Move document key listing behind the store API

The terminal editor listed documents by reading the flat store's obj- file
names, so a UI host depended on one storage layout. pure_store_keys now
lists keys through the selected store; per-object file stores share
store-keys.c, linked only by hosts that browse documents, so the default
CLI and HTTP hosts are unchanged. The source TUI ceiling reviews the
measured 368-byte cost.

1 files changed, 41 insertions, 0 deletions

diff --git a/prototypes/connections/store-keys.c b/prototypes/connections/store-keys.c
new file mode 100644
index 0000000..d5aeb69
--- /dev/null
+++ b/prototypes/connections/store-keys.c
@@ -0,0 +1,41 @@
+#define _POSIX_C_SOURCE 200809L
+#include "store.h"
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Key listing for the stores that publish each object as obj-KEY (the flat
+ * and paged formats). Linked only by hosts that browse documents, so the
+ * default CLI and HTTP hosts do not carry it. */
+static bool valid_key(const char *key) {
+    size_t length = strlen(key);
+    if (!length || length > 64) return false;
+    for (size_t i = 0; i < length; ++i) {
+        unsigned char c = (unsigned char)key[i];
+        if (!((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+              (c >= '0' && c <= '9') || c == '_' || c == '-')) return false;
+    }
+    return true;
+}
+
+PureResult pure_store_keys(const char *path, bool (*visit)(void *, const char *key),
+                           void *context) {
+    int descriptor = open(path, O_RDONLY | O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
+    DIR *directory = descriptor >= 0 ? fdopendir(descriptor) : NULL;
+    if (!directory) {
+        if (descriptor >= 0) close(descriptor);
+        return PURE_STORE_ERROR;
+    }
+    PureResult result = PURE_OK;
+    for (;;) {
+        errno = 0;
+        struct dirent *entry = readdir(directory);
+        if (!entry) { if (errno) result = PURE_STORE_ERROR; break; }
+        if (strncmp(entry->d_name, "obj-", 4) || !valid_key(entry->d_name + 4)) continue;
+        if (!visit(context, entry->d_name + 4)) break;
+    }
+    if (closedir(directory)) result = PURE_STORE_ERROR;
+    return result;
+}