Merge branch 'master' into read-only-local-store

This commit is contained in:
Ben Radford 2023-06-06 11:07:36 +01:00
commit e484278e9b
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GPG key ID: 9DF5D4640AB888D5
31 changed files with 213 additions and 106 deletions

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@ -21,7 +21,7 @@ jobs:
fetch-depth: 0
- name: Create backport PRs
# should be kept in sync with `version`
uses: zeebe-io/backport-action@v1.2.0
uses: zeebe-io/backport-action@v1.3.0
with:
# Config README: https://github.com/zeebe-io/backport-action#backport-action
github_token: ${{ secrets.GITHUB_TOKEN }}

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@ -19,7 +19,10 @@ jobs:
- uses: actions/checkout@v3
with:
fetch-depth: 0
- uses: cachix/install-nix-action@v20
- uses: cachix/install-nix-action@v21
with:
# The sandbox would otherwise be disabled by default on Darwin
extra_nix_config: "sandbox = true"
- run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
- uses: cachix/cachix-action@v12
if: needs.check_secrets.outputs.cachix == 'true'
@ -58,7 +61,7 @@ jobs:
with:
fetch-depth: 0
- run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
- uses: cachix/install-nix-action@v20
- uses: cachix/install-nix-action@v21
with:
install_url: https://releases.nixos.org/nix/nix-2.13.3/install
- uses: cachix/cachix-action@v12
@ -79,7 +82,7 @@ jobs:
steps:
- uses: actions/checkout@v3
- run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
- uses: cachix/install-nix-action@v20
- uses: cachix/install-nix-action@v21
with:
install_url: '${{needs.installer.outputs.installerURL}}'
install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"
@ -106,7 +109,7 @@ jobs:
- uses: actions/checkout@v3
with:
fetch-depth: 0
- uses: cachix/install-nix-action@v20
- uses: cachix/install-nix-action@v21
with:
install_url: https://releases.nixos.org/nix/nix-2.13.3/install
- run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV

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@ -1 +1 @@
2.16.0
2.17.0

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@ -105,6 +105,7 @@
- [CLI guideline](contributing/cli-guideline.md)
- [Release Notes](release-notes/release-notes.md)
- [Release X.Y (202?-??-??)](release-notes/rl-next.md)
- [Release 2.16 (2023-05-31)](release-notes/rl-2.16.md)
- [Release 2.15 (2023-04-11)](release-notes/rl-2.15.md)
- [Release 2.14 (2023-02-28)](release-notes/rl-2.14.md)
- [Release 2.13 (2023-01-17)](release-notes/rl-2.13.md)

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@ -38,11 +38,9 @@ contains Nix.
> **Warning**
>
> If you are building via the Nix daemon, it is the Nix daemon user
> account (that is, `root`) that should have SSH access to the remote
> machine. If you cant or dont want to configure `root` to be able to
> access to remote machine, you can use a private Nix store instead by
> passing e.g. `--store ~/my-nix`.
> If you are building via the Nix daemon, it is the Nix daemon user account (that is, `root`) that should have SSH access to a user (not necessarily `root`) on the remote machine.
>
> If you cant or dont want to configure `root` to be able to access the remote machine, you can use a private Nix store instead by passing e.g. `--store ~/my-nix` when running a Nix command from the local machine.
The list of remote machines can be specified on the command line or in
the Nix configuration file. The former is convenient for testing. For

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@ -17,3 +17,27 @@ These constants are built into the Nix language evaluator:
The built-in value `currentSystem` evaluates to the Nix platform
identifier for the Nix installation on which the expression is being
evaluated, such as `"i686-linux"` or `"x86_64-darwin"`.
Not available in [pure evaluation mode](@docroot@/command-ref/conf-file.md#conf-pure-eval).
- [`builtins.currentTime`]{#builtins-currentTime} (integer)
Return the [Unix time](https://en.wikipedia.org/wiki/Unix_time) at first evaluation.
Repeated references to that name will re-use the initially obtained value.
Example:
```console
$ nix repl
Welcome to Nix 2.15.1 Type :? for help.
nix-repl> builtins.currentTime
1683705525
nix-repl> builtins.currentTime
1683705525
```
The [store path](@docroot@/glossary.md#gloss-store-path) of a derivation depending on `currentTime` will differ for each evaluation.
Not available in [pure evaluation mode](@docroot@/command-ref/conf-file.md#conf-pure-eval).

