win32: make stat(2) try to identify the owner of files

Extend stat(2) so it tries to determine whether a file belongs to
the current user or not.  If not it's said to belong to root.

4 files changed, 76 insertions, 9 deletions

diff --git a/Config.in b/Config.in
index cd0cab412..2b4b81515 100644
--- a/Config.in
+++ b/Config.in
@@ -465,6 +465,14 @@ config FEATURE_EXTRA_FILE_DATA
         permits extra features such as warning of attempts to copy a file
         onto itself or to store a tar archive in itself.
 
+config FEATURE_IDENTIFY_OWNER
+        bool "Check whether files belong to current user (0.6 kb)"
+        default y
+        depends on FEATURE_EXTRA_FILE_DATA
+        help
+        Try to determine if files belong to the current user.  If they don't
+        they're listed as belonging to root.
+
 comment 'Build Options'
 
 config STATIC
diff --git a/configs/mingw32_defconfig b/configs/mingw32_defconfig
index cc0cf0359..c30ffa1b5 100644
--- a/configs/mingw32_defconfig
+++ b/configs/mingw32_defconfig
@@ -1,7 +1,7 @@
 #
 # Automatically generated make config: don't edit
 # Busybox version: 1.31.0.git
-# Tue Feb 12 08:23:28 2019
+# Fri Mar  1 08:50:17 2019
 #
 CONFIG_HAVE_DOT_CONFIG=y
 # CONFIG_PLATFORM_POSIX is not set
@@ -49,6 +49,7 @@ CONFIG_FEATURE_ICON=y
 CONFIG_FEATURE_ICON_ALL=y
 CONFIG_FEATURE_EURO=y
 CONFIG_FEATURE_EXTRA_FILE_DATA=y
+CONFIG_FEATURE_IDENTIFY_OWNER=y
 
 #
 # Build Options
diff --git a/configs/mingw64_defconfig b/configs/mingw64_defconfig
index 541090e2a..46cb6941f 100644
--- a/configs/mingw64_defconfig
+++ b/configs/mingw64_defconfig
@@ -1,7 +1,7 @@
 #
 # Automatically generated make config: don't edit
 # Busybox version: 1.31.0.git
-# Tue Feb 12 08:23:28 2019
+# Fri Mar  1 08:50:17 2019
 #
 CONFIG_HAVE_DOT_CONFIG=y
 # CONFIG_PLATFORM_POSIX is not set
@@ -49,6 +49,7 @@ CONFIG_FEATURE_ICON=y
 CONFIG_FEATURE_ICON_ALL=y
 CONFIG_FEATURE_EURO=y
 CONFIG_FEATURE_EXTRA_FILE_DATA=y
+CONFIG_FEATURE_IDENTIFY_OWNER=y
 
 #
 # Build Options
diff --git a/win32/mingw.c b/win32/mingw.c
index f748d2d09..d7bdc10f6 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -1,6 +1,9 @@
 #include "libbb.h"
 #include <userenv.h>
 #include "lazyload.h"
+#if ENABLE_FEATURE_IDENTIFY_OWNER
+#include <aclapi.h>
+#endif
 
 #if defined(__MINGW64_VERSION_MAJOR)
 #if ENABLE_GLOBBING
@@ -387,6 +390,47 @@ static int has_exec_format(const char *name)
         return 0;
 }
 
+#if ENABLE_FEATURE_IDENTIFY_OWNER
+static int file_belongs_to_me(HANDLE fh)
+{
+        PSID pSidOwner;
+        PSECURITY_DESCRIPTOR pSD;
+        static PTOKEN_USER user = NULL;
+        static int initialised = 0;
+        int equal;
+
+        /*  get SID of current user */
+        if (!initialised) {
+                HANDLE token;
+                DWORD ret = 0;
+
+                initialised = 1;
+                if (OpenThreadToken(GetCurrentThread(), TOKEN_QUERY, TRUE, &token) ||
+                                OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &token)) {
+                        GetTokenInformation(token, TokenUser, NULL, 0, &ret);
+                        if (ret <= 0 || (user=malloc(ret)) == NULL ||
+                                        !GetTokenInformation(token, TokenUser, user, ret, &ret)) {
+                                free(user);
+                                user = NULL;
+                        }
+                        CloseHandle(token);
+                }
+        }
+
+        if (user == NULL)
+                return TRUE;
+
+        /* get SID of file's owner */
+        if (GetSecurityInfo(fh, SE_FILE_OBJECT, OWNER_SECURITY_INFORMATION,
+                        &pSidOwner, NULL, NULL, NULL, &pSD) != ERROR_SUCCESS)
+                return FALSE;
+
+        equal = EqualSid(pSidOwner, user->User.Sid);
+        LocalFree(pSD);
+        return equal;
+}
+#endif
+
 /* We keep the do_lstat code in a separate function to avoid recursion.
  * When a path ends with a slash, the stat will fail with ENOENT. In
  * this case, we strip the trailing slashes and stat again.
@@ -439,21 +483,34 @@ static int do_lstat(int follow, const char *file_name, struct mingw_stat *buf)
                 }
 
 #if ENABLE_FEATURE_EXTRA_FILE_DATA
+#if ENABLE_FEATURE_IDENTIFY_OWNER
+                fh = CreateFile(file_name, READ_CONTROL, 0, NULL,
+                                                        OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+#else
                 fh = CreateFile(file_name, 0, 0, NULL, OPEN_EXISTING,
                                                         FILE_FLAG_BACKUP_SEMANTICS, NULL);
-                if (fh != INVALID_HANDLE_VALUE &&
-                                GetFileInformationByHandle(fh, &hdata)) {
-                        buf->st_dev = hdata.dwVolumeSerialNumber;
-                        buf->st_ino = hdata.nFileIndexLow |
-                                                        (((ino_t)hdata.nFileIndexHigh)<<32);
-                        buf->st_nlink = S_ISDIR(buf->st_mode) ? 2 : hdata.nNumberOfLinks;
+#endif
+                if (fh != INVALID_HANDLE_VALUE) {
+                        if (GetFileInformationByHandle(fh, &hdata)) {
+                                buf->st_dev = hdata.dwVolumeSerialNumber;
+                                buf->st_ino = hdata.nFileIndexLow |
+                                                (((ino_t)hdata.nFileIndexHigh)<<32);
+                                buf->st_nlink = S_ISDIR(buf->st_mode) ? 2 :
+                                                        hdata.nNumberOfLinks;
+                        }
+#if ENABLE_FEATURE_IDENTIFY_OWNER
+                        if (!file_belongs_to_me(fh)) {
+                                buf->st_uid = 0;
+                                buf->st_gid = 0;
+                        }
+#endif
+                        CloseHandle(fh);
                 }
                 else {
                         buf->st_uid = 0;
                         buf->st_gid = 0;
                         buf->st_mode &= ~(S_IROTH|S_IWOTH|S_IXOTH);
                 }
-                CloseHandle(fh);
 #endif
 
                 /*