history.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 * command history
 *
 * only implements in-memory history.
 */

/*
 *	This file contains
 *	a)	the original in-memory history  mechanism
 *	b)	a simple file saving history mechanism done by  sjg@zen
 *		define EASY_HISTORY to get this
 *	c)	a more complicated mechanism done by  [e-mail]
 *		that more closely follows the real ksh way of doing
 *		things. You need to have the mmap system call for this
 *		to work on your system
 */

#include "sh.h"
#include "ksh_stat.h"

#ifdef HISTORY
# ifdef EASY_HISTORY

#  ifndef HISTFILE
#   ifdef OS2
#    define HISTFILE "history.ksh"
#   else /* OS2 */
#    define HISTFILE ".pdksh_history"
#   endif /* OS2 */
#  endif

# else
/*	Defines and includes for the complicated case */

#  include <sys/file.h>
#  include <sys/mman.h>

/*
 *	variables for handling the data file
 */
static int	histfd;
static int	hsize;

static int hist_count_lines ARGS((unsigned char *, int));
static int hist_shrink ARGS((unsigned char *, int));
static unsigned char *hist_skip_back ARGS((unsigned char *,int *,int));
static void histload ARGS((Source *, unsigned char *, int));
static void histinsert ARGS((Source *, int, unsigned char *));
static void writehistfile ARGS((int, char *));
static int sprinkle ARGS((int));

#  ifdef MAP_FILE
#   define MAP_FLAGS	(MAP_FILE|MAP_PRIVATE)
#  else
#   define MAP_FLAGS	MAP_PRIVATE
#  endif

# endif	/* of EASY_HISTORY */

static int	hist_execute ARGS((char *cmd));
static int	hist_replace ARGS((char **hp, const char *pat, const char *rep,
				   int global));
static char   **hist_get ARGS((const char *str, int approx, int allow_cur));
static char   **hist_get_newest ARGS((int allow_cur));
static char   **hist_get_oldest ARGS(());
static void	histbackup ARGS((void));

static char   **current;	/* current postition in history[] */
static int	curpos;		/* current index in history[] */
static char    *hname;		/* current name of history file */
static int	hstarted;	/* set after hist_init() called */
static Source	*hist_source;


int
c_fc(wp)
	char **wp;
{
	struct shf *shf;
	struct temp UNINITIALIZED(*tf);
	char *p, *editor = (char *) 0;
	int gflag = 0, lflag = 0, nflag = 0, sflag = 0, rflag = 0;
	int optc;
	char *first = (char *) 0, *last = (char *) 0;
	char **hfirst, **hlast, **hp;

	while ((optc = ksh_getopt(wp, &builtin_opt, "e:glnrs0,1,2,3,4,5,6,7,8,9,")) != EOF)
		switch (optc) {
		  case 'e':
			p = builtin_opt.optarg;
			if (strcmp(p, "-") == 0)
				sflag++;
			else {
				editor = str_nsave(p, strlen(p) + 4, ATEMP);
				strcat(editor, " $_");
			}
			break;
		  case 'g': /* non-at&t ksh */
			gflag++;
			break;
		  case 'l':
			lflag++;
			break;
		  case 'n':
			nflag++;
			break;
		  case 'r':
			rflag++;
			break;
		  case 's':	/* posix version of -e - */
			sflag++;
			break;
		  /* kludge city - accept -num as -- -num (kind of) */
		  case '0': case '1': case '2': case '3': case '4':
		  case '5': case '6': case '7': case '8': case '9':
			p = shf_smprintf("-%c%s",
					optc, builtin_opt.optarg);
			if (!first)
				first = p;
			else if (!last)
				last = p;
			else {
				bi_errorf("too many arguments");
				return 1;
			}
			break;
		  case '?':
			return 1;
		}
	wp += builtin_opt.optind;

