Re: [PATCH 5/5] perf synthetic events: Remove use of sscanf from /proc reading

Jiri Olsa
2020-04-02T13:41:18Z

On Wed, Apr 01, 2020 at 04:39:45PM -0700, Ian Rogers wrote:

SNIP

> @@ -279,9 +353,9 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
> struct machine *machine,
> bool mmap_data)
> {
> - FILE *fp;
> unsigned long long t;
> char bf[BUFSIZ];
> + struct io io;
> bool truncation = false;
> unsigned long long timeout = proc_map_timeout * 1000000ULL;
> int rc = 0;
> @@ -294,28 +368,39 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
> snprintf(bf, sizeof(bf), "%s/proc/%d/task/%d/maps",
> machine->root_dir, pid, pid);
>
> - fp = fopen(bf, "r");
> - if (fp == NULL) {
> + io.fd = open(bf, O_RDONLY, 0);
> + if (io.fd < 0) {
> /*
> * We raced with a task exiting - just return:
> */
> pr_debug("couldn't open %s\n", bf);
> return -1;
> }
> + init_io(&io, io.fd, bf, sizeof(bf));
>
> event->header.type = PERF_RECORD_MMAP2;
> t = rdclock();
>
> - while (1) {
> - char prot[5];
> - char execname[PATH_MAX];
> - char anonstr[] = "//anon";
> - unsigned int ino;
> + while (!io.eof) {
> + static const char anonstr[] = "//anon";
> size_t size;
> - ssize_t n;
>
> - if (fgets(bf, sizeof(bf), fp) == NULL)
> - break;
> + /* ensure null termination since stack will be reused. */
> + strcpy(event->mmap2.filename, "");

could you just do 'event->mmap2.filename[0] = 0x0' instad ?

jirka

> +
> + /* 00400000-0040c000 r-xp 00000000 fd:01 41038 /bin/cat */
> + if (!read_proc_maps_line(&io,
> + &event->mmap2.start,
> + &event->mmap2.len,
> + &event->mmap2.prot,
> + &event->mmap2.flags,
> + &event->mmap2.pgoff,
> + &event->mmap2.maj,
> + &event->mmap2.min,
> + &event->mmap2.ino,
> + sizeof(event->mmap2.filename),
> + event->mmap2.filename))
> + continue;
>

SNIP