perf list: JSON escape encoding improvements

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>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Xin Gao <gaoxin@cdjrlc.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20221118024607.409083-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-list.c b/tools/perf/builtin-list.c
index f375033..137d73e 100644 (file)
--- 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 <linux/zalloc.h>
@@ -250,45 +251,56 @@ 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,
@@ -301,62 +313,71 @@ 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,
@@ -366,35 +387,39 @@ 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)