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perfme
/* Simple wrapper to allow a program to perf itself.
* Copyright Rusty Russell, Blockstream 2015.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* See <http://www.gnu.org/licenses/>.
*/
#include <ccan/err/err.h>
#include <ccan/str/str.h>
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#define PERFME_PREFIX "/tmp/perfme."
static void write_noerr(int fd)
{
int e = errno;
if (write(fd, "", 1) != 1)
/* Complain about warn_unused_result fascist bullshit */ ;
errno = e;
}
/* Child. Setup pid, run perf. */
static void exec_perf(int pfd[2], const char *perfpid, const char *perfout,
pid_t parent)
{
char pid[STR_MAX_CHARS(pid_t)];
int fd;
fd = open(perfpid, O_CREAT|O_EXCL|O_WRONLY, 0400);
if (fd < 0) {
write_noerr(pfd[1]);
err(1, "opening %s", perfpid);
}
sprintf(pid, "%u", getpid());
if (write(fd, pid, strlen(pid)) != strlen(pid)) {
write_noerr(pfd[1]);
err(1, "writing to %s", perfpid);
}
close(fd);
sprintf(pid, "%u", parent);
execlp("perf", "perf", "record", "-g", "-q",
"-p", pid,
"-o", perfout,
NULL);
write_noerr(pfd[1]);
err(1, "Execing perf");
}
int main(int argc, char *argv[])
{
pid_t parent = argv[1] ? atoi(argv[1]) : getppid();
char perfout[sizeof(PERFME_PREFIX) + STR_MAX_CHARS(parent)];
char perfpid[sizeof(perfout) + sizeof(".pid")];
err_set_progname(argv[0]);
sprintf(perfpid, PERFME_PREFIX "%u.pid", parent);
if (strends(argv[0], "perfme-stop")) {
char pid[STR_MAX_CHARS(pid_t)];
int r, fd = open(perfpid, O_RDONLY);
if (fd < 0)
err(1, "Opening %s", perfpid);
r = read(fd, pid, sizeof(pid) - 1);
if (r < 0)
err(1, "Reading %s", perfpid);
pid[r] = 0;
if (unlink(perfpid) != 0)
warn("Unlinking %s", perfpid);
if (atoi(pid) <= 0)
errx(1, "Invalid pid '%s' from %s", pid, perfpid);
if (kill(atoi(pid), SIGTERM) != 0)
err(1, "Stopping %s", pid);
exit(0);
} else if (strends(argv[0], "perfme-start")) {
int pfd[2];
sprintf(perfout, PERFME_PREFIX "%u", parent);
/* Use pipe to detect successful exec. */
if (pipe(pfd) != 0)
err(1, "Creating pipe");
switch (fork()) {
case 0:
close(pfd[0]);
fcntl(pfd[1], F_SETFD,
fcntl(pfd[1], F_GETFD)|FD_CLOEXEC);
exec_perf(pfd, perfpid, perfout, parent);
case -1:
err(1, "Forking");
default:
/* Parent. Wait for child. */
close(pfd[1]);
if (read(pfd[0], perfpid, 1) == 1)
exit(1);
fprintf(stderr, "Perf recording into %s\n", perfout);
exit(0);
}
}
errx(1, "Unknown name: am I perfme-start or perfme-stop?");
}
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