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histrap.c
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/* $OpenBSD: history.c,v 1.41 2015/09/01 13:12:31 tedu Exp $ */
/* $OpenBSD: trap.c,v 1.23 2010/05/19 17:36:08 jasper Exp $ */
/*-
* Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
* 2011, 2012, 2014, 2015, 2016, 2017, 2018
* mirabilos <m@mirbsd.org>
*
* Provided that these terms and disclaimer and all copyright notices
* are retained or reproduced in an accompanying document, permission
* is granted to deal in this work without restriction, including un-
* limited rights to use, publicly perform, distribute, sell, modify,
* merge, give away, or sublicence.
*
* This work is provided "AS IS" and WITHOUT WARRANTY of any kind, to
* the utmost extent permitted by applicable law, neither express nor
* implied; without malicious intent or gross negligence. In no event
* may a licensor, author or contributor be held liable for indirect,
* direct, other damage, loss, or other issues arising in any way out
* of dealing in the work, even if advised of the possibility of such
* damage or existence of a defect, except proven that it results out
* of said person's immediate fault when using the work as intended.
*/
#include "sh.h"
#if HAVE_SYS_FILE_H
#include <sys/file.h>
#endif
__RCSID("$MirOS: src/bin/mksh/histrap.c,v 1.167 2018/04/28 17:16:54 tg Exp $");
Trap sigtraps[ksh_NSIG + 1];
static struct sigaction Sigact_ign;
#if HAVE_PERSISTENT_HISTORY
static int histload(Source *, unsigned char *, size_t);
static int writehistline(int, int, const char *);
static void writehistfile(int, const char *);
#endif
static int hist_execute(char *, Area *);
static char **hist_get(const char *, bool, bool);
static char **hist_get_oldest(void);
static bool hstarted; /* set after hist_init() called */
static Source *hist_source;
#if HAVE_PERSISTENT_HISTORY
/*XXX imake style */
#if defined(__linux)
#define caddr_cast(x) ((void *)(x))
#else
#define caddr_cast(x) ((caddr_t)(x))
#endif
/* several OEs do not have these constants */
#ifndef MAP_FAILED
#define MAP_FAILED caddr_cast(-1)
#endif
/* some OEs need the default mapping type specified */
#ifndef MAP_FILE
#define MAP_FILE 0
#endif
/* current history file: name, fd, size */
static char *hname;
static int histfd = -1;
static off_t histfsize;
#endif
/* HISTSIZE default: size of saved history, persistent or standard */
#ifdef MKSH_SMALL
#define MKSH_DEFHISTSIZE 255
#else
#define MKSH_DEFHISTSIZE 2047
#endif
/* maximum considered size of persistent history file */
#define MKSH_MAXHISTFSIZE ((off_t)1048576 * 96)
/* hidden option */
#define HIST_DISCARD 5
int
c_fc(const char **wp)
{
struct shf *shf;
struct temp *tf;
bool gflag = false, lflag = false, nflag = false, rflag = false,
sflag = false;
int optc;
const char *p, *first = NULL, *last = NULL;
char **hfirst, **hlast, **hp, *editor = NULL;
if (!Flag(FTALKING_I)) {
bi_errorf("history %ss not available", Tfunction);
return (1);
}
while ((optc = ksh_getopt(wp, &builtin_opt,
"e:glnrs0,1,2,3,4,5,6,7,8,9,")) != -1)
switch (optc) {
case 'e':
p = builtin_opt.optarg;
if (ksh_isdash(p))
sflag = true;
else {
size_t len = strlen(p);
/* almost certainly not overflowing */
editor = alloc(len + 4, ATEMP);
memcpy(editor, p, len);
memcpy(editor + len, Tspdollaru, 4);
}
break;
/* non-AT&T ksh */
case 'g':
gflag = true;
break;
case 'l':
lflag = true;
break;
case 'n':
nflag = true;
break;
case 'r':
rflag = true;
break;
/* POSIX version of -e - */
case 's':
sflag = true;
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(Ttoo_many_args);
return (1);
}
break;
case '?':
return (1);
}
wp += builtin_opt.optind;
/* Substitute and execute command */
if (sflag) {
