exec.c

#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>
#include "env.h"
#include "path.h"
#include "execution.h"
#include "minishell.h"

/*
 * find executable file in dirpath.
 *
 *   filename: filename
 *   dirpath: the directory to search
 *
 *   return:  fullpath of found executable file,
 *            otherwise return NULL.
 */
char	*find_executable_file_in_dir(char *filename, char *dirpath)
{
	DIR				*dir;
	struct dirent	*dirp;
	struct stat		buf;
	char			*fullpath;

	dir = opendir(dirpath);
	if (!dir)
		return (NULL);
	dirp = readdir(dir);
	while (dirp)
	{
		if (ft_strcmp(dirp->d_name, filename) == 0)
		{
			fullpath = path_join(dirpath, dirp->d_name);
			if (!fullpath)
				return (free_and_rtn_ptr(dir, NULL));
			if (stat(fullpath, &buf) == 0 && S_ISREG(buf.st_mode))
				return (free_and_rtn_ptr(dir, fullpath));
			free(fullpath);
		}
		dirp = readdir(dir);
	}
	return (free_and_rtn_ptr(dir, NULL));
}

/*
 * This function search file in directories in dirs and try to execute.
 */
static char	*search_and_exec_file_from_dirs(char *filename,
	char **argv, char **dirs)
{
	char		**envs;
	int			i;
	char		*executable_path;
	char		*last_executable_path;

	i = 0;
	last_executable_path = NULL;
	envs = vars2environ(g_shell.vars);
	while (dirs[i])
	{
		if (dirs[i])
			executable_path = find_executable_file_in_dir(filename, dirs[i]);
		if (executable_path)
		{
			free(last_executable_path);
			last_executable_path = ft_strdup(executable_path);
			execve(executable_path, argv, envs);
		}
		free(executable_path);
		i++;
	}
	free_ptrarr((void **)envs);
	return (last_executable_path);
}

/*
 * This function search file in directories in $PATH and try to execute.
 */
char	*search_and_exec_file_from_path_env(char *filename, char **argv)
{
	t_var		*path_env_var;
	char		**dirs;
	char		*last_executable_path;

	path_env_var = get_env("PATH");
	if (!path_env_var || !path_env_var->value)
		return (NULL);
	dirs = get_colon_units(path_env_var->value, "./");
	last_executable_path = search_and_exec_file_from_dirs(filename, argv, dirs);
	free_ptrarr((void **)dirs);
	return (last_executable_path);
}

/*
 * This function works just like execvp.
 *
 * filename: filename or filepath.
 * argv: arguments that is passed to execution program
 *
 * return: If exec command successful, no value will be returned.
 *         This function returning value means exec or other function is failed.
 */
int	cmd_execvp(char *filename, char **argv)
{
	char		*executable_path;

	errno = 0;
	executable_path = filename;
	if (ft_strchr(filename, '/'))
		execve(filename, argv, vars2environ(g_shell.vars));
	else
		executable_path = search_and_exec_file_from_path_env(filename, argv);
	if (executable_path && is_directory(executable_path))
		put_minish_err_msg_and_exit(126, executable_path, "Is a directory");
	if (errno == ENOEXEC && is_executable(executable_path))
		exit(0);
	else if (errno == ENOEXEC && !is_executable(executable_path))
		errno = EACCES;
	if (errno && executable_path)
		put_minish_err_msg(executable_path, strerror(errno));
	else
		put_minish_err_msg(filename, "command not found");
	if (errno && errno != ENOENT)
		exit(126);
	exit(127);
}