src/database_flatfile.c

@@ -373,13 +373,10 @@ _ff_add_message(const char* type, const char* stanza_id, const char* archive_id,
     g_date_time_unref(dt);
 
     // Determine which JID to use for the log file path (the "other" party)
-    const char* contact = NULL;
     const Jid* myjid = connection_get_jid();
-    if (myjid && myjid->barejid && g_strcmp0(from_barejid, myjid->barejid) == 0) {
-        contact = to_barejid;
-    } else {
-        contact = from_barejid;
-    }
+    gboolean is_outgoing = myjid && myjid->barejid
+                           && g_strcmp0(from_barejid, myjid->barejid) == 0;
+    const char* contact = is_outgoing ? to_barejid : from_barejid;
 
     auto_gchar gchar* log_path = ff_get_log_path(contact);
 

src/database_flatfile.h

@@ -148,6 +148,17 @@ ProfMessage* ff_parsed_to_profmessage(ff_parsed_line_t* pl);
 
 // --- Integrity verification (database_flatfile_verify.c) ---
 
+// Run integrity checks against one contact's history.log (or every contact
+// when contact_barejid == NULL).
+//
+// Returns a freshly allocated GSList<integrity_issue_t*> reporting:
+//   - File-level: missing log, BOM, CRLF, empty, wrong permissions
+//   - Line-level: invalid UTF-8, control characters, unparsable lines,
+//                 timestamps out of order, duplicate stanza-id /
+//                 archive-id (tracked separately)
+//   - Cross-line: broken `corrects:` LMC references
+//
+// Callers must free with g_slist_free_full(issues, integrity_issue_free).
 GSList* ff_verify_integrity(const gchar* const contact_barejid);
 
 #endif

src/database_flatfile_parser.c

@@ -98,7 +98,7 @@ ff_get_message_enc_type(const char* const encstr)
 
 // Sanitise a JID for use as a directory name.
 // 1. Replace '@' with '_at_'
-// 2. Reject / strip path-separator and traversal characters: '/', '\0', '..'
+// 2. Reject / strip path-separator and traversal characters: '/', '\\', '..'
 // This prevents a malicious federated JID like "../../../tmp/pwned" from
 // escaping the log directory tree.
 char*
@@ -107,36 +107,32 @@ ff_jid_to_dir(const char* jid)
     if (!jid || jid[0] == '\0')
         return NULL;
 
-    // Replace '@' first
-    char* step1 = str_replace(jid, "@", "_at_");
-    if (!step1)
+    // Replace '@' with '_at_' (str_replace returns a freshly allocated string)
+    char* result = str_replace(jid, "@", "_at_");
+    if (!result)
         return NULL;
 
-    // Replace '/' and '\\' with '_' to prevent path traversal
-    GString* out = g_string_sized_new(strlen(step1));
-    for (const char* p = step1; *p; p++) {
-        if (*p == '/' || *p == '\\') {
-            g_string_append_c(out, '_');
-        } else {
-            g_string_append_c(out, *p);
-        }
+    // Replace path-separator characters in place
+    for (char* p = result; *p; p++) {
+        if (*p == '/' || *p == '\\')
+            *p = '_';
     }
-    free(step1);
 
     // Collapse any remaining ".." sequences to "__" (belt-and-suspenders)
-    char* result = g_string_free(out, FALSE);
     char* dotdot;
     while ((dotdot = strstr(result, "..")) != NULL) {
         dotdot[0] = '_';
         dotdot[1] = '_';
     }
 
-    // Reject empty result
     if (result[0] == '\0') {
-        g_free(result);
+        free(result);
         return NULL;
     }
-    return result;
+    // Callers free via g_free, str_replace allocates via malloc — handover.
+    char* gresult = g_strdup(result);
+    free(result);
+    return gresult;
 }
 
 // Get the base directory for a contact's logs:
@@ -172,15 +168,12 @@ ff_get_log_path(const char* contact_barejid)
 gboolean
 ff_ensure_dir(const char* path)
 {
-    if (g_file_test(path, G_FILE_TEST_IS_DIR)) {
-        // Verify it's not a symlink
-        struct stat st;
-        if (g_lstat(path, &st) == 0 && S_ISLNK(st.st_mode)) {
-            log_error("flatfile: directory path is a symlink, refusing: %s", path);
-            return FALSE;
-        }
-        return TRUE;
+    if (g_file_test(path, G_FILE_TEST_IS_SYMLINK)) {
+        log_error("flatfile: directory path is a symlink, refusing: %s", path);
+        return FALSE;
     }
+    if (g_file_test(path, G_FILE_TEST_IS_DIR))
+        return TRUE;
     if (g_mkdir_with_parents(path, S_IRWXU) != 0) {
         log_error("flatfile: Could not create directory: %s (errno=%d)", path, errno);
         return FALSE;
@@ -231,25 +224,25 @@ ff_unescape_message(const char* text)
         return g_strdup("");
     GString* out = g_string_sized_new(strlen(text));
     for (const char* p = text; *p; p++) {
-        if (*p == '\\' && *(p + 1)) {
-            p++;
-            switch (*p) {
-            case '\\':
-                g_string_append_c(out, '\\');
-                break;
-            case 'n':
-                g_string_append_c(out, '\n');
-                break;
-            case 'r':
-                g_string_append_c(out, '\r');
-                break;
-            default:
-                g_string_append_c(out, '\\');
-                g_string_append_c(out, *p);
-                break;
-            }
-        } else {
+        if (*p != '\\' || !*(p + 1)) {
             g_string_append_c(out, *p);
+            continue;
+        }
+        p++;
+        switch (*p) {
+        case '\\':
+            g_string_append_c(out, '\\');
+            break;
+        case 'n':
+            g_string_append_c(out, '\n');
+            break;
+        case 'r':
+            g_string_append_c(out, '\r');
+            break;
+        default:
+            g_string_append_c(out, '\\');
+            g_string_append_c(out, *p);
+            break;
         }
     }
     return g_string_free(out, FALSE);
@@ -296,31 +289,31 @@ ff_unescape_meta_value(const char* val)
         return NULL;
     GString* out = g_string_sized_new(strlen(val));
     for (const char* p = val; *p; p++) {
-        if (*p == '\\' && *(p + 1)) {
-            p++;
-            switch (*p) {
-            case '|':
-                g_string_append_c(out, '|');
-                break;
-            case ']':
-                g_string_append_c(out, ']');
-                break;
-            case '\\':
-                g_string_append_c(out, '\\');
-                break;
-            case 'n':
-                g_string_append_c(out, '\n');
-                break;
-            case 'r':
-                g_string_append_c(out, '\r');
-                break;
-            default:
-                g_string_append_c(out, '\\');
-                g_string_append_c(out, *p);
-                break;
-            }
-        } else {
+        if (*p != '\\' || !*(p + 1)) {
             g_string_append_c(out, *p);
+            continue;
+        }
+        p++;
+        switch (*p) {
+        case '|':
+            g_string_append_c(out, '|');
+            break;
+        case ']':
+            g_string_append_c(out, ']');
+            break;
+        case '\\':
+            g_string_append_c(out, '\\');
+            break;
+        case 'n':
+            g_string_append_c(out, '\n');
+            break;
+        case 'r':
+            g_string_append_c(out, '\r');
+            break;
+        default:
+            g_string_append_c(out, '\\');
+            g_string_append_c(out, *p);
+            break;
         }
     }
     return g_string_free(out, FALSE);
@@ -376,11 +369,8 @@ ff_readline(FILE* fp, gboolean* truncated)
         if (truncated)
             *truncated = FALSE;
         // Return empty string so caller's loop continues (parse will reject it).
-        // Use malloc() so callers can always use free() consistently.
-        char* empty = malloc(1);
-        if (empty)
-            empty[0] = '\0';
-        return empty;
+        // strdup() so callers can always free() consistently.
+        return strdup("");
     }
     if (truncated)
         *truncated = FALSE;
@@ -465,21 +455,14 @@ ff_write_line(FILE* fp, const char* timestamp, const char* type, const char* enc
     }
 
