NetBSD/usr.bin/vi/ex/ex_cscope.c

/*-
 * Copyright (c) 1994, 1996
 *	Rob Mayoff.  All rights reserved.
 * Copyright (c) 1996
 *	Keith Bostic.  All rights reserved.
 *
 * See the LICENSE file for redistribution information.
 */

#include "config.h"

#ifndef lint
static const char sccsid[] = "@(#)ex_cscope.c	10.6 (Berkeley) 5/16/96";
#endif /* not lint */

#include <sys/param.h>
#include <sys/types.h>		/* XXX: param.h may not have included types.h */
#include <sys/queue.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>

#include <bitstring.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>

#include "../common/common.h"
#include "tag.h"

#define	CSCOPE_DBFILE		"cscope.out"
#define	CSCOPE_PATHS		"cscope.tpath"

/*
 * 0name	find all uses of name
 * 1name	find definition of name
 * 2name	find all function calls made from name
 * 3name	find callers of name
 * 4string	find text string (cscope 12.9)
 * 4name	find assignments to name (cscope 13.3)
 * 5pattern	change pattern -- NOT USED
 * 6pattern	find pattern
 * 7name	find files with name as substring
 * 8name	find files #including name
 */
#define	FINDHELP "\
find c|d|e|f|g|i|s|t buffer|pattern\n\
      c: find callers of name\n\
      d: find all function calls made from name\n\
      e: find pattern\n\
      f: find files with name as substring\n\
      g: find definition of name\n\
      i: find files #including name\n\
      s: find all uses of name\n\
      t: find assignments to name"

static int cscope_add __P((SCR *, EXCMD *, char *));
static int cscope_find __P((SCR *, EXCMD*, char *));
static int cscope_help __P((SCR *, EXCMD *, char *));
static int cscope_kill __P((SCR *, EXCMD *, char *));
static int cscope_reset __P((SCR *, EXCMD *, char *));

typedef struct _cc {
	char	 *name;
	int	(*function) __P((SCR *, EXCMD *, char *));
	char	 *help_msg;
	char	 *usage_msg;
} CC;

static CC const cscope_cmds[] = {
	{ "add",   cscope_add,
	   "Add a new cscope database", "add db-name" },
	{ "find",  cscope_find,
	  "Query the databases for a pattern", FINDHELP },
	{ "help",  cscope_help,
	  "Show help for cscope commands", "help [command]" },
	{ "kill",  cscope_kill,
	  "Kill a cscope connection", "kill number" },
	{ "reset", cscope_reset,
	  "Discard all current cscope connections", "reset" },
	{ NULL }
};

static TAGQ	*create_cs_cmd __P((SCR *, char *, size_t *));
static int	 csc_help __P((SCR *, char *));
static void	 csc_file __P((SCR *,
		    CSC *, char *, char **, size_t *, int *));
static int	 get_paths __P((SCR *, CSC *));
static CC const	*lookup_ccmd __P((char *));
static int	 parse __P((SCR *, CSC *, TAGQ *, int *));
static int	 read_prompt __P((SCR *, CSC *));
static int	 run_cscope __P((SCR *, CSC *));
static int	 start_cscopes __P((SCR *, EXCMD *));
static int	 terminate __P((SCR *, CSC *, int));

/*
 * ex_cscope --
 *	Perform an ex cscope.
 *
 * PUBLIC: int ex_cscope __P((SCR *, EXCMD *));
 */
int
ex_cscope(sp, cmdp)
	SCR *sp;
	EXCMD *cmdp;
{
	CC const *ccp;
	EX_PRIVATE *exp;
	int i;
	char *cmd, *p;

	/* Initialize the default cscope directories. */
	exp = EXP(sp);
	if (!F_ISSET(exp, EXP_CSCINIT) && start_cscopes(sp, cmdp))
		return (1);
	F_SET(exp, EXP_CSCINIT);

