1 /*
2 *
3 * Pathname management routines for DWB C programs.
4 *
5 * Applications should initialize a dwbinit array with the string
6 * pointers and arrays that need to be updated, and then hand that
7 * array to DWBinit before much else happens in their main program.
8 * DWBinit calls DWBhome to get the current home directory. DWBhome
9 * uses the last definition of DWBENV (usually "DWBHOME") in file
10 * DWBCONFIG (e.g., /usr/lib/dwb3.4) or the value assigned to that
11 * variable in the environment if the DWBCONFIG file doesn't exist,
12 * can't be read, or doesn't define DWBENV.
13 *
14 * DWBCONFIG must be a simple shell script - comments, a definition
15 * of DWBHOME, and perhaps an export or echo is about all that's
16 * allowed. The parsing in DWBhome is simple and makes no attempt
17 * to duplicate the shell. It only looks for DWBHOME= as the first
18 * non-white space string on a line, so
19 *
20 * #
21 * # A sample DWBCONFIG shell script
22 * #
23 *
24 * DWBHOME=/usr/add-on/dwb3.4
25 * export DWBHOME
26 *
27 * means DWBhome would return "/usr/add-on/dwb3.4" for the DWB home
28 * directory. A DWBCONFIG file means there can only be one working
29 * copy of a DWB release on a system, which seems like a good idea.
30 * Using DWBCONFIG also means programs will always include correct
31 * versions of files (e.g., prologues or macro packages).
32 *
33 * Relying on an environment variable guarantees nothing. You could
34 * execute a version of dpost, but your environment might point at
35 * incorrect font tables or prologues. Despite the obvious problems
36 * we've also implemented an environment variable approach, but it's
37 * only used if there's no DWBCONFIG file.
38 *
39 * DWBinit calls DWBhome to get the DWB home directory prefix and
40 * then marches through its dwbinit argument, removing the default
41 * home directory and prepending the new home. DWBinit stops when
42 * it reaches an element that has NULL for its address and value
43 * fields. Pointers in a dwbinit array are reallocated and properly
44 * initialized; arrays are simply reinitialized if there's room.
45 * All pathnames that are to be adjusted should be relative. For
46 * example,
47 *
48 * char *fontdir = "lib/font";
49 * char xyzzy[25] = "etc/xyzzy";
50 *
51 * would be represented in a dwbinit array as,
52 *
53 * dwbinit allpaths[] = {
54 * &fontdir, NULL, 0,
55 * NULL, xyzzy, sizeof(xyzzy),
56 * NULL, NULL, 0
57 * };
58 *
59 * The last element must have NULL entries for the address and
60 * value fields. The main() routine would then do,
61 *
62 * #include "dwbinit.h"
63 *
64 * main() {
65 *
66 * DWBinit("program name", allpaths);
67 * ...
68 * }
69 *
70 * Debugging is enabled if DWBDEBUG is in the environment and has
71 * the value ON. Output is occasionally useful and probably should
72 * be documented.
73 *
74 */
75
76 #include <stdio.h>
77 #include <ctype.h>
78 #include <string.h>
79 #include <stdlib.h>
80
81 #include "dwbinit.h"
82
83 #ifndef DWBCONFIG
84 #define DWBCONFIG "/dev/null"
85 #endif
86
87 #ifndef DWBENV
88 #define DWBENV "DWBHOME"
89 #endif
90
91 #ifndef DWBHOME
92 #define DWBHOME ""
93 #endif
94
95 #ifndef DWBDEBUG
96 #define DWBDEBUG "DWBDEBUG"
97 #endif
98
99 #ifndef DWBPREFIX
100 #define DWBPREFIX "\\*(.P"
101 #endif
102
103 /*****************************************************************************/
104
DWBdebug(dwbinit * ptr,int level)105 void DWBdebug(dwbinit *ptr, int level)
106 {
107
108 char *path;
109 char *home;
110 static char *debug = NULL;
111
112 /*
113 *
114 * Debugging output, but only if DWBDEBUG is defined to be ON in the
115 * environment. Dumps general info the first time through.
116 *
117 */
118
119 if ( debug == NULL && (debug = getenv(DWBDEBUG)) == NULL )
120 debug = "OFF";
121
122 if ( strcmp(debug, "ON") == 0 ) {
123 if ( level == 0 ) {
124 fprintf(stderr, "Environment variable: %s\n", DWBENV);
125 fprintf(stderr, "Configuration file: %s\n", DWBCONFIG);
126 fprintf(stderr, "Default home: %s\n", DWBHOME);
127 if ( (home = DWBhome()) != NULL )
128 fprintf(stderr, "Current home: %s\n", home);
129 } /* End if */
130
131 fprintf(stderr, "\n%s pathnames:\n", level == 0 ? "Original" : "Final");
132 for ( ; ptr->value != NULL || ptr->address != NULL; ptr++ ) {
133 if ( (path = ptr->value) == NULL ) {
134 path = *ptr->address;
135 fprintf(stderr, " pointer: %s\n", path);
136 } else fprintf(stderr, " array[%d]: %s\n", ptr->length, path);
137 if ( level == 0 && *path == '/' )
138 fprintf(stderr, " WARNING - absolute path\n");
139 } /* End for */
140 } /* End if */
141
142 } /* End of DWBdebug */
143
144 /*****************************************************************************/
145
DWBhome(void)146 char *DWBhome(void)
147 {
148
149 FILE *fp;
150 char *ptr;
151 char *path;
152 int len;
153 char buf[200];
154 char *home = NULL;
155
156 /*
157 *
158 * Return the DWB home directory. Uses the last definition of DWBENV
159 * (usually "DWBHOME") in file DWBCONFIG (perhaps /usr/lib/dwb3.4) or
160 * the value assigned to the variable named by the DWBENV string in
161 * the environment if DWBCONFIG doesn't exist or doesn't define DWBENV.
