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/* newgrp.c
This file is part of Cygwin.
This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#include <string.h>
#include <wchar.h>
#include <locale.h>
#include <grp.h>
#include <pwd.h>
#include <sys/cygwin.h>
#include <w32api/windows.h>
#include <w32api/userenv.h>
#define PATH_PREFIX "PATH=/usr/bin:"
char *
create_env_var (const char *name, const char *val)
{
char *var, *cp;
var = (char *) calloc (strlen (name) + strlen (val) + 2, sizeof (char *));
cp = stpcpy (var, name);
*cp++ = '=';
stpcpy (cp, val);
return var;
}
char **
create_child_env (struct passwd *pw)
{
char **posix_env, *cp;
wchar_t *win_env, *wep;
size_t max_cnt = 0;
size_t idx = 0;
HANDLE token;
/* Fecth Windows default environment of current user */
if (!OpenProcessToken (GetCurrentProcess (),
TOKEN_QUERY | TOKEN_DUPLICATE, &token))
{
fprintf (stderr, "%s: creating environment failed with error %u "
"(OpenProcessToken)\n",
program_invocation_short_name, GetLastError ());
return NULL;
}
if (!CreateEnvironmentBlock ((PVOID *) &win_env, token, FALSE))
{
fprintf (stderr, "%s: creating environment failed with error %u "
"(CreateEnvironmentBlock)\n",
program_invocation_short_name, GetLastError ());
CloseHandle (token);
return NULL;
}
CloseHandle (token);
/* Convert to Posix env */
for (wep = win_env; *wep; wep = wcschr (wep, '\0') + 1)
++max_cnt;
posix_env = (char **) calloc (max_cnt + 6, sizeof (char *));
if (!posix_env)
{
fprintf (stderr, "%s: allocating environment failed: %s\n",
program_invocation_short_name, strerror (errno));
return NULL;
}
for (wep = win_env; *wep; ++idx, wep = wcschr (wep, '\0') + 1)
{
/* For $PATH we must prepend /usr/bin to the converted POSIX path list */
if (!wcsncasecmp (wep, L"PATH=", 5))
{
size_t len = cygwin_conv_path_list (CCP_WIN_W_TO_POSIX,
wep + 5, NULL, 0);
posix_env[idx] = (char *) calloc (sizeof (PATH_PREFIX) + len,
sizeof (char *));
if (!posix_env[idx])
{
fprintf (stderr, "%s: allocating environment failed: %s\n",
program_invocation_short_name, strerror (errno));
return NULL;
}
cp = stpcpy (posix_env[idx], PATH_PREFIX);
cygwin_conv_path_list (CCP_WIN_W_TO_POSIX, wep + 5, cp, len);
}
else
{
size_t len = wcstombs (NULL, wep, 0);
if (len == (size_t) -1)
{
fprintf (stderr,
"%s: invalid char in environment variable: %ls\n",
program_invocation_short_name, wep);
return NULL;
}
posix_env[idx] = (char *) calloc (len + 1, sizeof (char *));
if (!posix_env[idx])
{
fprintf (stderr, "%s: allocating environment failed: %s\n",
program_invocation_short_name, strerror (errno));
return NULL;
}
wcstombs (posix_env[idx], wep, len + 1);
}
}
DestroyEnvironmentBlock (win_env);
/* Add USER, LOGNAME, HOME, LANG, just like sshd */
posix_env[idx++] = create_env_var ("USER", pw->pw_name);
posix_env[idx++] = create_env_var ("LOGNAME", pw->pw_name);
posix_env[idx++] = create_env_var ("HOME", pw->pw_dir);
cp = getenv("LANG");
if (cp)
posix_env[idx] = create_env_var ("LANG", cp);
cp = getenv("TERM");
if (cp)
posix_env[idx] = create_env_var ("TERM", cp);
return posix_env;
}
int
main (int argc, const char **argv)
{
const char *cmd, **cmd_av, *fake_av[2];
struct passwd *pw;
struct group *gr;
char **child_env;
bool new_child_env = false;
gid_t gid;
setlocale (LC_ALL, "");
if (argc < 2 || (argv[1][0] == '-' && argv[1][1]))
{
fprintf (stderr, "Usage: %s [-] [group] [command [args...]]\n",
program_invocation_short_name);
return 1;
}
/* Check if we have to regenerate a stock environment */
if (argv[1][0] == '-')
{
new_child_env = true;
--argc;
++argv;
}
pw = getpwuid (getuid ());
/* Fetch group */
if (argv[1] == NULL)
{
gid = pw->pw_gid;
}
else
{
gr = getgrnam (argv[1]);
if (!gr)
{
fprintf (stderr, "%s: group '%s' does not exist\n",
program_invocation_short_name, argv[1]);
return 2;
}
gid = gr->gr_gid;
--argc;
++argv;
}
/* Set primary group */
if (setgid (gid) != 0)
{
fprintf (stderr, "%s: can't switch primary group to '%s'\n",
program_invocation_short_name, argv[1]);
return 2;
}
/* Maybe generate stock child environment */
if (!new_child_env)
child_env = environ;
else
{
child_env = create_child_env (pw);
if (!child_env)
return 3;
chdir (pw->pw_dir);
}
/* Set argc/argv for execvpe */
--argc;
++argv;
if (argc < 1)
{
if (!pw)
cmd = "/usr/bin/bash";
else
cmd = pw->pw_shell;
fake_av[0] = new_child_env ? "-" : cmd;
fake_av[1] = NULL;
cmd_av = fake_av;
}
else
{
cmd = argv[0];
cmd_av = argv;
}
/* Exec child process */
execvpe (cmd, (char **) cmd_av, child_env);
/* Oops */
fprintf (stderr, "%s: failed to start '%s': %s\n",
program_invocation_short_name, cmd, strerror (errno));
return 4;
}
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