     // Escape message body to prevent log injection
-    char* safe_msg = ff_escape_message(message_text);
+    auto_char char* safe_msg = ff_escape_message(message_text);
 
-    // Build complete line and write with a single fwrite()
-    GString* full_line = g_string_new(NULL);
-    g_string_printf(full_line, "%s %s %s: %s\n",
-                    timestamp, meta->str, sender->str, safe_msg);
-
-    size_t to_write = full_line->len;
-    size_t written = fwrite(full_line->str, 1, to_write, fp);
-    if (written != to_write) {
-        log_error("flatfile: partial write (%zu/%zu)", written, to_write);
+    int ret = fprintf(fp, "%s %s %s: %s\n",
+                      timestamp, meta->str, sender->str, safe_msg);
+    if (ret < 0) {
+        log_error("flatfile: fprintf failed (errno=%d)", errno);
     }
 
-    g_string_free(full_line, TRUE);
-    g_free(safe_msg);
     g_string_free(meta, TRUE);
     g_string_free(sender, TRUE);
 }
@@ -554,19 +537,19 @@ ff_unescape_sender_resource(const char* res)
         return NULL;
     GString* out = g_string_sized_new(strlen(res));
     for (const char* p = res; *p; p++) {
-        if (*p == '\\' && *(p + 1)) {
-            p++;
-            if (*p == '\\') {
-                g_string_append_c(out, '\\');
-            } else if (*p == ':' && *(p + 1) == ' ') {
-                g_string_append(out, ": ");
-                p++; // skip the space
-            } else {
-                // Unknown escape — preserve literally
-                g_string_append_c(out, '\\');
-                g_string_append_c(out, *p);
-            }
+        if (*p != '\\' || !*(p + 1)) {
+            g_string_append_c(out, *p);
+            continue;
+        }
+        p++;
+        if (*p == '\\') {
+            g_string_append_c(out, '\\');
+        } else if (*p == ':' && *(p + 1) == ' ') {
+            g_string_append(out, ": ");
+            p++; // skip the space
         } else {
+            // Unknown escape — preserve literally
+            g_string_append_c(out, '\\');
             g_string_append_c(out, *p);
         }
     }
@@ -598,6 +581,33 @@ ff_parsed_line_free(ff_parsed_line_t* pl)
     g_free(pl);
 }
 
+// Populate the parsed-line metadata fields from the pipe-split parts[]
+// (the contents of a "[...]" section). Index 0 is type, index 1 is enc;
+// remaining parts are key:value pairs (id:, aid:, corrects:, to:, to_res:, read:).
+static void
+_ff_parse_meta_parts(char** parts, ff_parsed_line_t* out)
+{
+    for (int i = 0; parts[i]; i++) {
+        if (i == 0) {
+            out->type = g_strdup(parts[i]);
+        } else if (i == 1) {
+            out->enc = g_strdup(parts[i]);
+        } else if (g_str_has_prefix(parts[i], FF_META_PREFIX_ID)) {
+            out->stanza_id = ff_unescape_meta_value(parts[i] + strlen(FF_META_PREFIX_ID));
+        } else if (g_str_has_prefix(parts[i], FF_META_PREFIX_AID)) {
+            out->archive_id = ff_unescape_meta_value(parts[i] + strlen(FF_META_PREFIX_AID));
+        } else if (g_str_has_prefix(parts[i], "corrects:")) {
+            out->replace_id = ff_unescape_meta_value(parts[i] + strlen("corrects:"));
+        } else if (g_str_has_prefix(parts[i], "to:")) {
+            out->to_jid = ff_unescape_meta_value(parts[i] + strlen("to:"));
+        } else if (g_str_has_prefix(parts[i], "to_res:")) {
+            out->to_resource = ff_unescape_meta_value(parts[i] + strlen("to_res:"));
+        } else if (g_str_has_prefix(parts[i], "read:")) {
+            out->marked_read = atoi(parts[i] + strlen("read:")) ? 1 : 0;
+        }
+    }
+}
+
 // Parse a single line. Returns NULL on parse failure.
 // Line format: {timestamp} [{metadata}] {sender}: {message}
 ff_parsed_line_t*
@@ -652,68 +662,45 @@ ff_parse_line(const char* line)
 
