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Subject[PATCH v1 3/4] perf list: Json escape encoding improvements
From
Use strbuf to make the string under construction's length
unlimited. Use the format %s to mean a literal string copy and %S to
signify a need to escape the string. Add supported for escaping a
newline character.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/builtin-list.c | 109 +++++++++++++++++++++++---------------
1 file changed, 67 insertions(+), 42 deletions(-)

diff --git a/tools/perf/builtin-list.c b/tools/perf/builtin-list.c
index 43c635d58627..30937e1dd82c 100644
--- a/tools/perf/builtin-list.c
+++ b/tools/perf/builtin-list.c
@@ -17,6 +17,7 @@
#include "util/metricgroup.h"
#include "util/string2.h"
#include "util/strlist.h"
+#include "util/strbuf.h"
#include <subcmd/pager.h>
#include <subcmd/parse-options.h>
#include <stdarg.h>
@@ -249,45 +250,56 @@ static void json_print_end(void *ps)
printf("%s]\n", print_state->need_sep ? "\n" : "");
}

-static void fix_escape_printf(const char *fmt, ...)
+static void fix_escape_printf(struct strbuf *buf, const char *fmt, ...)
{
va_list args;
- char buf[2048];
- size_t buf_pos = 0;

va_start(args, fmt);
+ strbuf_setlen(buf, 0);
for (size_t fmt_pos = 0; fmt_pos < strlen(fmt); fmt_pos++) {
switch (fmt[fmt_pos]) {
- case '%': {
- const char *s = va_arg(args, const char*);
-
+ case '%':
fmt_pos++;
- assert(fmt[fmt_pos] == 's');
- for (size_t s_pos = 0; s_pos < strlen(s); s_pos++) {
- switch (s[s_pos]) {
- case '\\':
- __fallthrough;
- case '\"':
- buf[buf_pos++] = '\\';
- assert(buf_pos < sizeof(buf));
- __fallthrough;
- default:
- buf[buf_pos++] = s[s_pos];
- assert(buf_pos < sizeof(buf));
- break;
+ switch (fmt[fmt_pos]) {
+ case 's': {
+ const char *s = va_arg(args, const char*);
+
+ strbuf_addstr(buf, s);
+ break;
+ }
+ case 'S': {
+ const char *s = va_arg(args, const char*);
+
+ for (size_t s_pos = 0; s_pos < strlen(s); s_pos++) {
+ switch (s[s_pos]) {
+ case '\n':
+ strbuf_addstr(buf, "\\n");
+ break;
+ case '\\':
+ __fallthrough;
+ case '\"':
+ strbuf_addch(buf, '\\');
+ __fallthrough;
+ default:
+ strbuf_addch(buf, s[s_pos]);
+ break;
+ }
}
+ break;
+ }
+ default:
+ pr_err("Unexpected format character '%c'\n", fmt[fmt_pos]);
+ strbuf_addch(buf, '%');
+ strbuf_addch(buf, fmt[fmt_pos]);
}
break;
- }
default:
- buf[buf_pos++] = fmt[fmt_pos];
- assert(buf_pos < sizeof(buf));
+ strbuf_addch(buf, fmt[fmt_pos]);
break;
}
}
va_end(args);
- buf[buf_pos] = '\0';
- fputs(buf, stdout);
+ fputs(buf->buf, stdout);
}

static void json_print_event(void *ps, const char *pmu_name, const char *topic,
@@ -300,62 +312,71 @@ static void json_print_event(void *ps, const char *pmu_name, const char *topic,
{
struct json_print_state *print_state = ps;
bool need_sep = false;
+ struct strbuf buf;

