25
24
#define _GNU_SOURCE /* TEMP_FAILURE_RETRY(), getline(),
26
asprintf(), O_CLOEXEC */
27
26
#include <stddef.h> /* size_t, NULL */
28
#include <stdlib.h> /* malloc(), exit(), EXIT_SUCCESS,
27
#include <stdlib.h> /* malloc(), exit(), EXIT_FAILURE,
28
EXIT_SUCCESS, realloc() */
30
29
#include <stdbool.h> /* bool, true, false */
31
#include <stdio.h> /* fileno(), fprintf(),
32
stderr, STDOUT_FILENO */
33
#include <sys/types.h> /* DIR, fdopendir(), stat(), struct
30
#include <stdio.h> /* perror, popen(), fileno(),
31
fprintf(), stderr, STDOUT_FILENO */
32
#include <sys/types.h> /* DIR, opendir(), stat(), struct
34
33
stat, waitpid(), WIFEXITED(),
35
34
WEXITSTATUS(), wait(), pid_t,
36
35
uid_t, gid_t, getuid(), getgid(),
38
37
#include <sys/select.h> /* fd_set, select(), FD_ZERO(),
39
38
FD_SET(), FD_ISSET(), FD_CLR */
40
39
#include <sys/wait.h> /* wait(), waitpid(), WIFEXITED(),
41
WEXITSTATUS(), WTERMSIG(),
43
41
#include <sys/stat.h> /* struct stat, stat(), S_ISREG() */
44
42
#include <iso646.h> /* and, or, not */
45
#include <dirent.h> /* DIR, struct dirent, fdopendir(),
43
#include <dirent.h> /* DIR, struct dirent, opendir(),
46
44
readdir(), closedir(), dirfd() */
47
45
#include <unistd.h> /* struct stat, stat(), S_ISREG(),
48
46
fcntl(), setuid(), setgid(),
49
47
F_GETFD, F_SETFD, FD_CLOEXEC,
50
48
access(), pipe(), fork(), close()
51
dup2(), STDOUT_FILENO, _exit(),
49
dup2, STDOUT_FILENO, _exit(),
52
50
execv(), write(), read(),
54
52
#include <fcntl.h> /* fcntl(), F_GETFD, F_SETFD,
56
#include <string.h> /* strsep, strlen(), asprintf(),
57
strsignal(), strcmp(), strncmp() */
54
#include <string.h> /* strsep, strlen(), asprintf() */
58
55
#include <errno.h> /* errno */
59
56
#include <argp.h> /* struct argp_option, struct
60
57
argp_state, struct argp,
64
61
#include <signal.h> /* struct sigaction, sigemptyset(),
65
62
sigaddset(), sigaction(),
66
63
sigprocmask(), SIG_BLOCK, SIGCHLD,
67
SIG_UNBLOCK, kill(), sig_atomic_t
64
SIG_UNBLOCK, kill() */
69
65
#include <errno.h> /* errno, EBADF */
70
#include <inttypes.h> /* intmax_t, PRIdMAX, strtoimax() */
71
#include <sysexits.h> /* EX_OSERR, EX_USAGE, EX_IOERR,
72
EX_CONFIG, EX_UNAVAILABLE, EX_OK */
73
#include <errno.h> /* errno */
74
#include <error.h> /* error() */
76
67
#define BUFFER_SIZE 256
78
69
#define PDIR "/lib/mandos/plugins.d"
79
70
#define AFILE "/conf/conf.d/mandos/plugin-runner.conf"
81
const char *argp_program_version = "plugin-runner " VERSION;
72
const char *argp_program_version = "plugin-runner 1.0";
82
73
const char *argp_program_bug_address = "<mandos@fukt.bsnet.se>";
84
77
typedef struct plugin{
85
78
char *name; /* can be NULL or any plugin name */
106
99
/* Gets an existing plugin based on name,
107
100
or if none is found, creates a new one */
108
101
static plugin *getplugin(char *name){
109
/* Check for existing plugin with that name */
110
for(plugin *p = plugin_list; p != NULL; p = p->next){
112
or (p->name and name and (strcmp(p->name, name) == 0))){
102
/* Check for exiting plugin with that name */
103
for (plugin *p = plugin_list; p != NULL; p = p->next){
104
if ((p->name == name)
105
or (p->name and name and (strcmp(p->name, name) == 0))){
116
109
/* Create a new plugin */
117
plugin *new_plugin = NULL;
119
new_plugin = malloc(sizeof(plugin));
120
