1#include <linux/compiler.h>
  2#include <linux/string.h>
  3#include <sys/types.h>
  4#include <sys/stat.h>
  5#include <unistd.h>
  6#include <string.h>
  7#include <stdlib.h>
  8#include <stdio.h>
  9#include "subcmd-util.h"
 10#include "exec-cmd.h"
 11#include "subcmd-config.h"
 12
 13#define MAX_ARGS	32
 14#define PATH_MAX	4096
 15
 16static const char *argv_exec_path;
 17static const char *argv0_path;
 18
 19void exec_cmd_init(const char *exec_name, const char *prefix,
 20		   const char *exec_path, const char *exec_path_env)
 21{
 22	subcmd_config.exec_name		= exec_name;
 23	subcmd_config.prefix		= prefix;
 24	subcmd_config.exec_path		= exec_path;
 25	subcmd_config.exec_path_env	= exec_path_env;
 26}
 27
 28#define is_dir_sep(c) ((c) == '/')
 29
 30static int is_absolute_path(const char *path)
 31{
 32	return path[0] == '/';
 33}
 34
 35static const char *get_pwd_cwd(void)
 36{
 37	static char cwd[PATH_MAX + 1];
 38	char *pwd;
 39	struct stat cwd_stat, pwd_stat;
 40	if (getcwd(cwd, PATH_MAX) == NULL)
 41		return NULL;
 42	pwd = getenv("PWD");
 43	if (pwd && strcmp(pwd, cwd)) {
 44		stat(cwd, &cwd_stat);
 45		if (!stat(pwd, &pwd_stat) &&
 46		    pwd_stat.st_dev == cwd_stat.st_dev &&
 47		    pwd_stat.st_ino == cwd_stat.st_ino) {
 48			strlcpy(cwd, pwd, PATH_MAX);
 49		}
 50	}
 51	return cwd;
 52}
 53
 54static const char *make_nonrelative_path(const char *path)
 55{
 56	static char buf[PATH_MAX + 1];
 57
 58	if (is_absolute_path(path)) {
 59		if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
 60			die("Too long path: %.*s", 60, path);
 61	} else {
 62		const char *cwd = get_pwd_cwd();
 63		if (!cwd)
 64			die("Cannot determine the current working directory");
 65		if (snprintf(buf, PATH_MAX, "%s/%s", cwd, path) >= PATH_MAX)
 66			die("Too long path: %.*s", 60, path);
 67	}
 68	return buf;
 69}
 70
 71char *system_path(const char *path)
 72{
 73	char *buf = NULL;
 74
 75	if (is_absolute_path(path))
 76		return strdup(path);
 77
 78	astrcatf(&buf, "%s/%s", subcmd_config.prefix, path);
 79
 80	return buf;
 81}
 82
 83const char *extract_argv0_path(const char *argv0)
 84{
 85	const char *slash;
 86
 87	if (!argv0 || !*argv0)
 88		return NULL;
 89	slash = argv0 + strlen(argv0);
 90
 91	while (argv0 <= slash && !is_dir_sep(*slash))
 92		slash--;
 93
 94	if (slash >= argv0) {
 95		argv0_path = strndup(argv0, slash - argv0);
 96		return argv0_path ? slash + 1 : NULL;
 97	}
 98
 99	return argv0;
100}
101
102void set_argv_exec_path(const char *exec_path)
103{
104	argv_exec_path = exec_path;
105	/*
106	 * Propagate this setting to external programs.
107	 */
108	setenv(subcmd_config.exec_path_env, exec_path, 1);
109}
110
111
112/* Returns the highest-priority location to look for subprograms. */
113char *get_argv_exec_path(void)
114{
115	char *env;
116
117	if (argv_exec_path)
118		return strdup(argv_exec_path);
119
120	env = getenv(subcmd_config.exec_path_env);
121	if (env && *env)
122		return strdup(env);
123
124	return system_path(subcmd_config.exec_path);
125}
126
127static void add_path(char **out, const char *path)
128{
129	if (path && *path) {
130		if (is_absolute_path(path))
131			astrcat(out, path);
132		else
133			astrcat(out, make_nonrelative_path(path));
134
135		astrcat(out, ":");
136	}
137}
138
139void setup_path(void)
140{
141	const char *old_path = getenv("PATH");
142	char *new_path = NULL;
143	char *tmp = get_argv_exec_path();
144
145	add_path(&new_path, tmp);
146	add_path(&new_path, argv0_path);
147	free(tmp);
148
149	if (old_path)
150		astrcat(&new_path, old_path);
151	else
152		astrcat(&new_path, "/usr/local/bin:/usr/bin:/bin");
153
154	setenv("PATH", new_path, 1);
155
156	free(new_path);
157}
158
159static const char **prepare_exec_cmd(const char **argv)
160{
161	int argc;
162	const char **nargv;
163
164	for (argc = 0; argv[argc]; argc++)
165		; /* just counting */
166	nargv = malloc(sizeof(*nargv) * (argc + 2));
167
168	nargv[0] = subcmd_config.exec_name;
169	for (argc = 0; argv[argc]; argc++)
170		nargv[argc + 1] = argv[argc];
171	nargv[argc + 1] = NULL;
172	return nargv;
173}
174
175int execv_cmd(const char **argv) {
176	const char **nargv = prepare_exec_cmd(argv);
177
178	/* execvp() can only ever return if it fails */
179	execvp(subcmd_config.exec_name, (char **)nargv);
180
181	free(nargv);
182	return -1;
183}
184
185
186int execl_cmd(const char *cmd,...)
187{
188	int argc;
189	const char *argv[MAX_ARGS + 1];
190	const char *arg;
191	va_list param;
192
193	va_start(param, cmd);
194	argv[0] = cmd;
195	argc = 1;
196	while (argc < MAX_ARGS) {
197		arg = argv[argc++] = va_arg(param, char *);
198		if (!arg)
199			break;
200	}
201	va_end(param);
202	if (MAX_ARGS <= argc) {
203		fprintf(stderr, " Error: too many args to run %s\n", cmd);
204		return -1;
205	}
206
207	argv[argc] = NULL;
208	return execv_cmd(argv);
209}