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1268
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1 /****************************************************************/ |
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2 /* */ |
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3 /* putenv(3) */ |
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4 /* */ |
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5 /* Change or add an environment entry */ |
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6 /* */ |
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7 /****************************************************************/ |
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8 /* origination 1987-Oct-7 T. Holm */ |
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9 /* (slightly modified by karl@cs.umb.edu for kpathsea.) */ |
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10 /****************************************************************/ |
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11 |
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12 /* for HAVE_PUTENV and const -- need nothing else. */ |
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13 #include <kpathsea/c-auto.h> |
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14 |
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15 #ifndef HAVE_PUTENV /* whole file */ |
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16 |
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17 /* |
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18 Path: hoptoad!pacbell!ames!ll-xn!mit-eddie!uw-beaver!ssc-vax!uvicctr!tholm |
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19 From: tholm@uvicctr.UUCP (Terrence W. Holm) |
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20 Newsgroups: comp.os.minix |
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21 Subject: putenv(3) |
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22 Message-ID: <395@uvicctr.UUCP> |
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23 Date: 5 May 88 06:40:52 GMT |
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24 Organization: University of Victoria, Victoria B.C. Canada |
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25 |
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26 EFTH Minix report #2 - May 1988 - putenv(3) |
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27 |
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28 This is an implementation of putenv(3) that we |
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29 wrote for Minix. Please consider this a public |
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30 domain program. |
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31 */ |
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32 |
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33 #define NULL 0 |
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34 #define PSIZE sizeof(char *) |
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35 |
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36 extern char **environ; |
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37 |
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38 char *strchr(); |
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39 char *malloc(); |
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40 |
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41 /****************************************************************/ |
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42 /* */ |
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43 /* int */ |
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44 /* putenv( entry ) */ |
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45 /* */ |
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46 /* The "entry" should follow the form */ |
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47 /* "NAME=VALUE". This routine will search the */ |
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48 /* user environment for "NAME" and replace its */ |
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49 /* value with "VALUE". */ |
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50 /* */ |
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51 /* Note that "entry" is not copied, it is used */ |
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52 /* as the environment entry. This means that it */ |
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53 /* must not be unallocated or otherwise modifed */ |
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54 /* by the caller, unless it is replaced by a */ |
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55 /* subsequent putenv(). */ |
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56 /* */ |
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57 /* If the name is not found in the environment, */ |
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58 /* then a new vector of pointers is allocated, */ |
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59 /* "entry" is put at the end and the global */ |
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60 /* variable "environ" is updated. */ |
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61 /* */ |
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62 /* This function normally returns 0, but -1 */ |
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63 /* is returned if it can not allocate enough */ |
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64 /* space using malloc(3), or "entry" does not */ |
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65 /* contain a '='. */ |
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66 /* */ |
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67 /****************************************************************/ |
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68 |
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69 |
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70 int |
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71 putenv( entry ) |
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72 char *entry; |
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73 { |
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74 unsigned length; |
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75 unsigned size; |
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76 char *temp; |
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77 char **p; |
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78 char **new_environ; |
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79 |
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80 /* Find the length of the "NAME=" */ |
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81 |
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82 temp = strchr(entry,'='); |
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83 if ( temp == 0 ) |
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84 return( -1 ); |
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85 |
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86 length = (unsigned) (temp - entry + 1); |
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87 |
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88 |
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89 /* Scan through the environment looking for "NAME=" */ |
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90 |
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91 for ( p=environ; *p != 0 ; p++ ) |
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92 if ( strncmp( entry, *p, length ) == 0 ) |
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93 { |
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94 *p = entry; |
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95 return( 0 ); |
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96 } |
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97 |
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98 |
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99 /* The name was not found, build a bigger environment */ |
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100 |
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101 size = p - environ; |
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102 |
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103 new_environ = (char **) malloc( (size+2)*PSIZE ); |
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104 |
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105 if ( new_environ == (char **) NULL ) |
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106 return( -1 ); |
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107 |
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108 memcpy ((char *) new_environ, (const char *) environ, size*PSIZE ); |
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109 |
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110 new_environ[size] = entry; |
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111 new_environ[size+1] = NULL; |
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112 |
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113 environ = new_environ; |
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114 |
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115 return(0); |
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116 } |
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117 |
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118 #endif /* not HAVE_PUTENV */ |
