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;
+}