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1 /* xputenv.c: set an environment variable without return. |
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2 |
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3 Copyright (C) 1993, 94, 95, 96, 97, 98 Karl Berry. |
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4 |
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5 This library is free software; you can redistribute it and/or |
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6 modify it under the terms of the GNU Library General Public |
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7 License as published by the Free Software Foundation; either |
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8 version 2 of the License, or (at your option) any later version. |
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9 |
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10 This library is distributed in the hope that it will be useful, |
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 Library General Public License for more details. |
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14 |
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15 You should have received a copy of the GNU Library General Public |
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16 License along with this library; if not, write to the Free Software |
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17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
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18 |
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19 #include <kpathsea/config.h> |
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20 |
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21 #ifdef WIN32 |
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22 #include <stdlib.h> |
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23 #else |
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24 /* Avoid implicit declaration warning. But since some systems do |
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25 declare it, don't use a prototype, for fear of conflicts. */ |
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26 extern int putenv (); |
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27 #endif /* not WIN32 */ |
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28 |
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29 /* This `x' function is different from the others in that it takes |
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30 different parameters than the standard function; but I find it much |
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31 more convenient to pass the variable and the value separately. Also, |
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32 this way we can guarantee that the environment value won't become |
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33 garbage. Also, putenv just overwrites old entries with |
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34 the new, and we want to reclaim that space -- this may be called |
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35 hundreds of times on a run. |
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36 |
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37 But naturally, some systems do it differently. In this case, it's |
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38 net2 that is smart and does its own saving/freeing. configure tries |
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39 to determine this. */ |
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40 |
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41 void |
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42 xputenv P2C(const_string, var_name, const_string, value) |
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43 { |
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44 string old_item = NULL; |
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45 string new_item = concat3 (var_name, "=", value); |
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46 unsigned name_len = strlen (var_name); |
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47 |
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48 #ifndef SMART_PUTENV |
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49 |
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50 static const_string *saved_env_items = NULL; |
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51 static unsigned saved_len; |
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52 boolean found = false; |
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53 |
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54 /* Check if we have saved anything yet. */ |
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55 if (!saved_env_items) |
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56 { |
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57 saved_env_items = XTALLOC1 (const_string); |
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58 saved_env_items[0] = var_name; |
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59 saved_len = 1; |
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60 } |
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61 else |
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62 { |
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63 /* Check if we've assigned VAR_NAME before. */ |
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64 unsigned i; |
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65 for (i = 0; i < saved_len && !found; i++) |
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66 { |
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67 if (STREQ (saved_env_items[i], var_name)) |
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68 { |
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69 found = true; |
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70 old_item = getenv (var_name); |
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71 #ifdef WIN32 |
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72 /* win32 putenv() removes the variable if called with |
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73 "VAR=". So we have to cope with this case. Distinction |
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74 is not made between the value being "" or the variable |
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75 not set. */ |
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76 if (old_item) |
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77 old_item -= (name_len + 1); |
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78 #else |
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79 assert (old_item); |
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80 /* Back up to the `NAME=' in the environment before the |
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81 value that getenv returns. */ |
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82 old_item -= (name_len + 1); |
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83 #endif |
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84 } |
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85 } |
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86 |
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87 if (!found) |
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88 { |
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89 /* If we haven't seen VAR_NAME before, save it. Assume it is |
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90 in safe storage. */ |
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91 saved_len++; |
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92 XRETALLOC (saved_env_items, saved_len, const_string); |
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93 saved_env_items[saved_len - 1] = var_name; |
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94 } |
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95 } |
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96 #endif /* not SMART_PUTENV */ |
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97 |
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98 /* If the old and the new values are identical, don't do anything. |
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99 This is both more memory-efficient and safer as far as our |
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100 assumptions (about how putenv is implemented in libc) go. */ |
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101 if (!old_item || !STREQ (old_item, new_item)) |
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102 { |
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103 char *new_val; |
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104 /* As far as I can see there's no way to distinguish between the |
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105 various errors; putenv doesn't have errno values. */ |
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106 if (putenv (new_item) < 0) |
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107 FATAL1 ("putenv (%s) failed", new_item); |
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108 |
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109 /* If their putenv copied `new_item', we can free it. */ |
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110 new_val = getenv (var_name); |
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111 if (new_val && new_val - name_len - 1 != new_item) |
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112 free (new_item); |
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113 |
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114 #ifndef SMART_PUTENV |
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115 /* Can't free `new_item' because its contained value is now in |
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116 `environ', but we can free `old_item', since it's been replaced. */ |
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117 #ifdef WIN32 |
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118 /* ... except on Win32, where old_item points to garbage if we set the |
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119 variable to "". So we recognize this special case. */ |
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120 if (old_item && value && *value) |
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121 #else |
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122 if (old_item) |
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123 #endif |
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124 free (old_item); |
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125 #endif /* not SMART_PUTENV */ |
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126 } |
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127 } |
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128 |
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129 |
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130 /* A special case for setting a variable to a numeric value |
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131 (specifically, KPATHSEA_DPI). We don't need to dynamically allocate |
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132 and free the string for the number, since it's saved as part of the |
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133 environment value. */ |
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134 |
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135 void |
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136 xputenv_int P2C(const_string, var_name, int, num) |
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137 { |
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138 char str[MAX_INT_LENGTH]; |
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139 sprintf (str, "%d", num); |
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140 |
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141 xputenv (var_name, str); |
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142 } |
