So I am trying to make my own version of chmod using C, the modifications are to make lowercase add permissions while uppercase remove permissions (instead of using + or - to add and remove). Also, I am trying to print a help message and exit if the command cannot be properly parsed, or there is no file specified. In the case I cannot change permissions (like in the instance I am not the user owner of the file) it should mark that file as having an exit status of 2. I have two versions, the first works ok, still needs the part that takes in input and modifies appropreatly. Not only that but it never recognizes the file name. The second is from the original chmod code that I modified, though its not even close to being in C. Help with eather would be greatly appreceated.
first version
#include <stdio.h>
#include <stdlib.h>
int debug = 0;
int main(int argc, char **argv)
{
extern char *optarg; extern int optind;
int c, err = 0;
int mflag=0, pflag=0, fflag=0;
char *sname = "default_sname", *fname;
static char usage[] = "usage: %s [-dmp] -f fname [-s sname] name [name ...]\n";
while ((c = getopt(argc, argv, "df:mps:")) != -1)
switch (c) {
case 'd':
debug = 1;
break;
case 'm':
mflag = 1;
break;
case 'p':
pflag = 1;
break;
case 'f':
fflag = 1;
fname = optarg;
break;
case 's':
sname = optarg;
break;
case '?':
err = 1;
break;
}
if (fflag == 0) {
fprintf(stderr, "%s: missing -f option\n", argv[0]);
fprintf(stderr, usage, argv[0]);
exit(1);
}
else if ((optind+14) > argc) {
printf("optind = %d, argc=%d\n", optind, argc);
fprintf(stderr, "%s: missing name\n", argv[0]);
fprintf(stderr, usage, argv[0]);
exit(1);
}
else if (err) {
fprintf(stderr, usage, argv[0]);
exit(1);
}
printf("debug = %d\n", debug);
printf("pflag = %d\n", pflag);
printf("mflag = %d\n", mflag);
printf("fname = \"%s\"\n", fname);
printf("sname = \"%s\"\n", sname);
if (optind < argc)
for (; optind < argc; optind++)
printf("argument: \"%s\"\n", argv[optind]);
else { printf("no arguments left to process\n");
}
while (argv[optind] != NULL){
if (argv[optind] == "-o"){
exit(0);
}
else{
argv[optind+1];
}
}
exit(2);
}
second version
#include <config.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>
#include "system.h"
#include "dev-ino.h"
#include "error.h"
#include "filemode.h"
#include "ignore-value.h"
#include "modechange.h"
#include "quote.h"
#include "quotearg.h"
#include "root-dev-ino.h"
#include "xfts.h"
#define PROGRAM_NAME "mychmod"
enum Change_status
{
CH_NOT_APPLIED,
CH_SUCCEEDED,
CH_FAILED,
CH_NO_CHANGE_REQUESTED
};
enum Verbosity
{
/* Print a message for each file that is processed. */
V_high,
/* Print a message for each file whose attributes we change. */
V_changes_only,
/* Do not be verbose. This is the default. */
V_off
};
/* The desired change to the mode. */
static struct mode_change *change;
/* The initial umask value, if it might be needed. */
static mode_t umask_value;
/* If true, change the modes of directories recursively. */
static bool recurse;
/* If true, force silence (suppress most of error messages). */
static bool force_silent;
/* If true, diagnose surprises from naive misuses like "mychmod -r file".
POSIX allows diagnostics here, as portable code is supposed to use
"mychmod -- -r file". */
static bool diagnose_surprises;
/* Level of verbosity. */
static enum Verbosity verbosity = V_off;
/* Pointer to the device and inode numbers of '/', when --recursive.
Otherwise NULL. */
static struct dev_ino *root_dev_ino;
/* For long options that have no equivalent short option, use a
non-character as a pseudo short option, starting with CHAR_MAX + 1. */
enum
{
NO_PRESERVE_ROOT = CHAR_MAX + 1,
PRESERVE_ROOT,
REFERENCE_FILE_OPTION
};
static struct option const long_options[] =
{
{"changes", no_argument, NULL, 'c'},
{"recursive", no_argument, NULL, 'R'},
{"no-preserve-root", no_argument, NULL, NO_PRESERVE_ROOT},
{"preserve-root", no_argument, NULL, PRESERVE_ROOT},
{"quiet", no_argument, NULL, 'f'},
{"reference", required_argument, NULL, REFERENCE_FILE_OPTION},
{"silent", no_argument, NULL, 'f'},
{"verbose", no_argument, NULL, 'v'},
{GETOPT_HELP_OPTION_DECL},
{GETOPT_VERSION_OPTION_DECL},
{NULL, 0, NULL, 0}
};
/* Return true if the mychmodable permission bits of FILE changed.