	/* Skip leading whitespace. */
	for (p = cmdp->argv[0]->bp, i = cmdp->argv[0]->len; i > 0; --i, ++p)
		if (!isspace(*p))
			break;
	if (i == 0)
		goto usage;

	/* Skip the command to any arguments. */
	for (cmd = p; i > 0; --i, ++p)
		if (isspace(*p))
			break;
	if (*p != '\0') {
		*p++ = '\0';
		for (; *p && isspace(*p); ++p);
	}

	if ((ccp = lookup_ccmd(cmd)) == NULL) {
usage:		msgq(sp, M_ERR, "309|Use \"cscope help\" for help");
		return (1);
	}

	/* Call the underlying function. */
	return (ccp->function(sp, cmdp, p));
}

/*
 * start_cscopes --
 *	Initialize the cscope package.
 */
static int
start_cscopes(sp, cmdp)
	SCR *sp;
	EXCMD *cmdp;
{
	size_t blen, len;
	char *bp, *cscopes, *p;

	/*
	 * EXTENSION #1:
	 *
	 * If the CSCOPE_DIRS environment variable is set, we treat it as a
	 * list of cscope directories that we're using, similar to the tags
	 * edit option.
	 *
	 * XXX
	 * This should probably be an edit option, although that implies that
	 * we start/stop cscope processes periodically, instead of once when
	 * the editor starts.
	 */
	if ((cscopes = getenv("CSCOPE_DIRS")) == NULL)
		return (0);
	len = strlen(cscopes);
	GET_SPACE_RET(sp, bp, blen, len);
	memcpy(bp, cscopes, len + 1);

	for (cscopes = bp; (p = strsep(&bp, "\t ")) != NULL;)
		if (*p != '\0')
			(void)cscope_add(sp, cmdp, p);
	return (0);
}

/*
 * cscope_add --
 *	The cscope add command.
 */
static int
cscope_add(sp, cmdp, dname)
	SCR *sp;
	EXCMD *cmdp;
	char *dname;
{
	struct stat sb;
	EX_PRIVATE *exp;
	CSC *csc;
	size_t len;
	char path[MAXPATHLEN];

	exp = EXP(sp);

	if (argv_exp2(sp, cmdp, dname, strlen(dname)))
		return (1);
	/*
	 *  0 args: impossible.
	 *  1 args: usage.
	 *  2 args: matched a directory.
	 * >2 args: object, too many args.
	 *
	 * The 1 args case depends on the argv_sexp() function refusing
	 * to return success without at least one non-blank character.
	 */
	switch (cmdp->argc) {
	case 0:
		abort();
		/* NOTREACHED */
	case 1:
		(void)csc_help(sp, "add");
		return (1);
	case 2:
		dname = cmdp->argv[1]->bp;
		break;
	default:
		ex_emsg(sp, dname, EXM_FILECOUNT);
		return (1);
	}

	/* If the database file doesn't exist, we're done. */
	(void)snprintf(path, sizeof(path),
	    "%s/%s", cmdp->argv[1]->bp, CSCOPE_DBFILE);
	if (stat(path, &sb)) {
		msgq(sp, M_SYSERR, path);
		return (1);
	}

	/* Allocate a cscope connection structure and initialize its fields. */
	len = strlen(dname);
	CALLOC_RET(sp, csc, CSC *, 1, sizeof(CSC) + len);
	csc->dname = csc->buf;
	csc->dlen = len;
	memcpy(csc->dname, dname, len);
	csc->mtime = sb.st_mtime;

	/* Get the search paths for the cscope. */
	if (get_paths(sp, csc))
		goto err;

	/* Start the cscope process. */
	if (run_cscope(sp, csc))
		goto err;

	/*
	 * Add the cscope connection to the screen's list.  From now on, 
	 * on error, we have to call terminate, which expects the csc to
	 * be on the chain.
	 */
	LIST_INSERT_HEAD(&exp->cscq, csc, q);

