Makefile.am

@@ -4,7 +4,9 @@ core_sources = \
 	src/chatlog.c src/chatlog.h \
 	src/database.h src/database.c \
 	src/database_sqlite.c \
-	src/database_flatfile.c \
+	src/database_flatfile.c src/database_flatfile.h \
+	src/database_flatfile_parser.c \
+	src/database_flatfile_verify.c \
 	src/log.h src/profanity.c src/common.h \
 	src/profanity.h src/xmpp/chat_session.c \
 	src/xmpp/chat_session.h src/xmpp/muc.c src/xmpp/muc.h src/xmpp/jid.h src/xmpp/jid.c \

src/database_flatfile.h

@@ -0,0 +1,110 @@
+/*
+ * database_flatfile.h
+ * vim: expandtab:ts=4:sts=4:sw=4
+ *
+ * Copyright (C) 2026 Profanity Contributors
+ *
+ * This file is part of Profanity.
+ *
+ * Profanity is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Profanity is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Profanity.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * Internal header shared between database_flatfile*.c modules.
+ * Not part of the public API — do not include from outside the flatfile backend.
+ */
+
+#ifndef DATABASE_FLATFILE_H
+#define DATABASE_FLATFILE_H
+
+#include <glib.h>
+#include <stdio.h>
+
+#include "database.h"
+#include "xmpp/xmpp.h"
+#include "xmpp/message.h"
+
+// --- Constants ---
+
+#define DIR_FLATLOG      "flatlog"
+#define FLATFILE_HEADER  "# profanity chat log — UTF-8, LF line endings\n# vim: set fileencoding=utf-8 fileformat=unix :\n"
+#define FF_MAX_LINE_LEN  (10 * 1024 * 1024) /* 10 MB — reject lines longer than this */
+#define FF_MAX_LMC_DEPTH 100                /* max correction chain depth */
+
+// --- Shared global ---
+
+// Account JID stored during init for path construction.
+// Defined in database_flatfile.c, used by all flatfile modules.
+extern char* g_flatfile_account_jid;
+
+// --- Parsed line structure ---
+
+typedef struct
+{
+    char* timestamp_str;
+    GDateTime* timestamp;
+    char* type;
+    char* enc;
+    char* stanza_id;
+    char* archive_id;
+    char* replace_id;
+    char* from_jid;
+    char* from_resource;
+    char* message;
+} ff_parsed_line_t;
+
+// --- Type conversion helpers ---
+
+const char* ff_get_message_type_str(prof_msg_type_t type);
+prof_msg_type_t ff_get_message_type_type(const char* const type);
+const char* ff_get_message_enc_str(prof_enc_t enc);
+prof_enc_t ff_get_message_enc_type(const char* const encstr);
+
+// --- Path helpers ---
+
+char* ff_jid_to_dir(const char* jid);
+char* ff_get_contact_dir(const char* contact_barejid);
+char* ff_get_log_path(const char* contact_barejid, GDateTime* dt);
+gboolean ff_ensure_dir(const char* path);
+
+// --- Escape / unescape ---
+
+char* ff_escape_message(const char* text);
+char* ff_unescape_message(const char* text);
+char* ff_escape_meta_value(const char* val);
+char* ff_unescape_meta_value(const char* val);
+
+// --- I/O ---
+
+char* ff_readline(FILE* fp, gboolean* truncated);
+void ff_write_line(FILE* fp, const char* timestamp, const char* type, const char* enc,
+                   const char* stanza_id, const char* archive_id, const char* replace_id,
+                   const char* from_jid, const char* from_resource, const char* message_text);
+
+// --- Parser helpers ---
+
+const char* ff_find_unescaped_char(const char* str, char ch);
+char** ff_split_meta(const char* meta);
+const char* ff_find_unescaped_colonspace(const char* str);
+char* ff_unescape_sender_resource(const char* res);
+
+// --- Parser ---
+
+void ff_parsed_line_free(ff_parsed_line_t* pl);
+ff_parsed_line_t* ff_parse_line(const char* line);
+ProfMessage* ff_parsed_to_profmessage(ff_parsed_line_t* pl);
+
+// --- Integrity verification (database_flatfile_verify.c) ---
+
+GSList* ff_verify_integrity(const gchar* const contact_barejid);
+
+#endif

src/database_flatfile_parser.c

@@ -0,0 +1,752 @@
+/*
+ * database_flatfile_parser.c
+ * vim: expandtab:ts=4:sts=4:sw=4
+ *
+ * Copyright (C) 2026 Profanity Contributors
+ *
+ * This file is part of Profanity.