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@ -2,8 +2,11 @@
## Recursive sets
Recursive sets are just normal sets, but the attributes can refer to
each other. For example,
Recursive sets are like normal [attribute sets](./values.md#attribute-set), but the attributes can refer to each other.
> *rec-attrset* = `rec {` [ *name* `=` *expr* `;` `]`... `}`
Example:
```nix
rec {
@ -12,7 +15,9 @@ rec {
}.x
```
evaluates to `123`. Note that without `rec` the binding `x = y;` would
This evaluates to `123`.
Note that without `rec` the binding `x = y;` would
refer to the variable `y` in the surrounding scope, if one exists, and
would be invalid if no such variable exists. That is, in a normal
(non-recursive) set, attributes are not added to the lexical scope; in a
@ -33,7 +38,10 @@ will crash with an `infinite recursion encountered` error message.
## Let-expressions
A let-expression allows you to define local variables for an expression.
For instance,
> *let-in* = `let` [ *identifier* = *expr* ]... `in` *expr*
Example:
```nix
let
@ -42,18 +50,19 @@ let
in x + y
```
evaluates to `"foobar"`.
This evaluates to `"foobar"`.
## Inheriting attributes
When defining a set or in a let-expression it is often convenient to
copy variables from the surrounding lexical scope (e.g., when you want
to propagate attributes). This can be shortened using the `inherit`
keyword. For instance,
When defining an [attribute set](./values.md#attribute-set) or in a [let-expression](#let-expressions) it is often convenient to copy variables from the surrounding lexical scope (e.g., when you want to propagate attributes).
This can be shortened using the `inherit` keyword.
Example:
```nix
let x = 123; in
{ inherit x;
{
inherit x;
y = 456;
}
```
@ -62,15 +71,23 @@ is equivalent to
```nix
let x = 123; in
{ x = x;
{
x = x;
y = 456;
}
```
and both evaluate to `{ x = 123; y = 456; }`. (Note that this works
because `x` is added to the lexical scope by the `let` construct.) It is
also possible to inherit attributes from another set. For instance, in
this fragment from `all-packages.nix`,
and both evaluate to `{ x = 123; y = 456; }`.
> **Note**
>
> This works because `x` is added to the lexical scope by the `let` construct.
It is also possible to inherit attributes from another attribute set.
Example:
In this fragment from `all-packages.nix`,
```nix
graphviz = (import ../tools/graphics/graphviz) {

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@ -35,17 +35,14 @@
## Attribute selection
> *attrset* `.` *attrpath* \[ `or` *expr* \]
Select the attribute denoted by attribute path *attrpath* from [attribute set] *attrset*.
If the attribute doesnt exist, return the *expr* after `or` if provided, otherwise abort evaluation.
<!-- FIXME: the following should to into its own language syntax section, but that needs more work to fit in well -->
An attribute path is a dot-separated list of [attribute names](./values.md#attribute-set).
An attribute path is a dot-separated list of attribute names.
An attribute name can be an identifier or a string.
> *attrpath* = *name* [ `.` *name* ]... \
> *name* = *identifier* | *string* \
> *identifier* ~ `[a-zA-Z_][a-zA-Z0-9_'-]*`
> *attrpath* = *name* [ `.` *name* ]...
[Attribute selection]: #attribute-selection

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@ -164,9 +164,17 @@ Note that lists are only lazy in values, and they are strict in length.
An attribute set is a collection of name-value-pairs (called *attributes*) enclosed in curly brackets (`{ }`).
An attribute name can be an identifier or a [string](#string).
An identifier must start with a letter (`a-z`, `A-Z`) or underscore (`_`), and can otherwise contain letters (`a-z`, `A-Z`), numbers (`0-9`), underscores (`_`), apostrophes (`'`), or dashes (`-`).
> *name* = *identifier* | *string* \
> *identifier* ~ `[a-zA-Z_][a-zA-Z0-9_'-]*`
Names and values are separated by an equal sign (`=`).
Each value is an arbitrary expression terminated by a semicolon (`;`).
> *attrset* = `{` [ *name* `=` *expr* `;` `]`... `}`
Attributes can appear in any order.
An attribute name may only occur once.
@ -182,15 +190,19 @@ Example:
This defines a set with attributes named `x`, `text`, `y`.
Attributes can be selected from a set using the `.` operator. For
instance,
Attributes can be accessed with the [`.` operator](./operators.md#attribute-selection).
Example:
```nix
{ a = "Foo"; b = "Bar"; }.a
```
evaluates to `"Foo"`. It is possible to provide a default value in an
attribute selection using the `or` keyword:
This evaluates to `"Foo"`.
It is possible to provide a default value in an attribute selection using the `or` keyword.
Example:
```nix
{ a = "Foo"; b = "Bar"; }.c or "Xyzzy"

