https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=5036d447c54c41968ccd19a6294f69e4085d0143
commit 5036d447c54c41968ccd19a6294f69e4085d0143 Author: Corinna Vinschen <[email protected]> Date: Thu Aug 19 21:17:11 2021 +0200 Cygwin: fhandler_procsys::readdir: fix NtQueryDirectoryObject usage As outlined in the previous patch, the non-atomicity of iterating over a directory in the NT namespace via NtQueryDirectoryObject one entry each, results in potential duplication of directory entries. Fix this for fhandler_procsys::readdir as well by fetching the entire dir inside fhandler_procsys::opendir, storing it in a buffer, and just return buffer content from fhandler_procsys::readdir. Fixes: 43f65cdd7dae ("fhandler_procsys.cc: New file.") Signed-off-by: Corinna Vinschen <[email protected]> Diff: --- winsup/cygwin/fhandler_procsys.cc | 82 +++++++++++++++++++++++++++------------ 1 file changed, 58 insertions(+), 24 deletions(-) diff --git a/winsup/cygwin/fhandler_procsys.cc b/winsup/cygwin/fhandler_procsys.cc index f8abbe7c0..02741d0e9 100644 --- a/winsup/cygwin/fhandler_procsys.cc +++ b/winsup/cygwin/fhandler_procsys.cc @@ -309,59 +309,88 @@ fhandler_procsys::opendir (int fd) UNICODE_STRING path; OBJECT_ATTRIBUTES attr; NTSTATUS status; - HANDLE h; + HANDLE dir_hdl; DIR *dir; mk_unicode_path (&path); InitializeObjectAttributes (&attr, &path, OBJ_CASE_INSENSITIVE, NULL, NULL); - status = NtOpenDirectoryObject (&h, DIRECTORY_QUERY, &attr); + status = NtOpenDirectoryObject (&dir_hdl, DIRECTORY_QUERY, &attr); if (!NT_SUCCESS (status)) { __seterrno_from_nt_status (status); return NULL; } + + void *dbi_buf = NULL; + ULONG size = 65536; + ULONG context = 0; + int iter; + for (iter = 0; iter <= 3; ++iter) /* Allows for a 512K buffer */ + { + void *new_buf = realloc (dbi_buf, size); + if (!new_buf) + goto err; + dbi_buf = new_buf; + status = NtQueryDirectoryObject (dir_hdl, dbi_buf, size, FALSE, TRUE, + &context, NULL); + if (!NT_SUCCESS (status)) + { + __seterrno_from_nt_status (status); + goto err; + } + if (status != STATUS_MORE_ENTRIES) + break; + size <<= 1; + } + if (iter > 3) + { + __seterrno_from_nt_status (STATUS_INSUFFICIENT_RESOURCES); + goto err; + } if (!(dir = fhandler_virtual::opendir (fd))) - NtClose (h); - else - dir->__handle = h; + goto err; + /* Note that dir->__handle points to the buffer, it does NOT contain an + actual handle! */ + dir->__handle = dbi_buf; + /* dir->__d_internal contains the number of objects returned in the buffer. */ + dir->__d_internal = context; return dir; + +err: + NtClose (dir_hdl); + free (dbi_buf); + return NULL; } int fhandler_procsys::readdir (DIR *dir, dirent *de) { - NTSTATUS status; - struct fdbi - { - DIRECTORY_BASIC_INFORMATION dbi; - WCHAR buf[2][NAME_MAX + 1]; - } f; + PDIRECTORY_BASIC_INFORMATION dbi; int res = EBADF; if (dir->__handle != INVALID_HANDLE_VALUE) { - BOOLEAN restart = dir->__d_position ? FALSE : TRUE; - status = NtQueryDirectoryObject (dir->__handle, &f, sizeof f, TRUE, - restart, (PULONG) &dir->__d_position, - NULL); - if (!NT_SUCCESS (status)) + dbi = ((PDIRECTORY_BASIC_INFORMATION) dir->__handle); + dbi += dir->__d_position; + if (dir->__d_position >= (__int32_t) dir->__d_internal + || dbi->ObjectName.Length == 0) res = ENMFILE; else { - sys_wcstombs (de->d_name, NAME_MAX + 1, f.dbi.ObjectName.Buffer, - f.dbi.ObjectName.Length / sizeof (WCHAR)); + sys_wcstombs (de->d_name, NAME_MAX + 1, dbi->ObjectName.Buffer, + dbi->ObjectName.Length / sizeof (WCHAR)); de->d_ino = hash_path_name (get_ino (), de->d_name); - if (RtlEqualUnicodeString (&f.dbi.ObjectTypeName, &ro_u_natdir, - FALSE)) + if (RtlEqualUnicodeString (&dbi->ObjectTypeName, &ro_u_natdir, FALSE)) de->d_type = DT_DIR; - else if (RtlEqualUnicodeString (&f.dbi.ObjectTypeName, &ro_u_natsyml, + else if (RtlEqualUnicodeString (&dbi->ObjectTypeName, &ro_u_natsyml, FALSE)) de->d_type = DT_LNK; - else if (!RtlEqualUnicodeString (&f.dbi.ObjectTypeName, &ro_u_natdev, + else if (!RtlEqualUnicodeString (&dbi->ObjectTypeName, &ro_u_natdev, FALSE)) de->d_type = DT_CHR; else /* Can't nail down "Device" objects without further testing. */ de->d_type = DT_UNKNOWN; + ++dir->__d_position; res = 0; } } @@ -378,7 +407,12 @@ fhandler_procsys::telldir (DIR *dir) void fhandler_procsys::seekdir (DIR *dir, long pos) { - dir->__d_position = pos; + if (pos < 0) + dir->__d_position = 0; + else if (pos > (__int32_t) dir->__d_internal) + dir->__d_position = (__int32_t) dir->__d_internal; + else + dir->__d_position = pos; } int @@ -386,7 +420,7 @@ fhandler_procsys::closedir (DIR *dir) { if (dir->__handle != INVALID_HANDLE_VALUE) { - NtClose (dir->__handle); + free (dir->__handle); dir->__handle = INVALID_HANDLE_VALUE; } return fhandler_virtual::closedir (dir);
