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systemd/SOURCES/0251-pstore-fixes-for-dmesg.txt-reconstruction.patch

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import CS systemd-252-18.el9
2023-09-21 20:32:36 +00:00
From a6d9977a0cafaaf1dcf5c7658d958aea8e5284f0 Mon Sep 17 00:00:00 2001
From: Eric DeVolder <eric.devolder@oracle.com>
Date: Mon, 21 Nov 2022 11:27:27 -0500
Subject: [PATCH] pstore: fixes for dmesg.txt reconstruction
This patch fixes problems with the re-assembly of the dmesg
from the records stored in pstore.
The current code simply ignores the last 6 characters of the
file name to form a base record id, which then groups any
pstore files with this base id into the reconstructed dmesg.txt.
This approach fails when the following oops generated the
following in pstore:
-rw-------. 1 root root 1808 Oct 27 22:07 dmesg-efi-166692286101001
-rw-------. 1 root root 1341 Oct 27 22:07 dmesg-efi-166692286101002
-rw-------. 1 root root 1812 Oct 27 22:07 dmesg-efi-166692286102001
-rw-------. 1 root root 1820 Oct 27 22:07 dmesg-efi-166692286102002
-rw-------. 1 root root 1807 Oct 27 22:07 dmesg-efi-166692286103001
-rw-------. 1 root root 1791 Oct 27 22:07 dmesg-efi-166692286103002
-rw-------. 1 root root 1773 Oct 27 22:07 dmesg-efi-166692286104001
-rw-------. 1 root root 1801 Oct 27 22:07 dmesg-efi-166692286104002
-rw-------. 1 root root 1821 Oct 27 22:07 dmesg-efi-166692286105001
-rw-------. 1 root root 1809 Oct 27 22:07 dmesg-efi-166692286105002
-rw-------. 1 root root 1804 Oct 27 22:07 dmesg-efi-166692286106001
-rw-------. 1 root root 1817 Oct 27 22:07 dmesg-efi-166692286106002
-rw-------. 1 root root 1792 Oct 27 22:07 dmesg-efi-166692286107001
-rw-------. 1 root root 1810 Oct 27 22:07 dmesg-efi-166692286107002
-rw-------. 1 root root 1717 Oct 27 22:07 dmesg-efi-166692286108001
-rw-------. 1 root root 1808 Oct 27 22:07 dmesg-efi-166692286108002
-rw-------. 1 root root 1764 Oct 27 22:07 dmesg-efi-166692286109001
-rw-------. 1 root root 1765 Oct 27 22:07 dmesg-efi-166692286109002
-rw-------. 1 root root 1796 Oct 27 22:07 dmesg-efi-166692286110001
-rw-------. 1 root root 1816 Oct 27 22:07 dmesg-efi-166692286110002
-rw-------. 1 root root 1793 Oct 27 22:07 dmesg-efi-166692286111001
-rw-------. 1 root root 1751 Oct 27 22:07 dmesg-efi-166692286111002
-rw-------. 1 root root 1813 Oct 27 22:07 dmesg-efi-166692286112001
-rw-------. 1 root root 1786 Oct 27 22:07 dmesg-efi-166692286112002
-rw-------. 1 root root 1754 Oct 27 22:07 dmesg-efi-166692286113001
-rw-------. 1 root root 1752 Oct 27 22:07 dmesg-efi-166692286113002
-rw-------. 1 root root 1803 Oct 27 22:07 dmesg-efi-166692286114001
-rw-------. 1 root root 1759 Oct 27 22:07 dmesg-efi-166692286114002
-rw-------. 1 root root 1805 Oct 27 22:07 dmesg-efi-166692286115001
-rw-------. 1 root root 1787 Oct 27 22:07 dmesg-efi-166692286115002
-rw-------. 1 root root 1815 Oct 27 22:07 dmesg-efi-166692286116001
