written;
+}
+
+size_t dwarfw_cie_write_def_cfa_expression(struct dwarfw_cie *cie,
+		const char *expr, size_t expr_len, FILE *f) {
+	size_t n, written = 0;
+
+	if (!(n = write_u8(DW_CFA_def_cfa_expression, f))) {
+		return 0;
+	}
+	written += n;
+
+	if (!(n = write_block(expr, expr_len, f))) {
+		return 0;
+	}
+	written += n;
+
+	return written;
+}
+
+size_t dwarfw_cie_write_expression(struct dwarfw_cie *cie,
+		uint64_t reg, const char *expr, size_t expr_len, FILE *f) {
+	size_t n, written = 0;
+
+	if (!(n = write_u8(DW_CFA_expression, f))) {
+		return 0;
+	}
+	written += n;
+
+	if (!(n = leb128_write_u64(reg, f, 0))) {
+		return 0;
+	}
+	written += n;
+
+	if (!(n = write_block(expr, expr_len, f))) {
+		return 0;
+	}
+	written += n;
+
+	return written;
+}
+
 size_t dwarfw_cie_write_val_offset(struct dwarfw_cie *cie, uint64_t reg,
 		long long int offset, FILE *f) {
 	size_t n, written = 0;

meson.build

@@ -23,9 +23,11 @@ lib_dwarfw = library(
 	meson.project_name(),
 	files(
 		'dwarfw.c',
+		'expressions.c',
 		'instructions.c',
 		'leb128.c',
 		'pointer.c',
+		'write.c',
 	),
 	include_directories: dwarfw_inc,
 	dependencies: [elf],

write.c

@@ -0,0 +1,13 @@
+#include "write.h"
+
+size_t write_u8(uint8_t b, FILE *f) {
+	return fwrite(&b, 1, sizeof(b), f);
+}
+
+size_t write_u16(uint16_t b, FILE *f) {
+	return fwrite(&b, 1, sizeof(b), f);
+}
+
+size_t write_u32(uint32_t b, FILE *f) {
+	return fwrite(&b, 1, sizeof(b), f);
+}