tw.help.c revision 167466 
1/* $Header: /p/tcsh/cvsroot/tcsh/tw.help.c,v 3.27 2006/08/24 20:56:31 christos Exp $ */
2/* tw.help.c: actually look up and print documentation on a file.
3 *	      Look down the path for an appropriate file, then print it.
4 *	      Note that the printing is NOT PAGED.  This is because the
5 *	      function is NOT meant to look at manual pages, it only does so
6 *	      if there is no .help file to look in.
7 */
8/*-
9 * Copyright (c) 1980, 1991 The Regents of the University of California.
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36#include "sh.h"
37
38RCSID("$tcsh: tw.help.c,v 3.27 2006/08/24 20:56:31 christos Exp $")
39
40#include "tw.h"
41#include "tc.h"
42
43
44static int f = -1;
45static	void		 cleanf		(int);
46static	Char    	*skipslist	(Char *);
47static	void		 nextslist 	(const Char *, Char *);
48
49static const char *const h_ext[] = {
50    ".help", ".1", ".8", ".6", "", NULL
51};
52
53void
54do_help(const Char *command)
55{
56    Char   *name, *cmd_p;
57
58    /* trim off the whitespace at the beginning */
59    while (*command == ' ' || *command == '\t')
60        command++;
61
62    /* copy the string to a safe place */
63    name = Strsave(command);
64    cleanup_push(name, xfree);
65
66    /* trim off the whitespace that may be at the end */
67    for (cmd_p = name;
68	 *cmd_p != ' ' && *cmd_p != '\t' && *cmd_p != '\0'; cmd_p++)
69	continue;
70    *cmd_p = '\0';
71
72    /* if nothing left, return */
73    if (*name == '\0') {
74	cleanup_until(name);
75	return;
76    }
77
78    if (adrof1(STRhelpcommand, &aliases)) {	/* if we have an alias */
79	jmp_buf_t osetexit;
80	size_t omark;
81
82	getexit(osetexit);	/* make sure to come back here */
83	omark = cleanup_push_mark();
84	if (setexit() == 0)
85	    aliasrun(2, STRhelpcommand, name);	/* then use it. */
86	cleanup_pop_mark(omark);
87	resexit(osetexit);	/* and finish up */
88    }
89    else {			/* else cat something to them */
90	Char *thpath, *hpath;	/* The environment parameter */
91	Char *curdir;	        /* Current directory being looked at */
92	struct Strbuf full = Strbuf_INIT;
93
94	/* got is, now "cat" the file based on the path $HPATH */
95
96	hpath = str2short(getenv(SEARCHLIST));
97	if (hpath == NULL)
98	    hpath = str2short(DEFAULTLIST);
99	thpath = hpath = Strsave(hpath);
100	cleanup_push(thpath, xfree);
101	curdir = xmalloc((Strlen(thpath) + 1) * sizeof (*curdir));
102	cleanup_push(curdir, xfree);
103	cleanup_push(&full, Strbuf_cleanup);
104
105	for (;;) {
106	    const char *const *sp;
107	    size_t ep;
108
109	    if (!*hpath) {
110		xprintf(CGETS(29, 1, "No help file for %S\n"), name);
111		break;
112	    }
113	    nextslist(hpath, curdir);
114	    hpath = skipslist(hpath);
115
116	    /*
117	     * now make the full path name - try first /bar/foo.help, then
118	     * /bar/foo.1, /bar/foo.8, then finally /bar/foo.6.  This is so
119	     * that you don't spit a binary at the tty when $HPATH == $PATH.
120	     */
121	    full.len = 0;
122	    Strbuf_append(&full, curdir);
123	    Strbuf_append(&full, STRslash);
124	    Strbuf_append(&full, name);
125	    ep = full.len;
126	    for (sp = h_ext; *sp; sp++) {
127		full.len = ep;
128		Strbuf_append(&full, str2short(*sp));
129		Strbuf_terminate(&full);
130		if ((f = xopen(short2str(full.s), O_RDONLY|O_LARGEFILE)) != -1)
131		    break;
132	    }
133	    if (f != -1) {
134	        unsigned char buf[512];
135		sigset_t oset, set;
136		struct sigaction osa, sa;
137		ssize_t len;
138
139		/* so cat it to the terminal */
140		cleanup_push(&f, open_cleanup);
141		sa.sa_handler = cleanf;
142		sigemptyset(&sa.sa_mask);
143		sa.sa_flags = 0;
144		(void)sigaction(SIGINT, &sa, &osa);
145		cleanup_push(&osa, sigint_cleanup);
146		(void)sigprocmask(SIG_UNBLOCK, &set, &oset);
147		cleanup_push(&oset, sigprocmask_cleanup);
148		while ((len = xread(f, buf, sizeof(buf))) > 0)
149		    (void) xwrite(SHOUT, buf, len);
150		cleanup_until(&f);
151#ifdef convex
152		/* print error in case file is migrated */
153		if (len == -1)
154		    stderror(ERR_SYSTEM, progname, strerror(errno));
155#endif /* convex */
156		break;
157	    }
158	}
159    }
160    cleanup_until(name);
161}
162
163static void
164/*ARGSUSED*/
165cleanf(int snum)
166{
167    USE(snum);
168    if (f != -1)
169	xclose(f);
170    f = -1;
171}
172
173/* these next two are stolen from CMU's man(1) command for looking down
174 * paths.  they are prety straight forward. */
175
176/*
177 * nextslist takes a search list and copies the next path in it
178 * to np.  A null search list entry is expanded to ".".
179 * If there are no entries in the search list, then np will point
180 * to a null string.
181 */
182
183static void
184nextslist(const Char *sl, Char *np)
185{
186    if (!*sl)
187	*np = '\000';
188    else if (*sl == ':') {
189	*np++ = '.';
190	*np = '\000';
191    }
192    else {
193	while (*sl && *sl != ':')
194	    *np++ = *sl++;
195	*np = '\000';
196    }
197}
198
199/*
200 * skipslist returns the pointer to the next entry in the search list.
201 */
202
203static Char *
204skipslist(Char *sl)
205{
206    while (*sl && *sl++ != ':')
207	continue;
208    return (sl);
209}
210