	/* Read the initial prompt from the cscope to make sure it's okay. */
	if (read_prompt(sp, csc)) {
		terminate(sp, csc, 0);
		return (1);
	}

	return (0);

err:	free(csc);
	return (1);
}

/*
 * get_paths --
 *	Get the directories to search for the files associated with this
 *	cscope database.
 */
static int
get_paths(sp, csc)
	SCR *sp;
	CSC *csc;
{
	struct stat sb;
	int fd, nentries;
	size_t len;
	char *p, **pathp, buf[MAXPATHLEN * 2];

	/*
	 * EXTENSION #2:
	 *
	 * If there's a cscope directory with a file named CSCOPE_PATHS, it
	 * contains a colon-separated list of paths in which to search for
	 * files returned by cscope.
	 *
	 * XXX
	 * These paths are absolute paths, and not relative to the cscope
	 * directory.  To fix this, rewrite the each path using the cscope
	 * directory as a prefix.
	 */
	(void)snprintf(buf, sizeof(buf), "%s/%s", csc->dname, CSCOPE_PATHS);
	if (stat(buf, &sb) == 0) {
		/* Read in the CSCOPE_PATHS file. */
		len = sb.st_size;
		MALLOC_RET(sp, csc->pbuf, char *, len + 1);
		if ((fd = open(buf, O_RDONLY, 0)) < 0 ||
		    read(fd, csc->pbuf, len) != len) {
			 msgq_str(sp, M_SYSERR, buf, "%s");
			 if (fd >= 0)
				(void)close(fd);
			 return (1);
		}
		(void)close(fd);
		csc->pbuf[len] = '\0';

		/* Count up the entries. */
		for (nentries = 0, p = csc->pbuf; *p != '\0'; ++p)
			if (p[0] == ':' && p[1] != '\0')
				++nentries;

		/* Build an array of pointers to the paths. */
		CALLOC_GOTO(sp,
		    csc->paths, char **, nentries + 1, sizeof(char **));
		for (pathp = csc->paths, p = strtok(csc->pbuf, ":");
		    p != NULL; p = strtok(NULL, ":"))
			*pathp++ = p;
		return (0);
	}

	/*
	 * If the CSCOPE_PATHS file doesn't exist, we look for files
	 * relative to the cscope directory.
	 */
	if ((csc->pbuf = strdup(csc->dname)) == NULL) {
		msgq(sp, M_SYSERR, NULL);
		return (1);
	}
	CALLOC_GOTO(sp, csc->paths, char **, 2, sizeof(char *));
	csc->paths[0] = csc->pbuf;
	return (0);

alloc_err:
	if (csc->pbuf != NULL) {
		free(csc->pbuf);
		csc->pbuf = NULL;
	}
	return (1);
}

/*
 * run_cscope --
 *	Fork off the cscope process.
 */
static int
run_cscope(sp, csc)
	SCR *sp;
	CSC *csc;
{
	int to_cs[2], from_cs[2];
	char cmd[MAXPATHLEN * 2];

	/*
	 * Cscope reads from to_cs[0] and writes to from_cs[1]; vi reads from
	 * from_cs[0] and writes to to_cs[1].
	 */
	to_cs[0] = to_cs[1] = from_cs[0] = from_cs[0] = -1;
	if (pipe(to_cs) < 0 || pipe(from_cs) < 0) {
		msgq(sp, M_SYSERR, "pipe");
		goto err;
	}
	switch (csc->pid = vfork()) {
	case -1:
		msgq(sp, M_SYSERR, "vfork");
err:		if (to_cs[0] != -1)
			(void)close(to_cs[0]);
		if (to_cs[1] != -1)
			(void)close(to_cs[1]);
		if (from_cs[0] != -1)
			(void)close(from_cs[0]);
		if (from_cs[1] != -1)
			(void)close(from_cs[1]);
		return (1);
	case 0:				/* child: run cscope. */
		(void)dup2(to_cs[0], STDIN_FILENO);
		(void)dup2(from_cs[1], STDOUT_FILENO);
		(void)dup2(from_cs[1], STDERR_FILENO);

