assemble.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <stdint.h>

#include "utils.h"

char *shell_escape(const char *str) {
	size_t len = strlen(str);
	char *escaped = malloc(4 * len + 1);

	size_t j = 0;
	for(size_t i = 0; i <= len; i++) {
		if(str[i] == '\'') {
			strcpy(escaped + j, "'\\''");
			j += 4;
		} else {
			escaped[j] = str[i];
			j++;
		}
	}

	escaped[j] = '\0';

	return escaped;
}

// TODO: Actually use a library to assemble instead of calling out to rasm2
bool assemble_string(char *str, uint8_t bits, uint64_t address, unsigned char **output, size_t *output_size, bool att_syntax) {
	*output_size = 0;
	*output = malloc(16);

	char *escaped = shell_escape(str);

	char *cmd;
	if(att_syntax) {
		asprintf(&cmd, "rasm2 -s att -a x86.as -b %u '%s'",
				 bits, escaped);
	} else {
		asprintf(&cmd, "rasm2 -a x86.nasm -b %u -o 0x%llx '%s'",
				 bits, address, escaped);
	}

	free(escaped);

	FILE *f = popen(cmd, "r");
	free(cmd);

	if(!f) {
		return false;
	}

	size_t bytes_read = 0;

	char buf[256];
	while(fgets(buf, sizeof(buf), f)) {
		size_t len = strlen(buf);
		*output_size += (len - 1) / 2;
		*output = realloc(*output, *output_size);
		for(int i = 0; i < len; i += 2) {
			(*output)[bytes_read++] = hex2int(buf[i]) * 0x10 + hex2int(buf[i + 1]);
		}
	}

	pclose(f);

	if(bytes_read == 0) {
		return false;
	}

	return true;
}