PATCH: zle history entry paranoia

PATCH: zle history entry paranoia

[Peter Stephenson]

I just had a crash after `fc -R' and then trying to search back in the
history because zle lost the plot somehow.  The crash was because a
quietgethist returned NULL; I presume the current zle history line was
not at the end at that point and there was no such line in the new
history.

This makes it safer by checking the return values of some
quietgethist's in zle_hist.c.  It's got the chunk for
accept-line-and-down-history embedded in it since that coincidentally
hits the same code and I haven't committed it yet.

Possibly it should reset the history line after fc -R, anyway, but that
requires an extra hook between the main shell and zle.

Index: Src/Zle/zle_hist.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Zle/zle_hist.c,v
retrieving revision 1.7
diff -u -r1.7 zle_hist.c
--- Src/Zle/zle_hist.c	5 Mar 2002 16:33:19 -0000	1.7
+++ Src/Zle/zle_hist.c	24 Jun 2002 17:25:44 -0000
@@ -48,7 +48,7 @@
 remember_edits(void)
 {
     Histent ent = quietgethist(histline);
-    if (metadiffer(ZLETEXT(ent), (char *) line, ll)) {
+    if (ent && metadiffer(ZLETEXT(ent), (char *) line, ll)) {
 	zsfree(ent->zle_text);
 	ent->zle_text = metafy((char *) line, ll, META_DUP);
     }
@@ -248,13 +248,13 @@
 int
 acceptlineanddownhistory(char **args)
 {
-    Histent he;
+    Histent he = quietgethist(histline);
 
-    if (!(he = movehistent(quietgethist(histline), 1, HIST_FOREIGN)))
-	return 1;
-    zpushnode(bufstack, ztrdup(he->text));
+    if (he && (he = movehistent(he, 1, HIST_FOREIGN))) {
+	zpushnode(bufstack, ztrdup(he->text));
+	stackhist = he->histnum;
+    }
     done = 1;
-    stackhist = he->histnum;
     return 0;
 }
 
@@ -301,7 +301,8 @@
 	str = srch_str;
 	hp = histpos;
     }
-    he = quietgethist(histline);
+    if (!(he = quietgethist(histline)))
+	return 1;
     while ((he = movehistent(he, -1, hist_skip_flags))) {
 	if (isset(HISTFINDNODUPS) && he->flags & HIST_DUP)
 	    continue;
@@ -349,7 +350,8 @@
 	str = srch_str;
 	hp = histpos;
     }
-    he = quietgethist(histline);
+    if (!(he = quietgethist(histline)))
+	return 1;
     while ((he = movehistent(he, 1, hist_skip_flags))) {
 	if (isset(HISTFINDNODUPS) && he->flags & HIST_DUP)
 	    continue;
@@ -578,7 +580,9 @@
 int
 zle_goto_hist(int ev, int n, int skipdups)
 {
-    Histent he = movehistent(quietgethist(ev), n, hist_skip_flags);
+    Histent he = quietgethist(ev);
+    if (!he || !(he = movehistent(he, n, hist_skip_flags)))
+	return 1;
     if (skipdups && n) {
 	n = n < 0? -1 : 1;
 	while (he && !metadiffer(ZLETEXT(he), (char *) line, ll))
@@ -752,11 +756,14 @@
     int odir = dir, sens = zmult == 1 ? 3 : 1;
     int hl = histline, savekeys = -1, feep = 0;
     Thingy cmd;
-    char *okeymap = ztrdup(curkeymapname);
+    char *okeymap;
     static char *previous_search = NULL;
     static int previous_search_len = 0;
     Histent he;
 
+    if (!(he = quietgethist(hl)))
+	return;
+
     clearlist = 1;
 
     if (*args) {
@@ -770,7 +777,7 @@
     strcpy(ibuf, ISEARCH_PROMPT);
     memcpy(ibuf + NORM_PROMPT_POS, (dir == 1) ? "fwd" : "bck", 3);
     remember_edits();
-    he = quietgethist(hl);
+    okeymap = ztrdup(curkeymapname);
     s = ZLETEXT(he);
     selectkeymap("main", 1);
     pos = metalen(s, cs);
@@ -1014,9 +1021,9 @@
 int
 infernexthistory(char **args)
 {
-    Histent he;
+    Histent he = quietgethist(histline);
 
-    if (!(he = infernexthist(quietgethist(histline), args)))
+    if (!he || !(he = infernexthist(he, args)))
 	return 1;
     zle_setline(he);
     return 0;
@@ -1200,7 +1207,8 @@
 	visrchsense = -visrchsense;
     }
     t0 = strlen(visrchstr);
-    he = quietgethist(histline);
+    if (!(he = quietgethist(histline)))
+	return 1;
     while ((he = movehistent(he, visrchsense, hist_skip_flags))) {
 	if (isset(HISTFINDNODUPS) && he->flags & HIST_DUP)
 	    continue;
@@ -1248,7 +1256,8 @@
 	zmult = n;
 	return ret;
     }
-    he = quietgethist(histline);
+    if (!(he = quietgethist(histline)))
+	return 1;
     while ((he = movehistent(he, -1, hist_skip_flags))) {
 	if (isset(HISTFINDNODUPS) && he->flags & HIST_DUP)
 	    continue;
@@ -1284,7 +1293,8 @@
 	zmult = n;
 	return ret;
     }
-    he = quietgethist(histline);
+    if (!(he = quietgethist(histline)))
+	return 1;
     while ((he = movehistent(he, 1, hist_skip_flags))) {
 	if (isset(HISTFINDNODUPS) && he->flags & HIST_DUP)
 	    continue;

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 392070


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Re: PATCH: zle history entry paranoia

[Wayne Davison]

On Mon, 24 Jun 2002, Peter Stephenson wrote:
> This makes it safer by checking the return values of some
> quietgethist's in zle_hist.c.

FYI: I gave the patch look, and it looks good to me.  The only "hmm"
spot was in the doisearch function where a couple calls got reordered
a bit, but a quick glance at the code satisfied me that things were OK.
Seems like a very reasonable change.

..wayne..