sbase

suckless unix tools
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commit 918bc21455a303220a18e578d9f5589aeaddd981
parent e5fedfaa3ffbd36eef5ea1311b4eef58edaefda9
Author: Eivind Uggedal <eivind@uggedal.com>
Date:   Fri May  8 08:16:57 +0000

ln: only check existence of src/to for hardlinks

This allows for creating dangling symlinks with force applied:

    # Before:
    $ ln -sf non-existant target
    ln: stat non-existent: No such file or directory
    $ ls -l target
    ls: lstat target: No such file or directory

    # After:
    $ ln -sf non-existant target
    $ ls -l target
    lrwxrwxrwx    1 eu    users   12 May 08 07:50 target -> non-existent

This also allows creating relative non-dangling symlinks with force applied:

    touch existant; mkdir dir

    # Before
    $ ln -sf ../existant dir
    ln: stat ../existant: No such file or directory
    $ ls -l dir

    # After
    $ ln -sf ../existant dir
    $ ls -l dir
    lrwxrwxrwx    1 eu    users   11 May 08 07:53 existant -> ../existant

The check for whether each src and to pairs are on the same device with the
same inode are only needed for hardlinks so that a forcefull link does
not remove the underlying file:

    touch f; mkdir dir

    # Before:
    $ ln -f f f dir
    ln: f and f are the same file
    $ ls -i f dir/f
    3670611 dir/f
    3670611 f

    # After:
    $ ln -f f f dir
    ln: f and f are the same file
    $ ls -i f dir/f
    4332236 dir/f
    4332236 f

Diffstat:
ln.c | 13++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/ln.c b/ln.c @@ -61,21 +61,20 @@ main(int argc, char *argv[]) for (; *argv; argc--, argv++) { if (!hasto) to = basename(*argv); - if (fflag) { + if (!sflag) { if (stat(*argv, &st) < 0) { weprintf("stat %s:", *argv); continue; } else if (fstatat(dirfd, to, &tost, AT_SYMLINK_NOFOLLOW) < 0) { if (errno != ENOENT) eprintf("stat %s:", to); - } else { - if (st.st_dev == tost.st_dev && st.st_ino == tost.st_ino) { - weprintf("%s and %s are the same file\n", *argv, *argv); - continue; - } - unlinkat(dirfd, to, 0); + } else if (st.st_dev == tost.st_dev && st.st_ino == tost.st_ino) { + weprintf("%s and %s are the same file\n", *argv, *argv); + continue; } } + if (fflag) + unlinkat(dirfd, to, 0); if ((!sflag ? linkat(AT_FDCWD, *argv, dirfd, to, flags) : symlinkat(*argv, dirfd, to)) < 0) { weprintf("%s %s <- %s:", fname, *argv, to);