+ *
+ * Profanity is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Profanity is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Profanity.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * Flat-file backend: type helpers, path helpers, escape/unescape,
+ * line I/O, and the tolerant log-line parser.
+ */
+
+#include "config.h"
+
+#include <sys/stat.h>
+#include <glib.h>
+#include <glib/gstdio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include "log.h"
+#include "common.h"
+#include "config/files.h"
+#include "database_flatfile.h"
+
+// =========================================================================
+// Type conversion helpers
+// =========================================================================
+
+const char*
+ff_get_message_type_str(prof_msg_type_t type)
+{
+    switch (type) {
+    case PROF_MSG_TYPE_CHAT:
+        return "chat";
+    case PROF_MSG_TYPE_MUC:
+        return "muc";
+    case PROF_MSG_TYPE_MUCPM:
+        return "mucpm";
+    case PROF_MSG_TYPE_UNINITIALIZED:
+        return "chat";
+    }
+    return "chat";
+}
+
+prof_msg_type_t
+ff_get_message_type_type(const char* const type)
+{
+    if (g_strcmp0(type, "chat") == 0) {
+        return PROF_MSG_TYPE_CHAT;
+    } else if (g_strcmp0(type, "muc") == 0) {
+        return PROF_MSG_TYPE_MUC;
+    } else if (g_strcmp0(type, "mucpm") == 0) {
+        return PROF_MSG_TYPE_MUCPM;
+    }
+    return PROF_MSG_TYPE_CHAT;
+}
+
+const char*
+ff_get_message_enc_str(prof_enc_t enc)
+{
+    switch (enc) {
+    case PROF_MSG_ENC_OX:
+        return "ox";
+    case PROF_MSG_ENC_PGP:
+        return "pgp";
+    case PROF_MSG_ENC_OTR:
+        return "otr";
+    case PROF_MSG_ENC_OMEMO:
+        return "omemo";
+    case PROF_MSG_ENC_NONE:
+        return "none";
+    }
+    return "none";
+}
+
+prof_enc_t
+ff_get_message_enc_type(const char* const encstr)
+{
+    if (g_strcmp0(encstr, "ox") == 0) {
+        return PROF_MSG_ENC_OX;
+    } else if (g_strcmp0(encstr, "pgp") == 0) {
+        return PROF_MSG_ENC_PGP;
+    } else if (g_strcmp0(encstr, "otr") == 0) {
+        return PROF_MSG_ENC_OTR;
+    } else if (g_strcmp0(encstr, "omemo") == 0) {
+        return PROF_MSG_ENC_OMEMO;
+    }
+    return PROF_MSG_ENC_NONE;
+}
+
+// =========================================================================
+// Path helpers
+// =========================================================================
+
+// Sanitise a JID for use as a directory name.
+// 1. Replace '@' with '_at_'
+// 2. Reject / strip path-separator and traversal characters: '/', '\0', '..'
+// This prevents a malicious federated JID like "../../../tmp/pwned" from
+// escaping the log directory tree.