} while(new_plugin == NULL and errno == EINTR);
121
if(new_plugin == NULL){
110
plugin *new_plugin = malloc(sizeof(plugin));
111
if (new_plugin == NULL){
124
114
char *copy_name = NULL;
125
115
if(name != NULL){
127
copy_name = strdup(name);
128
} while(copy_name == NULL and errno == EINTR);
116
copy_name = strdup(name);
129
117
if(copy_name == NULL){
137
*new_plugin = (plugin){ .name = copy_name,
140
.next = plugin_list };
122
*new_plugin = (plugin) { .name = copy_name,
125
.next = plugin_list };
143
new_plugin->argv = malloc(sizeof(char *) * 2);
144
} while(new_plugin->argv == NULL and errno == EINTR);
145
if(new_plugin->argv == NULL){
127
new_plugin->argv = malloc(sizeof(char *) * 2);
128
if (new_plugin->argv == NULL){
148
130
free(new_plugin);
152
133
new_plugin->argv[0] = copy_name;
153
134
new_plugin->argv[1] = NULL;
156
new_plugin->environ = malloc(sizeof(char *));
157
} while(new_plugin->environ == NULL and errno == EINTR);
136
new_plugin->environ = malloc(sizeof(char *));
158
137
if(new_plugin->environ == NULL){
161
139
free(new_plugin->argv);
162
140
free(new_plugin);
166
143
new_plugin->environ[0] = NULL;
404
373
.doc = "Group ID the plugins will run as", .group = 3 },
405
374
{ .name = "debug", .key = 132,
406
375
.doc = "Debug mode", .group = 4 },
408
* These reproduce what we would get without ARGP_NO_HELP
410
{ .name = "help", .key = '?',
411
.doc = "Give this help list", .group = -1 },
412
{ .name = "usage", .key = -3,
413
.doc = "Give a short usage message", .group = -1 },
414
{ .name = "version", .key = 'V',
415
.doc = "Print program version", .group = -1 },
419
error_t parse_opt(int key, char *arg, struct argp_state *state){
379
error_t parse_opt (int key, char *arg, __attribute__((unused))
380
struct argp_state *state) {
424
382
case 'g': /* --global-options */
427
while((plugin_option = strsep(&arg, ",")) != NULL){
428
if(not add_argument(getplugin(NULL), plugin_option)){
385
while((p = strsep(&arg, ",")) != NULL){
389
if(not add_argument(getplugin(NULL), p)){
390
perror("add_argument");
391
return ARGP_ERR_UNKNOWN;
434
396
case 'G': /* --global-env */
435
add_environment(getplugin(NULL), arg, true);
401
char *envdef = strdup(arg);
405
if(not add_environment(getplugin(NULL), envdef, true)){
406
perror("add_environment");
437
410
case 'o': /* --options-for */
439
char *option_list = strchr(arg, ':');
440
if(option_list == NULL){
441
argp_error(state, "No colon in \"%s\"", arg);
448
argp_error(state, "Empty plugin name");
453
while((option = strsep(&option_list, ",")) != NULL){
454
if(not add_argument(getplugin(arg), option)){
412
char *p_name = strsep(&arg, ":");
413
if(p_name[0] == '\0' or arg == NULL){
416
char *opt = strsep(&arg, ":");
417
if(opt[0] == '\0' or opt == NULL){
421
while((p = strsep(&opt, ",")) != NULL){
425
if(not add_argument(getplugin(p_name), p)){
426
perror("add_argument");
427
return ARGP_ERR_UNKNOWN;
460
432
case 'E': /* --env-for */
462
437
char *envdef = strchr(arg, ':');
463
438
if(envdef == NULL){
464
argp_error(state, "No colon in \"%s\"", arg);
441
char *p_name = strndup(arg, (size_t) (envdef-arg));
471
argp_error(state, "Empty plugin name");
446
if(not add_environment(getplugin(p_name), envdef, true)){
447
perror("add_environment");
475
add_environment(getplugin(arg), envdef, true);
478
451
case 'd': /* --disable */
