* [9front] libjson can print invalid json
@ 2022-11-17 21:52 Dave MacFarlane
2022-11-18 4:30 ` ori
0 siblings, 1 reply; 4+ messages in thread
From: Dave MacFarlane @ 2022-11-17 21:52 UTC (permalink / raw)
To: 9front
print("%J", json); can print invalid json if a JSON string in the object has a quotation mark in it.
I just threw together this patch to try and escape the strings from printjson() if anyone's interested
in it.
diff 30c5296f32b87d83529d772732726891e1261c9c uncommitted
--- a/sys/src/libjson/printjson.c
+++ b/sys/src/libjson/printjson.c
@@ -52,6 +52,38 @@
}
static int
+printstring(Fmt *f, char *s)
+{
+ int slen = strlen(s);
+ int i, nq=0;
+ int r;
+ char *dup, lastq;
+ for(i = 0; i < slen; i++)
+ if (s[i] == '"') nq++;
+
+ if (nq == 0)
+ return fmtprint(f, "\"%s\"", s);
+
+ r = fmtprint(f, "\"");
+
+ dup = strdup(s);
+ lastq = -1;
+ for(i = 0; i < slen; i++){
+ if(dup[i] == '"') {
+ dup[i] = 0;
+ r += fmtprint(f, "%s\\\"", &dup[lastq+1]);
+ lastq = i;
+ }
+ }
+
+ if (lastq != slen-1)
+ r += fmtprint(f, "%s", &dup[lastq+1]);
+ r += fmtprint(f, "\"");
+ free(dup);
+ return r;
+}
+
+static int
printjson(Fmt *f, JSON *j, int indent)
{
switch(j->t){
@@ -65,7 +97,7 @@
return fmtprint(f, "%f", j->n);
break;
case JSONString:
- return fmtprint(f, "\"%s\"", j->s);
+ return printstring(f, j->s);
break;
case JSONArray:
return printarray(f, j, indent+1);
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [9front] libjson can print invalid json
2022-11-17 21:52 [9front] libjson can print invalid json Dave MacFarlane
@ 2022-11-18 4:30 ` ori
2022-11-18 14:37 ` Dave MacFarlane
0 siblings, 1 reply; 4+ messages in thread
From: ori @ 2022-11-18 4:30 UTC (permalink / raw)
To: 9front
Quoth Dave MacFarlane <driusan@driusan.net>:
> print("%J", json); can print invalid json if a JSON string in the object has a quotation mark in it.
>
> I just threw together this patch to try and escape the strings from printjson() if anyone's interested
> in it.
>
> diff 30c5296f32b87d83529d772732726891e1261c9c uncommitted
> --- a/sys/src/libjson/printjson.c
> +++ b/sys/src/libjson/printjson.c
> @@ -52,6 +52,38 @@
> }
>
> static int
> +printstring(Fmt *f, char *s)
> +{
> + int slen = strlen(s);
> + int i, nq=0;
> + int r;
> + char *dup, lastq;
> + for(i = 0; i < slen; i++)
> + if (s[i] == '"') nq++;
> +
> + if (nq == 0)
> + return fmtprint(f, "\"%s\"", s);
> +
> + r = fmtprint(f, "\"");
> +
> + dup = strdup(s);
> + lastq = -1;
> + for(i = 0; i < slen; i++){
> + if(dup[i] == '"') {
> + dup[i] = 0;
> + r += fmtprint(f, "%s\\\"", &dup[lastq+1]);
> + lastq = i;
> + }
> + }
> +
> + if (lastq != slen-1)
> + r += fmtprint(f, "%s", &dup[lastq+1]);
> + r += fmtprint(f, "\"");
> + free(dup);
> + return r;
> +}
> +
I think we have a problem with more than just quotes; we're
not allowed any control characters, and we need to escape '\';
how's something like this (untested)?
static int
printstring(Fmt *f, char *s)
{
int n;
n = 0;
for(; *s; s++){
switch(*s){
case '\\': n += fmtstrcpy(f, "\\\\"); break;
case '\f': n += fmtstrcpy(f, "\\f"); break;
case '\b': n += fmtstrcpy(f, "\\b"); break;
case '\n': n += fmtstrcpy(f, "\\n"); break;
case '\r': n += fmtstrcpy(f, "\\r"); break;
case '\"': n += fmtstrcpy(f, "\\\""); break;
default:
if(*s < 0x20)
n += fmtprint(f, "\\u%04x", *s);
else
n += fmtrune(f, *s);
}
}
return n;
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [9front] libjson can print invalid json
2022-11-18 4:30 ` ori
@ 2022-11-18 14:37 ` Dave MacFarlane
2022-11-18 14:52 ` Dave MacFarlane
0 siblings, 1 reply; 4+ messages in thread
From: Dave MacFarlane @ 2022-11-18 14:37 UTC (permalink / raw)
To: 9front
It certainly looks more elegant than my code, but when I tested it it's missing the
beginning and ending quote character of the json string.