         // Parse metadata section [...]
         const char* bracket_end = ff_find_unescaped_char(bracket_start + 1, ']');
-        if (bracket_end) {
-            char* meta_content = g_strndup(bracket_start + 1, bracket_end - bracket_start - 1);
-
-            // Split by unescaped '|'
-            char** parts = ff_split_meta(meta_content);
-            if (parts) {
-                int i = 0;
-                for (; parts[i]; i++) {
-                    if (i == 0) {
-                        result->type = g_strdup(parts[i]);
-                    } else if (i == 1) {
-                        result->enc = g_strdup(parts[i]);
-                    } else if (g_str_has_prefix(parts[i], FF_META_PREFIX_ID)) {
-                        result->stanza_id = ff_unescape_meta_value(parts[i] + strlen(FF_META_PREFIX_ID));
-                    } else if (g_str_has_prefix(parts[i], FF_META_PREFIX_AID)) {
-                        result->archive_id = ff_unescape_meta_value(parts[i] + strlen(FF_META_PREFIX_AID));
-                    } else if (g_str_has_prefix(parts[i], "corrects:")) {
-                        result->replace_id = ff_unescape_meta_value(parts[i] + strlen("corrects:"));
-                    } else if (g_str_has_prefix(parts[i], "to:")) {
-                        result->to_jid = ff_unescape_meta_value(parts[i] + strlen("to:"));
-                    } else if (g_str_has_prefix(parts[i], "to_res:")) {
-                        result->to_resource = ff_unescape_meta_value(parts[i] + strlen("to_res:"));
-                    } else if (g_str_has_prefix(parts[i], "read:")) {
-                        result->marked_read = atoi(parts[i] + strlen("read:")) ? 1 : 0;
-                    }
-                }
-                g_strfreev(parts);
-            }
-            g_free(meta_content);
-
-            // Parse sender: message after '] '
-            const char* after_meta = bracket_end + 1;
-            if (*after_meta == ' ')
-                after_meta++;
-
-            // Find first *unescaped* ': ' which separates sender from message.
-            const char* colon = ff_find_unescaped_colonspace(after_meta);
-            if (colon) {
-                char* raw_sender = g_strndup(after_meta, colon - after_meta);
-
-                // Split sender into jid/resource, then unescape resource
-                char* slash = strchr(raw_sender, '/');
-                if (slash) {
-                    result->from_jid = g_strndup(raw_sender, slash - raw_sender);
-                    result->from_resource = ff_unescape_sender_resource(slash + 1);
-                } else {
-                    result->from_jid = g_strdup(raw_sender);
-                }
-                g_free(raw_sender);
-
-                result->message = ff_unescape_message(colon + 2);
-            } else {
-                // No ': ' found, treat entire rest as message with unknown sender
-                result->from_jid = g_strdup("unknown");
-                result->message = ff_unescape_message(after_meta);
-            }
-        } else {
+        if (!bracket_end) {
             // No closing bracket — malformed metadata
             ff_parsed_line_free(result);
             g_free(work);
             return NULL;
         }
+
+        auto_gchar gchar* meta_content = g_strndup(bracket_start + 1, bracket_end - bracket_start - 1);
+        char** parts = ff_split_meta(meta_content);
+        if (parts) {
+            _ff_parse_meta_parts(parts, result);
+            g_strfreev(parts);
+        }
+
+        // Parse sender: message after '] '
+        const char* after_meta = bracket_end + 1;
+        if (*after_meta == ' ')
+            after_meta++;
+
+        // Find first *unescaped* ': ' which separates sender from message.
+        const char* colon = ff_find_unescaped_colonspace(after_meta);
+        if (colon) {
+            auto_gchar gchar* raw_sender = g_strndup(after_meta, colon - after_meta);
+
+            // Split sender into jid/resource, then unescape resource
+            char* slash = strchr(raw_sender, '/');
+            if (slash) {
+                result->from_jid = g_strndup(raw_sender, slash - raw_sender);
+                result->from_resource = ff_unescape_sender_resource(slash + 1);
+            } else {
+                result->from_jid = g_strdup(raw_sender);
+            }
+
+            result->message = ff_unescape_message(colon + 2);
+        } else {
+            // No ': ' found, treat entire rest as message with unknown sender
+            result->from_jid = g_strdup("unknown");
+            result->message = ff_unescape_message(after_meta);
+        }
     } else if (first_space) {
         // Legacy/simple format without metadata: {timestamp} - {sender}: {msg}
         result->timestamp_str = g_strndup(work, first_space - work);

src/database_flatfile_verify.c

@@ -8,8 +8,26 @@
  * vim: expandtab:ts=4:sts=4:sw=4
  *
  * Flat-file backend: integrity verification (/history verify).
- * Checks: parsability, timestamp ordering, duplicate IDs, broken LMC
- * references, file permissions, BOM, CRLF, UTF-8, control chars.
+ *
+ * High-level flow (see ff_verify_integrity):
+ *   1. Resolve target contact directories — either a single contact (when
+ *      contact_barejid != NULL) or every contact directory under
+ *      flatlog/<account>/.
+ *   2. For each contact's history.log:
+ *        - Check file permissions (warn if not 0600).
+ *        - First pass: line-by-line UTF-8 / control-char / parser /
+ *          duplicate-id / timestamp-ordering checks. Records every
+ *          stanza-id and archive-id seen so the second pass can resolve
+ *          LMC references. stanza-id and archive-id are tracked in
+ *          *separate* hash tables — duplicate detection is reported
+ *          per id-kind to avoid spurious cross-kind warnings.
+ *        - Second pass: re-read the file and verify each `corrects:` link
+ *          points at a stanza-id that was seen in pass 1.
+ *   3. Aggregate every issue into a GSList<integrity_issue_t> and return
+ *      it to the caller, ready for /history verify rendering.
+ *
+ * The file is split into small helpers so each pass can be understood in
+ * isolation; ff_verify_integrity itself is just orchestration.
  */
 
 #include "config.h"
@@ -25,22 +43,32 @@
 #include "config/files.h"
 #include "database_flatfile.h"
 
-GSList*
-ff_verify_integrity(const gchar* const contact_barejid)
+// =========================================================================
+// Issue construction
+// =========================================================================
+
+static integrity_issue_t*
+_issue_new(integrity_level_t level, const char* file, int line, char* message)
 {
-    GSList* issues = NULL;
+    integrity_issue_t* issue = g_new0(integrity_issue_t, 1);
+    issue->level = level;
+    issue->file = g_strdup(file ? file : "");
+    issue->line = line;
+    issue->message = message; // takes ownership of the (g_strdup'd) message
+    return issue;
+}
 
-    if (!g_flatfile_account_jid) {
-        integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-        issue->level = INTEGRITY_ERROR;
-        issue->file = g_strdup("N/A");
-        issue->line = 0;
-        issue->message = g_strdup("Flat-file backend not initialized");
-        issues = g_slist_prepend(issues, issue);
-        return issues;
-    }
+// =========================================================================
+// Contact discovery
+// =========================================================================
 