		/* Close unused file descriptors. */
		(void)close(to_cs[1]);
		(void)close(from_cs[0]);

		/* Run the cscope command. */
#define	CSCOPE_CMD_FMT		"cd '%s' && exec cscope -dl"
		(void)snprintf(cmd, sizeof(cmd), CSCOPE_CMD_FMT, csc->dname);
		(void)execl("/bin/sh", "sh", "-c", cmd, NULL);
		msgq_str(sp, M_SYSERR, cmd, "execl: %s");
		_exit (127);
		/* NOTREACHED */
	default:			/* parent. */
		/* Close unused file descriptors. */
		(void)close(to_cs[0]);
		(void)close(from_cs[1]);

		/*
		 * Save the file descriptors for later duplication, and
		 * reopen as streams.
		 */
		csc->to_fd = to_cs[1];
		csc->to_fp = fdopen(to_cs[1], "w");
		csc->from_fd = from_cs[0];
		csc->from_fp = fdopen(from_cs[0], "r");
		break;
	}
	return (0);
}

/*
 * cscope_find --
 *	The cscope find command.
 */
static int
cscope_find(sp, cmdp, pattern)
	SCR *sp;
	EXCMD *cmdp;
	char *pattern;
{
	CSC *csc, *csc_next;
	EX_PRIVATE *exp;
	FREF *frp;
	TAGQ *rtqp, *tqp;
	TAG *rtp;
	recno_t lno;
	size_t cno, search;
	int force, istmp, matches;

	exp = EXP(sp);

	/* Check for connections. */
	if (exp->cscq.lh_first == NULL) {
		msgq(sp, M_ERR, "310|No cscope connections running");
		return (1);
	}

	/*
	 * Allocate all necessary memory before doing anything hard.  If the
	 * tags stack is empty, we'll need the `local context' TAGQ structure
	 * later.
	 */
	rtp = NULL;
	rtqp = NULL;
	if (exp->tq.cqh_first == (void *)&exp->tq) {
		/* Initialize the `local context' tag queue structure. */
		CALLOC_GOTO(sp, rtqp, TAGQ *, 1, sizeof(TAGQ));
		CIRCLEQ_INIT(&rtqp->tagq);

		/* Initialize and link in its tag structure. */
		CALLOC_GOTO(sp, rtp, TAG *, 1, sizeof(TAG));
		CIRCLEQ_INSERT_HEAD(&rtqp->tagq, rtp, q);
		rtqp->current = rtp; 
	}

	/* Create the cscope command. */
	if ((tqp = create_cs_cmd(sp, pattern, &search)) == NULL)
		goto err;

	/*
	 * Stick the current context in a convenient place, we'll lose it
	 * when we switch files.
	 */
	frp = sp->frp;
	lno = sp->lno;
	cno = sp->cno;
	istmp = F_ISSET(sp->frp, FR_TMPFILE) && !F_ISSET(cmdp, E_NEWSCREEN);

	/* Search all open connections for a match. */
	matches = 0;
	for (csc = exp->cscq.lh_first; csc != NULL; csc = csc_next) {
		/* Copy csc->q.lh_next here in case csc is killed. */
		csc_next = csc->q.le_next;

		/*
		 * Send the command to the cscope program.  (We skip the
		 * first two bytes of the command, because we stored the
		 * search cscope command character and a leading space
		 * there.)
		 */
		(void)fprintf(csc->to_fp, "%d%s\n", search, tqp->tag + 2);
		(void)fflush(csc->to_fp);

		/* Read the output. */
		if (parse(sp, csc, tqp, &matches)) {
			if (rtqp != NULL)
				free(rtqp);
			tagq_free(sp, tqp);
			return (1);
		}
	}

	if (matches == 0) {
		msgq(sp, M_INFO, "278|No matches for query");
		return (0);
	}

	tqp->current = tqp->tagq.cqh_first;