char *pat = NULL, *rep = NULL, *line;
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 = cstrchr(*wp + 1, '='))) {
strdupx(pat, *wp, ATEMP);
rep = pat + (p - *wp);
*rep++ = '\0';
wp++;
}
/* Check for search prefix */
if (!first && (first = *wp))
wp++;
if (last || *wp) {
bi_errorf(Ttoo_many_args);
return (1);
}
hp = first ? hist_get(first, false, false) :
hist_get_newest(false);
if (!hp)
return (1);
/* hist_replace */
if (!pat)
strdupx(line, *hp, ATEMP);
else {
char *s, *s1;
size_t len, pat_len, rep_len;
XString xs;
char *xp;
bool any_subst = false;
pat_len = strlen(pat);
rep_len = strlen(rep);
Xinit(xs, xp, 128, ATEMP);
for (s = *hp; (s1 = strstr(s, pat)) &&
(!any_subst || gflag); s = s1 + pat_len) {
any_subst = true;
len = s1 - s;
XcheckN(xs, xp, len + rep_len);
/*; first part */
memcpy(xp, s, len);
xp += len;
/* replacement */
memcpy(xp, rep, rep_len);
xp += rep_len;
}
if (!any_subst) {
bi_errorf(Tbadsubst);
return (1);
}
len = strlen(s) + 1;
XcheckN(xs, xp, len);
memcpy(xp, s, len);
xp += len;
line = Xclose(xs, xp);
}
return (hist_execute(line, ATEMP));
}
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(Ttoo_many_args);
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, tobool(lflag || last), lflag);
if (!hfirst)
return (1);
hlast = last ? hist_get(last, true, lflag) :
(lflag ? hist_get_newest(false) : hfirst);
if (!hlast)
return (1);
}
if (hfirst > hlast) {
char **temp;
temp = hfirst; hfirst = hlast; hlast = temp;
/* POSIX */
rflag = !rflag;
}
/* List history */
if (lflag) {
char *s, *t;
for (hp = rflag ? hlast : hfirst;
hp >= hfirst && hp <= hlast; hp += rflag ? -1 : 1) {
if (!nflag)
shf_fprintf(shl_stdout, Tf_lu,
(unsigned long)hist_source->line -
(unsigned long)(histptr - hp));
shf_putc('\t', shl_stdout);
/* print multi-line commands correctly */
s = *hp;
while ((t = strchr(s, '\n'))) {
*t = '\0';
shf_fprintf(shl_stdout, "%s\n\t", s);
*t++ = '\n';
s = t;
}
shf_fprintf(shl_stdout, Tf_sN, 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(Tf_temp, Tcreate, tf->tffn, cstrerror(errno));
return (1);
}
for (hp = rflag ? hlast : hfirst;
hp >= hfirst && hp <= hlast; hp += rflag ? -1 : 1)
shf_fprintf(shf, Tf_sN, *hp);
if (shf_close(shf) == -1) {
bi_errorf(Tf_temp, Twrite, tf->tffn, cstrerror(errno));
return (1);
}
/* Ignore setstr errors here (arbitrary) */
setstr(local("_", false), tf->tffn, KSH_RETURN_ERROR);
if ((optc = command(editor ? editor : TFCEDIT_dollaru, 0)))
return (optc);
{
struct stat statb;
XString xs;
char *xp;
ssize_t n;
if (!(shf = shf_open(tf->tffn, O_RDONLY, 0, 0))) {
bi_errorf(Tf_temp, Topen, tf->tffn, cstrerror(errno));
return (1);
}
if (stat(tf->tffn, &statb) < 0)
n = 128;
else if ((off_t)statb.st_size > MKSH_MAXHISTFSIZE) {
bi_errorf(Tf_toolarge, Thistory,
Tfile, (unsigned long)statb.st_size);
goto errout;
} else
n = (size_t)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(Tf_temp, Tread, tf->tffn,
cstrerror(shf_errno(shf)));
errout:
shf_close(shf);
return (1);
}
shf_close(shf);
*xp = '\0';
strip_nuls(Xstring(xs, xp), Xlength(xs, xp));
return (hist_execute(Xstring(xs, xp), hist_source->areap));
}
}
/* save cmd in history, execute cmd (cmd gets afree’d) */
static int
hist_execute(char *cmd, Area *areap)
{
static int last_line = -1;
/* Back up over last histsave */
if (histptr >= history && last_line != hist_source->line) {
hist_source->line--;
afree(*histptr, APERM);
histptr--;
last_line = hist_source->line;
}
histsave(&hist_source->line, cmd, HIST_STORE, true);
/* now *histptr == cmd without all trailing newlines */
afree(cmd, areap);
cmd = *histptr;
/* pdksh says POSIX doesn’t say this is done, testsuite needs it */
shellf(Tf_sN, cmd);
/*-
* 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.