480
453
plugin *p = getplugin(arg);
455
return ARGP_ERR_UNKNOWN;
486
460
case 'e': /* --enable */
488
462
plugin *p = getplugin(arg);
464
return ARGP_ERR_UNKNOWN;
494
469
case 128: /* --plugin-dir */
496
470
plugindir = strdup(arg);
471
if(plugindir == NULL){
498
475
case 129: /* --config-file */
499
476
/* This is already done by parse_opt_config_file() */
501
478
case 130: /* --userid */
502
tmpmax = strtoimax(arg, &tmp, 10);
503
if(errno != 0 or tmp == arg or *tmp != '\0'
504
or tmpmax != (uid_t)tmpmax){
505
argp_error(state, "Bad user ID number: \"%s\", using %"
506
PRIdMAX, arg, (intmax_t)uid);
479
uid = (uid_t)strtol(arg, NULL, 10);
511
481
case 131: /* --groupid */
512
tmpmax = strtoimax(arg, &tmp, 10);
513
if(errno != 0 or tmp == arg or *tmp != '\0'
514
or tmpmax != (gid_t)tmpmax){
515
argp_error(state, "Bad group ID number: \"%s\", using %"
516
PRIdMAX, arg, (intmax_t)gid);
482
gid = (gid_t)strtol(arg, NULL, 10);
521
484
case 132: /* --debug */
525
* These reproduce what we would get without ARGP_NO_HELP
527
case '?': /* --help */
528
state->flags &= ~(unsigned int)ARGP_NO_EXIT; /* force exit */
529
argp_state_help(state, state->out_stream, ARGP_HELP_STD_HELP);
530
case -3: /* --usage */
531
state->flags &= ~(unsigned int)ARGP_NO_EXIT; /* force exit */
532
argp_state_help(state, state->out_stream,
533
ARGP_HELP_USAGE | ARGP_HELP_EXIT_OK);
534
case 'V': /* --version */
535
fprintf(state->out_stream, "%s\n", argp_program_version);
539
* When adding more options before this line, remember to also add a
540
* "case" to the "parse_opt_config_file" function below.
542
487
case ARGP_KEY_ARG:
543
/* Cryptsetup always passes an argument, which is an empty
544
string if "none" was specified in /etc/crypttab. So if
545
argument was empty, we ignore it silently. */
488
fprintf(stderr, "Ignoring unknown argument \"%s\"\n", arg);
550
493
return ARGP_ERR_UNKNOWN;
552
return errno; /* Set to 0 at start */
555
498
/* This option parser is the same as parse_opt() above, except it
556
499
ignores everything but the --config-file option. */
557
error_t parse_opt_config_file(int key, char *arg,
558
__attribute__((unused))
559
struct argp_state *state){
500
error_t parse_opt_config_file (int key, char *arg,
501
__attribute__((unused))
502
struct argp_state *state) {
562
504
case 'g': /* --global-options */
563
505
case 'G': /* --global-env */
564
506
case 'o': /* --options-for */
661
594
custom_argv = realloc(custom_argv, sizeof(char *)
662
595
* ((unsigned int) custom_argc + 1));
663
596
if(custom_argv == NULL){
664
error(0, errno, "realloc");
665
exitstatus = EX_OSERR;
598
exitstatus = EXIT_FAILURE;
669
602
custom_argv[custom_argc-1] = new_arg;
670
custom_argv[custom_argc] = NULL;
603
custom_argv[custom_argc] = NULL;
674
ret = fclose(conffp);
675
} while(ret == EOF and errno == EINTR);
677
error(0, errno, "fclose");
678
exitstatus = EX_IOERR;
683
608
/* Check for harmful errors and go to fallback. Other errors might
684
609
not affect opening plugins */
685
if(errno == EMFILE or errno == ENFILE or errno == ENOMEM){
686
error(0, errno, "fopen");
687
exitstatus = EX_OSERR;
610
if (errno == EMFILE or errno == ENFILE or errno == ENOMEM){
612
exitstatus = EXIT_FAILURE;
691
/* If there were any arguments from the configuration file, pass
692