	/* Try to switch to the first tag. */
	force = FL_ISSET(cmdp->iflags, E_C_FORCE);
	if (F_ISSET(cmdp, E_NEWSCREEN)) {
		if (ex_tag_Nswitch(sp, tqp->current, force))
			goto err;

		/* Everything else gets done in the new screen. */
		sp = sp->nextdisp;
		exp = EXP(sp);
	} else
		if (ex_tag_nswitch(sp, tqp->current, force))
			goto err;

	/*
	 * If this is the first tag, put a `current location' queue entry
	 * in place, so we can pop all the way back to the current mark.
	 * Note, it doesn't point to much of anything, it's a placeholder.
	 */
	if (exp->tq.cqh_first == (void *)&exp->tq) {
		CIRCLEQ_INSERT_HEAD(&exp->tq, rtqp, q);
	} else
		rtqp = exp->tq.cqh_first;

	/* Link the current TAGQ structure into place. */
	CIRCLEQ_INSERT_HEAD(&exp->tq, tqp, q);

	(void)cscope_search(sp, tqp, tqp->current);

	/*
	 * Move the current context from the temporary save area into the
	 * right structure.
	 *
	 * If we were in a temporary file, we don't have a context to which
	 * we can return, so just make it be the same as what we're moving
	 * to.  It will be a little odd that ^T doesn't change anything, but
	 * I don't think it's a big deal.
	 */
	if (istmp) {
		rtqp->current->frp = sp->frp;
		rtqp->current->lno = sp->lno;
		rtqp->current->cno = sp->cno;
	} else {
		rtqp->current->frp = frp;
		rtqp->current->lno = lno;
		rtqp->current->cno = cno;
	}

	return (0);

err:
alloc_err:
	if (rtqp != NULL)
		free(rtqp);
	if (rtp != NULL)
		free(rtp);
	return (1);
}

/*
 * create_cs_cmd --
 *	Build a cscope command, creating and initializing the base TAGQ.
 */
static TAGQ *
create_cs_cmd(sp, pattern, searchp)
	SCR *sp;
	char *pattern;
	size_t *searchp;
{
	CB *cbp;
	TAGQ *tqp;
	size_t tlen;
	char *p;

	/*
	 * Cscope supports a "change pattern" command which we never use,
	 * cscope command 5.  Set CSCOPE_QUERIES[5] to " " since the user
	 * can't pass " " as the first character of pattern.  That way the
	 * user can't ask for pattern 5 so we don't need any special-case
	 * code.
	 */
#define	CSCOPE_QUERIES		"sgdct efi"

	if (pattern == NULL)
		goto usage;

	/* Skip leading blanks, check for command character. */
	for (; isblank(pattern[0]); ++pattern);
	if (pattern[0] == '\0' || !isblank(pattern[1]))
		goto usage;
	for (*searchp = 0, p = CSCOPE_QUERIES;
	    *p != '\0' && *p != pattern[0]; ++*searchp, ++p);
	if (*p == '\0') {
		msgq(sp, M_ERR,
		    "311|%s: unknown search type: use one of %s",
		    KEY_NAME(sp, pattern[0]), CSCOPE_QUERIES);
		return (NULL);
	}

	/* Skip <blank> characters to the pattern. */
	for (p = pattern + 1; *p != '\0' && isblank(*p); ++p);
	if (*p == '\0') {
usage:		(void)csc_help(sp, "find");
		return (NULL);
	}

	/* The user can specify the contents of a buffer as the pattern. */
	cbp = NULL;
	if (p[0] == '"' && p[1] != '\0' && p[2] == '\0')
		CBNAME(sp, cbp, p[1]);
	if (cbp != NULL) {
		p = cbp->textq.cqh_first->lb;
		tlen = cbp->textq.cqh_first->len;
	} else
		tlen = strlen(p);

