3 * server.c Set up and handle communications with a server process.
5 * Server Handling copyright 1992-1999 The Free Software Foundation
7 * Server Handling is free software.
8 * You may redistribute it and/or modify it under the terms of the
9 * GNU General Public License, as published by the Free Software
10 * Foundation; either version 2, or (at your option) any later version.
12 * Server Handling is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with Server Handling. See the file "COPYING". If not,
19 * write to: The Free Software Foundation, Inc.,
20 * 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
23 * As a special exception, The Free Software Foundation gives
24 * permission for additional uses of the text contained in his release
27 * The exception is that, if you link the ServerHandler library with other
28 * files to produce an executable, this does not by itself cause the
29 * resulting executable to be covered by the GNU General Public License.
30 * Your use of that executable is in no way restricted on account of
31 * linking the ServerHandler library code into it.
33 * This exception does not however invalidate any other reasons why
34 * the executable file might be covered by the GNU General Public License.
36 * This exception applies only to the code released by The Free
37 * Software Foundation under the name ServerHandler. If you copy code
38 * from other sources under the General Public License into a copy of
39 * ServerHandler, as the General Public License permits, the exception
40 * does not apply to the code that you add in this way. To avoid
41 * misleading anyone as to the status of such modified files, you must
42 * delete this exception notice from them.
44 * If you write modifications of your own for ServerHandler, it is your
45 * choice whether to permit this exception to apply to your modifications.
46 * If you do not wish that, delete this exception notice.
48 #include "auto-host.h"
50 #include "gansidecl.h"
56 /* If this particular system's header files define the macro `MAXPATHLEN',
57 we happily take advantage of it; otherwise we use a value which ought
58 to be large enough. */
60 # define MAXPATHLEN 4096
64 # define STDIN_FILENO 0
67 # define STDOUT_FILENO 1
76 #define tSCC static const char
82 #if !defined(volatile) && !defined(HAVE_VOLATILE)
86 STATIC volatile t_bool read_pipe_timeout;
87 STATIC pid_t server_master_pid = NOPROCESS;
89 static t_pchar def_args[] =
90 { (char *) NULL, (char *) NULL };
91 STATIC t_pf_pair server_pair =
92 { (FILE *) NULL, (FILE *) NULL };
93 STATIC pid_t server_id = NULLPROCESS;
95 * Arbitrary text that should not be found in the shell output.
96 * It must be a single line and appear verbatim at the start of
97 * the terminating output line.
99 tSCC z_done[] = "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd";
100 STATIC t_pchar p_cur_dir = (char *) NULL;
105 * Read data from a file pointer (a pipe to a process in this context)
106 * until we either get EOF or we get a marker line back.
107 * The read data are stored in a malloc-ed string that is truncated
108 * to size at the end. Input is assumed to be an ASCII string.
118 t_bool got_done = BOOL_FALSE;
120 text_size = sizeof (z_line) * 2;
121 pz_scan = pz_text = malloc (text_size);
123 if (pz_text == (char *) NULL)
124 return (char *) NULL;
131 read_pipe_timeout = BOOL_FALSE;
132 if (fgets (z_line, sizeof (z_line), fp) == (char *) NULL)
135 if (strncmp (z_line, z_done, sizeof (z_done) - 1) == 0)
137 got_done = BOOL_TRUE;
141 strcpy (pz_scan, z_line);
142 pz_scan += strlen (z_line);
143 used_ct = (size_t) (pz_scan - pz_text);
145 if (text_size - used_ct < sizeof (z_line))
147 size_t off = (size_t) (pz_scan - pz_text);
151 p = realloc ((void *) pz_text, text_size);
152 if (p == (void *) NULL)
154 fprintf (stderr, "Failed to get 0x%08lX bytes\n",
156 free ((void *) pz_text);
157 return (char *) NULL;
159 pz_text = (char *) p;
160 pz_scan = pz_text + off;
165 if (read_pipe_timeout || ! got_done)
167 free ((void *) pz_text);
168 return (char *) NULL;
171 while ((pz_scan > pz_text) && ISSPACE (pz_scan[-1]))
174 return realloc ((void *) pz_text, strlen (pz_text) + 1);
181 * Make certain the server process is dead, close the
182 * pipes to it and from it, finally NULL out the file pointers
187 if ( (server_id != NULLPROCESS)
188 && (server_master_pid == getpid ()))
190 kill ((pid_t) server_id, SIGKILL);
191 server_id = NULLPROCESS;
192 server_master_pid = NOPROCESS;
193 fclose (server_pair.pf_read);
194 fclose (server_pair.pf_write);
195 server_pair.pf_read = server_pair.pf_write = (FILE *) NULL;
200 * sig_handler really only handles the timeout and pipe signals.