them to parser as command line arguments */
616
/* If there was any arguments from configuration file,
617
pass them to parser as command arguments */
693
618
if(custom_argv != NULL){
694
ret = argp_parse(&argp, custom_argc, custom_argv,
695
ARGP_IN_ORDER | ARGP_NO_EXIT | ARGP_NO_HELP,
703
error(0, errno, "argp_parse");
704
exitstatus = EX_OSERR;
707
exitstatus = EX_CONFIG;
619
ret = argp_parse (&argp, custom_argc, custom_argv, ARGP_IN_ORDER,
621
if (ret == ARGP_ERR_UNKNOWN){
622
fprintf(stderr, "Unknown error while parsing arguments\n");
623
exitstatus = EXIT_FAILURE;
712
628
/* Parse actual command line arguments, to let them override the
714
ret = argp_parse(&argp, argc, argv,
715
ARGP_IN_ORDER | ARGP_NO_EXIT | ARGP_NO_HELP,
723
error(0, errno, "argp_parse");
724
exitstatus = EX_OSERR;
727
exitstatus = EX_USAGE;
630
ret = argp_parse (&argp, argc, argv, ARGP_IN_ORDER, 0, NULL);
631
if (ret == ARGP_ERR_UNKNOWN){
632
fprintf(stderr, "Unknown error while parsing arguments\n");
633
exitstatus = EXIT_FAILURE;
745
651
/* Strip permissions down to nobody */
748
error(0, errno, "setgid");
752
error(0, errno, "setuid");
755
/* Open plugin directory with close_on_exec flag */
661
if (plugindir == NULL){
664
dir = opendir(plugindir);
668
perror("Could not open plugin dir");
669
exitstatus = EXIT_FAILURE;
673
/* Set the FD_CLOEXEC flag on the directory, if possible */
758
if(plugindir == NULL){
759
dir_fd = open(PDIR, O_RDONLY |
762
#else /* not O_CLOEXEC */
764
#endif /* not O_CLOEXEC */
767
dir_fd = open(plugindir, O_RDONLY |
770
#else /* not O_CLOEXEC */
772
#endif /* not O_CLOEXEC */
776
error(0, errno, "Could not open plugin dir");
777
exitstatus = EX_UNAVAILABLE;
782
/* Set the FD_CLOEXEC flag on the directory */
783
ret = set_cloexec_flag(dir_fd);
785
error(0, errno, "set_cloexec_flag");
786
TEMP_FAILURE_RETRY(close(dir_fd));
787
exitstatus = EX_OSERR;
790
#endif /* O_CLOEXEC */
792
dir = fdopendir(dir_fd);
794
error(0, errno, "Could not open plugin dir");
795
TEMP_FAILURE_RETRY(close(dir_fd));
796
exitstatus = EX_OSERR;
675
int dir_fd = dirfd(dir);
677
ret = set_cloexec_flag(dir_fd);
679
perror("set_cloexec_flag");
680
exitstatus = EXIT_FAILURE;
931
805
if(p->environ[0] != NULL){
932
806
for(char **e = environ; *e != NULL; e++){
933
807
if(not add_environment(p, *e, false)){
934
error(0, errno, "add_environment");
808
perror("add_environment");
940
ret = (int)TEMP_FAILURE_RETRY(pipe(pipefd));
942
error(0, errno, "pipe");
943
exitstatus = EX_OSERR;
817
exitstatus = EXIT_FAILURE;
946
820
/* Ask OS to automatic close the pipe on exec */
947
821
ret = set_cloexec_flag(pipefd[0]);
949
error(0, errno, "set_cloexec_flag");
950
exitstatus = EX_OSERR;
823
perror("set_cloexec_flag");
824
exitstatus = EXIT_FAILURE;
953
827
ret = set_cloexec_flag(pipefd[1]);
955
error(0, errno, "set_cloexec_flag");
956
exitstatus = EX_OSERR;
829
perror("set_cloexec_flag");
830
exitstatus = EXIT_FAILURE;
959
833
/* Block SIGCHLD until process is safely in process list */
960
ret = (int)TEMP_FAILURE_RETRY(sigprocmask(SIG_BLOCK,
961
&sigchld_action.sa_mask,
834
ret = sigprocmask (SIG_BLOCK, &sigchld_action.sa_mask, NULL);
964
error(0, errno, "sigprocmask");
965
exitstatus = EX_OSERR;
836
perror("sigprocmask");
837
exitstatus = EXIT_FAILURE;
968
840
/* Starting a new process to be watched */