+char*
+ff_jid_to_dir(const char* jid)
+{
+    if (!jid || jid[0] == '\0')
+        return NULL;
+
+    // Replace '@' first
+    char* step1 = str_replace(jid, "@", "_at_");
+    if (!step1)
+        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);
+        }
+    }
+    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);
+        return NULL;
+    }
+    return result;
+}
+
+// Get the base directory for a contact's logs:
+// ~/.local/share/profanity/flatlog/{my_jid_dir}/{contact_jid_dir}/
+char*
+ff_get_contact_dir(const char* contact_barejid)
+{
+    if (!g_flatfile_account_jid || !contact_barejid)
+        return NULL;
+
+    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* contact_dir = ff_jid_to_dir(contact_barejid);
+
+    char* result = g_strdup_printf("%s/%s/%s", data_path, my_dir, contact_dir);
+    return result;
+}
+
+// Get the log file path for a contact on a specific date:
+// {contact_dir}/{YYYY_MM_DD}.log
+char*
+ff_get_log_path(const char* contact_barejid, GDateTime* dt)
+{
+    auto_gchar gchar* contact_dir = ff_get_contact_dir(contact_barejid);
+    if (!contact_dir)
+        return NULL;
+
+    auto_gchar gchar* date_str = g_date_time_format(dt, "%Y_%m_%d");
+    char* result = g_strdup_printf("%s/%s.log", contact_dir, date_str);
+    return result;
+}
+
+// Ensure the directory exists, create if needed.
+// Refuses to follow symlinks at the final component.
+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_mkdir_with_parents(path, S_IRWXU) != 0) {
+        log_error("flatfile: Could not create directory: %s (errno=%d)", path, errno);
+        return FALSE;
+    }
+    return TRUE;
+}
+
+// =========================================================================
+// Escape / unescape helpers
+// =========================================================================
+//
+// Message text and metadata values from remote peers can contain arbitrary
+// characters including newlines, pipes and brackets. Without escaping, a
+// crafted message could inject fake log lines (log injection / format
+// injection). We escape on write and unescape on read.
+
+// Escape message body: \ -> \\, \n -> \n literal, \r -> \r literal
+char*
+ff_escape_message(const char* text)
+{
+    if (!text)
+        return g_strdup("");
+    GString* out = g_string_sized_new(strlen(text));
+    for (const char* p = text; *p; p++) {
+        switch (*p) {
+        case '\\':
+            g_string_append(out, "\\\\");
+            break;
+        case '\n':
+            g_string_append(out, "\\n");
+            break;
+        case '\r':
+            g_string_append(out, "\\r");
+            break;
+        default:
+            g_string_append_c(out, *p);
+            break;
+        }
+    }
+    return g_string_free(out, FALSE);
+}
+
+// Unescape message body: \\  -> \, \n -> newline, \r -> CR
+char*
+ff_unescape_message(const char* text)
+{
+    if (!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 {
+            g_string_append_c(out, *p);
+        }
+    }
+    return g_string_free(out, FALSE);
+}
+
+// Escape metadata value (stanza_id, archive_id, replace_id):
+// these come from remote servers and may contain |, ], \, newlines.
+char*
+ff_escape_meta_value(const char* val)
+{
+    if (!val || strlen(val) == 0)
+        return NULL;
+    GString* out = g_string_sized_new(strlen(val));
+    for (const char* p = val; *p; p++) {
+        switch (*p) {
+        case '|':
+            g_string_append(out, "\\|");
+            break;
+        case ']':
+            g_string_append(out, "\\]");
+            break;
+        case '\\':
+            g_string_append(out, "\\\\");
+            break;
+        case '\n':
+            g_string_append(out, "\\n");
+            break;
+        case '\r':
+            g_string_append(out, "\\r");
+            break;
+        default:
+            g_string_append_c(out, *p);
+            break;
+        }
+    }
+    return g_string_free(out, FALSE);
+}
+
+// Unescape metadata value
+char*
+ff_unescape_meta_value(const char* val)
+{
+    if (!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 {
+            g_string_append_c(out, *p);
+        }
+    }
+    return g_string_free(out, FALSE);
+}
+
+// =========================================================================
+// Readline helper
+// =========================================================================
+//
+// POSIX getline() for dynamic-length lines. Returns line without trailing
+// newline, or NULL on EOF. Sets *truncated=TRUE if the line had no trailing
+// newline at EOF (partial write detection).
