Ticket MidnightCommander#4784: extract command pipe reading code into a function to avoid duplication

Signed-off-by: Yury V. Zaytsev <[email protected]>

Author: zyv

src/subshell/common.c

@@ -586,6 +586,66 @@ synchronize (void)
     // We can't do any better without modifying the shell(s)
 }
 
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Read data from command pipe with timeout, avoiding possible deadlock with the shell
+ *
+ * @param buffer       buffer to read data into
+ * @param buffer_size  size of the buffer
+ * @param bytes_read   pointer to store number of bytes read
+ * @return TRUE if data was successfully read, FALSE otherwise
+ */
+
+static gboolean
+read_command_buffer_with_timeout (const int nfds, void *buffer, const size_t buffer_size,
+                                  ssize_t *bytes_read)
+{
+    fd_set read_set;
+
+    struct timeval subshell_prompt_timer = {
+        .tv_sec = 1,
+        .tv_usec = 0,
+    };
+
+    while (TRUE)
+    {
+        FD_ZERO (&read_set);
+        FD_SET (command_buffer_pipe[READ], &read_set);
+        FD_SET (mc_global.tty.subshell_pty, &read_set);
+
+        const int rc = select (nfds, &read_set, NULL, NULL, &subshell_prompt_timer);
+
+        if (rc == -1)
+        {
+            if (errno == EINTR)
+                continue;
+
+            return FALSE;
+        }
+
+        if (rc == 0)
+            return FALSE;
+
+        // Keep reading the pty to avoid possible deadlock with the shell. Throw away the data.
+        if (FD_ISSET (mc_global.tty.subshell_pty, &read_set))
+        {
+            char buf[BUF_SMALL];
+            read_nonblock (mc_global.tty.subshell_pty, buf, sizeof (buf));
+        }
+
+        if (FD_ISSET (command_buffer_pipe[READ], &read_set))
+            break;
+    }
+
+    *bytes_read = read (command_buffer_pipe[READ], buffer, buffer_size);
+
+    // FIXME: what about bytes < 0?
+    if (*bytes_read == 0 || (size_t) *bytes_read == buffer_size)
+        return FALSE;
+
+    return TRUE;
+}
+
 /* --------------------------------------------------------------------------------------------- */
 /* Get the contents of the current subshell command line buffer, and */
 /* transfer the contents to the panel command prompt. */
@@ -602,8 +662,6 @@ read_command_line_buffer (gboolean test_mode)
         .tv_sec = 0,
         .tv_usec = 0,
     };
-    int command_buffer_length;
-    size_t command_buffer_char_length;
     int bash_version;
     int cursor_position;
     int rc;
@@ -614,13 +672,13 @@ read_command_line_buffer (gboolean test_mode)
     FD_ZERO (&read_set);
     FD_SET (command_buffer_pipe[READ], &read_set);
 
-    const int maxfdp = MAX (command_buffer_pipe[READ], mc_global.tty.subshell_pty);
+    const int nfds = MAX (command_buffer_pipe[READ], mc_global.tty.subshell_pty) + 1;
 
     /* First, flush the command buffer pipe. This pipe shouldn't be written
      * to under normal circumstances, but if it somehow does get written
      * to, we need to make sure to discard whatever data is there before
      * we try to use it. */
-    while ((rc = select (maxfdp + 1, &read_set, NULL, NULL, &subshell_prompt_timer)) != 0)
+    while ((rc = select (nfds, &read_set, NULL, NULL, &subshell_prompt_timer)) != 0)
     {
         if (rc == -1)
         {
@@ -642,91 +700,20 @@ read_command_line_buffer (gboolean test_mode)
     write_all (mc_global.tty.subshell_pty, ESC_STR SHELL_BUFFER_KEYBINDING,
                sizeof (ESC_STR SHELL_BUFFER_KEYBINDING) - 1);
 
-    subshell_prompt_timer.tv_sec = 1;
-
-    while (TRUE)
-    {
-        FD_ZERO (&read_set);
-        FD_SET (command_buffer_pipe[READ], &read_set);
-        FD_SET (mc_global.tty.subshell_pty, &read_set);
-
-        rc = select (maxfdp + 1, &read_set, NULL, NULL, &subshell_prompt_timer);
-
-        if (rc == -1)
-        {
-            if (errno == EINTR)
-                continue;
-
-            return FALSE;
-        }
-
-        if (rc == 0)
-            return FALSE;
-
-        if (FD_ISSET (mc_global.tty.subshell_pty, &read_set))
-        {
-            /* Keep reading the pty to avoid possible deadlock with the shell. Throw away the data.
-             */
-            char buf[BUF_SMALL];
-            read_nonblock (mc_global.tty.subshell_pty, buf, sizeof (buf));
-        }
-
-        if (FD_ISSET (command_buffer_pipe[READ], &read_set))
-            break;
-    }
-
-    bytes =
-        read (command_buffer_pipe[READ], subshell_command_buffer, sizeof (subshell_command_buffer));
-    // FIXME: what about bytes < 0?
-    if (bytes == 0 || (size_t) bytes == sizeof (subshell_command_buffer))
+    if (!read_command_buffer_with_timeout (nfds, subshell_command_buffer,
+                                           sizeof (subshell_command_buffer), &bytes))
         return FALSE;
 
-    command_buffer_char_length = (size_t) bytes - 1;
+    const size_t command_buffer_char_length = (size_t) bytes - 1;
     subshell_command_buffer[command_buffer_char_length] = '\0';
-    command_buffer_length = str_length (subshell_command_buffer);
+    const int command_buffer_length = str_length (subshell_command_buffer);
 
     // get cursor position
     write_all (mc_global.tty.subshell_pty, ESC_STR SHELL_CURSOR_KEYBINDING,
                sizeof (ESC_STR SHELL_CURSOR_KEYBINDING) - 1);
 
-    subshell_prompt_timer.tv_sec = 1;
-    subshell_prompt_timer.tv_usec = 0;
-
-    while (TRUE)
-    {
-        FD_ZERO (&read_set);
-        FD_SET (command_buffer_pipe[READ], &read_set);
-        FD_SET (mc_global.tty.subshell_pty, &read_set);
-
-        rc = select (maxfdp + 1, &read_set, NULL, NULL, &subshell_prompt_timer);
-
-        if (rc == -1)
-        {
-            if (errno == EINTR)
-                continue;
-
-            return FALSE;
-        }
-
-        if (rc == 0)
-            return FALSE;
-
-        if (FD_ISSET (mc_global.tty.subshell_pty, &read_set))
-        {
-            /* Keep reading the pty to avoid possible deadlock with the shell. Throw away the data.
-             */
-            char buf[BUF_SMALL];
-            read_nonblock (mc_global.tty.subshell_pty, buf, sizeof (buf));
-        }
-
-        if (FD_ISSET (command_buffer_pipe[READ], &read_set))
-            break;
-    }
-
-    bytes =
-        read (command_buffer_pipe[READ], subshell_cursor_buffer, sizeof (subshell_cursor_buffer));
-    // FIXME: what about bytes < 0?
-    if (bytes == 0)
+    if (!read_command_buffer_with_timeout (nfds, subshell_cursor_buffer,
+                                           sizeof (subshell_cursor_buffer), &bytes))
         return FALSE;
 
     subshell_cursor_buffer[(size_t) bytes - 1] = '\0';