\nThe first problem with discussing file last-access time is\nagreeing what you mean by a file’s last-access time.\n<\/p>\n
\nThe file system folks have one definition of the file last-access time,\nnamely the time the file was most recently opened and either read from\nor written to.\nThis is the value retrieved by functions like\n \nThe problem with this definition is that it doesn’t match the\nintuitive definition of last-access time, which is\n“the last time I<\/i> accessed the file,”\nemphasis on the I<\/i>.\nIn fact, the intuitive definition of access is more specific:\nIt’s\n“the last time I opened, modified, printed, or otherwise performed\nsome sort of purposeful action on the file.”\n<\/p>\n \nThis discrepancy between the file system definition and the intuitive\ndefinition means that a lot of operations trigger a file system access\nbut shouldn’t count as an access from the user interface point of view.\nHere are some examples:\n<\/p>\n \nWhenever some shell extension violates this rule,\nthe shell team gets a bug report from some customer saying,\n“The last-access time shown in Explorer is wrong.\nA document which hasn’t been accessed in months shows a last-access\ntime of today.\nAfter closer investigation, we found that the last-access time updates\nwhenever we\ninsert seemingly-innocuous operation here<\/i>.”\n<\/p>\n \nIf you’re writing a program which needs\nto access the file contents but you not want to update\nthe last-access time, you can use the \nAs the documentation notes, you have to call this function\nimmediately after opening the file.\n<\/p>\n \nGoing back to that linked comment:\nThe reason why viewing the Summary tab causes the last-access time\nto be updated is that the Summary tab retrieves its information\nby calling GetFileAttributesEx<\/code>,\nGetFileTime<\/code>,\nand FindFirstFile<\/code>.\n<\/p>\n\n
SetFileTime<\/code>\nfunction\n\nwith the special value 0xFFFFFFFF<\/code> in both members\nof the FILETIME<\/code> structure passed\nas the last-access time<\/a>.\nThis magic value means “do not change the last-access time\neven though I’m accessing the file.”\n<\/p>\n\nBOOL DoNotUpdateLastAccessTime(HANDLE hFile)\n{\n static const FILETIME ftLeaveUnchanged = { 0xFFFFFFFF, 0xFFFFFFFF };\n return SetFileTime(hFile, NULL, &ftLeaveUnchanged, NULL);\n}\n<\/pre>\nStgOpenStorage<\/code>, and there’s no way to tell\nthat function,\n“Hey, when you open the file in order to see if it has any\ndocument properties, do that\nDoNotUpdateLastAccessTime<\/code>\nthing so you don’t update the last access time.”\n<\/p>\n