+char*
+ff_readline(FILE* fp, gboolean* truncated)
+{
+    char* line = NULL;
+    size_t cap = 0;
+    ssize_t nread = getline(&line, &cap, fp);
+    if (nread == -1) {
+        free(line);
+        return NULL;
+    }
+    // Guard against pathological lines that could exhaust memory.
+    // getline() already allocated, so we free and skip if too long.
+    if (nread > FF_MAX_LINE_LEN) {
+        log_error("flatfile: line too long (%zd bytes), skipping", nread);
+        // Check newline termination before freeing
+        gboolean had_newline = (nread > 0 && line[nread - 1] == '\n');
+        free(line);
+        // Skip to next newline if the overlength line wasn't newline-terminated
+        if (!had_newline) {
+            int ch;
+            while ((ch = fgetc(fp)) != EOF && ch != '\n') {}
+        }
+        if (truncated)
+            *truncated = FALSE;
+        // Return empty string so caller's loop continues (parse will reject it)
+        return g_strdup("");
+    }
+    if (truncated)
+        *truncated = FALSE;
+    if (nread > 0 && line[nread - 1] == '\n') {
+        line[--nread] = '\0';
+    } else if (feof(fp)) {
+        // Line without trailing newline at EOF — likely a partial write
+        if (truncated)
+            *truncated = TRUE;
+    }
+    return line;
+}
+
+// =========================================================================
+// Line writer
+// =========================================================================
+//
+// Format: {ISO8601} [{type}|{enc}|id:{stanza_id}|aid:{archive_id}|corrects:{replace_id}] {from_jid}/{resource}: {message}
+//
+// Message text is escaped: \\ -> \\\\, newline -> \\n, CR -> \\r
+// Metadata values are escaped: |, ], \\, newline, CR
+// Lines starting with '#' are comments.
+// Empty lines are skipped.
+
+void
+ff_write_line(FILE* fp, const char* timestamp, const char* type, const char* enc,
+              const char* stanza_id, const char* archive_id, const char* replace_id,
+              const char* from_jid, const char* from_resource, const char* message_text)
+{
+    // Escape metadata values from remote peers
+    auto_gchar gchar* safe_sid = ff_escape_meta_value(stanza_id);
+    auto_gchar gchar* safe_aid = ff_escape_meta_value(archive_id);
+    auto_gchar gchar* safe_rid = ff_escape_meta_value(replace_id);
+
+    // Build metadata section: [type|enc|id:...|aid:...|corrects:...]
+    GString* meta = g_string_new("[");
+    g_string_append(meta, type ? type : "chat");
+    g_string_append_c(meta, '|');
+    g_string_append(meta, enc ? enc : "none");
+    if (safe_sid) {
+        g_string_append_printf(meta, "|id:%s", safe_sid);
+    }
+    if (safe_aid) {
+        g_string_append_printf(meta, "|aid:%s", safe_aid);
+    }
+    if (safe_rid) {
+        g_string_append_printf(meta, "|corrects:%s", safe_rid);
+    }
+    g_string_append_c(meta, ']');
+
+    // Build sender — escape ": " in the resource part to prevent
+    // the parser from splitting at the wrong point.
