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[findutils.git] / lib / nextelem.c
blob1689817d83cc2b2df7da53163c4d6b3999eb61e0
1 /* Return the next element of a path.
2 Copyright (C) 1992 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
18 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>,
19 inspired by John P. Rouillard <rouilj@cs.umb.edu>. */
21 #ifdef HAVE_CONFIG_H
22 #include <config.h>
23 #endif
25 #include <stdio.h>
26 #if defined(HAVE_STRING_H) || defined(STDC_HEADERS)
27 #include <string.h>
28 #else
29 #include <strings.h>
30 #ifndef strchr
31 #define strchr index
32 #endif
33 #endif
34 #if defined(STDC_HEADERS)
35 #include <stdlib.h>
36 #endif
38 /* Return the next element of a colon-separated path.
39 A null entry in the path is equivalent to "." (the current directory).
41 If NEW_PATH is non-NULL, set the path and return NULL.
42 If NEW_PATH is NULL, return the next item in the string, or
43 return NULL if there are no more elements. */
45 char *
46 next_element (new_path)
47 char *new_path;
49 static char *path = NULL; /* Freshly allocated copy of NEW_PATH. */
50 static char *end; /* Start of next element to return. */
51 static int final_colon; /* If zero, path didn't end with a colon. */
52 char *start; /* Start of path element to return. */
54 if (new_path)
56 if (path)
57 free (path);
58 end = path = strdup (new_path);
59 final_colon = 0;
60 return NULL;
63 if (*end == '\0')
65 if (final_colon)
67 final_colon = 0;
68 return ".";
70 return NULL;
73 start = end;
74 final_colon = 1; /* Maybe there will be one. */
76 end = strchr (start, ':');
77 if (end == start)
79 /* An empty path element. */
80 *end++ = '\0';
81 return ".";
83 else if (end == NULL)
85 /* The last path element. */
86 end = strchr (start, '\0');
87 final_colon = 0;
89 else
90 *end++ = '\0';
92 return start;
95 #ifdef TEST
96 int
97 main ()
99 char *p;
101 next_element (getenv ("PATH"));
102 while (p = next_element (NULL))
103 puts (p);
104 exit (0);
106 #endif /* TEST */