Add warning() and use it in DEBUG mode.

src/constants.h

@@ -35,6 +35,8 @@
 
 #ifdef DEBUG
 # define DEBUG_FILE "colored_stderr_debug_log.txt"
+/* Created in the user's home directory, appends to existing file. */
+# define WARNING_FILE "colored_stderr_warning_log.txt"
 #endif
 
 #endif

src/debug.h

@@ -20,20 +20,10 @@
 #ifndef DEBUG_H
 #define DEBUG_H 1
 
-static void debug(const char *format, ...) {
+static void debug_write(int fd, int first_call, const char *format, va_list ap) {
     char buffer[1024];
 
-    /* If the file doesn't exist, do nothing. Prevents writing log files in
-     * unexpected places. The user must create the file manually. */
-    int fd = open(DEBUG_FILE, O_WRONLY | O_APPEND);
-    if (fd == -1) {
-        return;
-    }
-
-    va_list ap;
-    va_start(ap, format);
     int written = vsnprintf(buffer, sizeof(buffer), format, ap);
-    va_end(ap);
     /* Overflow. */
     if ((size_t)written >= sizeof(buffer)) {
         written = sizeof(buffer) - 1;
@@ -43,8 +33,7 @@ static void debug(const char *format, ...) {
     DLSYM_FUNCTION(real_write, "write");
     DLSYM_FUNCTION(real_close, "close");
 
-    static int first_call = 0;
-    if (!first_call++) {
+    if (first_call) {
         char nl = '\n';
         real_write(fd, &nl, 1);
     }
@@ -52,4 +41,49 @@ static void debug(const char *format, ...) {
     real_close(fd);
 }
 
+static void debug(const char *format, ...) {
+    va_list ap;
+
+    /* If the file doesn't exist, do nothing. Prevents writing log files in
+     * unexpected places. The user must create the file manually. */
+    int fd = open(DEBUG_FILE, O_WRONLY | O_APPEND);
+    if (fd == -1) {
+        return;
+    }
+
+    static int call_count = 0;
+    call_count++;
+
+    va_start(ap, format);
+    debug_write(fd, call_count == 1, format, ap);
+    va_end(ap);
+}
+
+static void warning(const char *format, ...) {
+    va_list ap;
+
+    char *home = getenv("HOME");
+    if (!home) {
+        return;
+    }
+
+    char path[strlen(home) + 1 + strlen(WARNING_FILE) + 1];
+    strcpy(path, home);
+    strcat(path, "/");
+    strcat(path, WARNING_FILE);
+
+    /* Create the warning file if it doesn't exist yet. */
+    int fd = open(path, O_WRONLY | O_APPEND | O_CREAT, S_IRUSR | S_IWUSR);
+    if (fd == -1) {
+        return;
+    }
+
+    static int call_count = 0;
+    call_count++;
+
+    va_start(ap, format);
+    debug_write(fd, call_count == 1, format, ap);
+    va_end(ap);
+}
+
 #endif

src/trackfds.h

@@ -81,6 +81,10 @@ static void init_from_environment(void) {
 
     tracked_fds_list = malloc(tracked_fds_list_space * sizeof(*tracked_fds_list));
     if (!tracked_fds_list) {
+#ifdef DEBUG
+        warning("malloc(%zu): failed [%d]\n",
+                tracked_fds_list_space * sizeof(*tracked_fds_list), getpid());
+#endif
         return;
     }
 
@@ -122,6 +126,10 @@ static void update_environment_buffer(char *x) {
         int length = snprintf(x, 10 + 1, "%d", tracked_fds_list[i]);
         if (length >= 10 + 1) {
             /* Integer too big to fit the buffer, skip it. */
+#ifdef DEBUG
+            warning("update_environment_buffer_entry(): truncated fd: %d [%d]\n",
+                    tracked_fds_list[i], getpid());
+#endif
             continue;
         }
 
@@ -166,14 +174,15 @@ static void update_environment(void) {
 static void tracked_fds_add(int fd) {
     if (tracked_fds_list_count >= tracked_fds_list_space) {
         size_t new_space = tracked_fds_list_space + TRACKFDS_REALLOC_STEP;
-        int *tmp = realloc(tracked_fds_list, sizeof(*tracked_fds_list) * new_space);
+        int *tmp = realloc(tracked_fds_list,
+                           sizeof(*tracked_fds_list) * new_space);
         if (!tmp) {
             /* We can do nothing, just ignore the error. We made sure not to
              * destroy our state, so the new descriptor is ignored without any
              * other consequences. */
 #ifdef DEBUG
-            debug("realloc(tracked_fds_list, %zu) failed! [%d]\n",
-                  sizeof(*tracked_fds_list) * new_space, getpid());
+            warning("realloc(tracked_fds_list, %zu) failed! [%d]\n",
+                    sizeof(*tracked_fds_list) * new_space, getpid());
 #endif
             return;
         }