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// SPDX-License-Identifier: GPL-2.0
#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;
/* Setup environment variable for invoked shell script. */
setenv("PREFIX", prefix, 1);
}
#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);
}
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