+    GString* sender = g_string_new(from_jid ? from_jid : "unknown");
+    if (from_resource && strlen(from_resource) > 0) {
+        // Escape backslash and colon-space in resource
+        GString* safe_res = g_string_sized_new(strlen(from_resource));
+        for (const char* p = from_resource; *p; p++) {
+            if (*p == '\\') {
+                g_string_append(safe_res, "\\\\");
+            } else if (*p == ':' && *(p + 1) == ' ') {
+                g_string_append(safe_res, "\\: ");
+                p++; // skip the space too
+            } else {
+                g_string_append_c(safe_res, *p);
+            }
+        }
+        g_string_append_printf(sender, "/%s", safe_res->str);
+        g_string_free(safe_res, TRUE);
+    }
+
+    // Escape message body to prevent log injection
+    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;
+    ssize_t written = fwrite(full_line->str, 1, to_write, fp);
+    if (written != (ssize_t)to_write) {
+        log_error("flatfile: partial write (%zd/%zu)", written, to_write);
+    }
+
+    g_string_free(full_line, TRUE);
+    g_free(safe_msg);
+    g_string_free(meta, TRUE);
+    g_string_free(sender, TRUE);
+}
+
+// =========================================================================
+// Parser helpers
+// =========================================================================
+
+// Find the first occurrence of 'ch' that is not preceded by an unescaped backslash.
+const char*
+ff_find_unescaped_char(const char* str, char ch)
+{
+    if (!str)
+        return NULL;
+    for (const char* p = str; *p; p++) {
+        if (*p == '\\' && *(p + 1)) {
+            p++; // skip escaped character
+            continue;
+        }
+        if (*p == ch)
+            return p;
+    }
+    return NULL;
+}
+
+// Split metadata content on unescaped '|'. Returns a NULL-terminated array.
+// Caller must g_strfreev() the result.
+char**
+ff_split_meta(const char* meta)
+{
+    GPtrArray* arr = g_ptr_array_new();
+    const char* start = meta;
+    for (const char* p = meta;; p++) {
+        if (*p == '\\' && *(p + 1)) {
+            p++; // skip escaped char
+            continue;
+        }
+        if (*p == '|' || *p == '\0') {
+            g_ptr_array_add(arr, g_strndup(start, p - start));
+            if (*p == '\0')
+                break;
+            start = p + 1;
+        }
+    }
+    g_ptr_array_add(arr, NULL);
+    return (char**)g_ptr_array_free(arr, FALSE);
+}
+
+// Find first unescaped ": " (colon-space) in a string.
+const char*
+ff_find_unescaped_colonspace(const char* str)
+{
+    if (!str)
+        return NULL;
+    for (const char* p = str; *p; p++) {
+        if (*p == '\\' && *(p + 1)) {
+            p++; // skip escaped character
+            continue;
+        }
+        if (*p == ':' && *(p + 1) == ' ') {
+            return p;
+        }
+    }
+    return NULL;
+}
+
+// Unescape a sender resource: "\\" -> '\', "\: " -> ": "
+char*
+ff_unescape_sender_resource(const char* res)
+{
+    if (!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);
+            }
+        } else {
+            g_string_append_c(out, *p);
+        }
+    }
+    return g_string_free(out, FALSE);
+}
+
+// =========================================================================
+// Line parser
+// =========================================================================
+
+void
+ff_parsed_line_free(ff_parsed_line_t* pl)
+{
+    if (!pl)
+        return;
+    g_free(pl->timestamp_str);
+    if (pl->timestamp)
+        g_date_time_unref(pl->timestamp);
+    g_free(pl->type);
+    g_free(pl->enc);
+    g_free(pl->stanza_id);
+    g_free(pl->archive_id);
+    g_free(pl->replace_id);
+    g_free(pl->from_jid);
+    g_free(pl->from_resource);
+    g_free(pl->message);
+    g_free(pl);
+}
+
+// Parse a single line. Returns NULL on parse failure.
