common: don't force terminal log buffer to small size

Using the 'terminal-default' log level a client can request
to get all messages that would normally appear on the terminal.

8c2d73f112 changed the size of the
relevant buffer to 100 lines, which was prone to quickly overflowing
once you enable verbose or debug output.
This size is kept for the early terminal buffer but now enlarged
once a client actually requests this log level. This fixes the overflow
risk while not consuming more resources if this feature is unused.

common/msg.c

@@ -42,10 +42,12 @@
 #include "msg.h"
 #include "msg_control.h"
 
-// log buffer size (lines) for terminal level and logfile level
+// log buffer size (lines) logfile level
-#define TERM_BUF 100
 #define FILE_BUF 100
 
+// lines to accumulate before any client requests the terminal loglevel
+#define EARLY_TERM_BUF 100
+
 // logfile lines to accumulate during init before we know the log file name.
 // thousands of logfile lines during init can happen (especially with many
 // scripts, big config, etc), so we set 5000. If it cycles and messages are
@@ -921,7 +923,7 @@ void mp_msg_set_early_logging(struct mpv_global *global, bool enable)
     struct mp_log_root *root = global->log->root;
 
     mp_msg_set_early_logging_raw(global, enable, &root->early_buffer,
-                                 TERM_BUF, MP_LOG_BUFFER_MSGL_TERM);
+                                 EARLY_TERM_BUF, MP_LOG_BUFFER_MSGL_TERM);
 
     // normally MSGL_LOGFILE buffer gets a write thread, but not the early buf
     mp_msg_set_early_logging_raw(global, enable, &root->early_filebuffer,
@@ -938,8 +940,6 @@ struct mp_log_buffer *mp_msg_log_buffer_new(struct mpv_global *global,
     mp_mutex_lock(&root->lock);
 
     if (level == MP_LOG_BUFFER_MSGL_TERM) {
-        size = TERM_BUF;
-
         // The first thing which creates a terminal-level log buffer gets the
         // early log buffer, if it exists. This is supposed to enable a script
         // to grab log messages from before it was initialized. It's OK that
@@ -947,6 +947,7 @@ struct mp_log_buffer *mp_msg_log_buffer_new(struct mpv_global *global,
         if (root->early_buffer) {
             struct mp_log_buffer *buffer = root->early_buffer;
             root->early_buffer = NULL;
+            mp_msg_log_buffer_resize(buffer, size);
             buffer->wakeup_cb = wakeup_cb;
             buffer->wakeup_cb_ctx = wakeup_cb_ctx;
             mp_mutex_unlock(&root->lock);
@@ -976,6 +977,40 @@ struct mp_log_buffer *mp_msg_log_buffer_new(struct mpv_global *global,
     return buffer;
 }
 
+void mp_msg_log_buffer_resize(struct mp_log_buffer *buffer, int size)
+{
+    mp_mutex_lock(&buffer->lock);
+
+    assert(size > 0);
+    if (buffer->capacity < size &&
+        buffer->entry0 + buffer->num_entries <= buffer->capacity) {
+        // shortcut if buffer doesn't wrap
+        buffer->entries = talloc_realloc(buffer, buffer->entries,
+                                         struct mp_log_buffer_entry *, size);
+    } else if (buffer->capacity != size) {
+        struct mp_log_buffer_entry **entries =
+            talloc_array(buffer, struct mp_log_buffer_entry *, size);
+        int num_entries = 0;
+        for (int i = buffer->num_entries - 1; i >= 0; i--) {
+            int entry = (buffer->entry0 + i) % buffer->num_entries;
+            struct mp_log_buffer_entry *res = buffer->entries[entry];
+            if (num_entries < size) {
+                entries[num_entries++] = res;
+            } else {
+                talloc_free(res);
+                buffer->dropped += 1;
+            }
+        }
+        talloc_free(buffer->entries);
+        buffer->entries = entries;
+        buffer->entry0 = 0;
+        buffer->num_entries = num_entries;
+    }
+    buffer->capacity = size;
+
+    mp_mutex_unlock(&buffer->lock);
+}
+
 void mp_msg_log_buffer_set_silent(struct mp_log_buffer *buffer, bool silent)
 {
     mp_mutex_lock(&buffer->lock);

common/msg_control.h

@@ -35,6 +35,7 @@ struct mp_log_buffer *mp_msg_log_buffer_new(struct mpv_global *global,
                                             void *wakeup_cb_ctx);
 void mp_msg_log_buffer_destroy(struct mp_log_buffer *buffer);
 struct mp_log_buffer_entry *mp_msg_log_buffer_read(struct mp_log_buffer *buffer);
+void mp_msg_log_buffer_resize(struct mp_log_buffer *buffer, int size);
 void mp_msg_log_buffer_set_silent(struct mp_log_buffer *buffer, bool silent);
 
 int mp_msg_find_level(const char *s);