asmsh/compile.h

/* Copyright Yann Weber <asmsh@yannweb.net>
   This file is part of asmsh.

   asmsh is free software: you can redistribute it and/or modify it under the
   terms of the GNU General Public License as published by the Free Software
   Foundation, either version 3 of the License, or any later version.
   
   asmsh is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
   FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
   details.
   
   You should have received a copy of the GNU General Public License along
   with asmsh. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef ASMSH_COMPILE_H
#define ASMSH_COMPILE_H
#include "config.h"

#include <alloca.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/select.h>
#include <sys/signalfd.h>
#include <sys/types.h>
#include <sys/wait.h>

#include "logger.h"

/** Define the default assembler (GNU as) */
#define ASMSH_COMPILE_AS "as"
#define ASMSH_COMPILE_ARGS {"", "-O2", "-f", "-ad", "-o", NULL, "-c", "-", NULL}
#define ASMSH_COMPILE_OBJ "/tmp/asmsh_jit_XXXXXX"

typedef struct asmsh_asmc_ctx_s asmsh_asmc_ctx_t;
typedef struct asmsh_asmc_child_s asmsh_asmc_child_t;
typedef struct asmsh_bytecode_s asmsh_bytecode_t;

struct asmsh_asmc_child_s
{
	/** Compiler subprocess PID (waiting code on piped STDIN) */
	pid_t pid;
	/** Write endpoint of subprocess's piped STDIN  */
	int pipe_stdin;
	/** Read endpoint of subprocess's piped STDOUT & STDERR  */
	int pipe_stdout[2];
};

struct asmsh_asmc_ctx_s
{
	/** NULL terminated list of args for child subprocess,
	 * arg[0] is progname */
	char **args;
	/** Points on args[0] */
	char *progname;
	/** Points on the result path argument (value of -o) */
	char *respath;

	/** Compilation timeout  */
	struct timeval ctimeout;

	/** A child, that can be spawn in advance */
	asmsh_asmc_child_t child;

	/** If true pre spawn childs */
	char pre_spawn;
};

/** Compilation result, 1 instruction bytecode */
struct asmsh_bytecode_s
{
	/** Instruction bytes */
	unsigned char bytes[15];
	/** Instruction size */
	char size;
};

/**
 * Check if :
 * - contains no ';' nor '#' nor '\n'
 * - only contains char in range [0x20 .. 0x7E]
 * - do not begins by '.'
 *
 * @param char* The instruction to pre-check
 * @param char** If not null contains a reason on failure (and must be freed)
 * @return 0 if instr has a valid syntax else -1
 */
int asmsh_asmc_syntax(const char* instr, char **reason);

/** Return a default compilation context */
asmsh_asmc_ctx_t* asmsh_asmc_ctx_default();

/** Return a new compilation context
 * @param char* The assembler name/path
 * @param char* The result path for the compiled obj as mkstemp(3) template
 * @param char*[] The assembler list of arguments, without the argv[0] progname and with NULL as a placeholder for the result path
 * @param int If 0 no child are pre-spawned, else a child is spawned in returned context
 * @param struct timeval* Compilation timeout
 */
asmsh_asmc_ctx_t* asmsh_asmc_ctx(const char *progname, \
		const char *result_path, char* const args[], int pre_spawn,
		struct timeval *ctimeout);

/** Free all compile context resources */
void asmsh_asmc_ctx_free(asmsh_asmc_ctx_t *ctx);

/** Compile an instruction
 * @param asmsh_asmc_ctx_t* The context
 * @param const char* The instruction to compile
 * @param asmsh_bytecode_t* Pointer on the result struct
 * @return 0 if ok else -1  on failure with errno set
 */
int asmsh_asmc_compile(asmsh_asmc_ctx_t *ctx, const char *instr, asmsh_bytecode_t *res);

int asmsh_asmc_compile_unsafe(asmsh_asmc_ctx_t *ctx, const char *_instr, asmsh_bytecode_t *res);

/** Spawn an assembler process child process
 * @return 0 if no error else -1
 */
int asmsh_asmc_spawn(asmsh_asmc_ctx_t *ctx);

/**Child process main function
 * @param int[2][2] The pipes for stdin and stderr in this order
 * @param *char The path/name of the assembler executable
 * @param *char[] The NULL terminated list of arguments for the assembler
 * @return NEVER
 */
void asmsh_asmc_child(const int std_pipes[3][2], const char *progname, char* const args[]);

/** Given an object file, extract the "bytecode"
 *
 * Copy the .text segment of an ELF file
 * @param const char* the object file path
 * @param asmsh_bytecode_t* The result bytecode
 *
 * @return 0 if no error else -1
 */
int asmh_asmc_bytecode_from_obj(const char *objfile, asmsh_bytecode_t *bytecode);

/** Forge compiler arguments.
 *
 * The constructed arguments list will be allocated in args_o.
 * Put progname as first argument, result_tpl will replace the first NULL encountered
 * in the args_in array. args_in is an array of argument, that will be copied in
 * args_o. 
 * @param const char* The compiler name/path
 * @param const char* An mkstemp() file template
 * @param char *const[] The NULL terminated list of arguments, the first will
 * 	be replaced by the progname value. And the first encountered NULL will
 * 	be affected to the temporary result file (from result_tpl)
 * @param char** The resulting args
 * @return 0 if no error else -1
 */
int asmsh_asmc_buildarg(const char* progname, const char *result_tpl, \
		char *const args_in[],
		char ***args_o, char **progname_o, char **respath_o);


#endif