src/port/win32env.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * win32env.c
   4  *        putenv() and unsetenv() for win32, that updates both process
   5  *        environment and the cached versions in (potentially multiple)
   6  *        MSVCRT.
   7  *
   8  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
   9  * Portions Copyright (c) 1994, Regents of the University of California
  10  *
  11  *
  12  * IDENTIFICATION
  13  *        $PostgreSQL$
  14  *
  15  *-------------------------------------------------------------------------
  16  */
  17
  18 #include "c.h"
  19
  20 int
  21 pgwin32_putenv(const char *envval)
  22 {
  23         char       *envcpy;
  24         char       *cp;
  25
  26         /*
  27          * Each version of MSVCRT has its own _putenv() call in the runtime
  28          * library.
  29          *
  30          * If we're in VC 7.0 or later (means != mingw), update in the 6.0
  31          * MSVCRT.DLL environment as well, to work with third party libraries
  32          * linked against it (such as gnuwin32 libraries).
  33          */
  34 #if defined(_MSC_VER) && (_MSC_VER >= 1300)
  35         typedef int (_cdecl * PUTENVPROC) (const char *);
  36         HMODULE         hmodule;
  37         static PUTENVPROC putenvFunc = NULL;
  38         int                     ret;
  39
  40         if (putenvFunc == NULL)
  41         {
  42                 hmodule = GetModuleHandle("msvcrt");
  43                 if (hmodule == NULL)
  44                         return 1;
  45                 putenvFunc = (PUTENVPROC) GetProcAddress(hmodule, "_putenv");
  46                 if (putenvFunc == NULL)
  47                         return 1;
  48         }
  49         ret = putenvFunc(envval);
  50         if (ret != 0)
  51                 return ret;
  52 #endif   /* _MSC_VER >= 1300 */
  53
  54
  55         /*
  56          * Update the process environment - to make modifications visible to child
  57          * processes.
  58          *
  59          * Need a copy of the string so we can modify it.
  60          */
  61         envcpy = strdup(envval);
  62         cp = strchr(envcpy, '=');
  63         if (cp == NULL)
  64                 return -1;
  65         *cp = '\0';
  66         cp++;
  67         if (strlen(cp))
  68         {
  69                 /*
  70                  * Only call SetEnvironmentVariable() when we are adding a variable,
  71                  * not when removing it. Calling it on both crashes on at least
  72                  * certain versions of MingW.
  73                  */
  74                 if (!SetEnvironmentVariable(envcpy, cp))
  75                 {
  76                         free(envcpy);
  77                         return -1;
  78                 }
  79         }
  80         free(envcpy);
  81
  82         /* Finally, update our "own" cache */
  83         return _putenv(envval);
  84 }
  85
  86 void
  87 pgwin32_unsetenv(const char *name)
  88 {
  89         char       *envbuf;
  90
  91         envbuf = (char *) malloc(strlen(name) + 2);
  92         if (!envbuf)
  93                 return;
  94
  95         sprintf(envbuf, "%s=", name);
  96         pgwin32_putenv(envbuf);
  97         free(envbuf);
  98 }