Add server.breakagelog, a "special" stderr (fixes #1863)

* The breakage-log simply replaces stderr (the old stderr is moved away if needed for errorlog),
  and stderr isn't closed after forking.
  It defaults to stderr if started with -n (no daemonize), otherwise it defaults to /dev/null.
  It is _not_ reopened in log_error_cycle, as there may be many long running childs which have it
  still open anyway. Use a pipe-logger with cycle-support if you need it.


git-svn-id: svn://svn.lighttpd.net/lighttpd/trunk@2552 152afb58-edef-0310-8abb-c4023f1b3aa9

7 files changed, 85 insertions, 36 deletions

diff --git a/NEWS b/NEWS
index 6603b951..0a68a014 100644
--- a/NEWS
+++ b/NEWS
@@ -123,6 +123,7 @@ NEWS
   * Fix race condition with joblist thread condition/mutex (thx peto, fixes #1823)
   * Fix segfault if there is no mimetype for the error documents
   * Use unsigned int for secdownload.timeout (fixes #1966)
+  * Add server.breakagelog, a "special" stderr (fixes #1863)
 
 - 1.5.0-r19.. -
   * -F option added for spawn-fcgi
diff --git a/src/base.h b/src/base.h
index 9e36375f..d0ca8188 100644
--- a/src/base.h
+++ b/src/base.h
@@ -551,6 +551,7 @@ typedef struct {
 
 	buffer *errorlog_file;
 	unsigned short errorlog_use_syslog;
+	buffer *breakagelog_file;
 
 	unsigned short max_stat_threads;
 	unsigned short max_read_threads;
diff --git a/src/configfile.c b/src/configfile.c
index 82b4ec63..d4b5ac31 100644
--- a/src/configfile.c
+++ b/src/configfile.c
@@ -102,6 +102,7 @@ static int config_insert(server *srv) {
 		{ "etag.use-inode",              NULL, T_CONFIG_BOOLEAN, T_CONFIG_SCOPE_SERVER },     /* 54 */
 		{ "etag.use-mtime",              NULL, T_CONFIG_BOOLEAN, T_CONFIG_SCOPE_SERVER },     /* 55 */
 		{ "etag.use-size",               NULL, T_CONFIG_BOOLEAN, T_CONFIG_SCOPE_SERVER },     /* 56 */
+		{ "server.breakagelog",          NULL, T_CONFIG_STRING, T_CONFIG_SCOPE_SERVER },      /* 57 */
 
 		{ "server.host",                 "use server.bind instead", T_CONFIG_DEPRECATED, T_CONFIG_SCOPE_UNSET },
 		{ "server.docroot",              "use server.document-root instead", T_CONFIG_DEPRECATED, T_CONFIG_SCOPE_UNSET },
@@ -149,6 +150,7 @@ static int config_insert(server *srv) {
 	cv[49].destination = &(srv->srvconf.max_read_threads);
 	
 	cv[51].destination = &(srv->srvconf.log_timing);
+	cv[57].destination = srv->srvconf.breakagelog_file;
 
 	srv->config_storage = calloc(1, srv->config_context->used * sizeof(specific_config *));
 
diff --git a/src/log.c b/src/log.c
index 1d121660..401ab50d 100644
--- a/src/log.c
+++ b/src/log.c
@@ -41,6 +41,29 @@
 # define O_LARGEFILE 0
 #endif
 
+/* Close fd and _try_ to get a /dev/null for it instead.
+ * close() alone may trigger some bugs when a
+ * process opens another file and gets fd = STDOUT_FILENO or STDERR_FILENO
+ * and later tries to just print on stdout/stderr
+ *
+ * Returns 0 on success and -1 on failure (fd gets closed in all cases)
+ */
+int openDevNull(int fd) {
+	int tmpfd;
+	close(fd);
+#if defined(__WIN32)
+	/* Cygwin should work with /dev/null */
+	tmpfd = open("nul", O_RDWR);
+#else
+	tmpfd = open("/dev/null", O_RDWR);
+#endif
+	if (tmpfd != -1 && tmpfd != fd) {
+		dup2(tmpfd, fd);
+		close(tmpfd);
+	}
+	return (tmpfd != -1) ? 0 : -1;
+}
+
 /**
  * open the errorlog
  *
@@ -60,7 +83,7 @@ typedef struct {
 
 	/* the errorlog */
 	int fd;
-	enum { ERRORLOG_STDERR, ERRORLOG_FILE, ERRORLOG_SYSLOG } mode;
+	enum { ERRORLOG_FILE, ERRORLOG_FD, ERRORLOG_SYSLOG } mode;
 	buffer *buf;
 
 	time_t cached_ts;
@@ -75,8 +98,8 @@ void log_init(void) {
 
 	err = calloc(1, sizeof(*err));
 