162 * Skips the file lookup if DWBCONFIG can't be read. Returns NULL if
163 * there's no home directory.
164 *
165 */
166
167 if ( (fp = fopen(DWBCONFIG, "r")) != NULL ) {
168 len = strlen(DWBENV);
169 while ( fgets(buf, sizeof(buf), fp) != NULL ) {
170 for ( ptr = buf; isspace(*ptr); ptr++ ) ;
171 if ( strncmp(ptr, DWBENV, len) == 0 && *(ptr+len) == '=' ) {
172 path = ptr + len + 1;
173 for ( ptr = path; !isspace(*ptr) && *ptr != ';'; ptr++ ) ;
174 *ptr = '\0';
175 if ( home != NULL )
176 free(home);
177 if ( (home = malloc(strlen(path)+1)) != NULL )
178 strcpy(home, path);
179 } /* End if */
180 } /* End while */
181 fclose(fp);
182 } /* End if */
183
184 if ( home == NULL ) {
185 if ( (home = getenv(DWBENV)) == NULL ) {
186 if ( (home = DWBHOME) == NULL || *home == '\0' || *home == ' ' )
187 home = NULL;
188 } /* End if */
189 } /* End if */
190
191 while (home && *home == '/' && *(home +1) == '/') /* remove extra slashes */
192 home++;
193 return(home);
194
195 } /* End of DWBhome */
196
197 /*****************************************************************************/
198
DWBinit(char * prog,dwbinit * paths)199 void DWBinit(char *prog, dwbinit *paths)
200 {
201
202 char *prefix;
203 char *value;
204 char *path;
205 int plen;
206 int length;
207 dwbinit *opaths = paths;
208
209 /*
210 *
211 * Adjust the pathnames listed in paths, using the home directory
212 * returned by DWBhome(). Stops when it reaches an element that has
213 * NULL address and value fields. Assumes pathnames are relative,
214 * but changes everything. DWBdebug issues a warning if an original
215 * path begins with a /.
216 *
217 * A non-NULL address refers to a pointer, which is reallocated and
218 * then reinitialized. A NULL address implies a non-NULL value field
219 * and describes a character array that we only reinitialize. The
220 * length field for an array is the size of that array. The length
221 * field of a pointer is an increment that's added to the length
222 * required to store the new pathname string - should help when we
223 * want to change character arrays to pointers in applications like
224 * troff.
225 *
226 */
227
228 if ( (prefix = DWBhome()) == NULL ) {
229 fprintf(stderr, "%s: no DWB home directory\n", prog);
230 exit(1);
231 } /* End if */
232
233 DWBdebug(opaths, 0);
234 plen = strlen(prefix);
235
236 for ( ; paths->value != NULL || paths->address != NULL; paths++ ) {
237 if ( paths->address == NULL ) {
238 length = 0;
239 value = paths->value;
240 } else {
241 length = paths->length;
242 value = *paths->address;
243 } /* End else */
244
245 length += plen + 1 + strlen(value); /* +1 is for the '/' */
246
247 if ( (path = malloc(length+1)) == NULL ) {
248 fprintf(stderr, "%s: can't allocate pathname memory\n", prog);
249 exit(1);
250 } /* End if */
251
252 if ( *value != '\0' ) {
253 char *eop = prefix;
254 while(*eop++)
255 ;
256 eop -= 2;
257 if (*value != '/' && *eop != '/') {
258 sprintf(path, "%s/%s", prefix, value);
259 } else if (*value == '/' && *eop == '/') {
260 value++;
261 sprintf(path, "%s%s", prefix, value);
262 } else
263 sprintf(path, "%s%s", prefix, value);
264 } else
265 sprintf(path, "%s", prefix);
266
267 if ( paths->address == NULL ) {
268 if ( strlen(path) >= paths->length ) {
269 fprintf(stderr, "%s: no room for %s\n", prog, path);
270 exit(1);
271 } /* End if */
272 strcpy(paths->value, path);
273 free(path);
274 } else *paths->address = path;
275 } /* End for */
276
277 DWBdebug(opaths, 1);
278
279 } /* End of DWBinit */
280
281 /*****************************************************************************/
282
DWBprefix(char * prog,char * path,int length)283 void DWBprefix( char *prog, char *path, int length)
284 {
285
286 char *home;
287 char buf[512];
288 int len = strlen(DWBPREFIX);
289
290 /*
291 *
292 * Replace a leading DWBPREFIX string in path by the current DWBhome().
293 * Used by programs that pretend to handle .so requests. Assumes path
294 * is an array with room for length characters. The implementation is
295 * not great, but should be good enough for now. Also probably should
296 * have DWBhome() only do the lookup once, and remember the value if
297 * called again.
298 *
299 */
300
301 if ( strncmp(path, DWBPREFIX, len) == 0 ) {
302 if ( (home = DWBhome()) != NULL ) {
303 if ( strlen(home) + strlen(path+len) < length ) {
304 sprintf(buf, "%s%s", home, path+len);
305 strcpy(path, buf); /* assuming there's room in path */
306 } else fprintf(stderr, "%s: no room to grow path %s", prog, path);
307 } /* End if */
308 } /* End if */
309
310 } /* End of DWBprefix */
311
312 /*****************************************************************************/
313
314