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@ -0,0 +1,8 @@
# Release 2.16 (2023-05-31)
* Speed-up of downloads from binary caches.
The number of parallel downloads (also known as substitutions) has been separated from the [`--max-jobs` setting](../command-ref/conf-file.md#conf-max-jobs).
The new setting is called [`max-substitution-jobs`](../command-ref/conf-file.md#conf-max-substitution-jobs).
The number of parallel downloads is now set to 16 by default (previously, the default was 1 due to the coupling to build jobs).
* The function [`builtins.replaceStrings`](@docroot@/language/builtins.md#builtins-replaceStrings) is now lazy in the value of its second argument `to`. That is, `to` is only evaluated when its corresponding pattern in `from` is matched in the string `s`.

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@ -1,6 +1,2 @@
# Release X.Y (202?-??-??)
- Speed-up of downloads from binary caches.
The number of parallel downloads (also known as substitutions) has been separated from the [`--max-jobs` setting](../command-ref/conf-file.md#conf-max-jobs).
The new setting is called [`max-substitution-jobs`](../command-ref/conf-file.md#conf-max-substitution-jobs).
The number of parallel downloads is now set to 16 by default (previously, the default was 1 due to the coupling to build jobs).

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@ -119,8 +119,7 @@ release:
TODO: This script requires the right AWS credentials. Document.
TODO: This script currently requires a
`/home/eelco/Dev/nix-pristine` and
`/home/eelco/Dev/nixpkgs-pristine`.
`/home/eelco/Dev/nix-pristine`.
TODO: trigger nixos.org netlify: https://docs.netlify.com/configure-builds/build-hooks/
@ -141,7 +140,7 @@ release:
$ git checkout master
$ git pull
$ NEW_VERSION=2.13.0
$ echo -n $NEW_VERSION > .version
$ echo $NEW_VERSION > .version
$ git checkout -b bump-$NEW_VERSION
$ git commit -a -m 'Bump version'
$ git push --set-upstream origin bump-$NEW_VERSION