-	err->fd = -1;
-	err->mode = ERRORLOG_STDERR;
+	err->fd = STDERR_FILENO;
+	err->mode = ERRORLOG_FD;
 	err->buf = buffer_init();
 	err->cached_ts_str = buffer_init();
 
@@ -90,15 +113,18 @@ void log_free(void) {
 
 	switch(err->mode) {
 	case ERRORLOG_FILE:
-		close(err->fd);
+	case ERRORLOG_FD:
+		if (-1 != err->fd) {
+			if (STDERR_FILENO != err->fd)
+				close(err->fd);
+			err->fd = -1;
+		}
 		break;
 	case ERRORLOG_SYSLOG:
 #ifdef HAVE_SYSLOG_H
 		closelog();
 #endif
 		break;
-	case ERRORLOG_STDERR:
-		break;
 	}
 
 	buffer_free(err->buf);
@@ -109,17 +135,15 @@ void log_free(void) {
 	myconfig = NULL;
 }
 
-int log_error_open(buffer *file, int use_syslog) {
-	int fd;
-	int close_stderr = 1;
-
+int log_error_open(buffer *file, buffer *breakage_file, int use_syslog, int dont_daemonize) {
 	errorlog *err = myconfig;
 
 #ifdef HAVE_SYSLOG_H
 	/* perhaps someone wants to use syslog() */
 	openlog("lighttpd", LOG_CONS | LOG_PID, LOG_DAEMON);
 #endif
-	err->mode = ERRORLOG_STDERR;
+	err->mode = ERRORLOG_FD;
+	err->fd = STDERR_FILENO;
 
 	if (use_syslog) {
 		err->mode = ERRORLOG_SYSLOG;
@@ -141,17 +165,39 @@ int log_error_open(buffer *file, int use_syslog) {
 
 	TRACE("%s", "server started");
 
-	/* don't close stderr for debugging purposes if run in valgrind */
-	if (RUNNING_ON_VALGRIND) close_stderr = 0;
-	if (err->mode == ERRORLOG_STDERR) close_stderr = 0;
+	if (err->mode == ERRORLOG_FD && !dont_daemonize) {
+		/* We can only log to stderr in dont-daemonize mode */
+		err->fd = -1;
+	}
+
+	if (!buffer_is_empty(breakage_file)) {
+		int breakage_fd;
+
+		if (err->mode == ERRORLOG_FD) {
+			err->fd = dup(STDERR_FILENO);
+#ifdef FD_CLOEXEC
+			fcntl(err->fd, F_SETFD, FD_CLOEXEC);
+#endif
+		}
+
+		if (-1 == (breakage_fd = open(breakage_file->ptr, O_APPEND | O_WRONLY | O_CREAT | O_LARGEFILE, 0644))) {
+			log_error_write(NULL, __FILE__, __LINE__, "SBSS",
+					"opening breakagelog '", breakage_file,
+					"' failed: ", strerror(errno));
+
+			return -1;
+		}
 
-	/* move stderr to /dev/null */
-	if (close_stderr &&
-	    -1 != (fd = open("/dev/null", O_WRONLY))) {
-		close(STDERR_FILENO);
-		dup2(fd, STDERR_FILENO);
-		close(fd);
+		if (STDERR_FILENO != breakage_fd) {
+			dup2(breakage_fd, STDERR_FILENO);
+			close(breakage_fd);
+		}
+	} else if (!dont_daemonize) {
+		/* move stderr to /dev/null */
+		openDevNull(STDERR_FILENO);
 	}
+
+
 	return 0;
 }
 
@@ -206,7 +252,8 @@ int log_error_write(void *srv, const char *filename, unsigned int line, const ch
 
 	switch(err->mode) {
 	case ERRORLOG_FILE:
-	case ERRORLOG_STDERR:
+	case ERRORLOG_FD:
+		if (-1 == err->fd) return 0;
 		/* cache the generated timestamp */
 		t = time(NULL);
 
@@ -290,13 +337,10 @@ int log_error_write(void *srv, const char *filename, unsigned int line, const ch
 
 	switch(err->mode) {
 	case ERRORLOG_FILE:
+	case ERRORLOG_FD:
 		buffer_append_string_len(err->buf, CONST_STR_LEN("\n"));
 		write(err->fd, err->buf->ptr, err->buf->used - 1);
 		break;
-	case ERRORLOG_STDERR:
-		buffer_append_string_len(err->buf, CONST_STR_LEN("\n"));
-		write(STDERR_FILENO, err->buf->ptr, err->buf->used - 1);
-		break;
 #ifdef HAVE_SYSLOG_H
 	case ERRORLOG_SYSLOG:
 		syslog(LOG_ERR, "%s", err->buf->ptr);
@@ -320,7 +364,8 @@ int log_trace(const char *fmt, ...) {
 
 	switch(err->mode) {
 	case ERRORLOG_FILE:
-	case ERRORLOG_STDERR:
+	case ERRORLOG_FD:
+		if (-1 == err->fd) return 0;
 		/* cache the generated timestamp */
 		t = time(NULL);
 
