Suppress MSan false positives by wrapping *stat functions

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    • Storage Engines
    • 2023-07-25 Absolute unit, StorEng - 2023-08-08, ASeasonTooMany-2023-08-22, 2024-06-11 - Dinosaurs go rawr, 2024-06-25 - Climbing BTrees
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      MSan reports the use-of-uninitialized-value when writing to the lock file in wiredtiger_open. This appears when running any test after building with MSan on Ubuntu 22.04. It hasn't occurred on our evergreen testing as we don't have any tasks running on 22.04 yet.

      ==299140==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x7fa9f6a02aba in __conn_single /home/ubuntu/wiredtiger/src/conn/conn_api.c:1858:13
    #1 0x7fa9f6989472 in wiredtiger_open /home/ubuntu/wiredtiger/src/conn/conn_api.c:2816:5
    #2 0x5f3716 in create_database /home/ubuntu/wiredtiger/test/format/wts.c:436:5
    #3 0x608e97 in wts_create_database /home/ubuntu/wiredtiger/test/format/wts.c:571:5
    #4 0x5ca071 in main /home/ubuntu/wiredtiger/test/format/t.c:352:9
    #5 0x7fa9f5a29d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #6 0x7fa9f5a29e3f in __libc_start_main csu/../csu/libc-start.c:392:3
    #7 0x4215f4 in _start (/home/ubuntu/wiredtiger/build/test/format/t+0x4215f4)

      MSan can provide more information about where the memory was allocated by enabling origins tracking. This can be enabled by adding the -fsanitize-memory-track-origins flag in modes.cmake.

      # MSAN build variant flags.
set(msan_link_flags "-fsanitize=memory" "-fsanitize-memory-track-origins")
set(msan_compiler_c_flag "-fsanitize=memory" "-fno-optimize-sibling-calls" "-fsanitize-memory-track-origins")
set(msan_compiler_cxx_flag "-fsanitize=memory" "-fno-optimize-sibling-calls" "-fsanitize-memory-track-origins")

      Doing so gives the following MSan report after the warning above:

        Uninitialized value was stored to memory at
    #0 0x7fa9f7753974 in __posix_file_size /home/ubuntu/wiredtiger/src/os_posix/os_fs.c:514:16
    #1 0x7fa9f6a1fb59 in __wt_filesize /home/ubuntu/wiredtiger/src/include/os_fhandle_inline.h:138:13
    #2 0x7fa9f6a02969 in __conn_single /home/ubuntu/wiredtiger/src/conn/conn_api.c:1857:9
    #3 0x7fa9f6989472 in wiredtiger_open /home/ubuntu/wiredtiger/src/conn/conn_api.c:2816:5
    #4 0x5f3716 in create_database /home/ubuntu/wiredtiger/test/format/wts.c:436:5
    #5 0x608e97 in wts_create_database /home/ubuntu/wiredtiger/test/format/wts.c:571:5
    #6 0x5ca071 in main /home/ubuntu/wiredtiger/test/format/t.c:352:9
    #7 0x7fa9f5a29d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16

  Uninitialized value was created by an allocation of 'sb' in the stack frame of function '__posix_file_size'
    #0 0x7fa9f7753010 in __posix_file_size /home/ubuntu/wiredtiger/src/os_posix/os_fs.c:502

            Assignee:
            Andrew Morton
            Reporter:
            Sean Watt
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              Created:
              Updated:
              Resolved: