Log file (log::destination::file) now creates directory structure if needed.

You could already have something like:
log { source { !debug; all; } destination { file "ircd.%Y-%m-%d.log"; } }
But now you can also have:
log { source { !debug; all; } destination { file "%Y-%m-%d/ircd.log"; } }

This is especially useful if you output to multiple log files and then
want them grouped by date in a directory.

include/h.h

@@ -669,6 +669,9 @@ extern char *unreal_mktemp(const char *dir, const char *suffix);
 extern char *unreal_getpathname(const char *filepath, char *path);
 extern const char *unreal_getfilename(const char *path);
 extern const char *unreal_getmodfilename(const char *path);
+extern int unreal_create_directory_structure_for_file(const char *fname, mode_t mode);
+extern int unreal_create_directory_structure(const char *dname, mode_t mode);
+extern int unreal_mkdir(const char *pathname, mode_t mode);
 extern int unreal_copyfile(const char *src, const char *dest);
 extern int unreal_copyfileex(const char *src, const char *dest, int tryhardlink);
 extern time_t unreal_getfilemodtime(const char *filename);

src/log.c

@@ -986,17 +986,27 @@ void do_unreal_log_disk(LogLevel loglevel, const char *subsystem, const char *ev
 			l->logfd = fd_fileopen(l->file, O_CREAT|O_APPEND|O_WRONLY);
 			if (l->logfd == -1)
 			{
-				if (!loop.booted)
+				if (errno == ENOENT)
 				{
-					config_status("WARNING: Unable to write to '%s': %s", l->file, strerror(errno));
-				} else {
-					if (last_log_file_warning + 300 < TStime())
-					{
-						config_status("WARNING: Unable to write to '%s': %s. This warning will not re-appear for at least 5 minutes.", l->file, strerror(errno));
-						last_log_file_warning = TStime();
-					}
+					/* Create directory structure and retry */
+					unreal_create_directory_structure_for_file(l->file, 0777);
+					l->logfd = fd_fileopen(l->file, O_CREAT|O_APPEND|O_WRONLY);
+				}
+				if (l->logfd == -1)
+				{
+					/* Still failed! */
+					if (!loop.booted)
+					{
+						config_status("WARNING: Unable to write to '%s': %s", l->file, strerror(errno));
+					} else {
+						if (last_log_file_warning + 300 < TStime())
+						{
+							config_status("WARNING: Unable to write to '%s': %s. This warning will not re-appear for at least 5 minutes.", l->file, strerror(errno));
+							last_log_file_warning = TStime();
+						}
+					}
+					continue;
 				}
-				continue;
 			}
 		}
 

src/support.c

@@ -856,6 +856,63 @@ const char *unreal_getfilename(const char *path)
 	return end;
 }
 
+/** Wrapper for mkdir() so you don't need ifdefs everywhere for Windows.
+ * @returns 0 on failure!! (like mkdir)
+ */
+int unreal_mkdir(const char *pathname, mode_t mode)
+{
+#ifdef _WIN32
+	return mkdir(pathname);
+#else
+	return mkdir(pathname, mode);
+#endif
+}
+
+/** Create the entire directory structure.
+ * @param dname	The directory name, eg /home/irc/unrealircd/logs/2022/08/05
+ * @param mode	The mode to create with, eg 0777. Ignored on Windows.
+ * @returns 1 on success, 0 on failure.
+ */
+int unreal_create_directory_structure(const char *dname, mode_t mode)
+{
+	if (unreal_mkdir(dname, mode) == 0)
+	{
+		/* Ok, that failed as well, we have some work to do:
+		 * for every path element run mkdir().
+		 */
+		int lastresult;
+		char buf[512], *p;
+		strlcpy(buf, dname, sizeof(buf)); /* work on a copy */
+		for (p=strchr(buf+1, '/'); p; p=strchr(p+1, '/'))
+		{
+			*p = '\0';
+			unreal_mkdir(buf,mode);
+			*p = '/';
+		}
+		/* Finally, try the complete path */
+		if (unreal_mkdir(dname, mode))
+			return 0; /* failed */
+		/* fallthrough.... */
+	}
+	return 1; /* success */
+}
+
+/** Create entire directory structure for a path with a filename.
+ * @param fname	The full path name, eg /home/irc/unrealircd/logs/2022/08/05/ircd.log
+ * @param mode	The mode to create with, eg 0777. Ignored on Windows.
+ * @notes This is used as an easier way to call unreal_create_directory_structure()
+ *        if you have a filename instead of the directory part.
+ * @returns 1 on success, 0 on failure.
+ */
+int unreal_create_directory_structure_for_file(const char *fname, mode_t mode)
+{
+	char buf[PATH_MAX+1];
+	const char *path = unreal_getpathname(fname, buf);
+	if (!path)
+		return 0;
+	return unreal_create_directory_structure(path, mode);
+}
+
 /** Returns the special module tmp name for a given path.
  * The original string is not modified.
  */