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
7USE_LN(NEWTOY(ln, "<1vnfs", TOYFLAG_BIN))
8
9config 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
27void 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