-rw-------. 1 root root 1771 Oct 27 22:07 dmesg-efi-166692286116002
-rw-------. 1 root root 1816 Oct 27 22:07 dmesg-efi-166692286117002
-rw-------. 1 root root 1388 Oct 27 22:07 dmesg-efi-166692286701003
-rw-------. 1 root root 1824 Oct 27 22:07 dmesg-efi-166692286702003
-rw-------. 1 root root 1795 Oct 27 22:07 dmesg-efi-166692286703003
-rw-------. 1 root root 1805 Oct 27 22:07 dmesg-efi-166692286704003
-rw-------. 1 root root 1813 Oct 27 22:07 dmesg-efi-166692286705003
-rw-------. 1 root root 1821 Oct 27 22:07 dmesg-efi-166692286706003
-rw-------. 1 root root 1814 Oct 27 22:07 dmesg-efi-166692286707003
-rw-------. 1 root root 1812 Oct 27 22:07 dmesg-efi-166692286708003
-rw-------. 1 root root 1769 Oct 27 22:07 dmesg-efi-166692286709003
-rw-------. 1 root root 1820 Oct 27 22:07 dmesg-efi-166692286710003
-rw-------. 1 root root 1755 Oct 27 22:07 dmesg-efi-166692286711003
-rw-------. 1 root root 1790 Oct 27 22:07 dmesg-efi-166692286712003
-rw-------. 1 root root 1756 Oct 27 22:07 dmesg-efi-166692286713003
-rw-------. 1 root root 1763 Oct 27 22:07 dmesg-efi-166692286714003
-rw-------. 1 root root 1791 Oct 27 22:07 dmesg-efi-166692286715003
-rw-------. 1 root root 1775 Oct 27 22:07 dmesg-efi-166692286716003
-rw-------. 1 root root 1820 Oct 27 22:07 dmesg-efi-166692286717003
The "reconstructed" dmesg.txt that resulted from the above contained
the following (ignoring actual contents, just providing the Part info):
Emergency#3 Part17
Emergency#3 Part16
Emergency#3 Part15
Emergency#3 Part14
Emergency#3 Part13
Emergency#3 Part12
Emergency#3 Part11
Emergency#3 Part10
Emergency#3 Part9
Emergency#3 Part8
Emergency#3 Part7
Emergency#3 Part6
Emergency#3 Part5
Emergency#3 Part4
Emergency#3 Part3
Emergency#3 Part2
Emergency#3 Part1
Panic#2 Part17
Panic#2 Part16
Oops#1 Part16
Panic#2 Part15
Oops#1 Part15
Panic#2 Part14
Oops#1 Part14
Panic#2 Part13
Oops#1 Part13
Panic#2 Part12
Oops#1 Part12
Panic#2 Part11
Oops#1 Part11
Panic#2 Part10
Oops#1 Part10
Panic#2 Part9
Oops#1 Part9
Panic#2 Part8
Oops#1 Part8
Panic#2 Part7
Oops#1 Part7
Panic#2 Part6
Oops#1 Part6
Panic#2 Part5
Oops#1 Part5
Panic#2 Part4
Oops#1 Part4
Panic#2 Part3
Oops#1 Part3
Panic#2 Part2
Oops#1 Part2
Panic#2 Part1
Oops#1 Part1
The above is a interleaved mess of three dmesg dumps.
This patch fixes the above problems, and simplifies the dmesg
reconstruction process. The code now distinguishes between
records on EFI vs ERST, which have differently formatted
record identifiers. Using knowledge of the format of the
record ids allows vastly improved reconstruction process.
With this change in place, the above pstore records now
result in the following:
# ls -alR /var/lib/systemd/pstore
1666922861:
total 8
drwxr-xr-x. 4 root root 28 Nov 18 14:58 .
drwxr-xr-x. 7 root root 144 Nov 18 14:58 ..
drwxr-xr-x. 2 root root 4096 Nov 18 14:58 001
drwxr-xr-x. 2 root root 4096 Nov 18 14:58 002
1666922861/001:
total 100
drwxr-xr-x. 2 root root 4096 Nov 18 14:58 .
drwxr-xr-x. 4 root root 28 Nov 18 14:58 ..
