From 0fca5aae90d5a4e292db8db7b9c31c8390799368 Mon Sep 17 00:00:00 2001

From: Daniel Mack <zonque@gmail.com>

Date: Fri, 7 Mar 2014 14:43:59 +0100

Subject: [PATCH] manager: flush memory stream before using the buffer

When the manager receives a SIGUSR2 signal, it opens a memory stream

with open_memstream(), uses the returned file handle for logging, and

dumps the logged content with log_dump().

However, the char* buffer is only safe to use after the file handle has

been flushed with fflush, as the man pages states:

  When the stream is closed (fclose(3)) or flushed (fflush(3)), the

  locations pointed to by ptr and sizeloc are updated to contain,

  respectively, a pointer to the buffer and the current size of  the

  buffer.

  These values remain valid only as long as the caller performs no

  further output on the stream.  If further output is performed, then the

  stream must again be flushed before trying to access these variables.

Without that call, dump remains NULL and the daemon crashes in

log_dump().

Conflicts:

	src/core/manager.c

(cherry-picked from b2cdc6664ef6b56e47d38649d69b9943d9f9f5d0)

Resolves: #1147524

---

 src/core/manager.c | 17 +++++++++--------

 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/core/manager.c b/src/core/manager.c

index 4ad26e1..e48ea36 100644

--- a/src/core/manager.c

+++ b/src/core/manager.c

@@ -1536,11 +1536,12 @@ static int manager_process_signal_fd(Manager *m) {

                 }

                 case SIGUSR2: {

-                        FILE *f;

-                        char *dump = NULL;

+                        _cleanup_free_ char *dump = NULL;

+                        _cleanup_fclose_ FILE *f = NULL;

                         size_t size;

-                        if (!(f = open_memstream(&dump, &size))) {

+                        f = open_memstream(&dump, &size);

+                        if (!f) {

                                 log_warning("Failed to allocate memory stream.");

                                 break;

                         }

@@ -1549,16 +1550,16 @@ static int manager_process_signal_fd(Manager *m) {

                         manager_dump_jobs(m, f, "\t");

                         if (ferror(f)) {

-                                fclose(f);

-                                free(dump);

                                 log_warning("Failed to write status stream");

                                 break;

                         }

-                        fclose(f);

-                        log_dump(LOG_INFO, dump);

-                        free(dump);

+                        if (fflush(f)) {

+                                log_warning("Failed to flush status stream");

+                                break;

+                        }

+                        log_dump(LOG_INFO, dump);

                         break;

                 }