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      1 /* ln.c - Create filesystem links
      2  *
      3  * Copyright 2012 Andre Renaud <andre (at) 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 
     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