sd-journal: fix sd_journal_enumerate_unique skipping values

sd_journal_enumerate_unique will lock its mmap window to prevent it
from being released by calling mmap_cache_get with keep_always=true.
This call may return windows that are wider, but compatible with the
parameters provided to it.

This can result in a mismatch where the window to be released cannot
properly be selected, because we have more than one window matching the
parameters of mmap_cache_release. Therefore, introduce a release_cookie
to be used when releasing the window.

https://bugs.freedesktop.org/show_bug.cgi?id=79380

1 files changed, 3 insertions, 5 deletions

diff --git a/src/journal/mmap-cache.h b/src/journal/mmap-cache.h
index 647555a73e..76e5316248 100644
--- a/src/journal/mmap-cache.h
+++ b/src/journal/mmap-cache.h
@@ -40,14 +40,12 @@ int mmap_cache_get(
         uint64_t offset,
         size_t size,
         struct stat *st,
-        void **ret);
+        void **ret,
+        void **release_cookie);
 int mmap_cache_release(
         MMapCache *m,
         int fd,
-        int prot,
-        unsigned context,
-        uint64_t offset,
-        size_t size);
+        void *release_cookie);
 void mmap_cache_close_fd(MMapCache *m, int fd);
 void mmap_cache_close_context(MMapCache *m, unsigned context);