[PATCH v1 2/4] perf srcline: Simplify addr2line subprocess

From: Ian Rogers
Date: Thu Mar 30 2023 - 20:49:38 EST


Don't wrap stdin and stdout of subprocess with streams, use the api/io
library for buffering.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
tools/perf/util/srcline.c | 103 ++++++++++++++------------------------
1 file changed, 38 insertions(+), 65 deletions(-)

diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
index f0a96a834e4b..2da86e57215d 100644
--- a/tools/perf/util/srcline.c
+++ b/tools/perf/util/srcline.c
@@ -10,6 +10,8 @@
#include <linux/string.h>
#include <linux/zalloc.h>

+#include <api/io.h>
+
#include "util/dso.h"
#include "util/debug.h"
#include "util/callchain.h"
@@ -366,12 +368,6 @@ void dso__free_a2l(struct dso *dso)

#else /* HAVE_LIBBFD_SUPPORT */

-struct a2l_subprocess {
- struct child_process addr2line;
- FILE *to_child;
- FILE *from_child;
-};
-
static int filename_split(char *filename, unsigned int *line_nr)
{
char *sep;
@@ -393,28 +389,18 @@ static int filename_split(char *filename, unsigned int *line_nr)
return 0;
}

-static void addr2line_subprocess_cleanup(struct a2l_subprocess *a2l)
+static void addr2line_subprocess_cleanup(struct child_process *a2l)
{
- if (a2l->addr2line.pid != -1) {
- kill(a2l->addr2line.pid, SIGKILL);
- finish_command(&a2l->addr2line); /* ignore result, we don't care */
- a2l->addr2line.pid = -1;
- }
-
- if (a2l->to_child != NULL) {
- fclose(a2l->to_child);
- a2l->to_child = NULL;
- }
-
- if (a2l->from_child != NULL) {
- fclose(a2l->from_child);
- a2l->from_child = NULL;
+ if (a2l->pid != -1) {
+ kill(a2l->pid, SIGKILL);
+ finish_command(a2l); /* ignore result, we don't care */
+ a2l->pid = -1;
}

free(a2l);
}

-static struct a2l_subprocess *addr2line_subprocess_init(const char *addr2line_path,
+static struct child_process *addr2line_subprocess_init(const char *addr2line_path,
const char *binary_path)
{
const char *argv[] = {
@@ -422,54 +408,34 @@ static struct a2l_subprocess *addr2line_subprocess_init(const char *addr2line_pa
"-e", binary_path,
"-i", "-f", NULL
};
- struct a2l_subprocess *a2l = zalloc(sizeof(*a2l));
+ struct child_process *a2l = zalloc(sizeof(*a2l));
int start_command_status = 0;

- if (a2l == NULL)
- goto out;
-
- a2l->to_child = NULL;
- a2l->from_child = NULL;
+ if (a2l == NULL) {
+ pr_err("Failed to allocate memory for addr2line");
+ return NULL;
+ }

- a2l->addr2line.pid = -1;
- a2l->addr2line.in = -1;
- a2l->addr2line.out = -1;
- a2l->addr2line.no_stderr = 1;
+ a2l->pid = -1;
+ a2l->in = -1;
+ a2l->out = -1;
+ a2l->no_stderr = 1;

- a2l->addr2line.argv = argv;
- start_command_status = start_command(&a2l->addr2line);
- a2l->addr2line.argv = NULL; /* it's not used after start_command; avoid dangling pointers */
+ a2l->argv = argv;
+ start_command_status = start_command(a2l);
+ a2l->argv = NULL; /* it's not used after start_command; avoid dangling pointers */

if (start_command_status != 0) {
pr_warning("could not start addr2line (%s) for %s: start_command return code %d\n",
addr2line_path, binary_path, start_command_status);
- goto out;
- }
-
- a2l->to_child = fdopen(a2l->addr2line.in, "w");
- if (a2l->to_child == NULL) {
- pr_warning("could not open write-stream to addr2line (%s) of %s\n",
- addr2line_path, binary_path);
- goto out;
- }
-
- a2l->from_child = fdopen(a2l->addr2line.out, "r");
- if (a2l->from_child == NULL) {
- pr_warning("could not open read-stream from addr2line (%s) of %s\n",
- addr2line_path, binary_path);
- goto out;
+ addr2line_subprocess_cleanup(a2l);
+ return NULL;
}

return a2l;
-
-out:
- if (a2l)
- addr2line_subprocess_cleanup(a2l);
-
- return NULL;
}