*/
return (command(cmd, 0));
}
/*
* get pointer to history given pattern
* pattern is a number or string
*/
static char **
hist_get(const char *str, bool approx, bool allow_cur)
{
char **hp = NULL;
int n;
if (getn(str, &n)) {
hp = histptr + (n < 0 ? n : (n - hist_source->line));
if ((size_t)hp < (size_t)history) {
if (approx)
hp = hist_get_oldest();
else {
bi_errorf(Tf_sD_s, str, Tnot_in_history);
hp = NULL;
}
} else if ((size_t)hp > (size_t)histptr) {
if (approx)
hp = hist_get_newest(allow_cur);
else {
bi_errorf(Tf_sD_s, str, Tnot_in_history);
hp = NULL;
}
} else if (!allow_cur && hp == histptr) {
bi_errorf(Tf_sD_s, str, "invalid range");
hp = NULL;
}
} else {
bool anchored = *str == '?' ? (++str, false) : true;
/* the -1 is to avoid the current fc command */
if ((n = findhist(histptr - history - 1, 0, str, anchored)) < 0)
bi_errorf(Tf_sD_s, str, Tnot_in_history);
else
hp = &history[n];
}
return (hp);
}
/* Return a pointer to the newest command in the history */
char **
hist_get_newest(bool allow_cur)
{
if (histptr < history || (!allow_cur && histptr == history)) {
bi_errorf("no history (yet)");
return (NULL);
}
return (allow_cur ? histptr : histptr - 1);
}
/* Return a pointer to the oldest command in the history */
static char **
hist_get_oldest(void)
{
if (histptr <= history) {
bi_errorf("no history (yet)");
return (NULL);
}
return (history);
}
#if !defined(MKSH_NO_CMDLINE_EDITING) && !MKSH_S_NOVI
/* current position in history[] */
static char **current;
/*
* Return the current position.
*/
char **
histpos(void)
{
return (current);
}
int
histnum(int n)
{
int last = histptr - history;
if (n < 0 || n >= last) {
current = histptr;
return (last);
} else {
current = &history[n];
return (n);
}
}
#endif
/*
* This will become unnecessary if hist_get is modified to allow
* searching from positions other than the end, and in either
* direction.
