From 487cb8718e3aaaf118263cc5f0ef33879747eaea Mon Sep 17 00:00:00 2001
From: Evgeny <me@jeka.su>
Date: Thu, 2 Jul 2026 17:37:17 +0300
Subject: [PATCH] =?UTF-8?q?fix:=20preserve=20newlines=20in=20config=5Fupda?=
 =?UTF-8?q?ter=20insert/update=20=E2=80=94=20no=20extra=20newlines=20on=20?=
 =?UTF-8?q?key=20replacement,=20add=20leading=20nl=20when=20inserting=20at?=
 =?UTF-8?q?=20end=20without=20trailing=20nl?=
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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/config_updater.c | 61 +++++++++++++++++++++++++++-----------------
 1 file changed, 38 insertions(+), 23 deletions(-)

diff --git a/src/config_updater.c b/src/config_updater.c
index 21256003..66b1e39b 100644
--- a/src/config_updater.c
+++ b/src/config_updater.c
@@ -151,21 +151,25 @@ static int insert_or_replace_option(char **buf, size_t *buf_len, size_t *buf_cap
     char *opt_pos = find_option(*buf, *buf_len, option);
 
     if (opt_pos) {
-        // Find option line end
-        char *line_end = strchr(opt_pos, '\n');
+        // Determine if old line has trailing \n
+        char *nl = strchr(opt_pos, '\n');
+        int has_trailing_nl = (nl != NULL);
+        char *line_end = nl ? nl : *buf + *buf_len;
 
-        if (!line_end) line_end = *buf + *buf_len;
-        
         // Prepare new line
         char new_line[MAX_LINE_LEN];
-        int new_len = snprintf(new_line, sizeof(new_line), "%s=%s\n", option, value);
-
+        int new_len;
+        if (has_trailing_nl) {
+            new_len = snprintf(new_line, sizeof(new_line), "%s=%s\n", option, value);
+        } else {
+            new_len = snprintf(new_line, sizeof(new_line), "%s=%s", option, value);
+        }
         if (new_len <= 0 || new_len >= (int)sizeof(new_line)) return -1;
-        
+
         // Calculate length difference
-        size_t old_line_len = line_end - opt_pos + 1;
+        size_t old_line_len = has_trailing_nl ? (line_end - opt_pos + 1) : (line_end - opt_pos);
         long len_diff = new_len - old_line_len;
-        
+
         // Ensure buffer capacity
         if (*buf_len + len_diff + 1 > *buf_capacity) {
             *buf_capacity = *buf_len + len_diff + 1024;
@@ -177,11 +181,11 @@ static int insert_or_replace_option(char **buf, size_t *buf_len, size_t *buf_cap
             opt_pos = find_option(*buf, *buf_len, option);
 
             if (!opt_pos) return -1;
-            line_end = strchr(opt_pos, '\n');
-
-            if (!line_end) line_end = *buf + *buf_len;
+            nl = strchr(opt_pos, '\n');
+            has_trailing_nl = (nl != NULL);
+            line_end = nl ? nl : *buf + *buf_len;
         }
-        
+
         // Move content and insert new line
         memmove(opt_pos + new_len, line_end, *buf_len - (line_end - *buf) + 1);
 
@@ -194,24 +198,31 @@ static int insert_or_replace_option(char **buf, size_t *buf_len, size_t *buf_cap
         char *section_end = find_section_global(*buf, *buf_len);
 
         if (!section_end) return -1;
-        
+
         // Find end of global section (next [ or end of buffer)
         char *insert_pos = strchr(section_end, '[');
+        int need_leading_nl = 0;
 
-        if (!insert_pos) insert_pos = *buf + *buf_len;
-        else {
+        if (!insert_pos) {
+            insert_pos = *buf + *buf_len;
+            if (*buf_len > 0 && (*buf)[*buf_len - 1] != '\n')
+                need_leading_nl = 1;
+        } else {
             // Move to beginning of next line
             char *prev_nl = insert_pos;
             while (prev_nl > *buf && *prev_nl != '\n') prev_nl--;
             if (*prev_nl == '\n') insert_pos = prev_nl + 1;
         }
-        
+
         // Prepare new line
         char new_line[MAX_LINE_LEN];
-        int new_len = snprintf(new_line, sizeof(new_line), "%s=%s\n", option, value);
-
+        int new_len;
+        if (need_leading_nl)
+            new_len = snprintf(new_line, sizeof(new_line), "\n%s=%s\n", option, value);
+        else
+            new_len = snprintf(new_line, sizeof(new_line), "%s=%s\n", option, value);
         if (new_len <= 0 || new_len >= (int)sizeof(new_line)) return -1;
-        
+
         // Ensure buffer capacity
         if (*buf_len + new_len + 1 > *buf_capacity) {
             *buf_capacity = *buf_len + new_len + 1024;
@@ -224,15 +235,19 @@ static int insert_or_replace_option(char **buf, size_t *buf_len, size_t *buf_cap
 
             if (!section_end) return -1;
             insert_pos = strchr(section_end, '[');
+            need_leading_nl = 0;
 
-            if (!insert_pos) insert_pos = *buf + *buf_len;
-            else {
+            if (!insert_pos) {
+                insert_pos = *buf + *buf_len;
+                if (*buf_len > 0 && (*buf)[*buf_len - 1] != '\n')
+                    need_leading_nl = 1;
+            } else {
                 char *prev_nl = insert_pos;
                 while (prev_nl > *buf && *prev_nl != '\n') prev_nl--;
                 if (*prev_nl == '\n') insert_pos = prev_nl + 1;
             }
         }
-        
+
         // Move content and insert new line
         memmove(insert_pos + new_len, insert_pos, *buf_len - (insert_pos - *buf) + 1);