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From febbc3baae65db64692e3ae2852630c5e324ab43 Mon Sep 17 00:00:00 2001
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From: Michal Sekletar <msekleta@redhat.com>
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Date: Tue, 20 Feb 2018 14:16:15 +0100
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Subject: [PATCH] sd-journal: when picking up a new file, compare inode/device
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 info with previous open file by same name
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Let's make sure we aren't confused if a journal file is replaced by a
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different one (for example due to rotation) if we are in a q overflow:
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let's compare the inode/device information, and if it changed replace
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any open file object as needed.
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Fixes: #8198
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(cherry-picked from commit 32cb1983ad6f7084ff86e259ff079742a8139719)
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[msekleta: this is very slimmed down version of the above commit because
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a lot of code from is not applicable to RHEL-7 version]
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Related: #1540538
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---
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 src/journal/sd-journal.c | 35 +++++++++++++++++++++++++++++------
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 1 file changed, 29 insertions(+), 6 deletions(-)
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diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
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index e1cde6e1c..004fe646d 100644
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--- a/src/journal/sd-journal.c
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+++ b/src/journal/sd-journal.c
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@@ -1224,20 +1224,43 @@ static bool file_type_wanted(int flags, const char *filename) {
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 static int add_any_file(sd_journal *j, const char *path) {
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         JournalFile *f = NULL;
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+        struct stat st;
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         int r, k;
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         assert(j);
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         assert(path);
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-        if (path) {
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-                f = ordered_hashmap_get(j->files, path);
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-                if (f) {
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-                        /* Mark this file as seen in this generation. This is used to GC old files in
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-                         * process_q_overflow() to detect journal files that are still and discern them from those who
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-                         * are gone. */
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+        if (stat(path, &st) < 0) {
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+                r = log_debug_errno(errno, "Failed to stat file '%s': %m", path);
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+                return -errno;
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+        }
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+        if (S_ISDIR(st.st_mode)) {
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+                log_debug("Uh, file '%s' is a directory? Refusing.", path);
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+                return -EISDIR;
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+        }
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+        if (!S_ISREG(st.st_mode)) {
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+                log_debug("Uh, file '%s' is not a regular file? Refusing.", path);
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+                return -EBADFD;
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+        }
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+
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+        f = ordered_hashmap_get(j->files, path);
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+        if (f) {
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+
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+                if (f->last_stat.st_dev == st.st_dev &&
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+                    f->last_stat.st_ino == st.st_ino) {
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+
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+                        /* We already track this file, under the same path and with the same device/inode numbers, it's hence
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+                         * really the same. Mark this file as seen in this generation. This is used to GC old files in
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+                         * process_q_overflow() to detect journal files that are still and discern them from those who are
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+                         * gone. */
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                         f->last_seen_generation = j->generation;
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                         return 0;
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                 }
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+
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+                /* So we tracked a file under this name, but it has a different inode/device. In that case, it got
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+                 * replaced (probably due to rotation?), let's drop it hence from our list. */
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+                remove_file_real(j, f);
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+                f = NULL;
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         }
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         if (ordered_hashmap_size(j->files) >= JOURNAL_FILES_MAX) {