hyprctl: fix buffer overflowing writes to the socket

2 files changed, 41 insertions, 19 deletions

diff --git a/hyprctl/src/main.cpp b/hyprctl/src/main.cpp
index 7146c635..0a33f3ed 100644
--- a/hyprctl/src/main.cpp
+++ b/hyprctl/src/main.cpp
@@ -228,23 +228,23 @@ int request(std::string_view arg, int minArgs = 0, bool needRoll = false) {
     constexpr size_t BUFFER_SIZE         = 8192;
     char             buffer[BUFFER_SIZE] = {0};
 
-    sizeWritten = read(SERVERSOCKET, buffer, BUFFER_SIZE);
-
-    if (sizeWritten < 0) {
-        if (errno == EWOULDBLOCK)
-            log("Hyprland IPC didn't respond in time\n");
-        log("Couldn't read (6)");
-        return 6;
-    }
-
-    reply += std::string(buffer, sizeWritten);
-
-    while (sizeWritten == BUFFER_SIZE) {
+    // read all data until server closes the connection
+    // this handles partial writes on the server side under high load
+    while (true) {
         sizeWritten = read(SERVERSOCKET, buffer, BUFFER_SIZE);
+
         if (sizeWritten < 0) {
+            if (errno == EWOULDBLOCK)
+                log("Hyprland IPC didn't respond in time\n");
             log("Couldn't read (6)");
             return 6;
         }
+
+        if (sizeWritten == 0) {
+            // server closed connection, we're done
+            break;
+        }
+
         reply += std::string(buffer, sizeWritten);
     }
 
diff --git a/src/debug/HyprCtl.cpp b/src/debug/HyprCtl.cpp
index f3a9402d..1fcb3dd1 100644
--- a/src/debug/HyprCtl.cpp
+++ b/src/debug/HyprCtl.cpp
@@ -2210,16 +2210,38 @@ std::string CHyprCtl::makeDynamicCall(const std::string& input) {
 }
 
 static bool successWrite(int fd, const std::string& data, bool needLog = true) {
-    if (write(fd, data.c_str(), data.length()) > 0)
-        return true;
+    size_t                 totalWritten = 0;
+    size_t                 remaining    = data.length();
+    size_t                 waitsDone    = 0;
+    constexpr const size_t MAX_WAITS    = 20; // 2000µs = 2ms
 
-    if (errno == EAGAIN)
-        return true;
+    while (totalWritten < data.length()) {
+        ssize_t written = write(fd, data.c_str() + totalWritten, remaining);
 
-    if (needLog)
-        Log::logger->log(Log::ERR, "Couldn't write to socket. Error: " + std::string(strerror(errno)));
+        if (waitsDone > MAX_WAITS) {
+            Log::logger->log(Log::ERR, "Couldn't write to socket. Buffer was full and the client couldn't read in time.");
+            return false;
+        }
+
+        if (written < 0) {
+            if (errno == EAGAIN || errno == EWOULDBLOCK) {
+                // socket buffer full, wait a bit and retry
+                std::this_thread::sleep_for(std::chrono::microseconds(100));
+                waitsDone++;
+                continue;
+            }
+            if (needLog)
+                Log::logger->log(Log::ERR, "Couldn't write to socket. Error: {}", strerror(errno));
+            return false;
+        }
+
+        waitsDone = 0;
+
+        totalWritten += written;
+        remaining -= written;
+    }
 
-    return false;
+    return true;
 }
 
 static void runWritingDebugLogThread(const int conn) {