The old mode was OLD_MODE, but it was changed to NEW_MODE. */
static bool
mode_changed (int dir_fd, char const *file, char const *file_full_name,
mode_t old_mode, mode_t new_mode)
{
if (new_mode & (S_ISUID | S_ISGID | S_ISVTX))
{
/* The new mode contains unusual bits that the call to mychmod may
have silently cleared. Check whether they actually changed. */
struct stat new_stats;
if (fstatat (dir_fd, file, &new_stats, 0) != 0)
{
if (! force_silent)
error (0, errno, _("getting new attributes of %s"),
quote (file_full_name));
return false;
}
new_mode = new_stats.st_mode;
}
return ((old_mode ^ new_mode) & MYCHMOD_MODE_BITS) != 0;
}
/* Tell the user how/if the MODE of FILE has been changed.
CHANGED describes what (if anything) has happened. */
static void
describe_change (const char *file, mode_t old_mode, mode_t mode,
enum Change_status changed)
{
char perms[12]; /* "-rwxrwxrwx" ls-style modes. */
char old_perms[12];
const char *fmt;
if (changed == CH_NOT_APPLIED)
{
printf (_("neither symbolic link %s nor referent has been changed\n"),
quote (file));
return;
}
strmode (mode, perms);
perms[10] = '\0'; /* Remove trailing space. */
strmode (old_mode, old_perms);
old_perms[10] = '\0'; /* Remove trailing space. */
switch (changed)
{
case CH_SUCCEEDED:
fmt = _("mode of %s changed from %04lo (%s) to %04lo (%s)\n");
break;
case CH_FAILED:
fmt = _("failed to change mode of %s from %04lo (%s) to %04lo (%s)\n");
break;
case CH_NO_CHANGE_REQUESTED:
fmt = _("mode of %s retained as %04lo (%s)\n");
printf (fmt, quote (file),
(unsigned long int) (mode & CHMOD_MODE_BITS), &perms[1]);
return;
default:
abort ();
}
printf (fmt, quote (file),
(unsigned long int) (old_mode & CHMOD_MODE_BITS), &old_perms[1],
(unsigned long int) (mode & CHMOD_MODE_BITS), &perms[1]);
}
/* Change the mode of FILE.
Return true if successful. This function is called
once for every file system object that fts encounters. */
static bool
process_file (FTS *fts, FTSENT *ent)
{
char const *file_full_name = ent->fts_path;
char const *file = ent->fts_accpath;
const struct stat *file_stats = ent->fts_statp;
mode_t old_mode IF_LINT ( = 0);
mode_t new_mode IF_LINT ( = 0);
bool ok = true;
bool mychmod_succeeded = false;
switch (ent->fts_info)
{
case FTS_DP:
return true;
case FTS_NS:
/* For a top-level file or directory, this FTS_NS (stat failed)
indicator is determined at the time of the initial fts_open call.