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@ -15,7 +15,6 @@ my $evalId = $ARGV[0] or die "Usage: $0 EVAL-ID\n";
my $releasesBucketName = "nix-releases";
my $channelsBucketName = "nix-channels";
my $nixpkgsDir = "/home/eelco/Dev/nixpkgs-pristine";
my $TMPDIR = $ENV{'TMPDIR'} // "/tmp";
@ -200,26 +199,22 @@ for my $fn (glob "$tmpDir/*") {
}
}
# Update nix-fallback-paths.nix.
# Print new nix-fallback-paths.nix.
if ($isLatest) {
system("cd $nixpkgsDir && git pull") == 0 or die;
sub getStorePath {
my ($jobName) = @_;
my $buildInfo = decode_json(fetch("$evalUrl/job/$jobName", 'application/json'));
return $buildInfo->{buildoutputs}->{out}->{path} or die "cannot get store path for '$jobName'";
}
write_file("$nixpkgsDir/nixos/modules/installer/tools/nix-fallback-paths.nix",
print STDERR "nixos/modules/installer/tools/nix-fallback-paths.nix:\n" .
"{\n" .
" x86_64-linux = \"" . getStorePath("build.x86_64-linux") . "\";\n" .
" i686-linux = \"" . getStorePath("build.i686-linux") . "\";\n" .
" aarch64-linux = \"" . getStorePath("build.aarch64-linux") . "\";\n" .
" x86_64-darwin = \"" . getStorePath("build.x86_64-darwin") . "\";\n" .
" aarch64-darwin = \"" . getStorePath("build.aarch64-darwin") . "\";\n" .
"}\n");
system("cd $nixpkgsDir && git commit -a -m 'nix-fallback-paths.nix: Update to $version'") == 0 or die;
"}\n";
}
# Update the "latest" symlink.

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@ -246,8 +246,15 @@ printf -v _OLD_LINE_FMT "%b" $'\033[1;7;31m-'"$ESC ${RED}%L${ESC}"
printf -v _NEW_LINE_FMT "%b" $'\033[1;7;32m+'"$ESC ${GREEN}%L${ESC}"
_diff() {
# macOS Ventura doesn't ship with GNU diff. Print similar output except
# without +/- markers or dimming
if diff --version | grep -q "Apple diff"; then
printf -v CHANGED_GROUP_FORMAT "%b" "${GREEN}%>${RED}%<${ESC}"
diff --changed-group-format="$CHANGED_GROUP_FORMAT" "$@"
else
# simple colorized diff comatible w/ pre `--color` versions
diff --unchanged-group-format="$_UNCHANGED_GRP_FMT" --old-line-format="$_OLD_LINE_FMT" --new-line-format="$_NEW_LINE_FMT" --unchanged-line-format=" %L" "$@"
diff --unchanged-group-format="$_UNCHANGED_GRP_FMT" --old-line-format="$_OLD_LINE_FMT" --new-line-format="$_NEW_LINE_FMT" --unchanged-line-format=" %L" "$@"
fi
}
confirm_rm() {

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@ -2620,7 +2620,7 @@ Strings EvalSettings::getDefaultNixPath()
{
Strings res;
auto add = [&](const Path & p, const std::string & s = std::string()) {
if (pathExists(p)) {
if (pathAccessible(p)) {
if (s.empty()) {
res.push_back(p);
} else {

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@ -745,7 +745,13 @@ struct EvalSettings : Config
)"};
Setting<bool> pureEval{this, false, "pure-eval",
"Whether to restrict file system and network access to files specified by cryptographic hash."};
R"(
Pure evaluation mode ensures that the result of Nix expressions is fully determined by explicitly declared inputs, and not influenced by external state:
- Restrict file system and network access to files specified by cryptographic hash
- Disable [`bultins.currentSystem`](@docroot@/language/builtin-constants.md#builtins-currentSystem) and [`builtins.currentTime`](@docroot@/language/builtin-constants.md#builtins-currentTime)
)"
};
Setting<bool> enableImportFromDerivation{
this, true, "allow-import-from-derivation",

