Use dynamically-sized buffers in pgwin32_is_service().

Magnus Hagander

diff --git a/src/backend/port/win32/security.c b/src/backend/port/win32/security.c
index a81a925b0e033871167a6fd14b90aae6de475ffa..963a112249755ccd0e970d69f89d59457ddb3dee 100644 (file)
--- a/src/backend/port/win32/security.c
+++ b/src/backend/port/win32/security.c
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/port/win32/security.c,v 1.6 2004/11/09 13:01:25 petere Exp $
+ *       $PostgreSQL: pgsql/src/backend/port/win32/security.c,v 1.7 2004/11/16 19:52:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -14,6 +14,10 @@
 #include "postgres.h"
 
 
+static BOOL pgwin32_get_dynamic_tokeninfo(HANDLE token,
+                                                                                 TOKEN_INFORMATION_CLASS class, char **InfoBuffer,
+                                                                                 char *errbuf, int errsize);
+
 /*
  * Returns nonzero if the current user has administrative privileges,
  * or zero if not.
@@ -26,8 +30,8 @@ pgwin32_is_admin(void)
 {
        HANDLE          AccessToken;
        char       *InfoBuffer = NULL;
+       char        errbuf[256];
        PTOKEN_GROUPS Groups;
-       DWORD           InfoBufferSize;
        PSID            AdministratorsSid;
        PSID            PowerUsersSid;
        SID_IDENTIFIER_AUTHORITY NtAuthority = {SECURITY_NT_AUTHORITY};
@@ -41,36 +45,15 @@ pgwin32_is_admin(void)
                exit(1);
        }
 
-       if (GetTokenInformation(AccessToken, TokenGroups, NULL, 0, &InfoBufferSize))
+       if (!pgwin32_get_dynamic_tokeninfo(AccessToken, TokenGroups,
+                                                                          &InfoBuffer, errbuf, sizeof(errbuf)))
        {
-               write_stderr("could not get token information: got zero size\n");
+               write_stderr(errbuf);
                exit(1);
        }
 
-       if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
-       {
-               write_stderr("could not get token information: error code %d\n",
-                                        (int) GetLastError());
-               exit(1);
-       }
-
-       InfoBuffer = malloc(InfoBufferSize);
-       if (!InfoBuffer)
-       {
-               write_stderr("could not allocate %i bytes for token information\n",
-                                        (int) InfoBufferSize);
-               exit(1);
-       }
        Groups = (PTOKEN_GROUPS) InfoBuffer;
 
-       if (!GetTokenInformation(AccessToken, TokenGroups, InfoBuffer,
-                                                        InfoBufferSize, &InfoBufferSize))
-       {
-               write_stderr("could not get token information: error code %d\n",
-                                        (int) GetLastError());
-               exit(1);
-       }
-
        CloseHandle(AccessToken);
 
        if (!AllocateAndInitializeSid(&NtAuthority, 2,
@@ -131,10 +114,10 @@ pgwin32_is_service(void)
 {
        static int      _is_service = -1;
        HANDLE          AccessToken;
-       UCHAR           InfoBuffer[1024];
-       PTOKEN_GROUPS Groups = (PTOKEN_GROUPS) InfoBuffer;
-       PTOKEN_USER User = (PTOKEN_USER) InfoBuffer;
-       DWORD           InfoBufferSize;
+       char       *InfoBuffer = NULL;
+       char        errbuf[256];
+       PTOKEN_GROUPS Groups;
+       PTOKEN_USER User;
        PSID            ServiceSid;
        PSID            LocalSystemSid;
        SID_IDENTIFIER_AUTHORITY NtAuthority = {SECURITY_NT_AUTHORITY};
@@ -152,13 +135,15 @@ pgwin32_is_service(void)
        }
 
        /* First check for local system */
-       if (!GetTokenInformation(AccessToken, TokenUser, InfoBuffer, 1024, &InfoBufferSize))
+       if (!pgwin32_get_dynamic_tokeninfo(AccessToken, TokenUser, &InfoBuffer,
+                                                                          errbuf, sizeof(errbuf)))
        {
-               fprintf(stderr, "could not get token information: error code %d\n",
-                               (int) GetLastError());
+               fprintf(stderr,errbuf);
                return -1;
        }
 
+       User = (PTOKEN_USER) InfoBuffer;
+
        if (!AllocateAndInitializeSid(&NtAuthority, 1,
                                                  SECURITY_LOCAL_SYSTEM_RID, 0, 0, 0, 0, 0, 0, 0,
                                                                  &LocalSystemSid))
@@ -171,26 +156,31 @@ pgwin32_is_service(void)
        if (EqualSid(LocalSystemSid, User->User.Sid))
        {
                FreeSid(LocalSystemSid);
+               free(InfoBuffer);
                CloseHandle(AccessToken);
                _is_service = 1;
                return _is_service;
        }
 
        FreeSid(LocalSystemSid);
+       free(InfoBuffer);
 
        /* Now check for group SID */
-       if (!GetTokenInformation(AccessToken, TokenGroups, InfoBuffer, 1024, &InfoBufferSize))
+       if (!pgwin32_get_dynamic_tokeninfo(AccessToken, TokenGroups, &InfoBuffer,
+                                                                          errbuf, sizeof(errbuf)))
        {
-               fprintf(stderr, "could not get token information: error code %d\n",
-                               (int) GetLastError());
+               fprintf(stderr,errbuf);
                return -1;
        }
 
+       Groups = (PTOKEN_GROUPS) InfoBuffer;
+
        if (!AllocateAndInitializeSid(&NtAuthority, 1,
                                                           SECURITY_SERVICE_RID, 0, 0, 0, 0, 0, 0, 0,
                                                                  &ServiceSid))
        {
                fprintf(stderr, "could not get SID for service group\n");
+               free(InfoBuffer);
                CloseHandle(AccessToken);
                return -1;
        }
@@ -205,9 +195,54 @@ pgwin32_is_service(void)
                }
        }
 
+       free(InfoBuffer);
        FreeSid(ServiceSid);
 
        CloseHandle(AccessToken);
 
        return _is_service;
 }
+
+
+/*
+ * Call GetTokenInformation() on a token and return a dynamically sized
+ * buffer with the information in it. This buffer must be free():d by
+ * the calling function!
+ */
+static BOOL
+pgwin32_get_dynamic_tokeninfo(HANDLE token, TOKEN_INFORMATION_CLASS class,
+                                                         char **InfoBuffer, char *errbuf, int errsize)
+{
+       DWORD InfoBufferSize;
+
+       if (GetTokenInformation(token, class, NULL, 0, &InfoBufferSize))
+       {
+               snprintf(errbuf,errsize,"could not get token information: got zero size\n");
+               return FALSE;
+       }
+
+       if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+       {
+               snprintf(errbuf,errsize,"could not get token information: error code %d\n",
+                                (int) GetLastError());
+               return FALSE;
+       }
+
+       *InfoBuffer = malloc(InfoBufferSize);
+       if (*InfoBuffer == NULL)
+       {
+               snprintf(errbuf,errsize,"could not allocate %d bytes for token information\n",
+                                (int) InfoBufferSize);
+               return FALSE;
+       }
+
+       if (!GetTokenInformation(token, class, *InfoBuffer, 
+                                                        InfoBufferSize, &InfoBufferSize))
+       {
+               snprintf(errbuf,errsize,"could not get token information: error code %d\n",
+                                (int) GetLastError());
+               return FALSE;
+       }
+       
+       return TRUE;
+}