+// Line format: {timestamp} [{metadata}] {sender}: {message}
+ff_parsed_line_t*
+ff_parse_line(const char* line)
+{
+    if (!line || line[0] == '\0' || line[0] == '#') {
+        return NULL;
+    }
+
+    // Strip trailing \r if present (CRLF handling)
+    char* work = g_strdup(line);
+    gsize len = strlen(work);
+    if (len > 0 && work[len - 1] == '\r') {
+        work[len - 1] = '\0';
+        len--;
+    }
+    if (len == 0) {
+        g_free(work);
+        return NULL;
+    }
+
+    // UTF-8 validation
+    const gchar* end;
+    if (!g_utf8_validate(work, -1, &end)) {
+        log_warning("flatfile: invalid UTF-8 at byte offset %ld", (long)(end - work));
+        // Attempt Latin-1 fallback
+        gsize br, bw;
+        GError* err = NULL;
+        char* converted = g_convert(work, -1, "UTF-8", "ISO-8859-1", &br, &bw, &err);
+        if (converted) {
+            g_free(work);
+            work = converted;
+        } else {
+            if (err)
+                g_error_free(err);
+            g_free(work);
+            return NULL;
+        }
+    }
+
+    ff_parsed_line_t* result = g_malloc0(sizeof(ff_parsed_line_t));
+
+    // Parse timestamp — everything up to first space followed by '['
+    char* bracket_start = strchr(work, '[');
+    char* first_space = strchr(work, ' ');
+
+    if (bracket_start && first_space && first_space < bracket_start) {
+        // Standard format with metadata: {timestamp} [{meta}] {sender}: {msg}
+        result->timestamp_str = g_strndup(work, first_space - work);
+
+        // 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], "id:")) {
+                        result->stanza_id = ff_unescape_meta_value(parts[i] + 3);
+                    } else if (g_str_has_prefix(parts[i], "aid:")) {
+                        result->archive_id = ff_unescape_meta_value(parts[i] + 4);
+                    } else if (g_str_has_prefix(parts[i], "corrects:")) {
+                        result->replace_id = ff_unescape_meta_value(parts[i] + 9);
+                    }
+                }
+                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 {
+            // No closing bracket — malformed metadata
+            ff_parsed_line_free(result);
+            g_free(work);
+            return NULL;
+        }
+    } else if (first_space) {
+        // Legacy/simple format without metadata: {timestamp} - {sender}: {msg}
+        result->timestamp_str = g_strndup(work, first_space - work);
+        result->type = g_strdup("chat");
+        result->enc = g_strdup("none");
+
+        char* rest = first_space + 1;
+        // Skip " - " if present (chatlog.c format)
+        if (g_str_has_prefix(rest, "- ")) {
+            rest += 2;
+        }
+
+        char* colon = strstr(rest, ": ");
+        if (colon) {
+            char* sender = g_strndup(rest, colon - rest);
+            char* slash = strchr(sender, '/');
+            if (slash) {
+                result->from_jid = g_strndup(sender, slash - sender);
+                result->from_resource = g_strdup(slash + 1);
+            } else {
+                result->from_jid = g_strdup(sender);
+            }
+            g_free(sender);
+            result->message = ff_unescape_message(colon + 2);
+        } else {
+            result->from_jid = g_strdup("unknown");
+            result->message = ff_unescape_message(rest);
+        }
+    } else {
+        // No space at all — can't parse
+        ff_parsed_line_free(result);
+        g_free(work);
+        return NULL;
+    }
+
+    // Parse timestamp
+    result->timestamp = g_date_time_new_from_iso8601(result->timestamp_str, NULL);
+    if (!result->timestamp) {
+        log_warning("flatfile: unparsable timestamp: %s", result->timestamp_str);
+        ff_parsed_line_free(result);
+        g_free(work);
+        return NULL;
+    }
+
+    // Default type/enc if missing
+    if (!result->type)
+        result->type = g_strdup("chat");
+    if (!result->enc)
+        result->enc = g_strdup("none");
+
+    g_free(work);
+    return result;
+}
+
+// Convert parsed line to ProfMessage
+ProfMessage*
+ff_parsed_to_profmessage(ff_parsed_line_t* pl)
+{
+    ProfMessage* msg = message_init();
+    msg->id = pl->stanza_id ? g_strdup(pl->stanza_id) : NULL;
+    msg->from_jid = jid_create_from_bare_and_resource(pl->from_jid, pl->from_resource);
+    msg->plain = g_strdup(pl->message ? pl->message : "");
+    msg->timestamp = g_date_time_ref(pl->timestamp);
+    msg->type = ff_get_message_type_type(pl->type);
+    msg->enc = ff_get_message_enc_type(pl->enc);
+    return msg;
+}

src/database_flatfile_verify.c

@@ -0,0 +1,378 @@
+/*
+ * database_flatfile_verify.c
+ * vim: expandtab:ts=4:sts=4:sw=4
+ *
+ * Copyright (C) 2026 Profanity Contributors
+ *
+ * This file is part of Profanity.
