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Subject[PATCH 04/12] perf inject: Add facility to do in place update
Date
When there is a need to modify only timestamps, it is much simpler and
quicker to do it to the existing file rather than re-write all the
contents.

In preparation for that, add the ability to modify the input file in place.
In practice that just means making the file descriptor and mmaps writable.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/builtin-inject.c | 30 ++++++++++++++++++++++++++----
tools/perf/util/data.c | 3 ++-
tools/perf/util/data.h | 1 +
tools/perf/util/header.c | 5 +++++
tools/perf/util/session.c | 6 +++++-
5 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index ddccc0eb7390..ddfdeb85c586 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -43,6 +43,8 @@ struct perf_inject {
bool have_auxtrace;
bool strip;
bool jit_mode;
+ bool in_place_update;
+ bool in_place_update_dry_run;
const char *input_name;
struct perf_data output;
u64 bytes_written;
@@ -701,7 +703,7 @@ static int __cmd_inject(struct perf_inject *inject)
int ret = -EINVAL;
struct perf_session *session = inject->session;
struct perf_data *data_out = &inject->output;
- int fd = perf_data__fd(data_out);
+ int fd = inject->in_place_update ? -1 : perf_data__fd(data_out);
u64 output_data_offset;

signal(SIGINT, sig_handler);
@@ -759,14 +761,14 @@ static int __cmd_inject(struct perf_inject *inject)
if (!inject->itrace_synth_opts.set)
auxtrace_index__free(&session->auxtrace_index);

- if (!data_out->is_pipe)
+ if (!data_out->is_pipe && !inject->in_place_update)
lseek(fd, output_data_offset, SEEK_SET);

ret = perf_session__process_events(session);
if (ret)
return ret;

- if (!data_out->is_pipe) {
+ if (!data_out->is_pipe && !inject->in_place_update) {
if (inject->build_ids)
perf_header__set_feat(&session->header,
HEADER_BUILD_ID);
@@ -900,7 +902,27 @@ int cmd_inject(int argc, const char **argv)
return -1;
}

- if (perf_data__open(&inject.output)) {
+ if (inject.in_place_update) {
+ if (!strcmp(inject.input_name, "-")) {
+ pr_err("Input file name required for in-place updating\n");
+ return -1;
+ }
+ if (strcmp(inject.output.path, "-")) {
+ pr_err("Output file name must not be specified for in-place updating\n");
+ return -1;
+ }
+ if (!data.force && !inject.in_place_update_dry_run) {
+ char reply[10];
+
+ printf("The input file will be updated in place. OK? (y/n) ");
+ if (!fgets(reply, sizeof(reply), stdin) || strcmp(reply, "y\n")) {
+ pr_err("Aborted\n");
+ return -1;
+ }
+ }
+ if (!inject.in_place_update_dry_run)
+ data.in_place_update = true;
+ } else if (perf_data__open(&inject.output)) {
perror("failed to create output file");
return -1;
}
diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
index f29af4fc3d09..209fe63d4e49 100644
--- a/tools/perf/util/data.c
+++ b/tools/perf/util/data.c
@@ -239,11 +239,12 @@ static bool is_dir(struct perf_data *data)

static int open_file_read(struct perf_data *data)
{
+ int flags = data->in_place_update ? O_RDWR : O_RDONLY;
struct stat st;
int fd;
char sbuf[STRERR_BUFSIZE];

- fd = open(data->file.path, O_RDONLY);
+ fd = open(data->file.path, flags);
if (fd < 0) {
int err = errno;

diff --git a/tools/perf/util/data.h b/tools/perf/util/data.h
index 62a3e66fbee8..c9de82af5584 100644
--- a/tools/perf/util/data.h
+++ b/tools/perf/util/data.h
@@ -31,6 +31,7 @@ struct perf_data {
bool is_dir;
bool force;
bool use_stdio;
+ bool in_place_update;
enum perf_data_mode mode;

struct {
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index aa1e42518d37..02b13c7a23be 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3814,6 +3814,11 @@ int perf_session__read_header(struct perf_session *session)
if (perf_file_header__read(&f_header, header, fd) < 0)
return -EINVAL;

+ if (header->needs_swap && data->in_place_update) {
+ pr_err("In-place update not supported when byte-swapping is required\n");
+ return -EINVAL;
+ }
+
/*
* Sanity check that perf.data was written cleanly; data size is
* initialized to 0 and updated only if the on_exit function is run.
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index eba3769be3f1..edd068ea8a6c 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -2131,6 +2131,7 @@ struct reader {
u64 data_size;
u64 data_offset;
reader_cb_t process;
+ bool in_place_update;
};

static int
@@ -2164,7 +2165,9 @@ reader__process_events(struct reader *rd, struct perf_session *session,
mmap_prot = PROT_READ;
mmap_flags = MAP_SHARED;

- if (session->header.needs_swap) {
+ if (rd->in_place_update) {
+ mmap_prot |= PROT_WRITE;
+ } else if (session->header.needs_swap) {
mmap_prot |= PROT_WRITE;
mmap_flags = MAP_PRIVATE;
}
@@ -2250,6 +2253,7 @@ static int __perf_session__process_events(struct perf_session *session)
.data_size = session->header.data_size,
.data_offset = session->header.data_offset,
.process = process_simple,
+ .in_place_update = session->data->in_place_update,
};
struct ordered_events *oe = &session->ordered_events;
struct perf_tool *tool = session->tool;
--
2.17.1
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