https://cs.nyu.edu/~mwalfish/classes/21sp/labs/lab2.html#include #include #include #include ...

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https://cs.nyu.edu/~mwalfish/classes/21sp/labs/lab2.html#include  #include  #include  #include  #include  #include  #include  #include  #include  #include  #include  #include  #include  #include  #include  #include  static int err_code; /*  * here are some function signatures and macros that may be helpful.  */ void handle_error(char* fullname, char* action); bool test_file(char* pathandname); bool is_dir(char* pathandname); const char* ftype_to_str(mode_t mode); void list_file(char* pathandname, char* name, bool list_long); void list_dir(char* dirname, bool list_long, bool list_all, bool recursive); /*  * You can use the NOT_YET_IMPLEMENTED macro to error out when you reach parts  * of the code you have not yet finished implementing.  */ #define NOT_YET_IMPLEMENTED(msg)                  \     do {                                          \         printf("Not yet implemented: " msg "
"); \         exit(255);                                \     } while (0) /*  * PRINT_ERROR: This can be used to print the cause of an error returned by a  * system call. It can help with debugging and reporting error causes to  * the user. Example usage:  *     if ( error_condition ) {  *        PRINT_ERROR();  *     }  */ #define PRINT_ERROR(progname, what_happened, pathandname)               \     do {                                                                \         printf("%s: %s %s: %s
", progname, what_happened, pathandname, \                strerror(errno));                                        \     } while (0) /* PRINT_PERM_CHAR:  *  * This will be useful for -l permission printing.  It prints the given  * 'ch' if the permission exists, or "-" otherwise.  * Example usage:  *     PRINT_PERM_CHAR(sb.st_mode, S_IRUSR, "r");  */ #define PRINT_PERM_CHAR(mode, mask, ch) printf("%s", (mode & mask) ? ch : "-"); /*  * Get username for uid. Return 1 on failure, 0 otherwise.  */ static int uname_for_uid(uid_t uid, char* buf, size_t buflen) {     struct passwd* p = getpwuid(uid);     if (p == NULL) {         return 1;     }     strncpy(buf, p->pw_name, buflen);     return 0; } /*  * Get group name for gid. Return 1 on failure, 0 otherwise.  */ static int group_for_gid(gid_t gid, char* buf, size_t buflen) {     struct group* g = getgrgid(gid);     if (g == NULL) {         return 1;     }     strncpy(buf, g->gr_name, buflen);     return 0; } /*  * Format the supplied `struct timespec` in `ts` (e.g., from `stat.st_mtim`) as a  * string in `char *out`. Returns the length of the formatted string (see, `man  * 3 strftime`).  */ static size_t date_string(struct timespec* ts, char* out, size_t len) {     struct timespec now;     timespec_get(&now, TIME_UTC);     struct tm* t = localtime(&ts->tv_sec);     if (now.tv_sec tv_sec) {         // Future time, treat with care.         return strftime(out, len, "%b %e %Y", t);     } else {         time_t difference = now.tv_sec - ts->tv_sec;         if (difference   : display singular file:  ")     exit(0); } /*  * call this when there's been an error.  * The function should:  * - print a suitable error message (this is already implemented)  * - set appropriate bits in err_code  */ void handle_error(char* what_happened, char* fullname) {     PRINT_ERROR("ls", what_happened, fullname);     // TODO: your code here: inspect errno and set err_code accordingly.     return; } /*  * test_file():  * test whether stat() returns successfully and if not, handle error.  * Use this to test for whether a file or dir exists  */ bool test_file(char* pathandname) {     struct stat sb;     if (stat(pathandname, &sb)) {         handle_error("cannot access", pathandname);         return false;     }     return true; } /*  * is_dir(): tests whether the argument refers to a directory.  * precondition: test_file() returns true. that is, call this function  * only if test_file(pathandname) returned true.  */ bool is_dir(char* pathandname) {     /* TODO: fillin */     if (test_file(pathandname)) {         struct stat paths;         stat(pathandname, &paths);         return S_ISREG(paths.st_mode)     }     return false; } /* convert the mode field in a struct stat to a file type, for -l printing */ const char* ftype_to_str(mode_t mode) {     /* TODO: fillin */         char* temp = (char*)malloc(10);         memset(temp,0,10);         temp[0] = (mode & S_IFDIR) ? 'd' : '-';         temp[1] = (mode & S_IRUSR) ? 'R' : '-';         temp[2] = (mode & S_IWUSR) ? 'W' : '-';         temp[3] = (mode & S_IXUSR) ? 'X' : '-';         temp[4] = (mode & S_IRGRP) ? 'R' : '-';         temp[5] = (mode & S_IWGRP) ? 'W' : '-';         temp[6] = (mode & S_IXGRP) ? 'X' : '-';         temp[7] = (mode & S_IROTH) ? 'R' : '-';         temp[8] = (mode & S_IWOTH) ? 'W' : '-';         temp[9] = (mode & S_IXOTH) ? 'X' : '-';     return (const char*)temp; } /* list_file():  * implement the logic for listing a single file.  * This function takes:  *   - pathandname: the directory name plus the file name.  *   - name: just the name "component".  *   - list_long: a flag indicated whether the printout should be in  *   long mode.  *  *   The reason for this signature is convenience: some of the file-outputting  *   logic requires the full pathandname (specifically, testing for a directory  *   so you can print a '/' and outputting in long mode), and some of it  *   requires only the 'name' part. So we pass in both. An alternative  *   implementation would pass in pathandname and parse out 'name'.  */ void list_file(char* pathandname,char* name, bool list_long) {     /* TODO: fill in*/         dir *dirp         struct dirent *dp;         dirp = opendir(pathandname);         if (dirp) {         printf("%s
", dp->d_name);         closedir(dirp);         }         if (list_long) {         } } /* list_dir():  * implement the logic for listing a directory.  * This function takes:  *    - dirname: the name of the directory  *    - list_long: should the directory be listed in long mode?  *    - list_all: are we in "-a" mode?  *    - recursive: are we supposed to list sub-directories?  */ void list_dir(char* dirname, bool list_long, bool list_all, bool recursive) {     /* TODO: fill in      *   You'll probably want to make use of:      *       opendir()      *       readdir()      *       list_file()      *       snprintf() [to make the 'pathandname' argument to      *          list_file(). that requires

#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static int err_code; /* * here are some function...

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