-rw-------. 1 root root 1808 Oct 27 22:07 dmesg-efi-166692286101001
-rw-------. 1 root root 1812 Oct 27 22:07 dmesg-efi-166692286102001
-rw-------. 1 root root 1807 Oct 27 22:07 dmesg-efi-166692286103001
-rw-------. 1 root root 1773 Oct 27 22:07 dmesg-efi-166692286104001
-rw-------. 1 root root 1821 Oct 27 22:07 dmesg-efi-166692286105001
-rw-------. 1 root root 1804 Oct 27 22:07 dmesg-efi-166692286106001
-rw-------. 1 root root 1792 Oct 27 22:07 dmesg-efi-166692286107001
-rw-------. 1 root root 1717 Oct 27 22:07 dmesg-efi-166692286108001
-rw-------. 1 root root 1764 Oct 27 22:07 dmesg-efi-166692286109001
-rw-------. 1 root root 1796 Oct 27 22:07 dmesg-efi-166692286110001
-rw-------. 1 root root 1793 Oct 27 22:07 dmesg-efi-166692286111001
-rw-------. 1 root root 1813 Oct 27 22:07 dmesg-efi-166692286112001
-rw-------. 1 root root 1754 Oct 27 22:07 dmesg-efi-166692286113001
-rw-------. 1 root root 1803 Oct 27 22:07 dmesg-efi-166692286114001
-rw-------. 1 root root 1805 Oct 27 22:07 dmesg-efi-166692286115001
-rw-------. 1 root root 1815 Oct 27 22:07 dmesg-efi-166692286116001
-rw-r-----. 1 root root 28677 Nov 18 14:58 dmesg.txt
1666922861/002:
total 104
drwxr-xr-x. 2 root root 4096 Nov 18 14:58 .
drwxr-xr-x. 4 root root 28 Nov 18 14:58 ..
-rw-------. 1 root root 1341 Oct 27 22:07 dmesg-efi-166692286101002
-rw-------. 1 root root 1820 Oct 27 22:07 dmesg-efi-166692286102002
-rw-------. 1 root root 1791 Oct 27 22:07 dmesg-efi-166692286103002
-rw-------. 1 root root 1801 Oct 27 22:07 dmesg-efi-166692286104002
-rw-------. 1 root root 1809 Oct 27 22:07 dmesg-efi-166692286105002
-rw-------. 1 root root 1817 Oct 27 22:07 dmesg-efi-166692286106002
-rw-------. 1 root root 1810 Oct 27 22:07 dmesg-efi-166692286107002
-rw-------. 1 root root 1808 Oct 27 22:07 dmesg-efi-166692286108002
-rw-------. 1 root root 1765 Oct 27 22:07 dmesg-efi-166692286109002
-rw-------. 1 root root 1816 Oct 27 22:07 dmesg-efi-166692286110002
-rw-------. 1 root root 1751 Oct 27 22:07 dmesg-efi-166692286111002
-rw-------. 1 root root 1786 Oct 27 22:07 dmesg-efi-166692286112002
-rw-------. 1 root root 1752 Oct 27 22:07 dmesg-efi-166692286113002
-rw-------. 1 root root 1759 Oct 27 22:07 dmesg-efi-166692286114002
-rw-------. 1 root root 1787 Oct 27 22:07 dmesg-efi-166692286115002
-rw-------. 1 root root 1771 Oct 27 22:07 dmesg-efi-166692286116002
-rw-------. 1 root root 1816 Oct 27 22:07 dmesg-efi-166692286117002
-rw-r-----. 1 root root 30000 Nov 18 14:58 dmesg.txt
1666922867:
total 4
drwxr-xr-x. 3 root root 17 Nov 18 14:58 .
drwxr-xr-x. 7 root root 144 Nov 18 14:58 ..
drwxr-xr-x. 2 root root 4096 Nov 18 14:58 003
1666922867/003:
total 104
drwxr-xr-x. 2 root root 4096 Nov 18 14:58 .
drwxr-xr-x. 3 root root 17 Nov 18 14:58 ..