*/
int
findhist(int start, int fwd, const char *str, bool anchored)
{
char **hp;
int maxhist = histptr - history;
int incr = fwd ? 1 : -1;
size_t 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(mksh_ari_t n)
{
if (n > 0 && n != histsize) {
int cursize = histptr - history;
/* save most recent history */
if (n < cursize) {
memmove(history, histptr - n + 1, n * sizeof(char *));
cursize = n - 1;
}
history = aresize2(history, n, sizeof(char *), APERM);
histsize = n;
histptr = history + cursize;
}
}
#if HAVE_PERSISTENT_HISTORY
/*
* set history file; this can mean reloading/resetting/starting
* history file maintenance
*/
void
sethistfile(const char *name)
{
/* if not started then nothing to do */
if (hstarted == false)
return;
/* if the name is the same as the name we have */
if (hname && name && !strcmp(hname, name))
return;
/*
* it's a new name - possibly
*/
if (histfd != -1) {
/* yes the file is open */
(void)close(histfd);
histfd = -1;
histfsize = 0;
afree(hname, APERM);
hname = NULL;
/* let's reset the history */
histsave(NULL, NULL, HIST_DISCARD, true);
histptr = history - 1;
hist_source->line = 0;
}
if (name)
hist_init(hist_source);
}
#endif
/*
* initialise the history vector
*/
void
init_histvec(void)
{
if (history == (char **)NULL) {
histsize = MKSH_DEFHISTSIZE;
history = alloc2(histsize, sizeof(char *), APERM);
histptr = history - 1;
}
}
/*
* It turns out that there is a lot of ghastly hackery here
*/
#if !defined(MKSH_SMALL) && HAVE_PERSISTENT_HISTORY
/* do not save command in history but possibly sync */
bool
histsync(void)
{
bool changed = false;
/* called by histsave(), may not HIST_DISCARD, caller should flush */
if (histfd != -1) {
int lno = hist_source->line;
hist_source->line++;
writehistfile(0, NULL);
hist_source->line--;
if (lno != hist_source->line)
changed = true;
}
return (changed);
}
#endif
/*
* save command in history
*/
void
histsave(int *lnp, const char *cmd, int svmode, bool ignoredups)
{
static char *enqueued = NULL;
char **hp, *c;
const char *ccp;
if (svmode == HIST_DISCARD) {
afree(enqueued, APERM);
enqueued = NULL;
return;
}
if (svmode == HIST_APPEND) {
if (!enqueued)
svmode = HIST_STORE;
} else if (enqueued) {
c = enqueued;
enqueued = NULL;
--*lnp;
histsave(lnp, c, HIST_STORE, true);
afree(c, APERM);
}
if (svmode == HIST_FLUSH)
return;
ccp = strnul(cmd);
while (ccp > cmd && ccp[-1] == '\n')
--ccp;
strndupx(c, cmd, ccp - cmd, APERM);
if (svmode != HIST_APPEND) {
if (ignoredups &&
histptr >= history &&
!strcmp(c, *histptr)
#if !defined(MKSH_SMALL) && HAVE_PERSISTENT_HISTORY
&& !histsync()
#endif
) {
afree(c, APERM);
return;
}
++*lnp;
}
#if HAVE_PERSISTENT_HISTORY
if (svmode == HIST_STORE && histfd != -1)
writehistfile(*lnp, c);
#endif
if (svmode == HIST_QUEUE || svmode == HIST_APPEND) {
size_t nenq, ncmd;
if (!enqueued) {
if (*c)
enqueued = c;
else
afree(c, APERM);
return;
}
nenq = strlen(enqueued);
ncmd = strlen(c);
enqueued = aresize(enqueued, nenq + 1 + ncmd + 1, APERM);
enqueued[nenq] = '\n';
memcpy(enqueued + nenq + 1, c, ncmd + 1);
afree(c, APERM);
return;
}
hp = histptr;
if (++hp >= history + histsize) {
/* remove oldest command */
afree(*history, APERM);
for (hp = history; hp < history + histsize - 1; hp++)
hp[0] = hp[1];
}
*hp = c;
histptr = hp;
}
/*
* Write history data to a file nominated by HISTFILE;
* if HISTFILE is unset then history still happens, but
* the data is not written to a file. All copies of ksh
* looking at the file will maintain the same history.
* This is ksh behaviour.
