src/port/win32env.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * win32env.c
   4  *        putenv(), setenv(), and unsetenv() for win32.
   5  *
   6  * These functions update both the process environment and caches in
   7  * (potentially multiple) C run-time library (CRT) versions.
   8  *
   9  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
  10  * Portions Copyright (c) 1994, Regents of the University of California
  11  *
  12  *
  13  * IDENTIFICATION
  14  *        src/port/win32env.c
  15  *
  16  *-------------------------------------------------------------------------
  17  */
  18
  19 #include "c.h"
  20
  21
  22 /*
  23  * Note that unlike POSIX putenv(), this doesn't use the passed-in string
  24  * as permanent storage.
  25  */
  26 int
  27 pgwin32_putenv(const char *envval)
  28 {
  29         char       *envcpy;
  30         char       *cp;
  31         typedef int (_cdecl * PUTENVPROC) (const char *);
  32         static const char *const modulenames[] = {
  33                 "msvcrt",                               /* Visual Studio 6.0 / MinGW */
  34                 "msvcrtd",
  35                 "msvcr70",                              /* Visual Studio 2002 */
  36                 "msvcr70d",
  37                 "msvcr71",                              /* Visual Studio 2003 */
  38                 "msvcr71d",
  39                 "msvcr80",                              /* Visual Studio 2005 */
  40                 "msvcr80d",
  41                 "msvcr90",                              /* Visual Studio 2008 */
  42                 "msvcr90d",
  43                 "msvcr100",                             /* Visual Studio 2010 */
  44                 "msvcr100d",
  45                 "msvcr110",                             /* Visual Studio 2012 */
  46                 "msvcr110d",
  47                 "msvcr120",                             /* Visual Studio 2013 */
  48                 "msvcr120d",
  49                 "ucrtbase",                             /* Visual Studio 2015 and later */
  50                 "ucrtbased",
  51                 NULL
  52         };
  53         int                     i;
  54
  55         /*
  56          * Update process environment, making this change visible to child
  57          * processes and to CRTs initializing in the future.  Do this before the
  58          * _putenv() loop, for the benefit of any CRT that initializes during this
  59          * pgwin32_putenv() execution, after the loop checks that CRT.
  60          *
  61          * Need a copy of the string so we can modify it.
  62          */
  63         envcpy = strdup(envval);
  64         if (!envcpy)
  65                 return -1;
  66         cp = strchr(envcpy, '=');
  67         if (cp == NULL)
  68         {
  69                 free(envcpy);
  70                 return -1;
  71         }
  72         *cp = '\0';
  73         cp++;
  74         if (*cp)
  75         {
  76                 /*
  77                  * Only call SetEnvironmentVariable() when we are adding a variable,
  78                  * not when removing it. Calling it on both crashes on at least
  79                  * certain versions of MinGW.
  80                  */
  81                 if (!SetEnvironmentVariable(envcpy, cp))
  82                 {
  83                         free(envcpy);
  84                         return -1;
  85                 }
  86         }
  87         free(envcpy);
  88
  89         /*
  90          * Each CRT has its own _putenv() symbol and copy of the environment.
  91          * Update the environment in each CRT module currently loaded, so every
  92          * third-party library sees this change regardless of the CRT it links
  93          * against.  Addresses within these modules may become invalid the moment
  94          * we call FreeLibrary(), so don't cache them.
  95          */
  96         for (i = 0; modulenames[i]; i++)
  97         {
  98                 HMODULE         hmodule = NULL;
  99                 BOOL            res = GetModuleHandleEx(0, modulenames[i], &hmodule);
 100
 101                 if (res != 0 && hmodule != NULL)
 102                 {
 103                         PUTENVPROC      putenvFunc;
 104
 105                         putenvFunc = (PUTENVPROC) (pg_funcptr_t) GetProcAddress(hmodule, "_putenv");
 106                         if (putenvFunc)
 107                                 putenvFunc(envval);
 108                         FreeLibrary(hmodule);
 109                 }
 110         }
 111
 112         /*
 113          * Finally, update our "own" cache.  This is redundant with the loop
 114          * above, except when PostgreSQL itself links to a CRT not listed above.
 115          * Ideally, the loop does visit all possible CRTs, making this redundant.
 116          */
 117         return _putenv(envval);
 118 }
 119
 120 int
 121 pgwin32_setenv(const char *name, const char *value, int overwrite)
 122 {
 123         int                     res;
 124         char       *envstr;
 125
 126         /* Error conditions, per POSIX */
 127         if (name == NULL || name[0] == '\0' || strchr(name, '=') != NULL ||
 128                 value == NULL)
 129         {
 130                 errno = EINVAL;
 131                 return -1;
 132         }
 133
 134         /* No work if variable exists and we're not to replace it */
 135         if (overwrite == 0 && getenv(name) != NULL)
 136                 return 0;
 137
 138         envstr = (char *) malloc(strlen(name) + strlen(value) + 2);
 139         if (!envstr)                            /* not much we can do if no memory */
 140                 return -1;
 141
 142         sprintf(envstr, "%s=%s", name, value);
 143
 144         res = pgwin32_putenv(envstr);
 145         free(envstr);
 146         return res;
 147 }
 148
 149 int
 150 pgwin32_unsetenv(const char *name)
 151 {
 152         int                     res;
 153         char       *envbuf;
 154
 155         envbuf = (char *) malloc(strlen(name) + 2);
 156         if (!envbuf)
 157                 return -1;
 158
 159         sprintf(envbuf, "%s=", name);
 160         res = pgwin32_putenv(envbuf);
 161         free(envbuf);
 162         return res;
 163 }