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Merged
edolstra merged 2 commits into from
Feb 15, 2026
Merged

Upstream C store API improvements #352

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0b10d6f
add query_from_hash_part c API
pkpbynum Dec 10, 2025
93387a4
Add nix_store_copy_path C API
pkpbynum Dec 10, 2025
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9 changes: 9 additions & 0 deletions doc/manual/rl-next/c-api-new-store-methods.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
---
synopsis: "C API: New store API methods"
prs: [14766]
---

The C API now includes additional methods:

- `nix_store_query_path_from_hash_part()` - Get the full store path given its hash part
- `nix_store_copy_path()` - Copy a single store path between two stores, allows repairs and configuring signature checking
38 changes: 38 additions & 0 deletions src/libstore-c/nix_api_store.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -453,4 +453,42 @@ nix_err nix_derivation_get_outputs_and_optpaths(
NIXC_CATCH_ERRS
}

StorePath * nix_store_query_path_from_hash_part(nix_c_context * context, Store * store, const char * hash)
{
if (context)
context->last_err_code = NIX_OK;
try {
std::optional<nix::StorePath> s = store->ptr->queryPathFromHashPart(hash);

if (!s.has_value()) {
return nullptr;
}

return new StorePath{std::move(s.value())};
}
NIXC_CATCH_ERRS_NULL
}
Comment on lines +456 to +470
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@coderabbitai coderabbitai bot Feb 13, 2026

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⚠️ Potential issue | 🟡 Minor

Missing null validation for store and hash parameters.

Unlike nix_store_copy_path which validates its parameters, this function will crash if store is null (dereferencing store->ptr) or may have undefined behavior if hash is null. Consider adding validation for consistency:

🛡️ Proposed fix to add validation 
 StorePath * nix_store_query_path_from_hash_part(nix_c_context * context, Store * store, const char * hash)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
+        if (store == nullptr) {
+            nix_set_err_msg(context, NIX_ERR_UNKNOWN, "Store is null");
+            return nullptr;
+        }
+        if (hash == nullptr) {
+            nix_set_err_msg(context, NIX_ERR_UNKNOWN, "Hash is null");
+            return nullptr;
+        }
         std::optional<nix::StorePath> s = store->ptr->queryPathFromHashPart(hash);

Note: The existing nix_store_copy_closure function (line 344) also lacks null validation, so if following strict consistency with existing code, this could be considered optional.

🤖 Prompt for AI Agents 
In `@src/libstore-c/nix_api_store.cc` around lines 456 - 470, The function
nix_store_query_path_from_hash_part lacks null checks for the store and hash
params; add validation at the top (after setting context->last_err_code =
NIX_OK) to return nullptr and set context->last_err_code = NIX_ERR_INVALID_ARG
when store is null or hash is null, mirroring the behavior in
nix_store_copy_path, so you never dereference store->ptr or use a null hash;
keep the existing try/catch and NIXC_CATCH_ERRS_NULL flow otherwise.


nix_err nix_store_copy_path(
nix_c_context * context, Store * srcStore, Store * dstStore, const StorePath * path, bool repair, bool checkSigs)
{
if (context)
context->last_err_code = NIX_OK;
try {
if (srcStore == nullptr)
return nix_set_err_msg(context, NIX_ERR_UNKNOWN, "Source store is null");

if (dstStore == nullptr)
return nix_set_err_msg(context, NIX_ERR_UNKNOWN, "Destination store is null");

if (path == nullptr)
return nix_set_err_msg(context, NIX_ERR_UNKNOWN, "Store path is null");

auto repairFlag = repair ? nix::RepairFlag::Repair : nix::RepairFlag::NoRepair;
auto checkSigsFlag = checkSigs ? nix::CheckSigsFlag::CheckSigs : nix::CheckSigsFlag::NoCheckSigs;
nix::copyStorePath(*srcStore->ptr, *dstStore->ptr, path->path, repairFlag, checkSigsFlag);
}
NIXC_CATCH_ERRS
}

} // extern "C"
24 changes: 24 additions & 0 deletions src/libstore-c/nix_api_store.h
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Original file line number Diff line number Diff line change
Expand Up @@ -357,6 +357,30 @@ nix_err nix_derivation_get_outputs_and_optpaths(
nix_err nix_derivation_to_json(
nix_c_context * context, const nix_derivation * drv, nix_get_string_callback callback, void * userdata);

/**
* @brief Query the full store path given the hash part of a valid store
* path, or empty if no matching path is found.
*
* @param[out] context Optional, stores error information
* @param[in] store nix store reference
* @param[in] hash Hash part of path as a string
* @return Store path reference, NULL if no matching path is found.
*/
StorePath * nix_store_query_path_from_hash_part(nix_c_context * context, Store * store, const char * hash);

/**
* @brief Copy a path from one store to another.
*
* @param[out] context Optional, stores error information
* @param[in] srcStore nix source store reference
* @param[in] dstStore nix destination store reference
* @param[in] path The path to copy
* @param[in] repair Whether to repair the path
* @param[in] checkSigs Whether to check path signatures are trusted before copying
*/
nix_err nix_store_copy_path(
nix_c_context * context, Store * srcStore, Store * dstStore, const StorePath * path, bool repair, bool checkSigs);

// cffi end
#ifdef __cplusplus
}
Expand Down