With programs like mychmod, chown, and chgrp, that modify
permissions, it is possible that the file in question is
accessible when control reaches this point. So, if this is
the first time we've seen the FTS_NS for this file, tell
fts_read to stat it "again". */
if (ent->fts_level == 0 && ent->fts_number == 0)
{
ent->fts_number = 1;
fts_set (fts, ent, FTS_AGAIN);
return true;
}
if (! force_silent)
error (0, ent->fts_errno, _("cannot access %s"),
quote (file_full_name));
ok = false;
break;
case FTS_ERR:
if (! force_silent)
error (0, ent->fts_errno, "%s", quote (file_full_name));
ok = false;
break;
case FTS_DNR:
if (! force_silent)
error (0, ent->fts_errno, _("cannot read directory %s"),
quote (file_full_name));
ok = false;
break;
case FTS_SLNONE:
if (! force_silent)
error (0, 0, _("cannot operate on dangling symlink %s"),
quote (file_full_name));
ok = false;
break;
case FTS_DC: /* directory that causes cycles */
if (cycle_warning_required (fts, ent))
{
emit_cycle_warning (file_full_name);
return false;
}
break;
default:
break;
}
if (ok && ROOT_DEV_INO_CHECK (root_dev_ino, file_stats))
{
ROOT_DEV_INO_WARN (file_full_name);
/* Tell fts not to traverse into this hierarchy. */
fts_set (fts, ent, FTS_SKIP);
/* Ensure that we do not process "/" on the second visit. */
ignore_value (fts_read (fts));
return false;
}
if (ok)
{
old_mode = file_stats->st_mode;
new_mode = mode_adjust (old_mode, S_ISDIR (old_mode) != 0, umask_value,
change, NULL);
if (! S_ISLNK (old_mode))
{
if (chmodat (fts->fts_cwd_fd, file, new_mode) == 0)
mychmod_succeeded = true;
else
{
if (! force_silent)
error (0, errno, _("changing permissions of %s"),
quote (file_full_name));
ok = false;
}
}
}
if (verbosity != V_off)
{
bool changed = (mychmod_succeeded
&& mode_changed (fts->fts_cwd_fd, file, file_full_name,
old_mode, new_mode));
if (changed || verbosity == V_high)
{
enum Change_status ch_status =
(!ok ? CH_FAILED
: !mychmod_succeeded ? CH_NOT_APPLIED
: !changed ? CH_NO_CHANGE_REQUESTED
: CH_SUCCEEDED);
describe_change (file_full_name, old_mode, new_mode, ch_status);
}
}
if (mychmod_succeeded && (case == 'U' || case == 'G' || case == 'O'))
{
mode_t naively_expected_mode =
mode_adjust (old_mode, S_ISDIR (old_mode) != 0, 0, change, NULL);
if (new_mode & ~naively_expected_mode)
{
char new_perms[12];
char naively_expected_perms[12];
strmode (new_mode, new_perms);
strmode (naively_expected_mode, naively_expected_perms);
new_perms[10] = naively_expected_perms[10] = '\0';
error (0, 0,
_("%s: new permissions are %s, not %s"),
quotearg_colon (file_full_name),
new_perms + 1, naively_expected_perms + 1);
ok = false;
}
}
if ( ! recurse)
fts_set (fts, ent, FTS_SKIP);
return ok;
}
/* Recursively change the modes of the specified FILES (the last entry
of which is NULL). BIT_FLAGS controls how fts works.
Return true if successful. */
static bool
process_files (char **files, int bit_flags)
{
bool ok = true;
FTS *fts = xfts_open (files, bit_flags, NULL);
while (1)
{
FTSENT *ent;
ent = fts_read (fts);
if (ent == NULL)
{
if (errno != 0)
{
/* FIXME: try to give a better message */
if (! force_silent)
error (0, errno, _("fts_read failed"));
ok = false;
}
break;
}
ok &= process_file (fts, ent);
}
if (fts_close (fts) != 0)
{
error (0, errno, _("fts_close failed"));
ok = false;
}
return ok;
}
void
usage (int status)
{
if (status != EXIT_SUCCESS)
emit_try_help ();
else
{
printf (_("\
Usage: %s [OPTION]... MODE[,MODE]... FILE...\n\
or: %s [OPTION]... OCTAL-MODE FILE...\n\
or: %s [OPTION]... --reference=RFILE FILE...\n\
"),
program_name, program_name, program_name);
fputs (_("\
Change the mode of each FILE to MODE.\n\
With --reference, change the mode of each FILE to that of RFILE.\n\
\n\
"), stdout);
fputs (_("\
-c, --changes like verbose but report only when a change is made\n\
-f, --silent, --quiet suppress most error messages\n\