*
* This stuff uses mmap()
*
* This stuff is so totally broken it must eventually be
* redesigned, without mmap, better checks, support for
* larger files, etc. and handle partially corrupted files
*/
/*-
* Open a history file
* Format is:
* Bytes 1, 2:
* HMAGIC - just to check that we are dealing with the correct object
* Then follows a number of stored commands
* Each command is
* <command byte><command number(4 octets, big endian)><bytes><NUL>
*/
#define HMAGIC1 0xAB
#define HMAGIC2 0xCD
#define COMMAND 0xFF
#if HAVE_PERSISTENT_HISTORY
static const unsigned char sprinkle[2] = { HMAGIC1, HMAGIC2 };
static int
hist_persist_back(int srcfd)
{
off_t tot, mis;
ssize_t n, w;
char *buf, *cp;
int rv = 0;
#define MKSH_HS_BUFSIZ 4096
if ((tot = lseek(srcfd, (off_t)0, SEEK_END)) < 0 ||
lseek(srcfd, (off_t)0, SEEK_SET) < 0 ||
lseek(histfd, (off_t)0, SEEK_SET) < 0)
return (1);
if ((buf = malloc_osfunc(MKSH_HS_BUFSIZ)) == NULL)
return (1);
mis = tot;
while (mis > 0) {
if ((n = blocking_read(srcfd, (cp = buf),
MKSH_HS_BUFSIZ)) == -1) {
if (errno == EINTR) {
intrcheck();
continue;
}
goto copy_error;
}
mis -= n;
while (n) {
if (intrsig)
goto has_intrsig;
if ((w = write(histfd, cp, n)) != -1) {
n -= w;
cp += w;
continue;
}
if (errno == EINTR) {
has_intrsig:
intrcheck();
continue;
}
goto copy_error;
}
}
if (ftruncate(histfd, tot)) {
copy_error:
rv = 1;
}
free_osfunc(buf);
return (rv);
}
static void
hist_persist_init(void)
{
unsigned char *base;
int lines, fd;
enum { hist_init_first, hist_init_retry, hist_use_it } hs;
if (((hname = str_val(global("HISTFILE"))) == NULL) || !*hname) {
hname = NULL;
return;
}
strdupx(hname, hname, APERM);
hs = hist_init_first;
retry:
/* we have a file and are interactive */
if ((fd = binopen3(hname, O_RDWR | O_CREAT | O_APPEND, 0600)) < 0)
return;
if ((histfd = savefd(fd)) < 0)
return;
if (histfd != fd)
close(fd);
mksh_lockfd(histfd);
histfsize = lseek(histfd, (off_t)0, SEEK_END);
if (histfsize > MKSH_MAXHISTFSIZE) {
/* we ignore too large files but still append to them */
goto hist_init_tail;
} else if (histfsize > 2) {
/* we have some data, check its validity */
base = (void *)mmap(NULL, (size_t)histfsize, PROT_READ,
MAP_FILE | MAP_PRIVATE, histfd, (off_t)0);
if (base == (unsigned char *)MAP_FAILED)
goto hist_init_fail;
if (base[0] != HMAGIC1 || base[1] != HMAGIC2) {
munmap(caddr_cast(base), (size_t)histfsize);
goto hist_init_fail;
}
/* load _all_ data */
lines = histload(hist_source, base + 2, (size_t)histfsize - 2);
munmap(caddr_cast(base), (size_t)histfsize);
/* check if the file needs to be truncated */
if (lines > histsize && histptr >= history) {
/* you're fucked up with the current code, trust me */
char *nhname, **hp;
struct stat sb;
/* create temporary file */
nhname = shf_smprintf("%s.%d", hname, (int)procpid);
if ((fd = binopen3(nhname, O_RDWR | O_CREAT | O_TRUNC |
O_EXCL, 0600)) < 0) {
/* just don't truncate then, meh. */
hs = hist_use_it;
goto hist_trunc_dont;
}
if (fstat(histfd, &sb) >= 0 &&
chown(nhname, sb.st_uid, sb.st_gid)) {
/* abort the truncation then, meh. */
goto hist_trunc_abort;
}
/* we definitively want some magic in that file */
if (write(fd, sprinkle, 2) != 2)
goto hist_trunc_abort;
/* and of course the entries */
hp = history;
while (hp < histptr) {
if (!writehistline(fd,
hist_source->line - (histptr - hp), *hp))
goto hist_trunc_abort;
++hp;
}
/* now transfer back */
if (!hist_persist_back(fd)) {
/* success! */
hs = hist_use_it;
}
hist_trunc_abort:
/* remove temporary file */
close(fd);
fd = -1;
unlink(nhname);
/* use whatever is in the file now */
