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Fix bug in signal_demo and add error message on fork failure to signal tracing guide

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Jeremy Rifkin 2024-11-14 22:08:09 -06:00
parent 5a9a4f314d
commit 8866d70a32
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GPG Key ID: 19AA8270105E8EB4
2 changed files with 11 additions and 3 deletions
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8
docs/signal-safe-tracing.md
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@ -152,7 +152,11 @@ void do_signal_safe_trace(cpptrace::frame_ptr* buffer, std::size_t count) {
pipe_t input_pipe; pipe_t input_pipe;
pipe(input_pipe.data); pipe(input_pipe.data);
const pid_t pid = fork(); const pid_t pid = fork();
if(pid == -1) { return; /* Some error occurred */ } if(pid == -1) {
const char* fork_failure_message = "fork() failed\n";
write(STDERR_FILENO, fork_failure_message, strlen(fork_failure_message));
return;
}
if(pid == 0) { // child if(pid == 0) { // child
dup2(input_pipe.read_end, STDIN_FILENO); dup2(input_pipe.read_end, STDIN_FILENO);
close(input_pipe.read_end); close(input_pipe.read_end);
@ -161,7 +165,7 @@ void do_signal_safe_trace(cpptrace::frame_ptr* buffer, std::size_t count) {
const char* exec_failure_message = "exec(signal_tracer) failed: Make sure the signal_tracer executable is in " const char* exec_failure_message = "exec(signal_tracer) failed: Make sure the signal_tracer executable is in "
"the current working directory and the binary's permissions are correct.\n"; "the current working directory and the binary's permissions are correct.\n";
write(STDERR_FILENO, exec_failure_message, strlen(exec_failure_message)); write(STDERR_FILENO, exec_failure_message, strlen(exec_failure_message));
_exit(1); return;
} }
// Resolve to safe_object_frames and write those to the pipe // Resolve to safe_object_frames and write those to the pipe
for(std::size_t i = 0; i < count; i++) { for(std::size_t i = 0; i < count; i++) {

6
test/signal_demo.cpp
View File

@ -42,7 +42,11 @@ void handler(int signo, siginfo_t* info, void* context) {
pipe_t input_pipe; pipe_t input_pipe;
pipe(input_pipe.data); pipe(input_pipe.data);
const pid_t pid = fork(); const pid_t pid = fork();
if(pid == -1) { return; } if(pid == -1) {
const char* fork_failure_message = "fork() failed\n";
write(STDERR_FILENO, fork_failure_message, strlen(fork_failure_message));
_exit(1);
}
if(pid == 0) { // child if(pid == 0) { // child
dup2(input_pipe.read_end, STDIN_FILENO); dup2(input_pipe.read_end, STDIN_FILENO);
close(input_pipe.read_end); close(input_pipe.read_end);