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@ -1152,16 +1152,14 @@ drvName, Bindings * attrs, Value & v)
if (i->value->type() == nNull) continue;
}
if (i->name == state.sContentAddressed) {
contentAddressed = state.forceBool(*i->value, noPos, context_below);
if (contentAddressed)
experimentalFeatureSettings.require(Xp::CaDerivations);
if (i->name == state.sContentAddressed && state.forceBool(*i->value, noPos, context_below)) {
contentAddressed = true;
experimentalFeatureSettings.require(Xp::CaDerivations);
}
else if (i->name == state.sImpure) {
isImpure = state.forceBool(*i->value, noPos, context_below);
if (isImpure)
experimentalFeatureSettings.require(Xp::ImpureDerivations);
else if (i->name == state.sImpure && state.forceBool(*i->value, noPos, context_below)) {
isImpure = true;
experimentalFeatureSettings.require(Xp::ImpureDerivations);
}
/* The `args' attribute is special: it supplies the
@ -1503,7 +1501,7 @@ static RegisterPrimOp primop_storePath({
causes the path to be *copied* again to the Nix store, resulting
in a new path (e.g. `/nix/store/ld01dnzc-source-source`).
This function is not available in pure evaluation mode.
Not available in [pure evaluation mode](@docroot@/command-ref/conf-file.md#conf-pure-eval).
)",
.fun = prim_storePath,
});
@ -3910,13 +3908,8 @@ static void prim_replaceStrings(EvalState & state, const PosIdx pos, Value * * a
for (auto elem : args[0]->listItems())
from.emplace_back(state.forceString(*elem, pos, "while evaluating one of the strings to replace passed to builtins.replaceStrings"));
std::vector<std::pair<std::string, NixStringContext>> to;
to.reserve(args[1]->listSize());
for (auto elem : args[1]->listItems()) {
NixStringContext ctx;
auto s = state.forceString(*elem, ctx, pos, "while evaluating one of the replacement strings passed to builtins.replaceStrings");
to.emplace_back(s, std::move(ctx));
}
std::unordered_map<size_t, std::string> cache;
auto to = args[1]->listItems();
NixStringContext context;
auto s = state.forceString(*args[2], context, pos, "while evaluating the third argument passed to builtins.replaceStrings");
@ -3927,10 +3920,19 @@ static void prim_replaceStrings(EvalState & state, const PosIdx pos, Value * * a
bool found = false;
auto i = from.begin();
auto j = to.begin();
for (; i != from.end(); ++i, ++j)
size_t j_index = 0;
for (; i != from.end(); ++i, ++j, ++j_index)
if (s.compare(p, i->size(), *i) == 0) {
found = true;
res += j->first;
auto v = cache.find(j_index);
if (v == cache.end()) {
NixStringContext ctx;
auto ts = state.forceString(**j, ctx, pos, "while evaluating one of the replacement strings passed to builtins.replaceStrings");
v = (cache.emplace(j_index, ts)).first;
for (auto& path : ctx)
context.insert(path);
}
res += v->second;
if (i->empty()) {
if (p < s.size())
res += s[p];
@ -3938,9 +3940,6 @@ static void prim_replaceStrings(EvalState & state, const PosIdx pos, Value * * a
} else {
p += i->size();
}
for (auto& path : j->second)
context.insert(path);
j->second.clear();
break;
}
if (!found) {
@ -3958,7 +3957,11 @@ static RegisterPrimOp primop_replaceStrings({
.args = {"from", "to", "s"},
.doc = R"(
Given string *s*, replace every occurrence of the strings in *from*
with the corresponding string in *to*. For example,
with the corresponding string in *to*.
The argument *to* is lazy, that is, it is only evaluated when its corresponding pattern in *from* is matched in the string *s*
Example:
```nix
builtins.replaceStrings ["oo" "a"] ["a" "i"] "foobar"

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@ -286,9 +286,9 @@ static RegisterPrimOp primop_fetchurl({
