> "Tim Waugh" <[EMAIL PROTECTED]> wrote:
>> Summary: rm calls access() but it shouldn't
>>
>> Original Submission: See:
>> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=124699
>>
>> The rm program calls access() on the target file before calling unlink() on it.
>> This is unnecessary (unlink should tell you everything you need to know), and may
>> hang rm (it may be a symlink pointing to something on an unreachable NFS server).
Hi Tim,
Thanks for forwarding that report!
I'm considering applying the patch below. Unfortunately, rm (without -f)
must call access (via euidaccess) to determine whether it needs to issue
a prompt. With this patch, rm now calls both lstat and access for each
non-symlink it might unlink. Another good reason to use -f.
It is possible to use dir-entry (DT_*) type information to avoid
the lstat call, but I'm not sure it's worth it.
Index: remove.c
===================================================================
RCS file: /fetish/cu/src/remove.c,v
retrieving revision 1.111
diff -u -p -r1.111 remove.c
--- remove.c 29 May 2004 22:04:55 -0000 1.111
+++ remove.c 2 Jun 2004 16:37:24 -0000
@@ -539,6 +539,23 @@ is_empty_dir (char const *dir)
return saved_errno == 0 ? true : false;
}
+/* Return true if FILE is not a symbolic link and it is not writable.
+ Also return true if FILE cannot be lstat'ed. Otherwise, return false.
+ If lstat succeeds, set *BUF_P to BUF.
+ This is to avoid calling euidaccess when FILE is a symlink. */
+static bool
+write_protected_non_symlink (char const *file,
+ struct stat **buf_p,
+ struct stat *buf)
+{
+ if (lstat (file, buf) != 0)
+ return false;
+ *buf_p = buf;
+ if (S_ISLNK (buf->st_mode))
+ return false;
+ return euidaccess (file, W_OK) == -1 && errno == EACCES;
+}
+
/* Prompt whether to remove FILENAME, if required via a combination of
the options specified by X and/or file attributes. If the file may
be removed, return RM_OK. If the user declines to remove the file,
@@ -558,23 +575,30 @@ prompt (Dirstack_state const *ds, char c
Ternary *is_dir, Ternary *is_empty)
{
int write_protected = 0;
+ struct stat *sbuf = NULL;
+ struct stat buf;
+
*is_empty = T_UNKNOWN;
*is_dir = T_UNKNOWN;
if ((!x->ignore_missing_files && (x->interactive || x->stdin_tty)
- && (write_protected = (euidaccess (filename, W_OK) && errno == EACCES)))
+ && (write_protected = write_protected_non_symlink (filename,
+ &sbuf, &buf)))
|| x->interactive)
{
- struct stat sbuf;
- if (lstat (filename, &sbuf))
+ if (sbuf == NULL)
{
- /* lstat failed. This happens e.g., with `rm '''. */
- error (0, errno, _("cannot lstat %s"),
- quote (full_filename (filename)));
- return RM_ERROR;
+ sbuf = &buf;
+ if (lstat (filename, sbuf))
+ {
+ /* lstat failed. This happens e.g., with `rm '''. */
+ error (0, errno, _("cannot lstat %s"),
+ quote (full_filename (filename)));
+ return RM_ERROR;
+ }
}
- if (S_ISDIR (sbuf.st_mode) && !x->recursive)
+ if (S_ISDIR (sbuf->st_mode) && !x->recursive)
{
error (0, EISDIR, _("cannot remove directory %s"),
quote (full_filename (filename)));
@@ -582,7 +606,7 @@ prompt (Dirstack_state const *ds, char c
}
/* Using permissions doesn't make sense for symlinks. */
- if (S_ISLNK (sbuf.st_mode))
+ if (S_ISLNK (sbuf->st_mode))
{
if ( ! x->interactive)
return RM_OK;
@@ -593,12 +617,12 @@ prompt (Dirstack_state const *ds, char c
{
char const *quoted_name = quote (full_filename (filename));
- *is_dir = (S_ISDIR (sbuf.st_mode) ? T_YES : T_NO);
+ *is_dir = (S_ISDIR (sbuf->st_mode) ? T_YES : T_NO);
/* FIXME: use a variant of error (instead of fprintf) that doesn't
append a newline. Then we won't have to declare program_name in
this file. */
- if (S_ISDIR (sbuf.st_mode)
+ if (S_ISDIR (sbuf->st_mode)
&& x->recursive
&& mode == PA_DESCEND_INTO_DIR
&& ((*is_empty = (is_empty_dir (filename) ? T_YES : T_NO))
@@ -618,7 +642,7 @@ prompt (Dirstack_state const *ds, char c
(write_protected
? _("%s: remove write-protected %s %s? ")
: _("%s: remove %s %s? ")),
- program_name, file_type (&sbuf), quoted_name);
+ program_name, file_type (sbuf), quoted_name);
}
if (!yesno ())
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