The DT_UNKNOWN fallback code was getting the type of the wrong path,
causing readDir to report "directory" as the type of every file.
Reported by deepfire on IRC.
I.e., not readable to the nixbld group. This improves purity a bit for
non-chroot builds, because it prevents a builder from enumerating
store paths (i.e. it can only access paths it knows about).
Let's not just improve the error message itself, but also the behaviour
to actually work around the ntfs-3g symlink bug. If the readlink() call
returns a smaller size than the stat() call, this really isn't a problem
even if the symlink target really has changed between the calls.
So if stat() reports the size for the absolute path, it's most likely
that the relative path is smaller and thus it should also work for file
system bugs as mentioned in 93002d69fc58c2b71e2dfad202139230c630c53a.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Tested-by: John Ericson <Ericson2314@Yahoo.com>
A message like "error: reading symbolic link `...' : Success" really is
quite confusing, so let's not indicate "success" but rather point out
the real issue.
We could also limit the check of this to just check for non-negative
values, but this would introduce a race condition between stat() and
readlink() if the link target changes between those two calls, thus
leading to a buffer overflow vulnerability.
Reported by @Ericson2314 on IRC. Happened due to a possible ntfs-3g bug
where a relative symlink returned the absolute path (st_)size in stat()
while readlink() returned the relative size.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Tested-by: John Ericson <Ericson2314@Yahoo.com>
In low memory environments, "nix-env -qa" failed because the fork to
run the pager hit the kernel's overcommit limits. Using posix_spawn
gets around this. (Actually, you have to use posix_spawn with the
undocumented POSIX_SPAWN_USEVFORK flag, otherwise it just uses
fork/exec...)
Code that links to libnixexpr (e.g. plugins loaded with importNative, or
nix-exec) may want to provide custom value types and operations on
values of those types. For example, nix-exec is currently using sets
where a custom IO value type would be more appropriate. This commit
provides a generic hook for such types in the form of tExternal and the
ExternalBase virtual class, which contains all functions necessary for
libnixexpr's type-polymorphic functions (e.g. `showType`) to be
implemented.
The function ‘builtins.match’ takes a POSIX extended regular
expression and an arbitrary string. It returns ‘null’ if the string
does not match the regular expression. Otherwise, it returns a list
containing substring matches corresponding to parenthesis groups in
the regex. The regex must match the entire string (i.e. there is an
implied "^<pat>$" around the regex). For example:
match "foo" "foobar" => null
match "foo" "foo" => []
match "f(o+)(.*)" "foooobar" => ["oooo" "bar"]
match "(.*/)?([^/]*)" "/dir/file.nix" => ["/dir/" "file.nix"]
match "(.*/)?([^/]*)" "file.nix" => [null "file.nix"]
The following example finds all regular files with extension .nix or
.patch underneath the current directory:
let
findFiles = pat: dir: concatLists (mapAttrsToList (name: type:
if type == "directory" then
findFiles pat (dir + "/" + name)
else if type == "regular" && match pat name != null then
[(dir + "/" + name)]
else []) (readDir dir));
in findFiles ".*\\.(nix|patch)" (toString ./.)
