On 8/16/21 4:59 PM, Tomasz Kramkowski via Grub-devel wrote:
20def1a3c introduced support for file modification times to allow
comparison of file ages on EFI systems. This patch used
grub_datetime2unixtime which uses a 32 bit unix timestamp and as a
result did not allow the full range of times that FAT timestamps do.
In some situations a file with a timestamp of 1970-01-01 gets
transferred to a FAT partition, the timestamp ends up as 2098-01-01
because of FAT's use of the 1980-01-01 DOS epoch and lack of negative
timestamps.
Since 2098 is after 2038, this date cannot fit in a 32 bit timestamp.
Ideally grub should use 64 bit timestamps but I have not investigated
what kind of work would be required to support this.
Field mtime of struct grub_dirhook_info is already 64bit. See commit
81f1962393f4 ("fs: Use 64-bit type for filesystem timestamp"). Function
grub_datetime2unixtime needs to be fixed: The 2037 check should be
removed and the code has to be adjusted to correctly treat year 2100.
grub_unixtime2datetime already handles 64bit timestamps but ignores that
year 2100 is not a leap year:
grub_unixtime2datetime(4107585600) = 2100-02-29 12:00:00
This fixes bug #60565.
Reported-by: Naïm Favier <n+g...@monade.li>
Tested-by: Naïm Favier <n+g...@monade.li>
Signed-off-by: Tomasz Kramkowski <t...@the-tk.com>
---
grub-core/fs/fat.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/grub-core/fs/fat.c b/grub-core/fs/fat.c
index dd82e4ee3..34589d7db 100644
--- a/grub-core/fs/fat.c
+++ b/grub-core/fs/fat.c
@@ -1020,16 +1020,17 @@ grub_fat_dir (grub_device_t device, const char *path,
grub_fs_dir_hook_t hook,
info.mtimeset = grub_exfat_timestamp (grub_le_to_cpu32
(ctxt.entry.type_specific.file.m_time),
ctxt.entry.type_specific.file.m_time_tenth,
&info.mtime);
+ if (info.mtimeset == 0)
+ grub_dprintf("exfat", "invalid modification timestamp for %s\n", path);
According to the commit message there is nothing invalid about the
modification timestamp. It is a GRUB deficiency that it cannot handle
the same date range as FAT and exFAT.
So the message could be:
"GRUB cannot handle the modification timestamp for %s".
#else
if (ctxt.dir.attr & GRUB_FAT_ATTR_VOLUME_ID)
continue;
info.mtimeset = grub_fat_timestamp (grub_le_to_cpu16 (ctxt.dir.w_time),
grub_le_to_cpu16 (ctxt.dir.w_date),
&info.mtime);
-#endif
if (info.mtimeset == 0)
- grub_error (GRUB_ERR_OUT_OF_RANGE,
- "invalid modification timestamp for %s", path);
+ grub_dprintf("fat", "invalid modification timestamp for %s\n", path);
I suggest to use grub_error() for both messages.
Best regards
Heinrich
+#endif
if (hook (ctxt.filename, &info, hook_data))
break;
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