LXR toybox/toys/posix/ln.c

   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