hist_trunc_dont:
afree(nhname, ATEMP);
if (hs == hist_use_it)
goto hist_trunc_done;
goto hist_init_fail;
}
} else if (histfsize != 0) {
/* negative or too small... */
hist_init_fail:
/* ... or mmap failed or illegal */
hist_finish();
/* nuke the bogus file then retry, at most once */
if (!unlink(hname) && hs != hist_init_retry) {
hs = hist_init_retry;
goto retry;
}
if (hs != hist_init_retry)
bi_errorf(Tf_cant_ss_s,
"unlink HISTFILE", hname, cstrerror(errno));
histfsize = 0;
return;
} else {
/* size 0, add magic to the history file */
if (write(histfd, sprinkle, 2) != 2) {
hist_finish();
return;
}
}
hist_trunc_done:
if ((histfsize = lseek(histfd, (off_t)0, SEEK_END)) < 0)
goto hist_init_fail;
hist_init_tail:
mksh_unlkfd(histfd);
}
#endif
void
hist_init(Source *s)
{
histsave(NULL, NULL, HIST_DISCARD, true);
if (Flag(FTALKING) == 0)
return;
hstarted = true;
hist_source = s;
#if HAVE_PERSISTENT_HISTORY
hist_persist_init();
#endif
}
#if HAVE_PERSISTENT_HISTORY
/*
* load the history structure from the stored data
*/
static int
histload(Source *s, unsigned char *base, size_t bytes)
{
int lno = 0, lines = 0;
unsigned char *cp;
histload_loop:
/* !bytes check as some systems (older FreeBSDs) have buggy memchr */
if (!bytes || (cp = memchr(base, COMMAND, bytes)) == NULL)
return (lines);
/* advance base pointer past COMMAND byte */
bytes -= ++cp - base;
base = cp;
/* if there is no full string left, don't bother with the rest */
if (bytes < 5 || (cp = memchr(base + 4, '\0', bytes - 4)) == NULL)
return (lines);
/* load the stored line number */
lno = ((base[0] & 0xFF) << 24) | ((base[1] & 0xFF) << 16) |
((base[2] & 0xFF) << 8) | (base[3] & 0xFF);
/* store away the found line (@base[4]) */
++lines;
if (histptr >= history && lno - 1 != s->line) {
/* a replacement? */
char **hp;
if (lno >= s->line - (histptr - history) && lno <= s->line) {
hp = &histptr[lno - s->line];
afree(*hp, APERM);
strdupx(*hp, (char *)(base + 4), APERM);
}
} else {
s->line = lno--;
histsave(&lno, (char *)(base + 4), HIST_NOTE, false);
}
/* advance base pointer past NUL */
bytes -= ++cp - base;
base = cp;
/* repeat until no more */
goto histload_loop;
}
/*
* write a command to the end of the history file
*
* This *MAY* seem easy but it's also necessary to check
* that the history file has not changed in size.
* If it has - then some other shell has written to it and
* we should (re)read those commands to update our history
*/
static void
writehistfile(int lno, const char *cmd)
{
off_t sizenow;
size_t bytes;
unsigned char *base, *news;
mksh_lockfd(histfd);
if ((sizenow = lseek(histfd, (off_t)0, SEEK_END)) < 0)
goto bad;
else if (sizenow < histfsize) {
/* the file has shrunk; trust it just appending the new data */
/* well, for now, anyway… since mksh strdups all into memory */
/* we can use a nicer approach some time later… */
;
} else if (
/* ignore changes when the file is too large */
sizenow <= MKSH_MAXHISTFSIZE
&&
/* the size has changed, we need to do read updates */
sizenow > histfsize
) {
/* both sizenow and histfsize are <= MKSH_MAXHISTFSIZE */
bytes = (size_t)(sizenow - histfsize);
base = (void *)mmap(NULL, (size_t)sizenow, PROT_READ,
MAP_FILE | MAP_PRIVATE, histfd, (off_t)0);
if (base == (unsigned char *)MAP_FAILED)
goto bad;
news = base + (size_t)histfsize;
if (*news == COMMAND) {
hist_source->line--;
histload(hist_source, news, bytes);
hist_source->line++;
lno = hist_source->line;
} else
bytes = 0;
munmap(caddr_cast(base), (size_t)sizenow);
if (!bytes)
goto bad;
}
if (cmd && !writehistline(histfd, lno, cmd)) {
bad:
hist_finish();