-rw-------. 1 root root 1388 Oct 27 22:07 dmesg-efi-166692286701003
-rw-------. 1 root root 1824 Oct 27 22:07 dmesg-efi-166692286702003
-rw-------. 1 root root 1795 Oct 27 22:07 dmesg-efi-166692286703003
-rw-------. 1 root root 1805 Oct 27 22:07 dmesg-efi-166692286704003
-rw-------. 1 root root 1813 Oct 27 22:07 dmesg-efi-166692286705003
-rw-------. 1 root root 1821 Oct 27 22:07 dmesg-efi-166692286706003
-rw-------. 1 root root 1814 Oct 27 22:07 dmesg-efi-166692286707003
-rw-------. 1 root root 1812 Oct 27 22:07 dmesg-efi-166692286708003
-rw-------. 1 root root 1769 Oct 27 22:07 dmesg-efi-166692286709003
-rw-------. 1 root root 1820 Oct 27 22:07 dmesg-efi-166692286710003
-rw-------. 1 root root 1755 Oct 27 22:07 dmesg-efi-166692286711003
-rw-------. 1 root root 1790 Oct 27 22:07 dmesg-efi-166692286712003
-rw-------. 1 root root 1756 Oct 27 22:07 dmesg-efi-166692286713003
-rw-------. 1 root root 1763 Oct 27 22:07 dmesg-efi-166692286714003
-rw-------. 1 root root 1791 Oct 27 22:07 dmesg-efi-166692286715003
-rw-------. 1 root root 1775 Oct 27 22:07 dmesg-efi-166692286716003
-rw-------. 1 root root 1820 Oct 27 22:07 dmesg-efi-166692286717003
-rw-r-----. 1 root root 30111 Nov 18 14:58 dmesg.txt
Furthemore, pstore records on ERST are now able to accurately
identify the change in timestamp sequence in order to start a
new dmesg.txt, as needed.
(cherry picked from commit 5fbaa757077bde2db8d33b1c358518c41b990339)
Related: #2170883
---
src/pstore/pstore.c | 204 ++++++++++++++++++--------------------------
1 file changed, 83 insertions(+), 121 deletions(-)
diff --git a/src/pstore/pstore.c b/src/pstore/pstore.c
index d820ceb9f6..cfce994bec 100644
--- a/src/pstore/pstore.c
+++ b/src/pstore/pstore.c
@@ -115,7 +115,7 @@ static int compare_pstore_entries(const PStoreEntry *a, const PStoreEntry *b) {
return strcmp(a->dirent.d_name, b->dirent.d_name);
}
-static int move_file(PStoreEntry *pe, const char *subdir) {
+static int move_file(PStoreEntry *pe, const char *subdir1, const char *subdir2) {
_cleanup_free_ char *ifd_path = NULL, *ofd_path = NULL;
_cleanup_free_ void *field = NULL;
const char *suffix, *message;
@@ -129,7 +129,7 @@ static int move_file(PStoreEntry *pe, const char *subdir) {
if (!ifd_path)
return log_oom();
- ofd_path = path_join(arg_archivedir, subdir, pe->dirent.d_name);
+ ofd_path = path_join(arg_archivedir, subdir1, subdir2, pe->dirent.d_name);
if (!ofd_path)
return log_oom();
@@ -172,153 +172,115 @@ static int move_file(PStoreEntry *pe, const char *subdir) {
return 0;
}
-static int write_dmesg(const char *dmesg, size_t size, const char *id) {
- _cleanup_(unlink_and_freep) char *tmp_path = NULL;
+static int append_dmesg(PStoreEntry *pe, const char *subdir1, const char *subdir2) {
+ /* Append dmesg chunk to end, create if needed */
_cleanup_free_ char *ofd_path = NULL;
_cleanup_close_ int ofd = -1;
ssize_t wr;
- int r;
- if (size == 0)
- return 0;
+ assert(pe);
- assert(dmesg);
+ if (pe->content_size == 0)
+ return 0;
- ofd_path = path_join(arg_archivedir, id, "dmesg.txt");
+ ofd_path = path_join(arg_archivedir, subdir1, subdir2, "dmesg.txt");
if (!ofd_path)
return log_oom();
- ofd = open_tmpfile_linkable(ofd_path, O_CLOEXEC|O_CREAT|O_TRUNC|O_WRONLY, &tmp_path);
+ ofd = open(ofd_path, O_CREAT|O_NOFOLLOW|O_NOCTTY|O_CLOEXEC|O_APPEND|O_WRONLY, 0640);
if (ofd < 0)
- return log_error_errno(ofd, "Failed to open temporary file %s: %m", ofd_path);
- wr = write(ofd, dmesg, size);
+ return log_error_errno(ofd, "Failed to open file %s: %m", ofd_path);
+ wr = write(ofd, pe->content, pe->content_size);
if (wr < 0)
