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/**
* file: chown.c
* author: Tyler Murphy
*/
#include "command.h"
#include "lslib.h"
#include <dirent.h>
#include <grp.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <pwd.h>
/**
* File flags to be used with chown
*/
static struct {
bool recurse; /* -R if to recurse directorys */
bool list_changed; /* -c if to list what was changed */
bool verbose; /* -v if to list all output */
bool quiet; /* -f if to silence errors */
uid_t uid; /* the uid to set the file to */
gid_t gid; /* the gid to set the file to */
} flags;
/**
* Help function for chown
*/
static void help (void) {
printf("Usage: chown [-Rcvf]... USER[:[GRP]] FILE...\n\n");
printf("Change the owner and/or group of FILEs to USER and/or GRP\n\n");
printf("\t-R\tRecurse\n");
printf("\t-c\tList changed files\n");
printf("\t-v\tVerbose\n");
printf("\t-f\tHide errors\n");
}
/**
* Takes in each argument that has a single - and parses it
* @param c the character after the -
* @param next the next argument in argv that hasnt been parsed
* @reutrn if the next arg was used or if the arg was invalid
*/
static int short_arg(char c, char* next) {
UNUSED(next);
switch (c) {
case 'R':
flags.recurse = true;
break;
case 'c':
flags.list_changed = true;
break;
case 'v':
flags.verbose = true;
break;
case 'f':
flags.quiet = true;
break;
default:
return ARG_INVALID;
}
return ARG_UNUSED;
}
/**
* Given a file path change the filw ownership with the given flags
* @param path the file to change the ownership
*/
static void chown_file(char* path) {
/* allocate arguments on the stack */
int save; /* path buffer save */
struct stat s; /* file stats */
DIR* d; /* recursing dir if recursing */
struct dirent* file; /*if recursing current file being read */
save = push_path_buffer(path);
/* attempt to change file ownership, if failed error and return */
if (chown(get_path_buffer(), flags.uid, flags.gid) < 0) {
if (!flags.quiet) {
error_s("cannot chown '%s'", get_path_buffer()); /* error if failed */
}
pop_path_buffer(save); /* cleanup */
return;
} else if (flags.list_changed) { /* list changed if verbose */
output("changed '%s' to %u:%u", get_path_buffer(), flags.uid, flags.gid);
}
/* if not recurse dont do future checks and return */
if (!flags.recurse) {
pop_path_buffer(save);
return;
}
/* stat file info and return if failed */
if (lstat(get_path_buffer(), &s) < 0) {
if (!flags.quiet) {
error_s("cannot stat '%s'", get_path_buffer()); /* error if failed */
}
pop_path_buffer(save); /* clean up */
return;
}
/* if not dir, cannot recurse so return */
if (!S_ISDIR(s.st_mode)) {
pop_path_buffer(save); /* clean up */
return;
}
/* open dir, if failed return and error */
d = opendir(get_path_buffer());
if (d == NULL) {
if (!flags.quiet) {
error_s("cannot open dir '%s'", get_path_buffer()); /* error if failed */
}
pop_path_buffer(save); /* clean up */
return;
}
/* read each file in directory, and modify its ownership recursivly */
while ((file = readdir(d)) != NULL) {
if (is_dot_dir(file->d_name)) continue; /* if dot dir skip */
chown_file(file->d_name);
}
/* clean up */
closedir(d);
pop_path_buffer(save);
}
/**
* Parse a given user and group from a string
* @param str the stirng to parse
*/
static void parse_ownership(char* str) {
char* user = str; /* a copy of the input string */
char* group = NULL; /* the group name found in str */
char* end = NULL; /* the end of a string to parse a number if passed */
unsigned long i; /* a number i */
struct passwd* p = NULL; /* a user if found */
struct group* g = NULL; /* a group if found */
/* attempy to find a colon seperating the user and group in the string, if not parse it as a user only */
for (i = 0; i < strlen(str); i++) {
if (str[i] == ':') {
str[i] = '\0';
group = &str[i] + 1;
break;
}
}
/* attempt to parse input as a number */
flags.uid = strtol(user, &end, 10);
if (end != user) goto group; /* if successfull they ave a direct uid */
/* if not try to get the user by the string */
if ((p = getpwnam(user)) == NULL) {
error("invalid user '%s'", user); /* error and abort if failed */
} else {
flags.uid = p->pw_uid; /* update flags */
}
group:
/* if the group string was not found set the gorup to the user */
if (group == NULL) {
if (p == NULL) {
flags.gid = flags.uid; /* if a int was passed set that int to the group as well */
} else {
flags.gid = p->pw_gid; /* if a user was passed set the group to the users gid */
}
return;
}
/* if a group was passed, attempt to parse it as a gid first */
flags.gid = strtol(group, &end, 10);
if (end != group) return; /* if succssfull return were done */
/* otherwise try to get the group from the name */
if ((g = getgrnam(group)) == NULL) {
error("invalid group '%s'", group); /* error and abort if failed */
} else {
flags.gid = g->gr_gid; /* update gid */
}
}
COMMAND(chown_main) {
int start, i;
/* set default flags for chown */
flags.recurse = false;
flags.list_changed = false;
flags.verbose = false;
flags.quiet = false;
/* parse argument */
start = parse_args(argc, argv, help, short_arg, NULL);
/* if no more arguments error and abort since no ownership passed */
if (argc - start < 1) {
if (!flags.quiet) { /* if not set to hide errors */
error("no onwership passed");
} else {
return EXIT_FAILURE;
}
}
parse_ownership(argv[start]);
/* if not more arugumnets error and abort since no files passed */
if (argc - start < 1) {
if (!flags.quiet) { /* if not set to hide errors */
error("no files passed");
} else {
return EXIT_FAILURE;
}
}
/* change ownership for each file passed */
for (i = start + 1; i < argc; i++) {
chown_file(argv[i]);
}
return EXIT_SUCCESS; /* done */
}
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