	/* Substitute and execute command */
	if (sflag) {
		char *pat = (char *) 0, *rep = (char *) 0;

		if (editor || lflag || nflag || rflag) {
			bi_errorf("can't use -e, -l, -n, -r with -s (-e -)");
			return 1;
		}

		/* Check for pattern replacement argument */
		if (*wp && **wp && (p = strchr(*wp + 1, '='))) {
			pat = str_save(*wp, ATEMP);
			p = pat + (p - *wp);
			*p++ = '\0';
			rep = p;
			wp++;
		}
		/* Check for search prefix */
		if (!first && (first = *wp))
			wp++;
		if (last || *wp) {
			bi_errorf("too many arguments");
			return 1;
		}

		hp = first ? hist_get(first, FALSE, FALSE)
			   : hist_get_newest(FALSE);
		if (!hp)
			return 1;
		return hist_replace(hp, pat, rep, gflag);
	}

	if (editor && (lflag || nflag)) {
		bi_errorf("can't use -l, -n with -e");
		return 1;
	}

	if (!first && (first = *wp))
		wp++;
	if (!last && (last = *wp))
		wp++;
	if (*wp) {
		bi_errorf("too many arguments");
		return 1;
	}
	if (!first) {
		hfirst = lflag ? hist_get("-16", TRUE, TRUE)
			       : hist_get_newest(FALSE);
		if (!hfirst)
			return 1;
		/* can't fail if hfirst didn't fail */
		hlast = hist_get_newest(FALSE);
	} else {
		/* POSIX says not an error if first/last out of bounds
		 * when range is specified; at&t ksh and pdksh allow out of
		 * bounds for -l as well.
		 */
		hfirst = hist_get(first, (lflag || last) ? TRUE : FALSE,
				lflag ? TRUE : FALSE);
		if (!hfirst)
			return 1;
		hlast = last ? hist_get(last, TRUE, lflag ? TRUE : FALSE)
			    : (lflag ? hist_get_newest(FALSE) : hfirst);
		if (!hlast)
			return 1;
	}
	if (hfirst > hlast) {
		char **temp;

		temp = hfirst; hfirst = hlast; hlast = temp;
		rflag = !rflag; /* POSIX */
	}

	/* List history */
	if (lflag) {
		char *s, *t;
		const char *nfmt = nflag ? "\t" : "%d\t";

		for (hp = rflag ? hlast : hfirst;
		     hp >= hfirst && hp <= hlast; hp += rflag ? -1 : 1)
		{
			shf_fprintf(shl_stdout, nfmt,
				hist_source->line - (int) (histptr - hp));
			/* print multi-line commands correctly */
			for (s = *hp; (t = strchr(s, '\n')); s = t)
				shf_fprintf(shl_stdout, "%.*s\t", ++t - s, s);
			shf_fprintf(shl_stdout, "%s\n", s);
		}
		shf_flush(shl_stdout);
		return 0;
	}

	/* Run editor on selected lines, then run resulting commands */

	tf = maketemp(ATEMP, TT_HIST_EDIT, &e->temps);
	if (!(shf = tf->shf)) {
		bi_errorf("cannot create temp file %s - %s",
			tf->name, strerror(errno));
		return 1;
	}
	for (hp = rflag ? hlast : hfirst;
	     hp >= hfirst && hp <= hlast; hp += rflag ? -1 : 1)
		shf_fprintf(shf, "%s\n", *hp);
	if (shf_close(shf) == EOF) {
		bi_errorf("error writing temporary file - %s", strerror(errno));
		return 1;
	}

	/* Ignore setstr errors here (arbitrary) */
	setstr(local("_", FALSE), tf->name, KSH_RETURN_ERROR);

	/* XXX: source should not get trashed by this.. */
	{
		Source *sold = source;
		int ret;

		ret = command(editor ? editor : "${FCEDIT:-/bin/ed} $_");
		source = sold;
		if (ret)
			return ret;
	}