return log_error_errno(errno, "Failed to store dmesg to %s: %m", ofd_path);
- if (wr != (ssize_t)size)
- return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to store dmesg to %s. %zu bytes are lost.", ofd_path, size - wr);
- r = link_tmpfile(ofd, tmp_path, ofd_path);
- if (r < 0)
- return log_error_errno(r, "Failed to write temporary file %s: %m", ofd_path);
- tmp_path = mfree(tmp_path);
+ if ((size_t)wr != pe->content_size)
+ return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to store dmesg to %s. %zu bytes are lost.", ofd_path, pe->content_size - wr);
return 0;
}
-static void process_dmesg_files(PStoreList *list) {
+static int process_dmesg_files(PStoreList *list) {
/* Move files, reconstruct dmesg.txt */
- _cleanup_free_ char *dmesg = NULL, *dmesg_id = NULL;
- size_t dmesg_size = 0;
- bool dmesg_bad = false;
- PStoreEntry *pe;
+ _cleanup_free_ char *erst_subdir = NULL;
+ uint64_t last_record_id = 0;
+
+ /* When dmesg is written into pstore, it is done so in small chunks, whatever the exchange buffer
+ * size is with the underlying pstore backend (ie. EFI may be ~2KiB), which means an example
+ * pstore with approximately 64KB of storage may have up to roughly 32 dmesg files, some likely
+ * related.
+ *
+ * Here we look at the dmesg filename and try to discern if files are part of a related group,
+ * meaning the same original dmesg.
+ *
+ * The dmesg- filename contains the backend-type and the Common Platform Error Record, CPER,
+ * record id, a 64-bit number.
+ *
+ * Files are processed in reverse lexigraphical order so as to properly reconstruct original dmesg.*/
- /* Handle each dmesg file: files processed in reverse
- * order so as to properly reconstruct original dmesg */
for (size_t n = list->n_entries; n > 0; n--) {
- bool move_file_and_continue = false;
- _cleanup_free_ char *pe_id = NULL;
+ PStoreEntry *pe;
char *p;
- size_t plen;
pe = &list->entries[n-1];
if (pe->handled)
continue;
- if (!startswith(pe->dirent.d_name, "dmesg-"))
- continue;
-
if (endswith(pe->dirent.d_name, ".enc.z")) /* indicates a problem */
- move_file_and_continue = true;
- p = strrchr(pe->dirent.d_name, '-');
- if (!p)
- move_file_and_continue = true;
-
- if (move_file_and_continue) {
- /* A dmesg file on which we do NO additional processing */
- (void) move_file(pe, NULL);
- continue;
- }
-
- /* See if this file is one of a related group of files
- * in order to reconstruct dmesg */
-
- /* When dmesg is written into pstore, it is done so in
- * small chunks, whatever the exchange buffer size is
- * with the underlying pstore backend (ie. EFI may be
- * ~2KiB), which means an example pstore with approximately
- * 64KB of storage may have up to roughly 32 dmesg files
- * that could be related, depending upon the size of the
- * original dmesg.
- *
- * Here we look at the dmesg filename and try to discern
- * if files are part of a related group, meaning the same
- * original dmesg.
- *
- * The two known pstore backends are EFI and ERST. These
- * backends store data in the Common Platform Error
- * Record, CPER, format. The dmesg- filename contains the
- * CPER record id, a 64bit number (in decimal notation).
- * In Linux, the record id is encoded with two digits for
- * the dmesg part (chunk) number and 3 digits for the
- * count number. So allowing an additional digit to
- * compensate for advancing time, this code ignores the
- * last six digits of the filename in determining the
- * record id.
- *
- * For the EFI backend, the record id encodes an id in the
- * upper 32 bits, and a timestamp in the lower 32-bits.
