9d67b8b8 |
1 | #include <stdio.h> |
2 | #include <fcntl.h> |
3 | #include <unistd.h> |
4 | |
5 | #include <sys/stat.h> |
6 | |
7 | int main(int argc, char *argv[]) { |
8 | |
9 | int cur, flag_append, flag_force; |
10 | int fd_from, fd_to, mode; |
11 | char buf[1]; |
12 | |
13 | flag_append = 0; |
14 | flag_force = 0; |
15 | |
16 | while((cur = getopt(argc, argv, "af")) != -1) { |
17 | switch(cur) { |
18 | |
19 | case 'a': |
20 | flag_append = 1; |
21 | break; |
22 | |
23 | case 'f': |
24 | flag_force = 1; |
25 | break; |
26 | |
27 | default: |
28 | printf("invalid argument\n"); |
29 | return 1; |
30 | } |
31 | } |
32 | |
33 | if(argc - optind != 2) { |
34 | |
35 | printf("invalid number of args\n"); |
36 | return 1; |
37 | |
38 | } else if(flag_append && flag_force) { |
39 | |
40 | printf("cannot simultaneously specify overwrite and append\n"); |
41 | return 1; |
42 | } |
43 | |
44 | if(access(argv[optind + 1], F_OK) != -1 && !flag_append && !flag_force) { |
45 | |
46 | printf("destination file already exists, pass -f to overwrite\n"); |
47 | return 1; |
48 | } |
49 | |
50 | if(flag_force) mode = O_TRUNC; |
51 | else if(flag_append) mode = O_APPEND; |
52 | else mode = O_CREAT; |
53 | |
54 | fd_from = open(argv[optind], O_RDONLY); |
55 | fd_to = open(argv[optind + 1], mode | O_WRONLY, S_IRWXU); |
56 | |
57 | if(fd_from == -1) { |
58 | |
59 | printf("could not open source file\n"); |
60 | return 1; |
61 | |
62 | } else if(fd_to == -1 && !flag_force && !flag_append) { |
63 | |
64 | printf("could not create new destination file\n"); |
65 | return 1; |
66 | |
67 | } else if(fd_to == -1) { |
68 | |
69 | } |
70 | |
71 | while(read(fd_from, buf, 1) == 1) |
72 | write(fd_to, buf, 1); |
73 | |
74 | close(fd_from); |
75 | close(fd_to); |
76 | |
77 | return 0; |
78 | } |