.name = "__fetchurl",
.args = {"url"},
.doc = R"(
Download the specified URL and return the path of the downloaded
file. This function is not available if [restricted evaluation
mode](../command-ref/conf-file.md) is enabled.
Download the specified URL and return the path of the downloaded file.
Not available in [restricted evaluation mode](@docroot@/command-ref/conf-file.md#conf-restrict-eval).
)",
.fun = prim_fetchurl,
});
@ -338,8 +338,7 @@ static RegisterPrimOp primop_fetchTarball({
stdenv.mkDerivation { }
```
This function is not available if [restricted evaluation
mode](../command-ref/conf-file.md) is enabled.
Not available in [restricted evaluation mode](@docroot@/command-ref/conf-file.md#conf-restrict-eval).
)",
.fun = prim_fetchTarball,
});
@ -470,14 +469,9 @@ static RegisterPrimOp primop_fetchGit({
}
```
> **Note**
>
> Nix will refetch the branch in accordance with
> the option `tarball-ttl`.
Nix will refetch the branch according to the [`tarball-ttl`](@docroot@/command-ref/conf-file.md#conf-tarball-ttl) setting.
> **Note**
>
> This behavior is disabled in *Pure evaluation mode*.
This behavior is disabled in [pure evaluation mode](@docroot@/command-ref/conf-file.md#conf-pure-eval).
- To fetch the content of a checked-out work directory:

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@ -171,7 +171,7 @@ namespace nix {
hintfmt("value is %s while a string was expected", "an integer"),
hintfmt("while evaluating one of the strings to replace passed to builtins.replaceStrings"));
ASSERT_TRACE2("replaceStrings [ \"old\" ] [ true ] {}",
ASSERT_TRACE2("replaceStrings [ \"oo\" ] [ true ] \"foo\"",
TypeError,
hintfmt("value is %s while a string was expected", "a Boolean"),
hintfmt("while evaluating one of the replacement strings passed to builtins.replaceStrings"));

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@ -75,22 +75,28 @@ SourcePath SourcePath::resolveSymlinks() const
int linksAllowed = 1024;
for (auto & component : path) {
res.path.push(component);
while (true) {
if (auto st = res.maybeLstat()) {
std::list<std::string> todo;
for (auto & c : path)
todo.push_back(std::string(c));
while (!todo.empty()) {
auto c = *todo.begin();
todo.pop_front();
if (c == "" || c == ".")
;
else if (c == "..")
res.path.pop();
else {
res.path.push(c);
if (auto st = res.maybeLstat(); st && st->type == InputAccessor::tSymlink) {
if (!linksAllowed--)
throw Error("infinite symlink recursion in path '%s'", path);
if (st->type != InputAccessor::tSymlink) break;
auto target = res.readLink();
res.path.pop();
if (hasPrefix(target, "/"))
res = CanonPath(target);
else {
res.path.pop();
res.path.extend(CanonPath(target));
}
} else
break;
res.path = CanonPath::root;
todo.splice(todo.begin(), tokenizeString<std::list<std::string>>(target, "/"));
}
}
}

View file

@ -357,7 +357,7 @@ bool LocalDerivationGoal::cleanupDecideWhetherDiskFull()
for (auto & [_, status] : initialOutputs) {
if (!status.known) continue;
if (buildMode != bmCheck && status.known->isValid()) continue;
auto p = worker.store.printStorePath(status.known->path);
auto p = worker.store.toRealPath(status.known->path);
if (pathExists(chrootRootDir + p))
renameFile((chrootRootDir + p), p);
}

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@ -183,7 +183,7 @@ bool Settings::isWSL1()
Path Settings::getDefaultSSLCertFile()
{
for (auto & fn : {"/etc/ssl/certs/ca-certificates.crt", "/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt"})
if (pathExists(fn)) return fn;
if (pathAccessible(fn)) return fn;
