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