	{
		struct stat statb;
		XString xs;
		char *xp;
		int n;

		if (!(shf = shf_open(tf->name, O_RDONLY, 0, 0))) {
			bi_errorf("cannot open temp file %s", tf->name);
			return 1;
		}

		n = fstat(shf_fileno(shf), &statb) < 0 ? 128
			: statb.st_size + 1;
		Xinit(xs, xp, n, hist_source->areap);
		while ((n = shf_read(xp, Xnleft(xs, xp), shf)) > 0) {
			xp += n;
			if (Xnleft(xs, xp) <= 0)
				XcheckN(xs, xp, Xlength(xs, xp));
		}
		if (n < 0) {
			bi_errorf("error reading temp file %s - %s",
				tf->name, strerror(shf_errno(shf)));
			shf_close(shf);
			return 1;
		}
		shf_close(shf);
		*xp = '\0';
		strip_nuls(Xstring(xs, xp), Xlength(xs, xp));
		return hist_execute(Xstring(xs, xp));
	}
}

/* Save cmd in history, execute cmd (cmd gets trashed) */
static int
hist_execute(cmd)
	char *cmd;
{
	Source *sold;
	int ret;
	char *p, *q;

	histbackup();

	for (p = cmd; p; p = q) {
		if ((q = strchr(p, '\n'))) {
			*q++ = '\0'; /* kill the newline */
			if (!*q) /* ignore trailing newline */
				q = (char *) 0;
		}
#ifdef EASY_HISTORY
		if (p != cmd)
			histappend(p, TRUE);
		else
#endif /* EASY_HISTORY */
			histsave(++(hist_source->line), p, 1);

		shellf("%s\n", p); /* POSIX doesn't say this is done... */
		if ((p = q)) /* restore \n (trailing \n not restored) */
			q[-1] = '\n';
	}

	/* Commands are executed here instead of pushing them onto the
	 * input 'cause posix says the redirection and variable assignments
	 * in
	 *	X=y fc -e - 42 2> /dev/null
	 * are to effect the repeated commands environment.
	 */
	/* XXX: source should not get trashed by this.. */
	sold = source;
	ret = command(cmd);
	source = sold;
	return ret;
}

static int
hist_replace(hp, pat, rep, global)
	char **hp;
	const char *pat;
	const char *rep;
	int global;
{
	char *line;

	if (!pat)
		line = str_save(*hp, ATEMP);
	else {
		char *s, *s1;
		int pat_len = strlen(pat);
		int rep_len = strlen(rep);
		int len;
		XString xs;
		char *xp;
		int any_subst = 0;

		Xinit(xs, xp, 128, ATEMP);
		for (s = *hp; (s1 = strstr(s, pat))
			      && (!any_subst || global) ; s = s1 + pat_len)
		{
			any_subst = 1;
			len = s1 - s;
			XcheckN(xs, xp, len + rep_len);
			memcpy(xp, s, len);		/* first part */
			xp += len;
			memcpy(xp, rep, rep_len);	/* replacement */
			xp += rep_len;
		}
		if (!any_subst) {
			bi_errorf("substitution failed");
			return 1;
		}
		len = strlen(s) + 1;
		XcheckN(xs, xp, len);
		memcpy(xp, s, len);
		xp += len;
		line = Xclose(xs, xp);
	}
	return hist_execute(line);
}

/*
 * get pointer to history given pattern
 * pattern is a number or string
 */
static char **
hist_get(str, approx, allow_cur)
	const char *str;
	int approx;
	int allow_cur;
{
	char **hp = (char **) 0;
	int n;

	if (getn(str, &n)) {
		hp = histptr + (n < 0 ? n : (n - hist_source->line));
		if (hp < history) {
			if (approx)
				hp = hist_get_oldest();
			else {
				bi_errorf("%s: not in history", str);
				hp = (char **) 0;
			}
		} else if (hp > histptr) {
			if (approx)
				hp = hist_get_newest(allow_cur);
			else {
				bi_errorf("%s: not in history", str);
				hp = (char **) 0;
			}
		} else if (!allow_cur && hp == histptr) {
			bi_errorf("%s: invalid range", str);
			hp = (char **) 0;
		}
	} else {
		int anchored = *str == '?' ? (++str, 0) : 1;