+ *
+ * Profanity is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Profanity is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Profanity.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * Flat-file backend: integrity verification (/history verify).
+ * Checks: parsability, timestamp ordering, duplicate IDs, broken LMC
+ * references, file permissions, BOM, CRLF, UTF-8, control chars.
+ */
+
+#include "config.h"
+
+#include <sys/stat.h>
+#include <glib.h>
+#include <glib/gstdio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "log.h"
+#include "config/files.h"
+#include "database_flatfile.h"
+
+GSList*
+ff_verify_integrity(const gchar* const contact_barejid)
+{
+    GSList* issues = NULL;
+
+    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_append(issues, issue);
+        return issues;
+    }
+
+    // If contact specified, verify just that contact; otherwise discover all contacts
+    GSList* contact_dirs = NULL;
+
+    if (contact_barejid) {
+        auto_gchar gchar* cdir = ff_get_contact_dir(contact_barejid);
+        if (cdir && g_file_test(cdir, G_FILE_TEST_IS_DIR)) {
+            contact_dirs = g_slist_append(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_append(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_append(contact_dirs, full);
+                } else {
+                    g_free(full);
+                }
+            }
+            g_dir_close(dir);
+        }
+    }
+
+    // Verify each contact directory
+    for (GSList* cd = contact_dirs; cd; cd = cd->next) {
+        const char* cdir_path = cd->data;
+
+        GDir* dir = g_dir_open(cdir_path, 0, NULL);
+        if (!dir)
+            continue;
+
+        GSList* log_files = NULL;
+        const gchar* fname;
+        while ((fname = g_dir_read_name(dir)) != NULL) {
+            if (g_str_has_suffix(fname, ".log")) {
+                log_files = g_slist_insert_sorted(log_files,
+                                                  g_strdup_printf("%s/%s", cdir_path, fname),
+                                                  (GCompareFunc)g_strcmp0);
+            }
+        }
+        g_dir_close(dir);
+
+        GDateTime* prev_file_last_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);
+
+        for (GSList* lf = log_files; lf; lf = lf->next) {
+            const char* filepath = lf->data;
+            const char* basename = strrchr(filepath, '/');
+            basename = basename ? basename + 1 : filepath;
+
+            // 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_append(issues, issue);
+                }
+            }
+
+            FILE* fp = fopen(filepath, "r");
+            if (!fp)
+                continue;
+
+            // BOM check
+            int c1 = fgetc(fp);
+            int c2 = fgetc(fp);
+            int c3 = fgetc(fp);
+            if (c1 == 0xEF && c2 == 0xBB && c3 == 0xBF) {
+                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_append(issues, issue);
+            } else {
+                fseek(fp, 0, SEEK_SET);
+            }
+
+            char* buf = NULL;
+            int lineno = 0;
+            GDateTime* prev_ts = NULL;
+            GDateTime* first_ts = NULL;
+            GDateTime* last_ts = NULL;
+            gboolean has_crlf = FALSE;
+            gboolean is_empty = TRUE;
+
+            while ((buf = ff_readline(fp, NULL)) != NULL) {
+                lineno++;
+                gsize len = strlen(buf);
+
+                // CRLF check
+                if (len > 0 && buf[len - 1] == '\r') {
+                    has_crlf = TRUE;
+                    buf[--len] = '\0';
+                }
+
+                // Skip empty lines and comments
+                if (len == 0 || buf[0] == '#') {
+                    free(buf);
+                    continue;
+                }
+                is_empty = FALSE;
+
+                // UTF-8 validation
+                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_append(issues, issue);
+                    free(buf);
+                    continue;
+                }
