我实现ls的c代码在mac上不起作用

Question

I'm facing a strange problem, last night I was doing my homework for implementing ls on my linux , the code works fine there, now when I test it on imac, it doesn't work. It only reads the current directory, it doesn't include subdirectories.

#include <stdio.h>
#include <dirent.h>
#include <string.h>

#define GREEN "\x1b[32m"
#define BLUE "\x1b[34m"
#define WHITE "\x1b[37m"

void Usage() {
    fprintf(stderr, "\nUsage: exec [OPTION]... [DIR]...\n");
    fprintf(stderr, "List DIR's (directory) contents\n");
    fprintf(stderr, "\nOptions\n-R\tlist subdirectories recursively\n");
    return;
}

void RecDir(char * path, int flag) {
    DIR * dp = opendir(path);
    if(!dp) {
        perror(path);
        return;
    }
    struct dirent * ep;
    char newdir[512];
    printf(BLUE "\n%s :\n" WHITE, path);
    while((ep = readdir(dp)))
        if(strncmp(ep->d_name, ".", 1))
            printf(GREEN "\t%s" WHITE, ep->d_name);
    closedir(dp);
    dp = opendir(path);
    while((ep = readdir(dp))) if(strncmp(ep->d_name, ".", 1)) {
        if(flag && ep->d_type == 4) {
            sprintf(newdir, "%s/%s", path, ep->d_name);
            RecDir(newdir, 1);
        }
    }
    closedir(dp);
}

int main(int argc, char ** argv) {
    switch(argc) {
    case 2:
        if(strcmp(argv[1], "-R") == 0) 
            Usage();
        else 
            RecDir(argv[1], 0);
        break;
        case 3:
        if(strcmp(argv[1], "-R") == 0) 
            RecDir(argv[2], 1);
        else 
            Usage();
        break;
        default: 
            Usage();
    }
    return 0;
}

Answer 1

The flag variable was always 0 so i changed it while calling the RecDir() function so that it will go into the if block:

if(flag && ep->d_type == 4) {
            sprintf(newdir, "%s/%s", path, ep->d_name);
            printf("here:  %s\n",ep->d_name);
            RecDir(newdir, 1);
        }

and be able to call RecDir() function recursively.

#include <stdio.h>
#include <dirent.h>
#include <string.h>

#define GREEN "\x1b[32m"
#define BLUE "\x1b[34m"
#define WHITE "\x1b[37m"

void Usage() {
    fprintf(stderr, "\nUsage: exec [OPTION]... [DIR]...\n");
    fprintf(stderr, "List DIR's (directory) contents\n");
    fprintf(stderr, "\nOptions\n-R\tlist subdirectories recursively\n");
    return;
}

void RecDir(char * path, int flag) {
    DIR * dp = opendir(path);
    if(!dp) {
        perror(path);
        return;
    }
    struct dirent * ep;
    char newdir[512];
    printf(BLUE "\n%s :\n" WHITE, path);
    while((ep = readdir(dp)))
        if(strncmp(ep->d_name, ".", 1))
            printf(GREEN "\t%s" WHITE, ep->d_name);
    closedir(dp);
    dp = opendir(path);
    while((ep = readdir(dp))) if(strncmp(ep->d_name, ".", 1)) {
        //printf("In While %d\n",flag);
        if(flag && ep->d_type == 4) {
            sprintf(newdir, "%s/%s", path, ep->d_name);
            printf("here:  %s\n",ep->d_name);
            RecDir(newdir, 1);
        }
    }
    closedir(dp);
}

int main(int argc, char ** argv) {
    switch(argc) {
    case 2:
        if(strcmp(argv[1], "-R") == 0) 
            Usage();
        else 
            //supplied flag=1 instead of 0, explained above.
            RecDir(argv[1], 1);
        break;
        case 3: 
        if(strcmp(argv[1], "-R") == 0) {
            RecDir(argv[2], 1);
        }
        else 
            Usage();
        break;
        default: 
            Usage();
    }
    return 0;
}

Answer 2

Given that it's another operating system, you first need to confirm that d_type holds the value that you think it does. In the first loop, as debug, print out d_type as well as the name.

Note that in the second loop, you go through an awful lot of trouble scanning the directory a second time to recurse into subdirectories - and then at the last second decide not to if flag is 0 . Why not pre-test flag for 0 and simply not do the whole open-the-directory-again thing?