return "";
}

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@ -995,6 +995,18 @@ public:
| `~/.nix-profile` | `$XDG_STATE_HOME/nix/profile` |
| `~/.nix-defexpr` | `$XDG_STATE_HOME/nix/defexpr` |
| `~/.nix-channels` | `$XDG_STATE_HOME/nix/channels` |
If you already have Nix installed and are using [profiles](@docroot@/package-management/profiles.md) or [channels](@docroot@/package-management/channels.md), you should migrate manually when you enable this option.
If `$XDG_STATE_HOME` is not set, use `$HOME/.local/state/nix` instead of `$XDG_STATE_HOME/nix`.
This can be achieved with the following shell commands:
```sh
nix_state_home=${XDG_STATE_HOME-$HOME/.local/state}/nix
mkdir -p $nix_state_home
mv $HOME/.nix-profile $nix_state_home/profile
mv $HOME/.nix-defexpr $nix_state_home/defexpr
mv $HOME/.nix-channels $nix_state_home/channels
```
)"
};
};

View file

@ -50,6 +50,8 @@ constexpr std::array<ExperimentalFeatureDetails, 14> xpFeatureDetails = {{
or other impure derivations can rely on impure derivations. Finally,
an impure derivation cannot also be
[content-addressed](#xp-feature-ca-derivations).
This is a more explicit alternative to using [`builtins.currentTime`](@docroot@/language/builtin-constants.md#builtins-currentTime).
)",
},
{

View file

@ -202,7 +202,7 @@ namespace nix {
}
TEST(pathExists, bogusPathDoesNotExist) {
ASSERT_FALSE(pathExists("/home/schnitzel/darmstadt/pommes"));
ASSERT_FALSE(pathExists("/schnitzel/darmstadt/pommes"));
}
/* ----------------------------------------------------------------------------

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@ -266,6 +266,17 @@ bool pathExists(const Path & path)
return false;
}
bool pathAccessible(const Path & path)
{
try {
return pathExists(path);
} catch (SysError & e) {
// swallow EPERM
if (e.errNo == EPERM) return false;
throw;
}
}
Path readLink(const Path & path)
{

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@ -120,6 +120,14 @@ struct stat lstat(const Path & path);
*/
bool pathExists(const Path & path);
/**
* A version of pathExists that returns false on a permission error.
* Useful for inferring default paths across directories that might not
* be readable.
* @return true iff the given path can be accessed and exists
*/
bool pathAccessible(const Path & path);
/**
* Read the contents (target) of a symbolic link. The result is not
* in any way canonicalised.

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@ -102,6 +102,7 @@ way:
available in the flake. If this is undesirable, specify `path:<directory>` explicitly;
For example, if `/foo/bar` is a git repository with the following structure:
```
.
└── baz

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@ -35,3 +35,9 @@ nix-instantiate --eval -E 'assert 1 + 2 == 3; true'
# Check that symlink cycles don't cause a hang.
ln -sfn cycle.nix $TEST_ROOT/cycle.nix
(! nix eval --file $TEST_ROOT/cycle.nix)
# Check that relative symlinks are resolved correctly.
mkdir -p $TEST_ROOT/xyzzy $TEST_ROOT/foo
ln -sfn ../xyzzy $TEST_ROOT/foo/bar
printf 123 > $TEST_ROOT/xyzzy/default.nix
[[ $(nix eval --impure --expr "import $TEST_ROOT/foo/bar") = 123 ]]

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@ -1 +1 @@
[ "faabar" "fbar" "fubar" "faboor" "fubar" "XaXbXcX" "X" "a_b" ]
[ "faabar" "fbar" "fubar" "faboor" "fubar" "XaXbXcX" "X" "a_b" "fubar" ]

View file

@ -8,4 +8,5 @@ with builtins;
(replaceStrings [""] ["X"] "abc")
(replaceStrings [""] ["X"] "")
(replaceStrings ["-"] ["_"] "a-b")
(replaceStrings ["oo" "XX"] ["u" (throw "unreachable")] "foobar")
]