201 * This ensures that we do not wait forever on a request
202 * to our server, and also that if the server dies, we do not
203 * die from a sigpipe problem.
210 /* FIXME: this is illegal to do in a signal handler. */
212 "fixincl ERROR: sig_handler: killed pid %ld due to %s\n",
213 (long) server_id, signo == SIGPIPE ? "SIGPIPE" : "SIGALRM");
216 read_pipe_timeout = BOOL_TRUE;
221 * server_setup Establish the signal handler for PIPE and ALARM.
222 * Also establishes the current directory to give to the
223 * server process at the start of every server command.
228 static int atexit_done = 0;
230 if (atexit_done++ == 0)
231 atexit (close_server);
233 fputs ("NOTE: server restarted\n", stderr);
235 server_master_pid = getpid ();
237 signal (SIGPIPE, sig_handler);
238 signal (SIGALRM, sig_handler);
240 fputs ("trap : 1\n", server_pair.pf_write);
241 fflush (server_pair.pf_write);
242 p_cur_dir = getcwd ((char *) NULL, MAXPATHLEN + 1);
248 * Locate a shell suitable for use. For various reasons
249 * (like the use of "trap" in server_setup(), it must be a
252 * Most of the time, /bin/sh is preferred, but sometimes
253 * it's quite broken (like on Ultrix). autoconf lets you
254 * override with $CONFIG_SHELL, so we do the same.
260 char * shell = getenv ("CONFIG_SHELL");
271 * Run a shell command on the server. The command string
272 * passed in is wrapped inside the sequence:
274 * cd <original directory>
277 * echo <end-of-command-marker>
279 * This ensures that all commands start at a known place in
280 * the directory structure, that any incomplete output lines
281 * are completed and that our special marker sequence appears on
282 * a line by itself. We have chosen a marker that is
283 * excessively unlikely to be reproduced in normal output:
285 * "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd"
291 tSCC zNoServer[] = "Server not running, cannot run:\n%s\n\n";
292 t_bool retry = BOOL_TRUE;
295 /* IF the shell server process is not running yet,
296 THEN try to start it. */
297 if (server_id == NULLPROCESS)
299 def_args[0] = find_shell ();
301 server_id = proc2_fopen (&server_pair, def_args);
306 /* IF it is still not running, THEN return the nil string. */
309 char *pz = (char *) malloc (1);
310 fprintf (stderr, zNoServer, pz_cmd);
311 if (pz != (char *) NULL)
316 /* Make sure the process will pay attention to us, send the
317 supplied command, and then have it output a special marker that
319 fprintf (server_pair.pf_write, "cd %s\n%s\n\necho\necho %s\n",
320 p_cur_dir, pz_cmd, z_done);
321 fflush (server_pair.pf_write);
323 /* IF the server died and we received a SIGPIPE,
324 THEN return an empty string. */
325 if (server_id == NULLPROCESS)
327 char *pz = (char *) malloc (1);
328 fprintf (stderr, zNoServer, pz_cmd);
329 if (pz != (char *) NULL)
334 /* Now try to read back all the data. If we fail due to either a
335 sigpipe or sigalrm (timeout), we will return the nil string. */
337 char *pz = load_data (server_pair.pf_read);
339 if (pz == (char *) NULL)
349 fprintf (stderr, "CLOSING SHELL SERVER - command failure:\n\t%s\n",
351 pz = (char *) malloc (1);
352 if (pz != (char *) NULL)
356 fprintf( stderr, "run_shell command success: %s\n", pz );