89 lines
1.9 KiB
C
89 lines
1.9 KiB
C
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#include <stdbool.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <signal.h>
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#define _SDT_HAS_SEMAPHORES 1
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#include "sdt.h"
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#define SEC(name) __attribute__((section(name), used))
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#define BUF_SIZE 256
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/* defined in urandom_read_aux.c */
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void urand_read_without_sema(int iter_num, int iter_cnt, int read_sz);
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/* these are coming from urandom_read_lib{1,2}.c */
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void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz);
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void urandlib_read_without_sema(int iter_num, int iter_cnt, int read_sz);
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unsigned short urand_read_with_sema_semaphore SEC(".probes");
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static __attribute__((noinline))
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void urandom_read(int fd, int count)
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{
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char buf[BUF_SIZE];
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int i;
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for (i = 0; i < count; ++i) {
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read(fd, buf, BUF_SIZE);
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/* trigger USDTs defined in executable itself */
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urand_read_without_sema(i, count, BUF_SIZE);
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STAP_PROBE3(urand, read_with_sema, i, count, BUF_SIZE);
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/* trigger USDTs defined in shared lib */
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urandlib_read_without_sema(i, count, BUF_SIZE);
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urandlib_read_with_sema(i, count, BUF_SIZE);
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}
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}
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static volatile bool parent_ready;
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static void handle_sigpipe(int sig)
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{
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parent_ready = true;
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}
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int main(int argc, char *argv[])
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{
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int fd = open("/dev/urandom", O_RDONLY);
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int count = 4;
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bool report_pid = false;
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if (fd < 0)
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return 1;
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if (argc >= 2)
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count = atoi(argv[1]);
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if (argc >= 3) {
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report_pid = true;
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/* install SIGPIPE handler to catch when parent closes their
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* end of the pipe (on the other side of our stdout)
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*/
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signal(SIGPIPE, handle_sigpipe);
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}
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/* report PID and wait for parent process to send us "signal" by
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* closing stdout
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*/
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if (report_pid) {
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while (!parent_ready) {
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fprintf(stdout, "%d\n", getpid());
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fflush(stdout);
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}
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/* at this point stdout is closed, parent process knows our
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* PID and is ready to trace us
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*/
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}
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urandom_read(fd, count);
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close(fd);
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return 0;
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}
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