	/* Allocate and initialize the TAGQ structure. */
	CALLOC(sp, tqp, TAGQ *, 1, sizeof(TAGQ) + tlen + 3);
	if (tqp == NULL)
		return (NULL);
	CIRCLEQ_INIT(&tqp->tagq);
	tqp->tag = tqp->buf;
	tqp->tag[0] = pattern[0];
	tqp->tag[1] = ' ';
	tqp->tlen = tlen + 2;
	memcpy(tqp->tag + 2, p, tlen);
	tqp->tag[tlen + 2] = '\0';
	F_SET(tqp, TAG_CSCOPE);

	return (tqp);
}

/*
 * parse --
 *	Parse the cscope output.
 */
static int
parse(sp, csc, tqp, matchesp)
	SCR *sp;
	CSC *csc;
	TAGQ *tqp;
	int *matchesp;
{
	TAG *tp;
	recno_t slno;
	size_t dlen, nlen, slen;
	int ch, i, isnewer, nlines;
	char *dname, *name, *search, *p, *t, dummy[2], buf[2048];

	for (;;) {
		if (!fgets(buf, sizeof(buf), csc->from_fp))
			goto io_err;

		/*
		 * If the database is out of date, or there's some other
		 * problem, cscope will output error messages before the
		 * number-of-lines output.  Display/discard any output
		 * that doesn't match what we want.
		 */
#define	CSCOPE_NLINES_FMT	"cscope: %d lines%1[\n]"
		if (sscanf(buf, CSCOPE_NLINES_FMT, &nlines, dummy) == 2)
			break;
		if ((p = strchr(buf, '\n')) != NULL)
			*p = '\0';
		msgq(sp, M_ERR, "%s: \"%s\"", csc->dname, buf);
	}

	while (nlines--) {
		if (fgets(buf, sizeof(buf), csc->from_fp) == NULL)
			goto io_err;

		/* If the line's too long for the buffer, discard it. */
		if ((p = strchr(buf, '\n')) == NULL) {
			while ((ch = getc(csc->from_fp)) != EOF && ch != '\n');
			continue;
		}
		*p = '\0';

		/*
		 * The cscope output is in the following format:
		 *
		 *	<filename> <context> <line number> <pattern>
		 *
		 * Figure out how long everything is so we can allocate in one
		 * swell foop, but discard anything that looks wrong.
		 */
		for (p = buf, i = 0;
		    i < 3 && (t = strsep(&p, "\t ")) != NULL; ++i)
			switch (i) {
			case 0:			/* Filename. */
				name = t;
				nlen = strlen(name);
				break;
			case 1:			/* Context. */
				break;
			case 2:			/* Line number. */
				slno = (recno_t)atol(t);
				break;
			}
		if (i != 3 || p == NULL || t == NULL)
			continue;

		/* The rest of the string is the search pattern. */
		search = p;
		slen = strlen(p);

		/* Resolve the file name. */
		csc_file(sp, csc, name, &dname, &dlen, &isnewer);

		/*
		 * If the file was modified less recently than the cscope
		 * database, or there wasn't a search string, use the line
		 * number.
		 */
		if (!isnewer || strcmp(search, "<unknown>") == 0) {
			search = NULL;
			slen = 0;
		}

		/*
		 * Allocate and initialize a tag structure plus the variable
		 * length cscope information that follows it.
		 */
		CALLOC_RET(sp, tp,
		    TAG *, 1, sizeof(TAG) + dlen + 2 + nlen + 1 + slen + 1);
		tp->fname = tp->buf;
		if (dlen != 0) {
			memcpy(tp->fname, dname, dlen);
			tp->fname[dlen] = '/';
			++dlen;
		}
		memcpy(tp->fname + dlen, name, nlen + 1);
		tp->fnlen = dlen + nlen;
		tp->slno = slno;
		if (slen != 0) {
			tp->search = tp->fname + tp->fnlen + 1;
			memcpy(tp->search, search, (tp->slen = slen) + 1);
		}
		CIRCLEQ_INSERT_TAIL(&tqp->tagq, tp, q);