-    // If contact specified, verify just that contact; otherwise discover all contacts
+// Build the list of contact directories to verify. If contact_barejid is
+// supplied, the list is either a singleton or empty (and an INFO issue is
+// appended explaining no logs exist for that contact). Otherwise, every
+// subdirectory of flatlog/<account>/ is enumerated.
+static GSList*
+_collect_contact_dirs(const gchar* const contact_barejid, GSList** issues)
+{
     GSList* contact_dirs = NULL;
 
     if (contact_barejid) {
@@ -48,243 +76,283 @@ ff_verify_integrity(const gchar* const contact_barejid)
         if (cdir && g_file_test(cdir, G_FILE_TEST_IS_DIR)) {
             contact_dirs = g_slist_prepend(contact_dirs, g_strdup(cdir));
         } else {
-            integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-            issue->level = INTEGRITY_INFO;
-            issue->file = g_strdup(contact_barejid);
-            issue->line = 0;
-            issue->message = g_strdup("No log files found for this contact");
-            issues = g_slist_prepend(issues, issue);
-            return issues;
-        }
-    } else {
-        // Discover all contact directories
-        auto_gchar gchar* data_path = files_get_data_path(DIR_FLATLOG);
-        auto_gchar gchar* my_dir = ff_jid_to_dir(g_flatfile_account_jid);
-        auto_gchar gchar* base_dir = g_strdup_printf("%s/%s", data_path, my_dir);
-
-        GDir* dir = g_dir_open(base_dir, 0, NULL);
-        if (dir) {
-            const gchar* dname;
-            while ((dname = g_dir_read_name(dir)) != NULL) {
-                char* full = g_strdup_printf("%s/%s", base_dir, dname);
-                if (g_file_test(full, G_FILE_TEST_IS_DIR)) {
-                    contact_dirs = g_slist_prepend(contact_dirs, full);
-                } else {
-                    g_free(full);
-                }
-            }
-            g_dir_close(dir);
+            *issues = g_slist_prepend(*issues,
+                _issue_new(INTEGRITY_INFO, contact_barejid, 0,
+                           g_strdup("No log files found for this contact")));
         }
+        return contact_dirs;
     }
 
-    // Verify each contact directory (single history.log per contact)
-    for (GSList* cd = contact_dirs; cd; cd = cd->next) {
-        const char* cdir_path = cd->data;
+    auto_gchar gchar* data_path = files_get_data_path(DIR_FLATLOG);
+    auto_gchar gchar* my_dir = ff_jid_to_dir(g_flatfile_account_jid);
+    auto_gchar gchar* base_dir = g_strdup_printf("%s/%s", data_path, my_dir);
 
-        auto_gchar gchar* filepath = g_strdup_printf("%s/history.log", cdir_path);
-        if (!g_file_test(filepath, G_FILE_TEST_EXISTS))
-            continue;
+    GDir* dir = g_dir_open(base_dir, 0, NULL);
+    if (!dir)
+        return NULL;
 
-        const char* basename = "history.log";
+    const gchar* dname;
+    while ((dname = g_dir_read_name(dir)) != NULL) {
+        char* full = g_strdup_printf("%s/%s", base_dir, dname);
+        if (g_file_test(full, G_FILE_TEST_IS_DIR)) {
+            contact_dirs = g_slist_prepend(contact_dirs, full);
+        } else {
+            g_free(full);
+        }
+    }
+    g_dir_close(dir);
+    return contact_dirs;
+}
 
-        // Check file permissions
-        struct stat st;
-        if (g_stat(filepath, &st) == 0) {
-            if ((st.st_mode & 0777) != (S_IRUSR | S_IWUSR)) {
-                integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-                issue->level = INTEGRITY_WARNING;
-                issue->file = g_strdup(basename);
-                issue->line = 0;
-                issue->message = g_strdup_printf("File permissions are %o, expected 600 (sensitive data)", st.st_mode & 0777);
-                issues = g_slist_prepend(issues, issue);
-            }
+// =========================================================================
+// Permission check
+// =========================================================================
+
+static void
+_check_permissions(const char* filepath, const char* basename, GSList** issues)
+{
+    struct stat st;
+    if (g_stat(filepath, &st) != 0)
+        return;
+    if ((st.st_mode & 0777) == (S_IRUSR | S_IWUSR))
+        return;
+    *issues = g_slist_prepend(*issues,
+        _issue_new(INTEGRITY_WARNING, basename, 0,
+                   g_strdup_printf("File permissions are %o, expected 600 (sensitive data)",
+                                   st.st_mode & 0777)));
+}
+
+// =========================================================================
+// First pass: per-line content checks + id collection
+// =========================================================================
+//
+// For every non-empty, non-comment line:
+//   - validate UTF-8
+//   - flag control characters
+//   - try to parse via ff_parse_line(); if that fails, record the lineno
+//   - check timestamp monotonicity
+//   - flag duplicate stanza-id and duplicate archive-id (separate tables)
+//   - record every stanza-id encountered for LMC pass 2
+//
+// Also detects: BOM (informational), CRLF line endings (warning), empty
+// file (informational).
+
+static void
+_first_pass(FILE* fp, const char* basename,
+            GHashTable* seen_stanza_ids, GHashTable* seen_archive_ids,
+            GHashTable* all_stanza_ids, GSList** issues)
+{
+    if (ff_skip_bom(fp)) {
+        *issues = g_slist_prepend(*issues,
+            _issue_new(INTEGRITY_INFO, basename, 0,
+                       g_strdup("File has UTF-8 BOM — harmless but unnecessary")));
+    }
+
+    char* buf = NULL;
+    int lineno = 0;
+    GDateTime* prev_ts = NULL;
+    gboolean has_crlf = FALSE;
+    gboolean is_empty = TRUE;
+
+    while ((buf = ff_readline(fp, NULL)) != NULL) {
+        lineno++;
+        gsize len = strlen(buf);
+
+        if (len > 0 && buf[len - 1] == '\r') {
+            has_crlf = TRUE;
+            buf[--len] = '\0';
         }
 