-static int read_addr2line_record(struct a2l_subprocess *a2l,
+static int read_addr2line_record(struct io *io,
char **function,
char **filename,
unsigned int *line_nr)
@@ -494,7 +460,7 @@ static int read_addr2line_record(struct a2l_subprocess *a2l,
if (line_nr != NULL)
*line_nr = 0;

- if (getline(&line, &line_len, a2l->from_child) < 0 || !line_len)
+ if (io__getline(&line, &line_len, io) < 0 || !line_len)
goto error;
if (function != NULL)
*function = strdup(strim(line));
@@ -502,7 +468,7 @@ static int read_addr2line_record(struct a2l_subprocess *a2l,
zfree(&line);
line_len = 0;

- if (getline(&line, &line_len, a2l->from_child) < 0 || !line_len)
+ if (io__getline(&line, &line_len, io) < 0 || !line_len)
goto error;

if (filename_split(line, line_nr == NULL ? &dummy_line_nr : line_nr) == 0) {
@@ -546,13 +512,17 @@ static int addr2line(const char *dso_name, u64 addr,
struct inline_node *node,
struct symbol *sym __maybe_unused)
{
- struct a2l_subprocess *a2l = dso->a2l;
+ struct child_process *a2l = dso->a2l;
char *record_function = NULL;
char *record_filename = NULL;
unsigned int record_line_nr = 0;
int record_status = -1;
int ret = 0;
size_t inline_count = 0;
+ int len;
+ char buf[128];
+ ssize_t written;
+ struct io io;

if (!a2l) {
if (!filename__has_section(dso_name, ".debug_line"))
@@ -578,13 +548,16 @@ static int addr2line(const char *dso_name, u64 addr,
* though, because it may be genuinely unknown, in which case we'll get two sets of
* "??"/"??:0" lines.
*/
- if (fprintf(a2l->to_child, "%016"PRIx64"\n,\n", addr) < 0 || fflush(a2l->to_child) != 0) {
+ len = snprintf(buf, sizeof(buf), "%016"PRIx64"\n,\n", addr);
+ written = len > 0 ? write(a2l->in, buf, len) : -1;
+ if (written != len) {
if (!symbol_conf.disable_add2line_warn)
pr_warning("%s %s: could not send request\n", __func__, dso_name);
goto out;
}
+ io__init(&io, a2l->out, buf, sizeof(buf));

- switch (read_addr2line_record(a2l, &record_function, &record_filename, &record_line_nr)) {
+ switch (read_addr2line_record(&io, &record_function, &record_filename, &record_line_nr)) {
case -1:
if (!symbol_conf.disable_add2line_warn)
pr_warning("%s %s: could not read first record\n", __func__, dso_name);
@@ -594,7 +567,7 @@ static int addr2line(const char *dso_name, u64 addr,
* The first record was invalid, so return failure, but first read another
* record, since we asked a junk question and have to clear the answer out.
*/
- switch (read_addr2line_record(a2l, NULL, NULL, NULL)) {
+ switch (read_addr2line_record(&io, NULL, NULL, NULL)) {
case -1:
if (!symbol_conf.disable_add2line_warn)
pr_warning("%s %s: could not read delimiter record\n",
@@ -632,7 +605,7 @@ static int addr2line(const char *dso_name, u64 addr,
}

/* We have to read the records even if we don't care about the inline info. */
- while ((record_status = read_addr2line_record(a2l,
+ while ((record_status = read_addr2line_record(&io,
&record_function,
&record_filename,
&record_line_nr)) == 1) {
@@ -656,7 +629,7 @@ static int addr2line(const char *dso_name, u64 addr,

void dso__free_a2l(struct dso *dso)
{
- struct a2l_subprocess *a2l = dso->a2l;
+ struct child_process *a2l = dso->a2l;

if (!a2l)
return;
--
2.40.0.348.gf938b09366-goog