		++*matchesp;
	}

	(void)read_prompt(sp, csc);
	return (0);

io_err:	if (feof(csc->from_fp))
		errno = EIO;
	msgq_str(sp, M_SYSERR, "%s", csc->dname);
	terminate(sp, csc, 0);
	return (1);
}

/*
 * csc_file --
 *	Search for the right path to this file.
 */
static void
csc_file(sp, csc, name, dirp, dlenp, isnewerp)
	SCR *sp;
	CSC *csc;
	char *name, **dirp;
	size_t *dlenp;
	int *isnewerp;
{
	struct stat sb;
	char **pp, buf[MAXPATHLEN];

	/*
	 * Check for the file in all of the listed paths.  If we don't
	 * find it, we simply return it unchanged.  We have to do this
	 * now, even though it's expensive, because if the user changes
	 * directories, we can't change our minds as to where the file
	 * lives.
	 */
	for (pp = csc->paths; *pp != NULL; ++pp) {
		(void)snprintf(buf, sizeof(buf), "%s/%s", *pp, name);
		if (stat(buf, &sb) == 0) {
			*dirp = *pp;
			*dlenp = strlen(*pp);
			*isnewerp = sb.st_mtime >= csc->mtime;
			return;
		}
	}
	*dlenp = 0;
}

/*
 * cscope_help --
 *	The cscope help command.
 */
static int
cscope_help(sp, cmdp, subcmd)
	SCR *sp;
	EXCMD *cmdp;
	char *subcmd;
{
	return (csc_help(sp, subcmd));
}

/*
 * csc_help --
 *	Display help/usage messages.
 */
static int
csc_help(sp, cmd)
	SCR *sp;
	char *cmd;
{
	CC const *ccp;

	if (cmd != NULL && *cmd != '\0')
		if ((ccp = lookup_ccmd(cmd)) == NULL) {
			ex_printf(sp,
			    "%s doesn't match any cscope command\n", cmd);
			return (1);
		} else {
			ex_printf(sp,
		          "Command: %s (%s)\n", ccp->name, ccp->help_msg);
			ex_printf(sp, "  Usage: %s\n", ccp->usage_msg);
			return (0);
		}

	ex_printf(sp, "cscope commands:\n");
	for (ccp = cscope_cmds; ccp->name != NULL; ++ccp)
		ex_printf(sp, "  %*s: %s\n", 5, ccp->name, ccp->help_msg);
	return (0);
}

/*
 * cscope_kill --
 *	The cscope kill command.
 */
static int
cscope_kill(sp, cmdp, cn)
	SCR *sp;
	EXCMD *cmdp;
	char *cn;
{
	return (terminate(sp, NULL, atoi(cn)));
}

/*
 * terminate --
 *	Detach from a cscope process.
 */
static int
terminate(sp, csc, n)
	SCR *sp;
	CSC *csc;
	int n;
{
	EX_PRIVATE *exp;
	int i, pstat;

	exp = EXP(sp);

	/*
	 * We either get a csc structure or a number.  If not provided a
	 * csc structure, find the right one.
	 */
	if (csc == NULL) {
		if (n < 1)
			goto badno;
		for (i = 1, csc = exp->cscq.lh_first;
		    csc != NULL; csc = csc->q.le_next, i++)
			if (i == n)
				break;
		if (csc == NULL) {
badno:			msgq(sp, M_ERR, "312|%d: no such cscope session", n);
			return (1);
		}
	}

	/*
	 * XXX
	 * Theoretically, we have the only file descriptors to the process,
	 * so closing them should let it exit gracefully, deleting temporary
	 * files, etc.  The original vi cscope integration sent the cscope
	 * connection a SIGTERM signal, so I'm not sure if closing the file
	 * descriptors is sufficient.
	 */
	if (csc->from_fp != NULL)
		(void)fclose(csc->from_fp);
	if (csc->to_fp != NULL)
		(void)fclose(csc->to_fp);
	(void)waitpid(csc->pid, &pstat, 0);