@@ -384,13 +429,10 @@ int log_trace(const char *fmt, ...) {
 	/* write b */
 	switch(err->mode) {
 	case ERRORLOG_FILE:
+	case ERRORLOG_FD:
 		buffer_append_string_len(b, CONST_STR_LEN("\n"));
 		write(err->fd, b->ptr, b->used - 1);
 		break;
-	case ERRORLOG_STDERR:
-		buffer_append_string_len(b, CONST_STR_LEN("\n"));
-		write(STDERR_FILENO, b->ptr, b->used - 1);
-		break;
 #ifdef HAVE_SYSLOG_H
 	case ERRORLOG_SYSLOG:
 		syslog(LOG_ERR, "%s", b->ptr);
diff --git a/src/log.h b/src/log.h
index 52369d8e..616e6274 100644
--- a/src/log.h
+++ b/src/log.h
@@ -4,10 +4,15 @@
 #include "valgrind/valgrind.h"
 #include "buffer.h"
 
+/* Close fd and _try_ to get a /dev/null for it instead.
+ * Returns 0 on success and -1 on failure (fd gets closed in all cases)
+ */
+LI_API int openDevNull(int fd);
+
 LI_API void log_init(void);
 LI_API void log_free(void);
 
-LI_API int log_error_open(buffer *file, int use_syslog);
+LI_API int log_error_open(buffer* file, buffer* breakage_file, int use_syslog, int dont_daemonize);
 LI_API int log_error_close();
 LI_API int log_error_write(void *srv, const char *filename, unsigned int line, const char *fmt, ...);
 LI_API int log_error_cycle();
diff --git a/src/mod_rrdtool.c b/src/mod_rrdtool.c
index e70473ca..f7e4fad1 100644
--- a/src/mod_rrdtool.c
+++ b/src/mod_rrdtool.c
@@ -129,21 +129,17 @@ static int mod_rrd_create_pipe(server *srv, plugin_data *p) {
 		char *dash = "-";
 
 		/* move stdout to from_rrdtool_fd[1] */
-		close(STDOUT_FILENO);
 		dup2(from_rrdtool_fds[1], STDOUT_FILENO);
 		close(from_rrdtool_fds[1]);
 		/* not needed */
 		close(from_rrdtool_fds[0]);
 
 		/* move the stdin to to_rrdtool_fd[0] */
-		close(STDIN_FILENO);
 		dup2(to_rrdtool_fds[0], STDIN_FILENO);
 		close(to_rrdtool_fds[0]);
 		/* not needed */
 		close(to_rrdtool_fds[1]);
 
-		close(STDERR_FILENO);
-
 		/* set up args */
 		argc = 3;
 		args = malloc(sizeof(*args) * argc);
diff --git a/src/server.c b/src/server.c
index 1756fdc3..5090c9ce 100644
--- a/src/server.c
+++ b/src/server.c
@@ -203,6 +203,7 @@ static server *server_init(void) {
 	CLEAN(cond_check_buf);
 
 	CLEAN(srvconf.errorlog_file);
+	CLEAN(srvconf.breakagelog_file);
 	CLEAN(srvconf.groupname);
 	CLEAN(srvconf.username);
 	CLEAN(srvconf.changeroot);
@@ -297,6 +298,7 @@ static void server_free(server *srv) {
 	CLEAN(cond_check_buf);
 
 	CLEAN(srvconf.errorlog_file);
+	CLEAN(srvconf.breakagelog_file);
 	CLEAN(srvconf.groupname);
 	CLEAN(srvconf.username);
 	CLEAN(srvconf.changeroot);
@@ -1536,7 +1538,7 @@ int main (int argc, char **argv, char **envp) {
 		return -1;
 	}
 
-	if (-1 == log_error_open(srv->srvconf.errorlog_file, srv->srvconf.errorlog_use_syslog)) {
+	if (-1 == log_error_open(srv->srvconf.errorlog_file, srv->srvconf.breakagelog_file, srv->srvconf.errorlog_use_syslog, srv->srvconf.dont_daemonize)) {
 		log_error_write(srv, __FILE__, __LINE__, "s",
 				"opening errorlog failed, dying");