#include <linux/compiler.h>#include <linux/string.h>#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <string.h>#include <stdlib.h>#include <stdio.h>#include "subcmd-util.h"#include "exec-cmd.h"#include "subcmd-config.h" #define MAX_ARGS	32#define PATH_MAX	4096 static const char *argv_exec_path;static const char *argv0_path; void exec_cmd_init(const char *exec_name, const char *prefix,		   const char *exec_path, const char *exec_path_env){	subcmd_config.exec_name		= exec_name;	subcmd_config.prefix		= prefix;	subcmd_config.exec_path		= exec_path;	subcmd_config.exec_path_env	= exec_path_env;} #define is_dir_sep(c) ((c) == '/') static int is_absolute_path(const char *path){	return path[0] == '/';} static const char *get_pwd_cwd(void){	static char cwd[PATH_MAX + 1];	char *pwd;	struct stat cwd_stat, pwd_stat;	if (getcwd(cwd, PATH_MAX) == NULL)		return NULL;	pwd = getenv("PWD");	if (pwd && strcmp(pwd, cwd)) {		stat(cwd, &cwd_stat);		if (!stat(pwd, &pwd_stat) &&		    pwd_stat.st_dev == cwd_stat.st_dev &&		    pwd_stat.st_ino == cwd_stat.st_ino) {			strlcpy(cwd, pwd, PATH_MAX);		}	}	return cwd;} static const char *make_nonrelative_path(const char *path){	static char buf[PATH_MAX + 1]; 	if (is_absolute_path(path)) {		if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)			die("Too long path: %.*s", 60, path);	} else {		const char *cwd = get_pwd_cwd();		if (!cwd)			die("Cannot determine the current working directory");		if (snprintf(buf, PATH_MAX, "%s/%s", cwd, path) >= PATH_MAX)			die("Too long path: %.*s", 60, path);	}	return buf;} char *system_path(const char *path){	char *buf = NULL; 	if (is_absolute_path(path))		return strdup(path); 	astrcatf(&buf, "%s/%s", subcmd_config.prefix, path); 	return buf;} const char *extract_argv0_path(const char *argv0){	const char *slash; 	if (!argv0 || !*argv0)		return NULL;	slash = argv0 + strlen(argv0); 	while (argv0 <= slash && !is_dir_sep(*slash))		slash--; 	if (slash >= argv0) {		argv0_path = strndup(argv0, slash - argv0);		return argv0_path ? slash + 1 : NULL;	} 	return argv0;} void set_argv_exec_path(const char *exec_path){	argv_exec_path = exec_path;	/*	 * Propagate this setting to external programs.	 */	setenv(subcmd_config.exec_path_env, exec_path, 1);}  /* Returns the highest-priority location to look for subprograms. */char *get_argv_exec_path(void){	char *env; 	if (argv_exec_path)		return strdup(argv_exec_path); 	env = getenv(subcmd_config.exec_path_env);	if (env && *env)		return strdup(env); 	return system_path(subcmd_config.exec_path);} static void add_path(char **out, const char *path){	if (path && *path) {		if (is_absolute_path(path))			astrcat(out, path);		else			astrcat(out, make_nonrelative_path(path)); 		astrcat(out, ":");	}} void setup_path(void){	const char *old_path = getenv("PATH");	char *new_path = NULL;	char *tmp = get_argv_exec_path(); 	add_path(&new_path, tmp);	add_path(&new_path, argv0_path);	free(tmp); 	if (old_path)		astrcat(&new_path, old_path);	else		astrcat(&new_path, "/usr/local/bin:/usr/bin:/bin"); 	setenv("PATH", new_path, 1); 	free(new_path);} static const char **prepare_exec_cmd(const char **argv){	int argc;	const char **nargv; 	for (argc = 0; argv[argc]; argc++)		; /* just counting */	nargv = malloc(sizeof(*nargv) * (argc + 2)); 	nargv[0] = subcmd_config.exec_name;	for (argc = 0; argv[argc]; argc++)		nargv[argc + 1] = argv[argc];	nargv[argc + 1] = NULL;	return nargv;} int execv_cmd(const char **argv) {	const char **nargv = prepare_exec_cmd(argv); 	/* execvp() can only ever return if it fails */	execvp(subcmd_config.exec_name, (char **)nargv); 	free(nargv);	return -1;}  int execl_cmd(const char *cmd,...){	int argc;	const char *argv[MAX_ARGS + 1];	const char *arg;	va_list param; 	va_start(param, cmd);	argv[0] = cmd;	argc = 1;	while (argc < MAX_ARGS) {		arg = argv[argc++] = va_arg(param, char *);		if (!arg)			break;	}	va_end(param);	if (MAX_ARGS <= argc) {		fprintf(stderr, " Error: too many args to run %s\n", cmd);		return -1;	} 	argv[argc] = NULL;	return execv_cmd(argv);}