-        FILE* fp = fopen(filepath, "r");
-        if (!fp)
-            continue;
-
-        // BOM check
-        if (ff_skip_bom(fp)) {
-            integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-            issue->level = INTEGRITY_INFO;
-            issue->file = g_strdup(basename);
-            issue->line = 0;
-            issue->message = g_strdup("File has UTF-8 BOM — harmless but unnecessary");
-            issues = g_slist_prepend(issues, issue);
-        }
-
-        char* buf = NULL;
-        int lineno = 0;
-        GDateTime* prev_ts = NULL;
-        GHashTable* seen_ids = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
-        GHashTable* all_stanza_ids = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
-        gboolean has_crlf = FALSE;
-        gboolean is_empty = TRUE;
-
-        while ((buf = ff_readline(fp, NULL)) != NULL) {
-            lineno++;
-            gsize len = strlen(buf);
-
-            if (len > 0 && buf[len - 1] == '\r') {
-                has_crlf = TRUE;
-                buf[--len] = '\0';
-            }
-
-            if (len == 0 || buf[0] == '#') {
-                free(buf);
-                continue;
-            }
-            is_empty = FALSE;
-
-            const gchar* end;
-            if (!g_utf8_validate(buf, -1, &end)) {
-                integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-                issue->level = INTEGRITY_ERROR;
-                issue->file = g_strdup(basename);
-                issue->line = lineno;
-                issue->message = g_strdup_printf("Invalid UTF-8 at byte offset %ld", (long)(end - buf));
-                issues = g_slist_prepend(issues, issue);
-                free(buf);
-                continue;
-            }
-
-            for (gsize i = 0; i < len; i++) {
-                unsigned char ch = (unsigned char)buf[i];
-                if (ch < 0x20 && ch != '\t') {
-                    integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-                    issue->level = INTEGRITY_WARNING;
-                    issue->file = g_strdup(basename);
-                    issue->line = lineno;
-                    issue->message = g_strdup_printf("Contains control character 0x%02x", ch);
-                    issues = g_slist_prepend(issues, issue);
-                    break;
-                }
-            }
-
-            ff_parsed_line_t* pl = ff_parse_line(buf);
-            if (!pl) {
-                integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-                issue->level = INTEGRITY_ERROR;
-                issue->file = g_strdup(basename);
-                issue->line = lineno;
-                issue->message = g_strdup("Unparsable line");
-                issues = g_slist_prepend(issues, issue);
-                free(buf);
-                continue;
-            }
-
+        if (len == 0 || buf[0] == '#') {
             free(buf);
+            continue;
+        }
+        is_empty = FALSE;
 
-            // Timestamp ordering
-            if (prev_ts && g_date_time_compare(pl->timestamp, prev_ts) < 0) {
-                auto_gchar gchar* ts_cur = g_date_time_format_iso8601(pl->timestamp);
-                auto_gchar gchar* ts_prev = g_date_time_format_iso8601(prev_ts);
-                integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-                issue->level = INTEGRITY_WARNING;
-                issue->file = g_strdup(basename);
-                issue->line = lineno;
-                issue->message = g_strdup_printf("Timestamp out of order (%s after %s)", ts_cur, ts_prev);
-                issues = g_slist_prepend(issues, issue);
-            }
-            if (prev_ts)
-                g_date_time_unref(prev_ts);
-            prev_ts = g_date_time_ref(pl->timestamp);
-
-            // Duplicate stanza-id / archive-id
-            if (pl->stanza_id && strlen(pl->stanza_id) > 0) {
-                if (g_hash_table_contains(seen_ids, pl->stanza_id)) {
-                    integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-                    issue->level = INTEGRITY_WARNING;
-                    issue->file = g_strdup(basename);
-                    issue->line = lineno;
-                    issue->message = g_strdup_printf("Duplicate stanza-id \"%s\"", pl->stanza_id);
-                    issues = g_slist_prepend(issues, issue);
-                } else {
-                    g_hash_table_insert(seen_ids, g_strdup(pl->stanza_id), GINT_TO_POINTER(lineno));
-                }
-                g_hash_table_insert(all_stanza_ids, g_strdup(pl->stanza_id), GINT_TO_POINTER(lineno));
-            }
-            if (pl->archive_id && strlen(pl->archive_id) > 0) {
-                if (g_hash_table_contains(seen_ids, pl->archive_id)) {
-                    integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-                    issue->level = INTEGRITY_WARNING;
-                    issue->file = g_strdup(basename);
-                    issue->line = lineno;
-                    issue->message = g_strdup_printf("Duplicate archive-id \"%s\"", pl->archive_id);
-                    issues = g_slist_prepend(issues, issue);
-                } else {
-                    g_hash_table_insert(seen_ids, g_strdup(pl->archive_id), GINT_TO_POINTER(lineno));
-                }
-            }
-
-            ff_parsed_line_free(pl);
+        const gchar* end;
+        if (!g_utf8_validate(buf, -1, &end)) {
+            *issues = g_slist_prepend(*issues,
+                _issue_new(INTEGRITY_ERROR, basename, lineno,
+                           g_strdup_printf("Invalid UTF-8 at byte offset %ld", (long)(end - buf))));
+            free(buf);
+            continue;
         }
 
-        fclose(fp);
-
-        if (has_crlf) {
-            integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-            issue->level = INTEGRITY_WARNING;
-            issue->file = g_strdup(basename);
-            issue->line = 0;
-            issue->message = g_strdup("File uses Windows line endings (CRLF) — consider converting to LF");
-            issues = g_slist_prepend(issues, issue);
-        }
-
-        if (is_empty) {
-            integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-            issue->level = INTEGRITY_INFO;
-            issue->file = g_strdup(basename);
-            issue->line = 0;
-            issue->message = g_strdup("File is empty (no message lines)");
-            issues = g_slist_prepend(issues, issue);
-        }
-
-        // Second pass: check LMC references
-        fp = fopen(filepath, "r");
-        if (fp) {
-            int b1 = fgetc(fp);
-            int b2 = fgetc(fp);
-            int b3 = fgetc(fp);
-            if (!(b1 == 0xEF && b2 == 0xBB && b3 == 0xBF))
-                fseek(fp, 0, SEEK_SET);
-
-            lineno = 0;
-            while ((buf = ff_readline(fp, NULL)) != NULL) {
-                lineno++;
-                gsize len = strlen(buf);
-                if (len > 0 && buf[len - 1] == '\r')
-                    buf[--len] = '\0';
-                if (len == 0 || buf[0] == '#') {
-                    free(buf);
-                    continue;
-                }
-
-                ff_parsed_line_t* pl = ff_parse_line(buf);
-                free(buf);
-                if (!pl)
-                    continue;
-
-                if (pl->replace_id && strlen(pl->replace_id) > 0) {
-                    if (!g_hash_table_contains(all_stanza_ids, pl->replace_id)) {
-                        integrity_issue_t* issue = g_malloc0(sizeof(integrity_issue_t));
-                        issue->level = INTEGRITY_ERROR;
-                        issue->file = g_strdup(basename);
-                        issue->line = lineno;
-                        issue->message = g_strdup_printf("Broken correction reference: corrects:%s not found", pl->replace_id);
-                        issues = g_slist_prepend(issues, issue);
-                    }
-                }
-                ff_parsed_line_free(pl);
+        for (gsize i = 0; i < len; i++) {
+            unsigned char ch = (unsigned char)buf[i];
+            if (ch < 0x20 && ch != '\t') {
+                *issues = g_slist_prepend(*issues,
+                    _issue_new(INTEGRITY_WARNING, basename, lineno,
+                               g_strdup_printf("Contains control character 0x%02x", ch)));
+                break;
             }
-            fclose(fp);
         }
 
