| 1 | /* |
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| 2 | * Copyright (c) 1992-1998 Michael A. Cooper. |
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| 3 | * This software may be freely used and distributed provided it is not |
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| 4 | * sold for profit or used in part or in whole for commercial gain |
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| 5 | * without prior written agreement, and the author is credited |
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| 6 | * appropriately. |
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| 7 | */ |
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| 8 | |
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| 9 | #if defined(LIBC_SCCS) && !defined(lint) |
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| 10 | static char sccsid[] = "@(#)setenv.c 5.6 (Berkeley) 6/4/91"; |
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| 11 | #endif /* LIBC_SCCS and not lint */ |
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| 12 | |
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| 13 | #include <stddef.h> |
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| 14 | #include <stdlib.h> |
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| 15 | #include <string.h> |
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| 16 | |
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| 17 | char *_findenv(); |
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| 18 | |
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| 19 | /* |
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| 20 | * setenv -- |
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| 21 | * Set the value of the environmental variable "name" to be |
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| 22 | * "value". If rewrite is set, replace any current value. |
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| 23 | */ |
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| 24 | setenv(name, value, rewrite) |
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| 25 | register const char *name; |
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| 26 | register const char *value; |
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| 27 | int rewrite; |
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| 28 | { |
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| 29 | extern char **environ; |
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| 30 | static int alloced; /* if allocated space before */ |
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| 31 | register char *C; |
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| 32 | int l_value, offset; |
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| 33 | |
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| 34 | if (*value == '=') /* no `=' in value */ |
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| 35 | ++value; |
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| 36 | l_value = strlen(value); |
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| 37 | if ((C = _findenv(name, &offset))) { /* find if already exists */ |
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| 38 | if (!rewrite) |
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| 39 | return (0); |
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| 40 | if (strlen(C) >= l_value) { /* old larger; copy over */ |
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| 41 | while (*C++ = *value++); |
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| 42 | return (0); |
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| 43 | } |
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| 44 | } else { /* create new slot */ |
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| 45 | register int cnt; |
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| 46 | register char **P; |
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| 47 | |
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| 48 | for (P = environ, cnt = 0; *P; ++P, ++cnt); |
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| 49 | if (alloced) { /* just increase size */ |
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| 50 | environ = (char **)realloc((char *)environ, |
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| 51 | (size_t)(sizeof(char *) * (cnt + 2))); |
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| 52 | if (!environ) |
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| 53 | return (-1); |
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| 54 | } |
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| 55 | else { /* get new space */ |
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| 56 | alloced = 1; /* copy old entries into it */ |
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| 57 | P = (char **)malloc((size_t)(sizeof(char *) * |
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| 58 | (cnt + 2))); |
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| 59 | if (!P) |
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| 60 | return (-1); |
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| 61 | memcpy(P, environ, cnt * sizeof(char *)); |
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| 62 | environ = P; |
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| 63 | } |
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| 64 | environ[cnt + 1] = NULL; |
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| 65 | offset = cnt; |
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| 66 | } |
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| 67 | for (C = (char *)name; *C && *C != '='; ++C); /* no `=' in name */ |
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| 68 | if (!(environ[offset] = /* name + `=' + value */ |
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| 69 | malloc((size_t)((int)(C - name) + l_value + 2)))) |
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| 70 | return (-1); |
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| 71 | for (C = environ[offset]; (*C = *name++) && *C != '='; ++C) |
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| 72 | ; |
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| 73 | for (*C++ = '='; *C++ = *value++; ) |
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| 74 | ; |
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| 75 | return (0); |
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| 76 | } |
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| 77 | |
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| 78 | /* |
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| 79 | * unsetenv(name) -- |
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| 80 | * Delete environmental variable "name". |
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| 81 | */ |
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| 82 | void |
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| 83 | unsetenv(name) |
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| 84 | const char *name; |
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| 85 | { |
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| 86 | extern char **environ; |
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| 87 | register char **P; |
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| 88 | int offset; |
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| 89 | |
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| 90 | while (_findenv(name, &offset)) /* if set multiple times */ |
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| 91 | for (P = &environ[offset];; ++P) |
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| 92 | if (!(*P = *(P + 1))) |
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| 93 | break; |
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| 94 | } |
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