972
} while(pid == -1 and errno == EINTR);
974
error(0, errno, "fork");
975
exitstatus = EX_OSERR;
844
exitstatus = EXIT_FAILURE;
979
848
/* this is the child process */
980
849
ret = sigaction(SIGCHLD, &old_sigchld_action, NULL);
982
error(0, errno, "sigaction");
985
ret = sigprocmask(SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
854
ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
987
error(0, errno, "sigprocmask");
856
perror("sigprocmask");
991
860
ret = dup2(pipefd[1], STDOUT_FILENO); /* replace our stdout */
993
error(0, errno, "dup2");
997
866
if(dirfd(dir) < 0){
1002
871
if(p->environ[0] == NULL){
1003
872
if(execv(filename, p->argv) < 0){
1004
error(0, errno, "execv for %s", filename);
1008
877
if(execve(filename, p->argv, p->environ) < 0){
1009
error(0, errno, "execve for %s", filename);
1015
884
/* Parent process */
1016
TEMP_FAILURE_RETRY(close(pipefd[1])); /* Close unused write end of
885
close(pipefd[1]); /* Close unused write end of pipe */
1019
887
plugin *new_plugin = getplugin(dirst->d_name);
1020
if(new_plugin == NULL){
1021
error(0, errno, "getplugin");
1022
ret = (int)(TEMP_FAILURE_RETRY
1023
(sigprocmask(SIG_UNBLOCK, &sigchld_action.sa_mask,
888
if (new_plugin == NULL){
890
ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
1026
error(0, errno, "sigprocmask");
892
perror("sigprocmask");
1028
exitstatus = EX_OSERR;
894
exitstatus = EXIT_FAILURE;
1065
928
free_plugin_list();
1069
932
/* Main loop while running plugins exist */
1070
933
while(plugin_list){
1071
934
fd_set rfds = rfds_all;
1072
935
int select_ret = select(maxfd+1, &rfds, NULL, NULL, NULL);
1073
if(select_ret == -1 and errno != EINTR){
1074
error(0, errno, "select");
1075
exitstatus = EX_OSERR;
936
if (select_ret == -1){
938
exitstatus = EXIT_FAILURE;
1078
941
/* OK, now either a process completed, or something can be read
1079
942
from one of them */
1080
for(plugin *proc = plugin_list; proc != NULL;){
943
for(plugin *proc = plugin_list; proc != NULL; proc = proc->next){
1081
944
/* Is this process completely done? */
1082
if(proc->completed and proc->eof){
945
if(proc->eof and proc->completed){
1083
946
/* Only accept the plugin output if it exited cleanly */
1084
947
if(not WIFEXITED(proc->status)
1085
948
or WEXITSTATUS(proc->status) != 0){
1086
949
/* Bad exit by plugin */
1089
952
if(WIFEXITED(proc->status)){
1090
fprintf(stderr, "Plugin %s [%" PRIdMAX "] exited with"
1091
" status %d\n", proc->name,
1092
(intmax_t) (proc->pid),
953
fprintf(stderr, "Plugin %u exited with status %d\n",
954
(unsigned int) (proc->pid),
1093
955
WEXITSTATUS(proc->status));
1094
} else if(WIFSIGNALED(proc->status)){
1095
fprintf(stderr, "Plugin %s [%" PRIdMAX "] killed by"
1096
" signal %d: %s\n", proc->name,
1097
(intmax_t) (proc->pid),
1098
WTERMSIG(proc->status),
1099
strsignal(WTERMSIG(proc->status)));
956
} else if(WIFSIGNALED(proc->status)) {
957
fprintf(stderr, "Plugin %u killed by signal %d\n",
958
(unsigned int) (proc->pid),
959
WTERMSIG(proc->status));
1100
960
} else if(WCOREDUMP(proc->status)){
1101
fprintf(stderr, "Plugin %s [%" PRIdMAX "] dumped"
1102
" core\n", proc->name, (intmax_t) (proc->pid));
961
fprintf(stderr, "Plugin %d dumped core\n",
962
(unsigned int) (proc->pid));
1106
966
/* Remove the plugin */
1107
FD_CLR(proc->fd, &rfds_all); /* Spurious warning from