		/* the -1 is to avoid the current fc command */
		n = findhist(histptr - history - 1, 0, str, anchored);
		if (n < 0) {
			bi_errorf("%s: not in history", str);
			hp = (char **) 0;
		} else
			hp = &history[n];
	}
	return hp;
}

/* Return a pointer to the newest command in the history */
static char **
hist_get_newest(allow_cur)
	int allow_cur;
{
	if (histptr < history || (!allow_cur && histptr == history)) {
		bi_errorf("no history (yet)");
		return (char **) 0;
	}
	if (allow_cur)
		return histptr;
	return histptr - 1;
}

/* Return a pointer to the newest command in the history */
static char **
hist_get_oldest()
{
	if (histptr <= history) {
		bi_errorf("no history (yet)");
		return (char **) 0;
	}
	return history;
}

/******************************/
/* Back up over last histsave */
/******************************/
static void
histbackup()
{
	static int last_line = -1;

	if (histptr >= history && last_line != hist_source->line) {
		hist_source->line--;
		afree((void*)*histptr, APERM);
		histptr--;
		last_line = hist_source->line;
	}
}

/*
 * Return the current position.
 */
char **
histpos()
{
	return current;
}

int
histN()
{
	return curpos;
}

int
histnum(n)
	int	n;
{
	int	last = histptr - history;

	if (n < 0 || n >= last) {
		current = histptr;
		curpos = last;
		return last;
	} else {
		current = &history[n];
		curpos = n;
		return n;
	}
}

/*
 * This will become unecessary if hist_get is modified to allow
 * searching from positions other than the end, and in either
 * direction.
 */
int
findhist(start, fwd, str, anchored)
	int	start;
	int	fwd;
	const char  *str;
	int	anchored;
{
	char	**hp;
	int	maxhist = histptr - history;
	int	incr = fwd ? 1 : -1;
	int	len = strlen(str);

	if (start < 0 || start >= maxhist)
		start = maxhist;

	hp = &history[start];
	for (; hp >= history && hp <= histptr; hp += incr)
		if ((anchored && strncmp(*hp, str, len) == 0)
		    || (!anchored && strstr(*hp, str)))
			return hp - history;

	return -1;
}

/*
 *	set history
 *	this means reallocating the dataspace
 */
void
sethistsize(n)
	int n;
{
	if (n > 0 && n != histsize) {
		int cursize = histptr - history;

		/* save most recent history */
		if (n < cursize) {
			memmove(history, histptr - n, n * sizeof(char *));
			cursize = n;
		}

		history = (char **)aresize(history, n*sizeof(char *), APERM);

		histsize = n;
		histptr = history + cursize;
	}
}

/*
 *	set history file
 *	This can mean reloading/resetting/starting history file
 *	maintenance
 */
void
sethistfile(name)
	const char *name;
{
	/* if not started then nothing to do */
	if (hstarted == 0)
		return;

	/* if the name is the same as the name we have */
	if (hname && strcmp(hname, name) == 0)
		return;

	/*
	 * its a new name - possibly
	 */
# ifdef EASY_HISTORY
	if (hname) {
		afree(hname, APERM);
		hname = NULL;
	}
# else
	if (histfd) {
		/* yes the file is open */
		(void) close(histfd);
		histfd = 0;
		hsize = 0;
		afree(hname, APERM);
		hname = NULL;
		/* let's reset the history */
		histptr = history - 1;
		hist_source->line = 0;
	}
# endif

	hist_init(hist_source);
}

/*
 *	initialise the history vector
 */
void
init_histvec()
{
	if (history == (char **)NULL) {
		histsize = HISTORYSIZE;
		history = (char **)alloc(histsize*sizeof (char *), APERM);