1 /* ln.c - Create filesystem links
2  *
3  * Copyright 2012 Andre Renaud <andre@bluewatersys.com>
4  *
5  * See http://opengroup.org/onlinepubs/9699919799/utilities/ln.html
6 
7 USE_LN(NEWTOY(ln, "<1vnfs", TOYFLAG_BIN))
8 
9 config LN
10   bool "ln"
11   default y
12   help
13     usage: ln [-sfnv] [FROM...] TO
14 
15     Create a link between FROM and TO.
16     With only one argument, create link in current directory.
17 
18     -s	Create a symbolic link
19     -f	Force the creation of the link, even if TO already exists
20     -n	Symlink at destination treated as file
21     -v	Verbose
22 */
23 
24 #define FOR_ln
25 #include "toys.h"
26 
ln_main(void)27 void ln_main(void)
28 {
29   char *dest = toys.optargs[--toys.optc], *new;
30   struct stat buf;
31   int i;
32 
33   // With one argument, create link in current directory.
34   if (!toys.optc) {
35     toys.optc++;
36     dest=".";
37   }
38 
39   // Is destination a directory?
40   if (((toys.optflags&FLAG_n) ? lstat : stat)(dest, &buf)
41     || !S_ISDIR(buf.st_mode))
42   {
43     if (toys.optc>1) error_exit("'%s' not a directory", dest);
44     buf.st_mode = 0;
45   }
46 
47   for (i=0; i<toys.optc; i++) {
48     int rc;
49     char *oldnew, *try = toys.optargs[i];
50 
51     if (S_ISDIR(buf.st_mode)) new = xmprintf("%s/%s", dest, basename(try));
52     else new = dest;
53 
54     // Force needs to unlink the existing target (if any). Do that by creating
55     // a temp version and renaming it over the old one, so we can retain the
56     // old file in cases we can't replace it (such as hardlink between mounts).
57     oldnew = new;
58     if (toys.optflags & FLAG_f) {
59       new = xmprintf("%s_XXXXXX", new);
60       rc = mkstemp(new);
61       if (rc >= 0) {
62         close(rc);
63         if (unlink(new)) perror_msg("unlink '%s'", new);
64       }
65     }
66 
67     rc = (toys.optflags & FLAG_s) ? symlink(try, new) : link(try, new);
68     if (toys.optflags & FLAG_f) {
69       if (!rc) {
70         int temp;
71 
72         rc = rename(new, oldnew);
73         temp = errno;
74         if (rc && unlink(new)) perror_msg("unlink '%s'", new);
75         errno = temp;
76       }
77       free(new);
78       new = oldnew;
79     }
80     if (rc)
81       perror_msg("cannot create %s link from '%s' to '%s'",
82         (toys.optflags & FLAG_s) ? "symbolic" : "hard", try, new);
83     else
84       if (toys.optflags & FLAG_v) fprintf(stderr, "'%s' -> '%s'\n", new, try);
85 
86     if (new != dest) free(new);
87   }
88 }
89