After I added them, it passed the tests I wrote for my code.
static int
printstring(Fmt *f, char *s)
{
int n;
n = fmtrune(f, '"');
for(; *s; s++){
switch(*s){
case '\\': n += fmtstrcpy(f, "\\\\"); break;
case '\f': n += fmtstrcpy(f, "\\f"); break;
case '\b': n += fmtstrcpy(f, "\\b"); break;
case '\n': n += fmtstrcpy(f, "\\n"); break;
case '\r': n += fmtstrcpy(f, "\\r"); break;
case '\"': n += fmtstrcpy(f, "\\\""); break;
default:
if(*s < 0x20)
n += fmtprint(f, "\\u%04x", *s);
else
n += fmtrune(f, *s);
}
}
n = fmtrune(f, '"');
return n;
}
Here's what I used to test it:
#include <u.h>
#include <libc.h>
#include <json.h>
void testJSON(char *s) {
print("%s\n", s);
JSON *j = jsonparse(s);
print("%J\n", j);
char *str = smprint("%J", j);
assert(jsonparse(str) != nil);
free(j);
free(str);
}
void main(void) {
JSON *j;
char *str;
JSONfmtinstall();
testJSON("{\"abc\": \"\"}");
testJSON("{\"abc\": \"hello\"}");
testJSON("{\"abc\": \"\\\"hello\"}");
testJSON("{\"abc\": \"hello\\\"\"}");
testJSON("{\"abc\": \"he\\\"llo\"}");
testJSON("{\"abc\": \"\\\"he\\\"llo\\\"\"}");
testJSON("{\"abc\": \"hello\\t\"}");
exits("");
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [9front] libjson can print invalid json
2022-11-18 14:37 ` Dave MacFarlane
@ 2022-11-18 14:52 ` Dave MacFarlane
0 siblings, 0 replies; 4+ messages in thread
From: Dave MacFarlane @ 2022-11-18 14:52 UTC (permalink / raw)
To: 9front
I was curious about keys and it looks like there's also a bug
where they're not being properly escaped. Here's a diff that
fixes that as well.
cpu% git/diff .
diff 30c5296f32b87d83529d772732726891e1261c9c uncommitted
--- a/sys/src/libjson/printjson.c
+++ b/sys/src/libjson/printjson.c
@@ -7,6 +7,32 @@
static int printobject(Fmt*, JSON*, int);
static int
+printstring(Fmt *f, char *s)
+{
+ int n;
+
+ n = fmtrune(f, '"');
+ for(; *s; s++){
+ switch(*s){
+ case '\\': n += fmtstrcpy(f, "\\\\"); break;
+ case '\f': n += fmtstrcpy(f, "\\f"); break;
+ case '\b': n += fmtstrcpy(f, "\\b"); break;
+ case '\n': n += fmtstrcpy(f, "\\n"); break;
+ case '\r': n += fmtstrcpy(f, "\\r"); break;
+ case '\"': n += fmtstrcpy(f, "\\\""); break;
+ default:
+
+ if(*s < 0x20)
+ n += fmtprint(f, "\\u%04x", *s);
+ else
+ n += fmtrune(f, *s);
+ }
+ }
+ n = fmtrune(f, '"');
+ return n;
+}
+
+static int
printarray(Fmt *f, JSON *j, int indent)
{
JSONEl *jl;
@@ -41,7 +67,8 @@
for(jl = j->first; jl != nil; jl = jl->next){
for(i = 0; i < indent; i++)
fmtprint(f, "\t");
- r += fmtprint(f, "\"%s\": ", jl->name);
+ r += printstring(f, jl->name);
+ r += fmtprint(f, ": ");
r += printjson(f, jl->val, indent);
r += fmtprint(f, "%s\n", jl->next != nil ? "," : "");
}
@@ -65,7 +92,7 @@
return fmtprint(f, "%f", j->n);
break;
case JSONString:
- return fmtprint(f, "\"%s\"", j->s);
+ return printstring(f, j->s);
break;
case JSONArray:
return printarray(f, j, indent+1);
^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-11-17 21:52 [9front] libjson can print invalid json Dave MacFarlane
2022-11-18 4:30 ` ori
2022-11-18 14:37 ` Dave MacFarlane
2022-11-18 14:52 ` Dave MacFarlane
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