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(same_name): New function.

Browse Source 
(do_link): Use it to test reliably whether A and B (from
ln --force A B) are hard links to the same file.
From Andreas Schwab.
This commit is contained in:
Jim Meyering
1996-06-26 12:02:02 +00:00
parent 325411e109
commit 216777ea17
1 changed files with 39 additions and 6 deletions
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45
src/ln.c
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@@ -63,6 +63,7 @@ int symlink ();
while (0)
char *basename ();
char *dirname ();
enum backup_type get_version ();
int isdir ();
int yesno ();
@@ -119,6 +120,37 @@ static struct option const long_options[] =
{NULL, 0, NULL, 0}
};
/* Check whether SOURCE and DEST point to the same name in the same
directory. */
static int
same_name (char *source, char *dest)
{
struct stat source_dir_stats;
struct stat dest_dir_stats;
char *source_dirname, *dest_dirname;
source_dirname = dirname (source);
dest_dirname = dirname (dest);
if (source_dirname == NULL || dest_dirname == NULL)
error (1, 0, _("virtual memory exhausted"));
if (stat (source_dirname, &source_dir_stats))
/* Shouldn't happen. */
error (1, errno, "%s", source_dirname);
if (stat (dest_dirname, &dest_dir_stats))
/* Shouldn't happen. */
error (1, errno, "%s", dest_dirname);
free (source_dirname);
free (dest_dirname);
return (source_dir_stats.st_dev == dest_dir_stats.st_dev
&& source_dir_stats.st_ino == dest_dir_stats.st_ino
&& STREQ (basename (source), basename (dest)));
}
/* Make a link DEST to the (usually) existing file SOURCE.
Symbolic links to nonexistent files are allowed.
If DEST is a directory, put the link to SOURCE in that directory.
@@ -166,12 +198,13 @@ do_link (const char *source, const char *dest)
&& (!symlink || stat (source, &source_stats) == 0)
&& source_stats.st_dev == dest_stats.st_dev
&& source_stats.st_ino == dest_stats.st_ino
/* The following is an attempt to detect reliably whether
removing DEST will also remove SOURCE. It is defeated
by an invocation like `ln -f foo ./foo' when foo has more
than one hard link. FIXME: if anyone can tell me how to
do this better (yet still reliably), please do. */
&& (source_stats.st_nlink == 1 || STREQ (source, dest)))
/* The following detects whether removing DEST will also remove
SOURCE. If the file has only one link then both are surely
the same link. Otherwise we check whether they point to the
same names in the same directory. The latter is meaningless
when making a symbolic link. */
&& (source_stats.st_nlink == 1
|| (!symlink && same_name (source, dest))))
{
error (0, 0, _("`%s' and `%s' are the same file"), source, dest);
return 1;