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#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include "ftrace.h"
#include "trinity.h"
static int trace_fd = -1;
// TODO: if passed a dir, generate filename with datestamp
static const char defaultdumpfilename[] = "/boot/trace.txt";
const char *ftracedumpname = defaultdumpfilename;
static void dump_trace(void)
{
int tracein, traceout;
ssize_t in = -1, out = -1;
char buffer[4096];
const char tracefile[] = "/sys/kernel/debug/tracing/trace";
tracein = open(tracefile, O_RDONLY);
if (tracein == -1) {
if (errno != -EEXIST)
output(0, "Error opening %s : %s\n", tracefile, strerror(errno));
goto fail_tracein;
}
traceout = open(ftracedumpname, O_CREAT | O_WRONLY, 0600);
if (traceout == -1) {
output(0, "Error opening %s : %s\n", ftracedumpname, strerror(errno));
goto fail_traceout;
}
while (in != 0) {
in = read(tracein, buffer, 4096);
if (in > 0) {
out = write(traceout, buffer, in);
if (out == -1) {
output(0, "Error writing trace to %s. %s\n", ftracedumpname, strerror(errno));
goto fail;
}
}
if (in == -1) {
output(0, "something went wrong reading from trace. %s\n", strerror(errno));
goto fail;
}
}
output(0, "Dumped trace to %s\n", ftracedumpname);
fail:
fsync(traceout);
close(traceout);
fail_traceout:
close(tracein);
fail_tracein:
if (ftracedumpname != defaultdumpfilename) {
free((void *)ftracedumpname);
ftracedumpname = NULL;
}
}
void setup_ftrace(void)
{
//todo: check for root
trace_fd = open("/sys/kernel/debug/tracing/tracing_on", O_WRONLY);
if (trace_fd == -1) {
if (errno != -EEXIST) {
output(0, "Error opening tracing_on : %s\n", strerror(errno));
return;
}
}
output(0, "Opened ftrace tracing_on as fd %d\n", trace_fd);
output(0, "Ftrace log will be dumped to %s\n", ftracedumpname);
}
void stop_ftrace(void)
{
if (trace_fd != -1) {
if (write(trace_fd, "0", 1) == -1) {
output(0, "Stopping ftrace failed! %s\n", strerror(errno));
return;
}
dump_trace();
return;
}
}
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