gdb/putenv.c

   1 /****************************************************************/
   2 /*                                                              */
   3 /*      putenv(3)                                               */
   4 /*                                                              */
   5 /*              Change or add an environment entry              */
   6 /*                                                              */
   7 /****************************************************************/
   8 /*   origination        1987-Oct-7               T. Holm        */
   9 /****************************************************************/
  10
  11 /*
  12 From pacbell!ames!ll-xn!mit-eddie!uw-beaver!ssc-vax!uvicctr!tholm Wed May  4 23:40:52 1988
  13 Path: hoptoad!pacbell!ames!ll-xn!mit-eddie!uw-beaver!ssc-vax!uvicctr!tholm
  14 From: tholm@uvicctr.UUCP (Terrence W. Holm)
  15 Newsgroups: comp.os.minix
  16 Subject: putenv(3)
  17 Message-ID: <395@uvicctr.UUCP>
  18 Date: 5 May 88 06:40:52 GMT
  19 Reply-To: tholm@uvicctr.UUCP (Terrence W. Holm)
  20 Organization: University of Victoria, Victoria B.C. Canada
  21 Lines: 296
  22
  23
  24 EFTH Minix report #2  - May 1988 -  putenv(3)
  25
  26
  27 This is an implementation of putenv(3) that we
  28 wrote for Minix. Please consider this a public
  29 domain program.
  30 */
  31
  32 #include <stdio.h>
  33
  34
  35 #define  PSIZE  sizeof(char *)
  36
  37
  38 extern  char  **environ;
  39
  40
  41 char  *index();
  42 char  *malloc();
  43
  44
  45 /****************************************************************/
  46 /*                                                              */
  47 /*      putenv( entry )                                         */
  48 /*                                                              */
  49 /*              The "entry" should follow the form              */
  50 /*              "NAME=VALUE". This routine will search the      */
  51 /*              user environment for "NAME" and replace its     */
  52 /*              value with "VALUE".                             */
  53 /*                                                              */
  54 /*              Note that "entry" is not copied, it is used     */
  55 /*              as the environment entry. This means that it    */
  56 /*              must not be unallocated or otherwise modifed    */
  57 /*              by the caller, unless it is replaced by a       */
  58 /*              subsequent putenv().                            */
  59 /*                                                              */
  60 /*              If the name is not found in the environment,    */
  61 /*              then a new vector of pointers is allocated,     */
  62 /*              "entry" is put at the end and the global        */
  63 /*              variable "environ" is updated.                  */
  64 /*                                                              */
  65 /*              This function normally returns NULL, but -1     */
  66 /*              is returned if it can not allocate enough       */
  67 /*              space using malloc(3), or "entry" does not      */
  68 /*              contain a '='.                                  */
  69 /*                                                              */
  70 /****************************************************************/
  71
  72
  73 putenv( entry )
  74   char *entry;
  75
  76   {
  77   unsigned length;
  78   unsigned size;
  79   char     **p;
  80   char     **new_environ;
  81
  82   /*  Find the length of the "NAME="  */
  83
  84   if ( (length=(unsigned) index(entry,'=')) == NULL )
  85     return( -1 );
  86
  87   length = length - (unsigned) entry + 1;
  88
  89
  90   /*  Scan through the environment looking for "NAME="  */
  91
  92   for ( p=environ; *p != 0 ; p++ )
  93     if ( strncmp( entry, *p, length ) == 0 )
  94       {
  95       *p = entry;
  96       return( NULL );
  97       }
  98
  99
 100   /*  The name was not found, build a bigger environment  */
 101
 102   size = p - environ;
 103
 104   new_environ = (char **) malloc( (size+2)*PSIZE );
 105
 106   if ( new_environ == NULL )
 107     return( -1 );
 108
 109   bcopy( (char *) environ, (char *) new_environ, size*PSIZE );
 110
 111   new_environ[size]   = entry;
 112   new_environ[size+1] = NULL;
 113
 114   environ = new_environ;
 115
 116   return(NULL);
 117   }