+        ff_parsed_line_t* pl = ff_parse_line(buf);
+        if (!pl) {
+            *issues = g_slist_prepend(*issues,
+                _issue_new(INTEGRITY_ERROR, basename, lineno,
+                           g_strdup("Unparsable line")));
+            free(buf);
+            continue;
+        }
+        free(buf);
+
+        if (prev_ts && g_date_time_compare(pl->timestamp, prev_ts) < 0) {
+            auto_gchar gchar* ts_cur = g_date_time_format_iso8601(pl->timestamp);
+            auto_gchar gchar* ts_prev = g_date_time_format_iso8601(prev_ts);
+            *issues = g_slist_prepend(*issues,
+                _issue_new(INTEGRITY_WARNING, basename, lineno,
+                           g_strdup_printf("Timestamp out of order (%s after %s)", ts_cur, ts_prev)));
+        }
         if (prev_ts)
             g_date_time_unref(prev_ts);
-        g_hash_table_destroy(seen_ids);
-        g_hash_table_destroy(all_stanza_ids);
+        prev_ts = g_date_time_ref(pl->timestamp);
+
+        if (pl->stanza_id && pl->stanza_id[0] != '\0') {
+            if (g_hash_table_contains(seen_stanza_ids, pl->stanza_id)) {
+                *issues = g_slist_prepend(*issues,
+                    _issue_new(INTEGRITY_WARNING, basename, lineno,
+                               g_strdup_printf("Duplicate stanza-id \"%s\"", pl->stanza_id)));
+            } else {
+                g_hash_table_insert(seen_stanza_ids, g_strdup(pl->stanza_id), GINT_TO_POINTER(lineno));
+            }
+            g_hash_table_insert(all_stanza_ids, g_strdup(pl->stanza_id), GINT_TO_POINTER(lineno));
+        }
+        if (pl->archive_id && pl->archive_id[0] != '\0') {
+            if (g_hash_table_contains(seen_archive_ids, pl->archive_id)) {
+                *issues = g_slist_prepend(*issues,
+                    _issue_new(INTEGRITY_WARNING, basename, lineno,
+                               g_strdup_printf("Duplicate archive-id \"%s\"", pl->archive_id)));
+            } else {
+                g_hash_table_insert(seen_archive_ids, g_strdup(pl->archive_id), GINT_TO_POINTER(lineno));
+            }
+        }
+
+        ff_parsed_line_free(pl);
+    }
+
+    if (prev_ts)
+        g_date_time_unref(prev_ts);
+
+    if (has_crlf) {
+        *issues = g_slist_prepend(*issues,
+            _issue_new(INTEGRITY_WARNING, basename, 0,
+                       g_strdup("File uses Windows line endings (CRLF) — consider converting to LF")));
+    }
+    if (is_empty) {
+        *issues = g_slist_prepend(*issues,
+            _issue_new(INTEGRITY_INFO, basename, 0,
+                       g_strdup("File is empty (no message lines)")));
+    }
+}
+
+// =========================================================================
+// Second pass: LMC reference resolution
+// =========================================================================
+//
+// Walks the file again, and for every line that carries a `corrects:` link,
+// checks that the referenced stanza-id was seen in pass 1. Broken references
+// surface as INTEGRITY_ERROR.
+
+static void
+_lmc_pass(FILE* fp, const char* basename, GHashTable* all_stanza_ids, GSList** issues)
+{
+    ff_skip_bom(fp);
+
+    char* buf = NULL;
+    int lineno = 0;
+
+    while ((buf = ff_readline(fp, NULL)) != NULL) {
+        lineno++;
+        gsize len = strlen(buf);
+        if (len > 0 && buf[len - 1] == '\r')
+            buf[--len] = '\0';
+        if (len == 0 || buf[0] == '#') {
+            free(buf);
+            continue;
+        }
+
+        ff_parsed_line_t* pl = ff_parse_line(buf);
+        free(buf);
+        if (!pl)
+            continue;
+
+        if (pl->replace_id && pl->replace_id[0] != '\0'
+            && !g_hash_table_contains(all_stanza_ids, pl->replace_id)) {
+            *issues = g_slist_prepend(*issues,
+                _issue_new(INTEGRITY_ERROR, basename, lineno,
+                           g_strdup_printf("Broken correction reference: corrects:%s not found",
+                                           pl->replace_id)));
+        }
+        ff_parsed_line_free(pl);
+    }
+}
+
+// =========================================================================
+// Per-contact verification
+// =========================================================================
+
+static void
+_verify_contact_dir(const char* cdir_path, GSList** issues)
+{
+    auto_gchar gchar* filepath = g_strdup_printf("%s/history.log", cdir_path);
+    if (!g_file_test(filepath, G_FILE_TEST_EXISTS)) {
+        log_debug("flatfile verify: skipping %s (no history.log)", cdir_path);
+        return;
+    }
+
+    const char* basename = "history.log";
+
+    _check_permissions(filepath, basename, issues);
+
+    FILE* fp = fopen(filepath, "r");
+    if (!fp) {
+        log_warning("flatfile verify: cannot open %s for reading", filepath);
+        return;
+    }
+
+    // Separate tables by id-kind: a stanza-id and an archive-id can legitimately
+    // share the same string without that being a duplicate.
+    GHashTable* seen_stanza_ids = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+    GHashTable* seen_archive_ids = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+    GHashTable* all_stanza_ids = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+
+    _first_pass(fp, basename, seen_stanza_ids, seen_archive_ids, all_stanza_ids, issues);
+    fclose(fp);
+
+    // Second pass: LMC references
+    fp = fopen(filepath, "r");
+    if (fp) {
+        _lmc_pass(fp, basename, all_stanza_ids, issues);
+        fclose(fp);
+    }
+
+    g_hash_table_destroy(seen_stanza_ids);
+    g_hash_table_destroy(seen_archive_ids);
+    g_hash_table_destroy(all_stanza_ids);
+}
+
+// =========================================================================
+// Public entry point
+// =========================================================================
+
+GSList*
+ff_verify_integrity(const gchar* const contact_barejid)
+{
+    GSList* issues = NULL;
+
+    if (!g_flatfile_account_jid) {
+        issues = g_slist_prepend(issues,
+            _issue_new(INTEGRITY_ERROR, "N/A", 0,
+                       g_strdup("Flat-file backend not initialized")));
+        return issues;
+    }
+
+    GSList* contact_dirs = _collect_contact_dirs(contact_barejid, &issues);
+
+    for (GSList* cd = contact_dirs; cd; cd = cd->next) {
+        _verify_contact_dir((const char*)cd->data, &issues);
     }
 
