mips/masm/gen/section.c

#include "../gen.h"

#include <strings.h>
#include <string.h>
#include <stdlib.h>
#include <merror.h>

struct section_default {
	char *name;
	int name_len;

	bool read;
	bool write;
	bool execute;
	int alignment;
};

#define SECTION_DEFAULTS_LEN 7
#define MAPPING(name, ...) {name, sizeof(name), __VA_ARGS__}
static const struct section_default section_defaults[SECTION_DEFAULTS_LEN] = {
	MAPPING(".text", true, false, true, 4),
	MAPPING(".code", true, false, true, 4),
	MAPPING(".data", true, true, false, 1),
	MAPPING(".stack", true, true, false, 1),
	MAPPING(".rodata", true, false, false, 1),
	MAPPING(".bss", true, true, false, 1),
	MAPPING(".robss", true, false, false, 1),
};

static void section_get_default_perm(struct section *sec, const char *name)
{
	for (int i = 0; i < SECTION_DEFAULTS_LEN; i++) {
		const struct section_default *defaults = &section_defaults[i];
		if (strncasecmp(name, defaults->name, defaults->name_len))
			continue;
		sec->read = defaults->read;
		sec->write = defaults->write;
		sec->execute = defaults->execute;
		sec->align = defaults->alignment;
		break;
	}
}

int gen_get_section(struct generator *gen, struct section **res,
		    struct string *name)
{
	/// find the section if it exists
	for (size_t i = 0; i < gen->sections_len; i++) {
		struct section *sec = &gen->sections[i];
		if (sec->name.len != name->len)
			continue;
		if (strcmp(sec->name.str, name->str) != 0)
			continue;
		*res = sec;
		return 0;
	}

	/// allocate a new one if it doesnt
	size_t size = gen->sections_size ? gen->sections_size * 2 : 8;
	void *new = realloc(gen->sections, size * sizeof(struct section));
	if (new == NULL) {
		PERROR("cannot realloc");
		return 1;
	}

	gen->sections_size = size;
	gen->sections = new;

	struct section *sec = &gen->sections[gen->sections_len++];
	if (section_init(sec, name))
		return 1;

	*res = sec;
	return 0;
}

int section_init(struct section *sec, struct string *name)
{
	sec->len = 0;
	sec->size = 0;
	sec->align = 1;
	sec->data = NULL;
	sec->read = true;
	sec->write = true;
	sec->execute = false;

	// set defaults
	section_get_default_perm(sec, name->str);

	// alloc reftab
	if (reftab_init(&sec->reftab))
		return 1;

	// copy name
	if (string_clone(&sec->name, name))
		return 1;

	return 0;
}

int section_extend(struct section *section, size_t space)
{
	size_t newlen = section->len + space;
	if (newlen < section->size)
		return M_SUCCESS;

	size_t size = section->size ? section->size * 2 + newlen : newlen * 2;
	void *new = realloc(section->data, size);
	if (new == NULL) {
		PERROR("cannot realloc");
		return M_ERROR;
	}
	section->size = size;
	section->data = new;

	return M_SUCCESS;
}

int section_push(struct section *section, void *data, size_t len)
{
	size_t newlen = section->len + len;
	size_t zeros = newlen % section->align;
	if (zeros)
		zeros = section->align - zeros;

	if (section_extend(section, len + zeros))
		return M_ERROR;

	memset(section->data + section->len, 0, zeros);
	memcpy(section->data + section->len + zeros, data, len);
	section->len += len + zeros;

	return M_SUCCESS;
}

int section_zero(struct section *section, size_t len)
{
	size_t zeros = section->len % section->align;
	if (zeros)
		zeros = section->align - zeros;

	if (section_extend(section, len + zeros))
		return M_ERROR;

	memset(section->data + section->len, 0, len + zeros);
	section->len += len + zeros;

	return M_SUCCESS;
}

void section_free(struct section *section)
{
	reftab_free(&section->reftab);
	string_free(&section->name);
	free(section->data);
}