+
+                // Control character check
+                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_append(issues, issue);
+                        break;
+                    }
+                }
+
+                // Parse line
+                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_append(issues, issue);
+                    free(buf);
+                    continue;
+                }
+
+                free(buf); // done with raw line
+
+                if (!first_ts)
+                    first_ts = g_date_time_ref(pl->timestamp);
+                if (last_ts)
+                    g_date_time_unref(last_ts);
+                last_ts = g_date_time_ref(pl->timestamp);
+
+                // Timestamp order within file
+                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_append(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_append(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_append(issues, issue);
+                    } else {
+                        g_hash_table_insert(seen_ids, g_strdup(pl->archive_id), GINT_TO_POINTER(lineno));
+                    }
+                }
+
+                ff_parsed_line_free(pl);
+            }
+
+            fclose(fp);
+
+            // CRLF warning for file
+            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_append(issues, issue);
+            }
+
+            // Empty file
+            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_append(issues, issue);
+            }
+
+            // Cross-file timestamp ordering
+            if (first_ts && prev_file_last_ts) {
+                if (g_date_time_compare(first_ts, prev_file_last_ts) < 0) {
+                    auto_gchar gchar* ts_first = g_date_time_format_iso8601(first_ts);
+                    auto_gchar gchar* ts_prev_last = g_date_time_format_iso8601(prev_file_last_ts);
+                    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("First timestamp (%s) is before previous file's last timestamp (%s)",
+                                                     ts_first, ts_prev_last);
+                    issues = g_slist_append(issues, issue);
+                }
+            }
+
+            if (prev_file_last_ts)
+                g_date_time_unref(prev_file_last_ts);
+            prev_file_last_ts = last_ts ? g_date_time_ref(last_ts) : NULL;
+
+            if (prev_ts)
+                g_date_time_unref(prev_ts);
+            if (first_ts)
+                g_date_time_unref(first_ts);
+            if (last_ts)
+                g_date_time_unref(last_ts);
+        }
+
+        // Second pass: check LMC references across all files
+        for (GSList* lf = log_files; lf; lf = lf->next) {
+            const char* filepath = lf->data;
+            const char* basename_lmc = strrchr(filepath, '/');
+            basename_lmc = basename_lmc ? basename_lmc + 1 : filepath;
+
+            FILE* fp = fopen(filepath, "r");
+            if (!fp)
+                continue;
+
+            // Skip BOM
+            int b1 = fgetc(fp);
+            int b2 = fgetc(fp);
+            int b3 = fgetc(fp);
+            if (!(b1 == 0xEF && b2 == 0xBB && b3 == 0xBF)) {
+                fseek(fp, 0, SEEK_SET);
+            }
+
+            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 && 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_lmc);
+                        issue->line = lineno;
+                        issue->message = g_strdup_printf("Broken correction reference: corrects:%s not found", pl->replace_id);
+                        issues = g_slist_append(issues, issue);
+                    }
+                }
+                ff_parsed_line_free(pl);
+            }
+            fclose(fp);
+        }
+
+        if (prev_file_last_ts)
+            g_date_time_unref(prev_file_last_ts);
+        g_hash_table_destroy(seen_ids);
+        g_hash_table_destroy(all_stanza_ids);
+        g_slist_free_full(log_files, g_free);
+    }
+
+    g_slist_free_full(contact_dirs, g_free);
+    return issues;
+}