     g_slist_free_full(contact_dirs, g_free);

src/database_sqlite.c

@@ -128,6 +128,8 @@ _sqlite_init(ProfAccount* account)
 
     auto_char char* filename = _get_db_filename(account);
     if (!filename) {
+        log_error("Error initializing SQLite database: could not derive chatlog.db path for account '%s'.",
+                  account && account->jid ? account->jid : "(unknown)");
         sqlite3_shutdown();
         return FALSE;
     }
@@ -147,6 +149,28 @@ _sqlite_init(ProfAccount* account)
         return TRUE;
     }
 
+    // ChatLogs schema overview:
+    //   id                AUTOINCREMENT primary key. Used internally as the
+    //                     anchor for LMC (Last Message Correction) chains.
+    //   from_jid/to_jid   Bare JIDs (NOT NULL). Used for window resolution.
+    //   from_resource     Resource of the sender (NULLable for legacy rows).
+    //   to_resource       Resource of the recipient (NULLable).
+    //   message           Plaintext after decryption / format normalisation.
+    //   timestamp         ISO-8601 (UTC). Indexed for range queries.
+    //   type              "chat" | "muc" | "mucpm" (mirrors prof_msg_type_t).
+    //   stanza_id         XEP-0359 unique-and-stable id, used for dedup +
+    //                     LMC sender lookup.
+    //   archive_id        MAM (XEP-0313) archive id; dedupes rebroadcast.
+    //   encryption        "none" | "omemo" | "otr" | "pgp" | "ox"
+    //                     (mirrors prof_enc_t).
+    //   marked_read       0/1 — for unread-message badge bookkeeping.
+    //   replace_id        XEP-0308 message-correction stanza-id of the
+    //                     original message this row replaces.
+    //   replaces_db_id    Local FK back-link: id of the row this row
+    //                     corrects. Set on insert when replace_id resolves.
+    //   replaced_by_db_id Inverse FK: id of the most recent correction.
+    //                     Maintained by the AFTER INSERT trigger below so
+    //                     readers can follow the chain forward in O(1).
     const char* query = "CREATE TABLE IF NOT EXISTS `ChatLogs` ("
                         "`id` INTEGER PRIMARY KEY AUTOINCREMENT, "
                         "`from_jid` TEXT NOT NULL, "

tests/functionaltests/functionaltests.c

@@ -234,6 +234,7 @@ main(int argc, char* argv[])
         PROF_FUNC_TEST(message_db_history_service_chars),
         PROF_FUNC_TEST(message_db_history_verify),
         PROF_FUNC_TEST(message_db_history_lmc),
+        PROF_FUNC_TEST(message_db_history_multi_resource),
 
         /* Basic message send/receive */
         PROF_FUNC_TEST(message_send),

tests/functionaltests/test_history.c

@@ -472,3 +472,67 @@ message_db_history_lmc(void** state)
     assert_false(prof_output_exact("lmc-before-correction-aaa"));
     prof_timeout_reset();
 }
+
+/*
+ * Test: messages from the SAME bare JID but with DIFFERENT resources are
+ * stored together in one contact's history AND remain distinguishable on
+ * reopen — the resource part of the sender JID must be preserved per row,
+ * not collapsed.
+ *
+ * Flow:
+ *   1. /history on
+ *   2. buddy1@localhost/phone   sends msg A
+ *   3. buddy1@localhost/laptop  sends msg B
+ *   4. buddy1@localhost/tablet  sends msg C
+ *   5. Close the auto-opened chat window so its in-memory buffer is gone.
+ *   6. /msg buddy1@localhost — chatwin_new() rehydrates from DB.
+ *   7. All three bodies must reappear, AND the resource markers
+ *      "/phone", "/laptop", "/tablet" must each be visible on at least one
+ *      history line (PREF_RESOURCE_MESSAGE is on by default in the test
+ *      profile, so the renderer prefixes each line with "Buddy1/<res>").
+ */
+void
+message_db_history_multi_resource(void** state)
+{
+    prof_connect();
+
+    prof_input("/history on");
+    assert_true(prof_output_regex("Chat history enabled\\."));
+
+    stbbr_send(
+        "<message id='res-multi-A' to='stabber@localhost' "
+        "from='buddy1@localhost/phone' type='chat'>"
+        "<body>multi-resource-A-from-phone</body>"
+        "</message>");
+    assert_true(prof_output_exact("<< chat message: Buddy1/phone (win 2)"));
+
+    stbbr_send(
+        "<message id='res-multi-B' to='stabber@localhost' "
+        "from='buddy1@localhost/laptop' type='chat'>"
+        "<body>multi-resource-B-from-laptop</body>"
+        "</message>");
+    assert_true(prof_output_exact("<< chat message: Buddy1/laptop (win 2)"));
+
+    stbbr_send(
+        "<message id='res-multi-C' to='stabber@localhost' "
+        "from='buddy1@localhost/tablet' type='chat'>"
+        "<body>multi-resource-C-from-tablet</body>"
+        "</message>");
+    assert_true(prof_output_exact("<< chat message: Buddy1/tablet (win 2)"));
+
+    prof_input("/close 2");
+    assert_true(prof_output_exact("Closed window 2"));
+
+    prof_input("/msg buddy1@localhost");
+
+    /* All three bodies must be present in history (single-contact aggregation) */
+    assert_true(prof_output_exact("multi-resource-A-from-phone"));
+    assert_true(prof_output_exact("multi-resource-B-from-laptop"));
+    assert_true(prof_output_exact("multi-resource-C-from-tablet"));
+
+    /* Each resource must remain identifiable on rehydrate — proves we don't
+     * lose per-row resource info when loading the same JID's chat back. */
+    assert_true(prof_output_regex("Buddy1/phone"));
+    assert_true(prof_output_regex("Buddy1/laptop"));
+    assert_true(prof_output_regex("Buddy1/tablet"));
+}

