/* 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/>.
*/
#include "mmap_parse.h"

void child_mmap_init(child_mmap_l *maps)
{
	bzero(maps, sizeof(*maps));
}


int child_mmap_get(pid_t child_pid, child_mmap_l *maps)
{
	char procfs_path[PATH_MAX+1];
	int ret, maps_fd;
	
	if(child_pid == -1)
	{
		errno = EINVAL;
		return -1;
	}

	ret = snprintf(procfs_path, PATH_MAX, "/proc/%d/maps", child_pid);
	if(ret < 0) { return -1; }
	procfs_path[ret] = '\0';

	if((maps_fd = open(procfs_path, O_RDONLY)) < 0)
	{
		return -1;
	}

	if(child_mmap_get_fd(maps_fd, maps) < 0)
	{
		ret = -1;
	}
	else
	{
		ret = 0;
	}

	close(maps_fd);
	return ret;
}

int child_mmap_get_fd(int maps_fd, child_mmap_l *maps)
{
	const int RDBUF_SZ = 4095;
	char rdbuf[RDBUF_SZ+1];
	char *line, *endline;
	int ret;
	size_t curmap;
	void *tmp;
	
	curmap = 0;

	do
	{
		ret = read(maps_fd, rdbuf, RDBUF_SZ);
		if(ret < 0) { goto err; }
		else if(ret == 0) { break; }
		rdbuf[ret] = '\0';
		line = endline = rdbuf;
		while(*endline)
		{
			if(*endline == '\n')
			{
				if(maps->size <= curmap)
				{
					if(_child_mmap_alloc(curmap, maps) < 0)
					{
						goto err;
					}
				}

				*endline = '\0';
				ret = child_mmap_parseline(line, &maps->maps[curmap]);
				if(ret < 0) { goto err; }
				line = endline + 1;
				curmap++;
			}
			endline++;
		}
	}while(1);

	close(maps_fd);

	if(curmap < maps->size)
	{
		tmp = realloc(maps->maps, sizeof(child_mmap_t) * curmap);
		if(!tmp)
		{
			perror("err");
			goto err;
		}
		maps->maps = tmp;
		maps->size = curmap;
	}

	return 0;
err:
	ret = errno;
	close(maps_fd);
	errno = ret;
	return -1;
}


int child_mmap_parseline(char *line, child_mmap_t *maps)
{
	char *orig, *endptr;
	unsigned long long parsed;
	int cperm;
	size_t i;
	int major;

	const char perms[3] = "rwx";
	const int perms_val[3] = {PROT_READ, PROT_WRITE, PROT_EXEC};

#define parsefield(line, sep, base, mapfield) {\
	unsigned long long p; char *endptr;\
	errno = 0;\
	p = strtoull(*line, &endptr, base);\
	if(errno || *endptr != sep) {\
		dprintf(2, "*line : '%s' %s\n", *line, #mapfield);\
		if(errno != ERANGE) { errno=EINVAL; }\
		goto err_inval;\
	}\
	*mapfield=(typeof(*mapfield))p;\
	*line = endptr+1;\
}
	
	orig = line;

	parsefield(&line, '-', 16, &maps->start);
	parsefield(&line, ' ', 16, &maps->stop);

	cperm = 1;
	maps->perm = 0;
	for(i=0; i<3; i++)
	{
		if(*line == perms[i])
		{
			maps->perm |= perms_val[i];
		}
		else if (*line != '-')
		{
			goto err_inval;
		}
		line++;
		cperm <<= 1;
	}
	switch(*line)
	{
		case 'p':
			maps->perm |= MAP_PRIVATE;
			break;
		case 's':
			maps->perm |= MAP_SHARED;
			break;
		default:
			goto err_inval;
	}

	line++;

	parsefield(&line, ' ', 16, &maps->offset);
	parsefield(&line, ':', 10, &major);
	parsefield(&line, ' ', 10, &maps->device);
	maps->device |= major << 8; // WARNING : hardcoded major shift
	//parsefield(&line, ' ', 10, &maps->inode);

	errno = 0;
	parsed = strtoull(line, &endptr, 10);
	if(errno || (*endptr != ' ' && *endptr != '\0'))
	{
		if(errno != ERANGE) { errno = EINVAL; }
		goto err_inval;
	}
	maps->inode = parsed;
	line = endptr;

	while(*line==' ') { line++; }

	maps->pathname = strndup(line, PATH_MAX * 8);

	return 0;

	err_inval:
		dprintf(2, "Invalid procfs/[pid]/maps content '%s'", orig);
		return -1;
}

int _child_mmap_alloc(size_t curmap, child_mmap_l *maps)
{
	void *tmp;
	maps->size++;
	if(curmap == 0)
	{
		tmp = malloc(sizeof(child_mmap_t));
	}
	else
	{
		tmp = realloc(maps->maps,
			sizeof(child_mmap_t) * maps->size);
	}
	if(!tmp)
	{
		perror("Unable to allocate maps description");
		return -1;
	}
	maps->maps = tmp;
	return 0;
}