- * So ignoring the least significant 6 digits has proven
- * to generally identify related dmesg entries. */
-#define PSTORE_FILENAME_IGNORE 6
-
- /* determine common portion of record id */
- ++p; /* move beyond dmesg- */
- plen = strlen(p);
- if (plen > PSTORE_FILENAME_IGNORE) {
- pe_id = memdup_suffix0(p, plen - PSTORE_FILENAME_IGNORE);
- if (!pe_id) {
- log_oom();
- return;
- }
- } else
- pe_id = mfree(pe_id);
-
- /* Now move file from pstore to archive storage */
- move_file(pe, pe_id);
-
- if (dmesg_bad)
continue;
-
- /* If the current record id is NOT the same as the
- * previous record id, then start a new dmesg.txt file */
- if (!streq_ptr(pe_id, dmesg_id)) {
- /* Encountered a new dmesg group, close out old one, open new one */
- (void) write_dmesg(dmesg, dmesg_size, dmesg_id);
- dmesg_size = 0;
-
- /* now point dmesg_id to storage of pe_id */
- free_and_replace(dmesg_id, pe_id);
- }
-
- /* Reconstruction of dmesg is done as a useful courtesy: do not fail, but don't write garbled
- * output either. */
- size_t needed = strlen(pe->dirent.d_name) + strlen(":\n") + pe->content_size + 1;
- if (!GREEDY_REALLOC(dmesg, dmesg_size + needed)) {
- log_oom();
- dmesg_bad = true;
+ if (!startswith(pe->dirent.d_name, "dmesg-"))
continue;
- }
-
- dmesg_size += sprintf(dmesg + dmesg_size, "%s:\n", pe->dirent.d_name);
- if (pe->content) {
- memcpy(dmesg + dmesg_size, pe->content, pe->content_size);
- dmesg_size += pe->content_size;
- }
- pe_id = mfree(pe_id);
+ if ((p = startswith(pe->dirent.d_name, "dmesg-efi-"))) {
+ /* For the EFI backend, the 3 least significant digits of record id encodes a
+ * "count" number, the next 2 least significant digits for the dmesg part
+ * (chunk) number, and the remaining digits as the timestamp. See
+ * linux/drivers/firmware/efi/efi-pstore.c in efi_pstore_write(). */
+ _cleanup_free_ char *subdir1 = NULL, *subdir2 = NULL;
+ size_t plen = strlen(p);
+
+ if (plen < 6)
+ continue;
+
+ /* Extract base record id */
+ subdir1 = strndup(p, plen - 5);
+ if (!subdir1)
+ return log_oom();
+ /* Extract "count" field */
+ subdir2 = strndup(p + plen - 3, 3);
+ if (!subdir2)
+ return log_oom();
+
+ /* Now move file from pstore to archive storage */
+ (void) move_file(pe, subdir1, subdir2);
+
+ /* Append to the dmesg */
+ (void) append_dmesg(pe, subdir1, subdir2);
+ } else if ((p = startswith(pe->dirent.d_name, "dmesg-erst-"))) {
+ /* For the ERST backend, the record is a monotonically increasing number, seeded as
+ * a timestamp. See linux/drivers/acpi/apei/erst.c in erst_writer(). */
+ uint64_t record_id;
+
+ if (safe_atou64(p, &record_id) < 0)
+ continue;
+ if (last_record_id - 1 != record_id)
+ /* A discontinuity in the number has been detected, this current record id
+ * will become the directory name for all pieces of the dmesg in this
+ * series. */
+ if (free_and_strdup(&erst_subdir, p) < 0)
+ return log_oom();
+
+ /* Now move file from pstore to archive storage */
+ (void) move_file(pe, erst_subdir, NULL);
+
+ /* Append to the dmesg */
+ (void) append_dmesg(pe, erst_subdir, NULL);
+
+ /* Update, but keep erst_subdir for next file */
+ last_record_id = record_id;
+ } else
+ log_debug("Unknown backend, ignoring \"%s\".", pe->dirent.d_name);
}
-
- if (!dmesg_bad)
- (void) write_dmesg(dmesg, dmesg_size, dmesg_id);
+ return 0;
}
static int list_files(PStoreList *list, const char *sourcepath) {
@@ -394,11 +356,11 @@ static int run(int argc, char *argv[]) {
typesafe_qsort(list.entries, list.n_entries, compare_pstore_entries);
/* Process known file types */
- process_dmesg_files(&list);
+ (void) process_dmesg_files(&list);
/* Move left over files out of pstore */
for (size_t n = 0; n < list.n_entries; n++)
- move_file(&list.entries[n], NULL);
+ (void) move_file(&list.entries[n], NULL, NULL);
return 0;
}
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