967
FD_CLR(proc->fd, &rfds_all);
1110
969
/* Block signal while modifying process_list */
1111
ret = (int)TEMP_FAILURE_RETRY(sigprocmask
1113
&sigchld_action.sa_mask,
970
ret = sigprocmask(SIG_BLOCK, &sigchld_action.sa_mask, NULL);
1116
error(0, errno, "sigprocmask");
1117
exitstatus = EX_OSERR;
972
perror("sigprocmask");
973
exitstatus = EXIT_FAILURE;
1121
plugin *next_plugin = proc->next;
1122
976
free_plugin(proc);
1125
977
/* We are done modifying process list, so unblock signal */
1126
ret = (int)(TEMP_FAILURE_RETRY
1127
(sigprocmask(SIG_UNBLOCK,
1128
&sigchld_action.sa_mask, NULL)));
978
ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask,
1130
error(0, errno, "sigprocmask");
1131
exitstatus = EX_OSERR;
981
perror("sigprocmask");
982
exitstatus = EXIT_FAILURE;
1135
986
if(plugin_list == NULL){
1142
992
/* This process exited nicely, so print its buffer */
1144
994
bool bret = print_out_password(proc->buffer,
1145
995
proc->buffer_length);
1147
error(0, errno, "print_out_password");
1148
exitstatus = EX_IOERR;
997
perror("print_out_password");
998
exitstatus = EXIT_FAILURE;
1153
1003
/* This process has not completed. Does it have any output? */
1154
if(proc->eof or not FD_ISSET(proc->fd, &rfds)){ /* Spurious
1004
if(proc->eof or not FD_ISSET(proc->fd, &rfds)){
1157
1005
/* This process had nothing to say at this time */
1161
1008
/* Before reading, make the process' data buffer large enough */
1162
1009
if(proc->buffer_length + BUFFER_SIZE > proc->buffer_size){
1163
1010
proc->buffer = realloc(proc->buffer, proc->buffer_size
1164
1011
+ (size_t) BUFFER_SIZE);
1165
if(proc->buffer == NULL){
1166
error(0, errno, "malloc");
1167
exitstatus = EX_OSERR;
1012
if (proc->buffer == NULL){
1014
exitstatus = EXIT_FAILURE;
1170
1017
proc->buffer_size += BUFFER_SIZE;
1172
1019
/* Read from the process */
1173
sret = TEMP_FAILURE_RETRY(read(proc->fd,
1175
+ proc->buffer_length,
1020
ret = read(proc->fd, proc->buffer + proc->buffer_length,
1178
1023
/* Read error from this process; ignore the error */
1184
1028
proc->eof = true;
1186
proc->buffer_length += (size_t) sret;
1030
proc->buffer_length += (size_t) ret;
1194
if(plugin_list == NULL or (exitstatus != EXIT_SUCCESS
1195
and exitstatus != EX_OK)){
1038
if(plugin_list == NULL or exitstatus != EXIT_SUCCESS){
1196
1039
/* Fallback if all plugins failed, none are found or an error
1199
1042
fprintf(stderr, "Going to fallback mode using getpass(3)\n");
1200
1043
char *passwordbuffer = getpass("Password: ");
1201
size_t len = strlen(passwordbuffer);
1202
/* Strip trailing newline */
1203
if(len > 0 and passwordbuffer[len-1] == '\n'){
1204
passwordbuffer[len-1] = '\0'; /* not strictly necessary */
1207
bret = print_out_password(passwordbuffer, len);
1044
bret = print_out_password(passwordbuffer, strlen(passwordbuffer));
1209
error(0, errno, "print_out_password");
1210
exitstatus = EX_IOERR;
1046
perror("print_out_password");
1047
exitstatus = EXIT_FAILURE;
1214
1051
/* Restore old signal handler */
1215
1052
ret = sigaction(SIGCHLD, &old_sigchld_action, NULL);
1217
error(0, errno, "sigaction");
1218
exitstatus = EX_OSERR;
1054
perror("sigaction");
1055
exitstatus = EXIT_FAILURE;
1221
1058
if(custom_argv != NULL){
1222
1059
for(char **arg = custom_argv+1; *arg != NULL; arg++){