tests/functionaltests/test_history.h

@@ -10,3 +10,4 @@ void message_db_history_newline(void** state);
 void message_db_history_service_chars(void** state);
 void message_db_history_verify(void** state);
 void message_db_history_lmc(void** state);
+void message_db_history_multi_resource(void** state);

tests/unittests/test_database_export.c

@@ -500,6 +500,66 @@ test_ff_parse_line_invalid_timestamp(void** state)
     assert_null(pl);
 }
 
+void
+test_ff_parse_line_empty_timestamp(void** state)
+{
+    /* The space before "[" makes the timestamp empty -> g_date_time_new_from_iso8601
+       must reject it. */
+    ff_parsed_line_t* pl = ff_parse_line(
+        " [chat|none] a@b.com: msg");
+    assert_null(pl);
+}
+
+void
+test_ff_parse_line_partial_iso_timestamp(void** state)
+{
+    /* Year-only or yyyy-mm without time portion is not ISO-8601 enough for
+       g_date_time_new_from_iso8601 — must fail rather than silently succeed. */
+    assert_null(ff_parse_line("2025 [chat|none] a@b.com: msg"));
+    assert_null(ff_parse_line("2025-06-15 [chat|none] a@b.com: msg"));
+}
+
+void
+test_ff_parse_line_garbage_timestamp(void** state)
+{
+    /* Random characters where timestamp should be — parse failure, no segfault. */
+    assert_null(ff_parse_line("@@@@@@ [chat|none] a@b.com: msg"));
+    assert_null(ff_parse_line("12345 [chat|none] a@b.com: msg"));
+}
+
+void
+test_ff_parse_line_impossible_calendar_date(void** state)
+{
+    /* Day 32 / Month 13 — well-formed ISO syntax but impossible date,
+       g_date_time_new_from_iso8601 returns NULL. */
+    assert_null(ff_parse_line(
+        "2025-13-01T12:00:00Z [chat|none] a@b.com: msg"));
+    assert_null(ff_parse_line(
+        "2025-06-32T12:00:00Z [chat|none] a@b.com: msg"));
+    assert_null(ff_parse_line(
+        "2025-06-15T25:00:00Z [chat|none] a@b.com: msg"));
+}
+
+void
+test_ff_parse_line_negative_year_timestamp(void** state)
+{
+    /* Negative year is not parseable by g_date_time_new_from_iso8601. */
+    assert_null(ff_parse_line(
+        "-0001-06-15T12:00:00Z [chat|none] a@b.com: msg"));
+}
+
+void
+test_ff_parse_line_far_future_timestamp(void** state)
+{
+    /* Year 9999 is valid ISO-8601 and should parse — sanity check that we
+       don't artificially reject valid far-future dates. */
+    ff_parsed_line_t* pl = ff_parse_line(
+        "9999-12-31T23:59:59Z [chat|none] a@b.com: hi");
+    assert_non_null(pl);
+    assert_non_null(pl->timestamp);
+    ff_parsed_line_free(pl);
+}
+
 /* ================================================================
  * Type / enc conversion round-trip
  * ================================================================ */

tests/unittests/test_database_export.h

@@ -34,6 +34,12 @@ void test_ff_parse_line_comment(void** state);
 void test_ff_parse_line_legacy_format(void** state);
 void test_ff_parse_line_no_metadata(void** state);
 void test_ff_parse_line_invalid_timestamp(void** state);
+void test_ff_parse_line_empty_timestamp(void** state);
+void test_ff_parse_line_partial_iso_timestamp(void** state);
+void test_ff_parse_line_garbage_timestamp(void** state);
+void test_ff_parse_line_impossible_calendar_date(void** state);
+void test_ff_parse_line_negative_year_timestamp(void** state);
+void test_ff_parse_line_far_future_timestamp(void** state);
 
 /* type/enc conversion round-trip */
 void test_ff_type_str_roundtrip(void** state);

tests/unittests/test_database_stress.c

@@ -1106,15 +1106,11 @@ test_stress_lmc_many_corrections(void** state)
     int corrections_found = 0;
 
     while (1) {
-        char* buf = ff_readline(fp, NULL);
+        auto_char char* buf = ff_readline(fp, NULL);
         if (!buf)
             break;
-        if (buf[0] == '#' || buf[0] == '\0') {
-            free(buf);
-            continue;
-        }
+        // ff_parse_line already rejects empty/comment lines, no need to pre-filter.
         ff_parsed_line_t* pl = ff_parse_line(buf);
-        free(buf);
         if (pl) {
             total_parsed++;
             if (pl->replace_id && strlen(pl->replace_id) > 0)

tests/unittests/unittests.c

@@ -692,6 +692,12 @@ main(int argc, char* argv[])
         cmocka_unit_test(test_ff_parse_line_legacy_format),
         cmocka_unit_test(test_ff_parse_line_no_metadata),
         cmocka_unit_test(test_ff_parse_line_invalid_timestamp),
+        cmocka_unit_test(test_ff_parse_line_empty_timestamp),
+        cmocka_unit_test(test_ff_parse_line_partial_iso_timestamp),
+        cmocka_unit_test(test_ff_parse_line_garbage_timestamp),
+        cmocka_unit_test(test_ff_parse_line_impossible_calendar_date),
+        cmocka_unit_test(test_ff_parse_line_negative_year_timestamp),
+        cmocka_unit_test(test_ff_parse_line_far_future_timestamp),
 
         // Type/enc round-trip
         cmocka_unit_test(test_ff_type_str_roundtrip),