1 files changed, 74 insertions, 32 deletions

diff --git a/src/nvim/log.c b/src/nvim/log.c
index d059e28d5d..f1dbe61dda 100644
--- a/src/nvim/log.c
+++ b/src/nvim/log.c
@@ -7,20 +7,17 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <uv.h>
 
 #include "nvim/log.h"
 #include "nvim/types.h"
 #include "nvim/os/os.h"
 #include "nvim/os/time.h"
 
-/// First location of the log file used by log_path_init()
-#define USR_LOG_FILE "$NVIM_LOG_FILE"
+#define LOG_FILE_ENV "NVIM_LOG_FILE"
 
-/// Fall back location of the log file used by log_path_init()
-#define USR_LOG_FILE_2 "$HOME" _PATHSEPSTR ".nvimlog"
-
-/// Cached location of the log file set by log_path_init()
-static char expanded_log_file_path[MAXPATHL + 1] = { 0 };
+/// Cached location of the expanded log file path decided by log_path_init().
+static char log_file_path[MAXPATHL + 1] = { 0 };
 
 static uv_mutex_t mutex;
 
@@ -28,31 +25,53 @@ static uv_mutex_t mutex;
 # include "log.c.generated.h"
 #endif
 
-/// Initialize path to log file
+static bool log_try_create(char *fname)
+{
+  if (fname == NULL || fname[0] == '\0') {
+    return false;
+  }
+  FILE *log_file = fopen(fname, "a");
+  if (log_file == NULL) {
+    return false;
+  }
+  fclose(log_file);
+  return true;
+}
+
+/// Initializes path to log file. Sets $NVIM_LOG_FILE if empty.
 ///
-/// Tries to use #USR_LOG_FILE, then falls back #USR_LOG_FILE_2. Path to log
+/// Tries $NVIM_LOG_FILE, or falls back to $XDG_DATA_HOME/nvim/log. Path to log
 /// file is cached, so only the first call has effect, unless first call was not
-/// successful. To make initialization not succeed either a bug in expand_env()
-/// is needed or both `$NVIM_LOG_FILE` and `$HOME` environment variables
-/// undefined.
+/// successful. Failed initialization indicates either a bug in expand_env()
+/// or both $NVIM_LOG_FILE and $HOME environment variables are undefined.
 ///
 /// @return true if path was initialized, false otherwise.
 static bool log_path_init(void)
 {
-  if (expanded_log_file_path[0]) {
+  if (log_file_path[0]) {
     return true;
   }
-  expand_env((char_u *)USR_LOG_FILE, (char_u *)expanded_log_file_path,
-             sizeof(expanded_log_file_path) - 1);
-  // if the log file path expansion failed then fall back to stderr
-  if (strcmp(USR_LOG_FILE, expanded_log_file_path) == 0) {
-    memset(expanded_log_file_path, 0, sizeof(expanded_log_file_path));
-    expand_env((char_u *)USR_LOG_FILE_2, (char_u *)expanded_log_file_path,
-               sizeof(expanded_log_file_path) - 1);
-    if (strcmp(USR_LOG_FILE_2, expanded_log_file_path) == 0) {
-      memset(expanded_log_file_path, 0, sizeof(expanded_log_file_path));
+  size_t size = sizeof(log_file_path);
+  expand_env((char_u *)"$" LOG_FILE_ENV, (char_u *)log_file_path,
+             (int)size - 1);
+  if (strequal("$" LOG_FILE_ENV, log_file_path)
+      || log_file_path[0] == '\0'
+      || os_isdir((char_u *)log_file_path)
+      || !log_try_create(log_file_path)) {
+    // Invalid $NVIM_LOG_FILE or failed to expand; fall back to default.
+    char *defaultpath = stdpaths_user_data_subpath("log", 0, true);
+    size_t len = xstrlcpy(log_file_path, defaultpath, size);
+    xfree(defaultpath);
+    // Fall back to .nvimlog
+    if (len >= size || !log_try_create(log_file_path)) {
+      len = xstrlcpy(log_file_path, ".nvimlog", size);
+    }
+    // Fall back to stderr
+    if (len >= size || !log_try_create(log_file_path)) {
+      log_file_path[0] = '\0';
       return false;
     }
+    os_setenv(LOG_FILE_ENV, log_file_path, true);
   }
   return true;
 }
@@ -75,6 +94,10 @@ void log_unlock(void)
 bool do_log(int log_level, const char *func_name, int line_num, bool eol,
             const char* fmt, ...) FUNC_ATTR_UNUSED
 {
+  if (log_level < MIN_LOG_LEVEL) {
+    return false;
+  }
+
   log_lock();
   bool ret = false;
   FILE *log_file = open_log_file();
@@ -97,26 +120,42 @@ end:
   return ret;
 }
 
+void log_uv_handles(void *loop)
+{
+  uv_loop_t *l = loop;
+  log_lock();
+  FILE *log_file = open_log_file();
+
+  if (log_file == NULL) {
+    goto end;
+  }
+
+  uv_print_all_handles(l, log_file);
+
+  if (log_file != stderr && log_file != stdout) {
+    fclose(log_file);
+  }
+end:
+  log_unlock();
+}
+
 /// Open the log file for appending.
 ///
-/// @return The FILE* specified by the USR_LOG_FILE path or stderr in case of
-///         error
+/// @return FILE* decided by log_path_init() or stderr in case of error
 FILE *open_log_file(void)
 {
   static bool opening_log_file = false;
-
   // check if it's a recursive call
   if (opening_log_file) {
     do_log_to_file(stderr, ERROR_LOG_LEVEL, __func__, __LINE__, true,
-                   "Trying to LOG() recursively! Please fix it.");
+                   "Cannot LOG() recursively.");
     return stderr;
   }
 
-  // expand USR_LOG_FILE if needed and open the file
   FILE *log_file = NULL;
   opening_log_file = true;
   if (log_path_init()) {
-    log_file = fopen(expanded_log_file_path, "a");
+    log_file = fopen(log_file_path, "a");
   }
   opening_log_file = false;
 
@@ -124,10 +163,13 @@ FILE *open_log_file(void)
     return log_file;
   }
 
+  // May happen if:
+  //  - LOG() is called before early_init()
+  //  - Directory does not exist
+  //  - File is not writable
   do_log_to_file(stderr, ERROR_LOG_LEVEL, __func__, __LINE__, true,
-                 "Couldn't open USR_LOG_FILE, logging to stderr! This may be "
-                 "caused by attempting to LOG() before initialization "
-                 "functions are called (e.g. init_homedir()).");
+                 "Logging to stderr, failed to open $" LOG_FILE_ENV ": %s",
+                 log_file_path);
   return stderr;
 }
 
@@ -152,7 +194,7 @@ static bool v_do_log_to_file(FILE *log_file, int log_level,
     [DEBUG_LOG_LEVEL]   = "DEBUG",
     [INFO_LOG_LEVEL]    = "INFO ",
     [WARNING_LOG_LEVEL] = "WARN ",
-    [ERROR_LOG_LEVEL]   = "ERROR"
+    [ERROR_LOG_LEVEL]   = "ERROR",
   };
   assert(log_level >= DEBUG_LOG_LEVEL && log_level <= ERROR_LOG_LEVEL);