| 1 | /* Return the next element of a path.
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| 2 | Copyright (C) 1992 Free Software Foundation, Inc.
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| 3 |
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| 4 | This program is free software; you can redistribute it and/or modify
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| 5 | it under the terms of the GNU General Public License as published by
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| 6 | the Free Software Foundation; either version 2, or (at your option)
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| 7 | any later version.
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| 8 |
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| 9 | This program is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU General Public License
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| 15 | along with this program; if not, write to the Free Software
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| 16 | Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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| 17 | USA.
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| 18 | */
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| 19 |
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| 20 | /* Written by David MacKenzie <djm@gnu.org>,
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| 21 | inspired by John P. Rouillard <rouilj@cs.umb.edu>. */
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| 22 |
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| 23 | #ifdef HAVE_CONFIG_H
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| 24 | #include <config.h>
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| 25 | #endif
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| 26 |
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| 27 | #include <stdio.h>
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| 28 | #if defined(HAVE_STRING_H) || defined(STDC_HEADERS)
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| 29 | #include <string.h>
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| 30 | #else
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| 31 | #include <strings.h>
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| 32 | #ifndef strchr
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| 33 | #define strchr index
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| 34 | #endif
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| 35 | #endif
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| 36 | #if defined(STDC_HEADERS)
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| 37 | #include <stdlib.h>
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| 38 | #endif
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| 39 |
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| 40 | #include "nextelem.h"
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| 41 |
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| 42 |
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| 43 | /* Return the next element of a colon-separated path.
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| 44 | A null entry in the path is equivalent to "." (the current directory).
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| 45 |
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| 46 | If NEW_PATH is non-NULL, set the path and return NULL.
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| 47 | If NEW_PATH is NULL, return the next item in the string, or
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| 48 | return NULL if there are no more elements. */
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| 49 |
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| 50 | char *
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| 51 | next_element (const char *new_path, int curdir_ok)
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| 52 | {
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| 53 | static char *path = NULL; /* Freshly allocated copy of NEW_PATH. */
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| 54 | static char *end; /* Start of next element to return. */
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| 55 | static int final_colon; /* If zero, path didn't end with a colon. */
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| 56 | char *start; /* Start of path element to return. */
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| 57 |
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| 58 | if (new_path)
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| 59 | {
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| 60 | if (path)
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| 61 | free (path);
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| 62 | end = path = strdup (new_path);
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| 63 | final_colon = 0;
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| 64 | return NULL;
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| 65 | }
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| 66 |
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| 67 | if (*end == '\0')
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| 68 | {
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| 69 | if (final_colon)
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| 70 | {
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| 71 | final_colon = 0;
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| 72 | return curdir_ok ? "." : "";
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| 73 | }
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| 74 | return NULL;
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| 75 | }
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| 76 |
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| 77 | start = end;
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| 78 | final_colon = 1; /* Maybe there will be one. */
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| 79 |
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| 80 | end = strchr (start, ':');
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| 81 | if (end == start)
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| 82 | {
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| 83 | /* An empty path element. */
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| 84 | *end++ = '\0';
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| 85 | return curdir_ok ? "." : "";
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| 86 | }
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| 87 | else if (end == NULL)
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| 88 | {
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| 89 | /* The last path element. */
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| 90 | end = strchr (start, '\0');
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| 91 | final_colon = 0;
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| 92 | }
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| 93 | else
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| 94 | *end++ = '\0';
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| 95 |
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| 96 | return start;
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| 97 | }
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| 98 |
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| 99 | #ifdef TEST
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| 100 | int
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| 101 | main ()
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| 102 | {
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| 103 | char *p;
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| 104 |
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| 105 | next_element (getenv ("PATH"));
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| 106 | while (p = next_element (NULL))
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| 107 | puts (p);
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| 108 | exit (0);
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| 109 | }
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| 110 | #endif /* TEST */
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