Replace symlink_exists with pathExists

As it turns out the orignal implementation of symlink_exists cannot be
used in Nix because it did now std::filesystem::filesystem_error.
The new implementation fixes that but is now actually the same as
pathExists except for the path type.

Author: Mic92

src/libfetchers/git.cc

@@ -533,7 +533,7 @@ struct GitInputScheme : InputScheme
     static MakeNotAllowedError makeNotAllowedError(std::filesystem::path repoPath)
     {
         return [repoPath{std::move(repoPath)}](const CanonPath & path) -> RestrictedPathError {
-            if (fs::symlink_exists(repoPath / path.rel()))
+            if (pathExists(repoPath / path.rel()))
                 return RestrictedPathError(
                     "Path '%1%' in the repository %2% is not tracked by Git.\n"
                     "\n"

src/libflake/flake.cc

@@ -811,7 +811,7 @@ LockedFlake lockFlake(
                             auto relPath = (topRef.subdir == "" ? "" : topRef.subdir + "/") + "flake.lock";
                             auto outputLockFilePath = *sourcePath / relPath;
 
-                            bool lockFileExists = fs::symlink_exists(outputLockFilePath);
+                            bool lockFileExists = pathExists(outputLockFilePath);
 
                             auto s = chomp(diff);
                             if (lockFileExists) {

src/libstore/unix/build/derivation-builder.cc

@@ -1969,9 +1969,10 @@ void DerivationBuilderImpl::runChild()
                     if (pathExists(path))
                         ss.push_back(path);
 
-                if (settings.caFile != "" && pathExists(settings.caFile)) {
+                if (settings.caFile != "") {
                     Path caFile = settings.caFile;
-                    pathsInChroot.try_emplace("/etc/ssl/certs/ca-certificates.crt", canonPath(caFile, true), true);
+                    if (pathExists(caFile))
+                       pathsInChroot.try_emplace("/etc/ssl/certs/ca-certificates.crt", canonPath(caFile, true), true);
                 }
             }
 

src/libutil/file-system.cc

@@ -31,18 +31,6 @@
 
 namespace nix {
 
-namespace fs {
-  using namespace std::filesystem;
-
-  bool symlink_exists(const std::filesystem::path & path) {
-      try {
-          return std::filesystem::exists(std::filesystem::symlink_status(path));
-      } catch (const std::filesystem::filesystem_error & e) {
-          throw SysError("cannot check existence of %1%", path);
-      }
-  }
-}
-
 DirectoryIterator::DirectoryIterator(const std::filesystem::path& p) {
     try {
         // **Attempt to create the underlying directory_iterator**
@@ -243,9 +231,9 @@ std::optional<struct stat> maybeLstat(const Path & path)
 }
 
 
-bool pathExists(const Path & path)
+bool pathExists(const std::filesystem::path & path)
 {
-    return maybeLstat(path).has_value();
+    return maybeLstat(path.string()).has_value();
 }
 
 bool pathAccessible(const std::filesystem::path & path)

src/libutil/include/nix/util/file-system.hh

@@ -126,26 +126,8 @@ std::optional<struct stat> maybeLstat(const Path & path);
 
 /**
  * @return true iff the given path exists.
- *
- * In the process of being deprecated for `fs::symlink_exists`.
- */
-bool pathExists(const Path & path);
-
-namespace fs {
-
-/**
- * TODO: we may actually want to use pathExists instead of this function
- *  ```
- *  symlink_exists(p) = std::filesystem::exists(std::filesystem::symlink_status(p))
- *  ```
- *  Missing convenience analogous to
- *  ```
- *  std::filesystem::exists(p) = std::filesystem::exists(std::filesystem::status(p))
- *  ```
  */
-bool symlink_exists(const std::filesystem::path & path);
-
-} // namespace fs
+bool pathExists(const std::filesystem::path & path);
 
 /**
  * Canonicalize a path except for the last component.

src/nix/eval.cc

@@ -76,7 +76,7 @@ struct CmdEval : MixJSON, InstallableValueCommand, MixReadOnlyOption
         if (writeTo) {
             logger->stop();
 
-            if (fs::symlink_exists(*writeTo))
+            if (pathExists(*writeTo))
                 throw Error("path '%s' already exists", writeTo->string());
 
             std::function<void(Value & v, const PosIdx pos, const fs::path & path)> recurse;