+ strbuf_init(&buf, 0);
printf("%s{\n", print_state->need_sep ? ",\n" : "");
print_state->need_sep = true;
if (pmu_name) {
- fix_escape_printf("\t\"Unit\": \"%s\"", pmu_name);
+ fix_escape_printf(&buf, "\t\"Unit\": \"%S\"", pmu_name);
need_sep = true;
}
if (topic) {
- fix_escape_printf("%s\t\"Topic\": \"%s\"", need_sep ? ",\n" : "", topic);
+ fix_escape_printf(&buf, "%s\t\"Topic\": \"%S\"", need_sep ? ",\n" : "", topic);
need_sep = true;
}
if (event_name) {
- fix_escape_printf("%s\t\"EventName\": \"%s\"", need_sep ? ",\n" : "", event_name);
+ fix_escape_printf(&buf, "%s\t\"EventName\": \"%S\"", need_sep ? ",\n" : "",
+ event_name);
need_sep = true;
}
if (event_alias && strlen(event_alias)) {
- fix_escape_printf("%s\t\"EventAlias\": \"%s\"", need_sep ? ",\n" : "", event_alias);
+ fix_escape_printf(&buf, "%s\t\"EventAlias\": \"%S\"", need_sep ? ",\n" : "",
+ event_alias);
need_sep = true;
}
if (scale_unit && strlen(scale_unit)) {
- fix_escape_printf("%s\t\"ScaleUnit\": \"%s\"", need_sep ? ",\n" : "",
+ fix_escape_printf(&buf, "%s\t\"ScaleUnit\": \"%S\"", need_sep ? ",\n" : "",
scale_unit);
need_sep = true;
}
if (event_type_desc) {
- fix_escape_printf("%s\t\"EventType\": \"%s\"", need_sep ? ",\n" : "",
+ fix_escape_printf(&buf, "%s\t\"EventType\": \"%S\"", need_sep ? ",\n" : "",
event_type_desc);
need_sep = true;
}
if (deprecated) {
- fix_escape_printf("%s\t\"Deprecated\": \"%s\"", need_sep ? ",\n" : "",
+ fix_escape_printf(&buf, "%s\t\"Deprecated\": \"%S\"", need_sep ? ",\n" : "",
deprecated ? "1" : "0");
need_sep = true;
}
if (desc) {
- fix_escape_printf("%s\t\"BriefDescription\": \"%s\"", need_sep ? ",\n" : "", desc);
+ fix_escape_printf(&buf, "%s\t\"BriefDescription\": \"%S\"", need_sep ? ",\n" : "",
+ desc);
need_sep = true;
}
if (long_desc) {
- fix_escape_printf("%s\t\"PublicDescription\": \"%s\"", need_sep ? ",\n" : "",
+ fix_escape_printf(&buf, "%s\t\"PublicDescription\": \"%S\"", need_sep ? ",\n" : "",
long_desc);
need_sep = true;
}
if (encoding_desc) {
- fix_escape_printf("%s\t\"Encoding\": \"%s\"", need_sep ? ",\n" : "", encoding_desc);
+ fix_escape_printf(&buf, "%s\t\"Encoding\": \"%S\"", need_sep ? ",\n" : "",
+ encoding_desc);
need_sep = true;
}
if (metric_name) {
- fix_escape_printf("%s\t\"MetricName\": \"%s\"", need_sep ? ",\n" : "", metric_name);
+ fix_escape_printf(&buf, "%s\t\"MetricName\": \"%S\"", need_sep ? ",\n" : "",
+ metric_name);
need_sep = true;
}
if (metric_expr) {
- fix_escape_printf("%s\t\"MetricExpr\": \"%s\"", need_sep ? ",\n" : "", metric_expr);
+ fix_escape_printf(&buf, "%s\t\"MetricExpr\": \"%S\"", need_sep ? ",\n" : "",
+ metric_expr);
need_sep = true;
}
printf("%s}", need_sep ? "\n" : "");
+ strbuf_release(&buf);
}

static void json_print_metric(void *ps __maybe_unused, const char *group,
@@ -365,35 +386,39 @@ static void json_print_metric(void *ps __maybe_unused, const char *group,
{
struct json_print_state *print_state = ps;
bool need_sep = false;
+ struct strbuf buf;

+ strbuf_init(&buf, 0);
printf("%s{\n", print_state->need_sep ? ",\n" : "");
print_state->need_sep = true;
if (group) {
- fix_escape_printf("\t\"MetricGroup\": \"%s\"", group);
+ fix_escape_printf(&buf, "\t\"MetricGroup\": \"%S\"", group);
need_sep = true;
}
if (name) {
- fix_escape_printf("%s\t\"MetricName\": \"%s\"", need_sep ? ",\n" : "", name);
+ fix_escape_printf(&buf, "%s\t\"MetricName\": \"%S\"", need_sep ? ",\n" : "", name);
need_sep = true;
}
if (expr) {
- fix_escape_printf("%s\t\"MetricExpr\": \"%s\"", need_sep ? ",\n" : "", expr);
+ fix_escape_printf(&buf, "%s\t\"MetricExpr\": \"%S\"", need_sep ? ",\n" : "", expr);
need_sep = true;
}
if (unit) {
- fix_escape_printf("%s\t\"ScaleUnit\": \"%s\"", need_sep ? ",\n" : "", unit);
+ fix_escape_printf(&buf, "%s\t\"ScaleUnit\": \"%S\"", need_sep ? ",\n" : "", unit);
need_sep = true;
}
if (desc) {
- fix_escape_printf("%s\t\"BriefDescription\": \"%s\"", need_sep ? ",\n" : "", desc);
+ fix_escape_printf(&buf, "%s\t\"BriefDescription\": \"%S\"", need_sep ? ",\n" : "",
+ desc);
need_sep = true;
}
if (long_desc) {
- fix_escape_printf("%s\t\"PublicDescription\": \"%s\"", need_sep ? ",\n" : "",
+ fix_escape_printf(&buf, "%s\t\"PublicDescription\": \"%S\"", need_sep ? ",\n" : "",
long_desc);
need_sep = true;
}
printf("%s}", need_sep ? "\n" : "");
+ strbuf_release(&buf);
}

int cmd_list(int argc, const char **argv)
--
2.38.1.431.g37b22c650d-goog
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