	/* Discard cscope connection information. */
	LIST_REMOVE(csc, q);
	if (csc->pbuf != NULL)
		free(csc->pbuf);
	if (csc->paths != NULL)
		free(csc->paths);
	free(csc);
	return (0);
}

/*
 * cscope_reset --
 *	The cscope reset command.
 */
static int
cscope_reset(sp, cmdp, notusedp)
	SCR *sp;
	EXCMD *cmdp;
	char *notusedp;
{
	EX_PRIVATE *exp;

	for (exp = EXP(sp); exp->cscq.lh_first != NULL;)
		if (cscope_kill(sp, cmdp, "1"))
			return (1);
	return (0);
}

/*
 * cscope_display --
 *	Display current connections.
 *
 * PUBLIC: int cscope_display __P((SCR *));
 */
int
cscope_display(sp)
	SCR *sp;
{
	EX_PRIVATE *exp;
	CSC *csc;
	int i;

	exp = EXP(sp);
	if (exp->cscq.lh_first == NULL) {
		ex_printf(sp, "No cscope connections.\n");
		return (0);
	}
	for (i = 1,
	    csc = exp->cscq.lh_first; csc != NULL; ++i, csc = csc->q.le_next)
		ex_printf(sp,
		    "%2d %s (process %lu)\n", i, csc->dname, (u_long)csc->pid);
	return (0);
}

/*
 * cscope_search --
 *	Search a file for a cscope entry.
 *
 * PUBLIC: int cscope_search __P((SCR *, TAGQ *, TAG *));
 */
int
cscope_search(sp, tqp, tp)
	SCR *sp;
	TAGQ *tqp;
	TAG *tp;
{
	MARK m;

	/* If we don't have a search pattern, use the line number. */
	if (tp->search == NULL) {
		if (!db_exist(sp, tp->slno)) {
			tag_msg(sp, TAG_BADLNO, tqp->tag);
			return (1);
		}
		m.lno = tp->slno;
	} else {
		/*
		 * Search for the tag; cheap fallback for C functions
		 * if the name is the same but the arguments have changed.
		 */
		m.lno = 1;
		m.cno = 0;
		if (f_search(sp, &m, &m,
		    tp->search, NULL, SEARCH_CSCOPE | SEARCH_FILE)) {
			tag_msg(sp, TAG_SEARCH, tqp->tag);
			return (1);
		}

		/*
		 * !!!
		 * Historically, tags set the search direction if it wasn't
		 * already set.
		 */
		if (sp->searchdir == NOTSET)
			sp->searchdir = FORWARD;
	}

	/*
	 * !!!
	 * Tags move to the first non-blank, NOT the search pattern start.
	 */
	sp->lno = m.lno;
	sp->cno = 0;
	(void)nonblank(sp, sp->lno, &sp->cno);
	return (0);
}


/*
 * lookup_ccmd --
 *	Return a pointer to the command structure.
 */
static CC const *
lookup_ccmd(name)
	char *name;
{
	CC const *ccp;
	size_t len;

	len = strlen(name);
	for (ccp = cscope_cmds; ccp->name != NULL; ++ccp)
		if (strncmp(name, ccp->name, len) == 0)
			return (ccp);
	return (NULL);
}

/*
 * read_prompt --
 *	Read a prompt from cscope.
 */
static int
read_prompt(sp, csc)
	SCR *sp;
	CSC *csc;
{
	int ch;

#define	CSCOPE_PROMPT		">> "
	for (;;) {
		while ((ch =
		    getc(csc->from_fp)) != EOF && ch != CSCOPE_PROMPT[0]);
		if (ch == EOF) {
			terminate(sp, csc, 0);
			return (1);
		}
		if (getc(csc->from_fp) != CSCOPE_PROMPT[1])
			continue;
		if (getc(csc->from_fp) != CSCOPE_PROMPT[2])
			continue;
		break;
	}
	return (0);
}