-v, --verbose output a diagnostic for every file processed\n\
"), stdout);
fputs (_("\
--no-preserve-root do not treat '/' specially (the default)\n\
--preserve-root fail to operate recursively on '/'\n\
"), stdout);
fputs (_("\
--reference=RFILE use RFILE's mode instead of MODE values\n\
"), stdout);
fputs (_("\
-R, --recursive change files and directories recursively\n\
"), stdout);
fputs (HELP_OPTION_DESCRIPTION, stdout);
fputs (VERSION_OPTION_DESCRIPTION, stdout);
fputs (_("\
\n\
Each MODE is of the form '[ugoa]*([-+=]([rwxXst]*|[ugo]))+|[-+=][0-7]+'.\n\
"), stdout);
emit_ancillary_info (PROGRAM_NAME); }
exit (status);
}
/* Parse the ASCII mode given on the command line into a linked list
of 'struct mode_change' and apply that to each file argument. */
int
main (int argc, char **argv)
{
char *mode = NULL;
size_t mode_len = 0;
size_t mode_alloc = 0;
bool ok;
bool preserve_root = false;
char const *reference_file = NULL;
int c;
initialize_main (&argc, &argv);
set_program_name (argv[0]);
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
atexit (close_stdout);
recurse = force_silent = diagnose_surprises = false;
while ((c = getopt_long (argc, argv,
("Rcfvr::w::x::X::s::t::u::g::o::a::U::G::O::,::+::=::"
"0::1::2::3::4::5::6::7::"),
long_options, NULL))
!= -1)
{
switch (c)
{
case 'r':
case 'w':
case 'x':
case 'X':
case 's':
case 't':
case 'u':
case 'g':
case 'o':
case 'a':
case 'U':
case 'G':
case 'O';
case '':
case '=':
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
/* Support nonportable uses like "mychmod -w", but diagnose
surprises due to umask confusion. Even though "--", "--r",
etc., are valid modes, there is no "case '-'" here since
getopt_long reserves leading "--" for long options. */
{
/* Allocate a mode string (e.g., "-rwx") by concatenating
the argument containing this option. If a previous mode
string was given, concatenate the previous string, a
comma, and the new string (e.g., "-s,-rwx"). */
char const *arg = argv[optind - 1];
size_t arg_len = strlen (arg);
size_t mode_comma_len = mode_len + !!mode_len;
size_t new_mode_len = mode_comma_len + arg_len;
if (mode_alloc <= new_mode_len)
{
mode_alloc = new_mode_len + 1;
mode = X2REALLOC (mode, &mode_alloc);
}
mode[mode_len] = ',';
memcpy (mode + mode_comma_len, arg, arg_len + 1);
mode_len = new_mode_len;
diagnose_surprises = true;
}
break;
case NO_PRESERVE_ROOT:
preserve_root = false;
break;
case PRESERVE_ROOT:
preserve_root = true;
break;
case REFERENCE_FILE_OPTION:
reference_file = optarg;
break;
case 'R':
recurse = true;
break;
case 'c':
verbosity = V_changes_only;
break;
case 'f':
force_silent = true;
break;
case 'v':
verbosity = V_high;
break;
case_GETOPT_HELP_CHAR;
case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
default:
usage (EXIT_FAILURE);
}
}
if (reference_file)
{
if (mode)
{
error (0, 0, _("cannot combine mode and --reference options"));
usage (EXIT_FAILURE);
}
}
else
{
if (!mode)
mode = argv[optind++];
}
if (optind >= argc)
{
if (!mode || mode != argv[optind - 1])
error (0, 0, _("missing operand"));
else
error (0, 0, _("missing operand after %s"), quote (argv[argc - 1]));
usage (EXIT_FAILURE);
}
if (reference_file)
{
change = mode_create_from_ref (reference_file);
if (!change)
error (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
quote (reference_file));
}
else
{
change = mode_compile (mode);
if (!change)
{
error (0, 0, _("invalid mode: %s"), quote (mode));
usage (EXIT_FAILURE);
}
umask_value = umask (0);
}
if (recurse && preserve_root)
{
static struct dev_ino dev_ino_buf;
root_dev_ino = get_root_dev_ino (&dev_ino_buf);
if (root_dev_ino == NULL)
error (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
quote ("/"));
}
else
{
root_dev_ino = NULL;
}
ok = process_files (argv + optind,
FTS_COMFOLLOW | FTS_PHYSICAL | FTS_DEFER_STAT);
return ok ? EXIT_SUCCESS : EXIT_FAILURE;
}
Thank you for your time and help in this matter!