Refactor function gdbExtendedBacktrace:
* return as soon as an error condition is detected, thus preventing the need for deep nested if-branches. * Add some additional comments * Return true or false, false indicating an error, true indicating success git-svn-id: svn+ssh://svn.gna.org/svn/warzone/trunk@5389 4a71c877-e1ca-e34f-864e-861f7616d084master
Giel van Schijndel
parent
6953f0fd6d
commit
2d6615a30a
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@ -383,83 +383,114 @@ static void setFatalSignalHandler(SigActionHandler signalHandler)
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* Dumps a backtrace of the stack to the given output stream.
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*
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* @param dumpFile a POSIX file descriptor to write the resulting backtrace to.
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*
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* @return false if any failure occurred, preventing a full "extended"
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* backtrace.
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*/
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static void gdbExtendedBacktrace(int const dumpFile)
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static bool gdbExtendedBacktrace(int const dumpFile)
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{
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if (programIsAvailable && gdbIsAvailable)
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{
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int gdbPipe[2];
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if (pipe(gdbPipe) == 0)
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{
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const pid_t pid = fork();
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if (pid == (pid_t)0)
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{
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char *gdbArgv[] = { gdbPath, programPath, programPID, NULL };
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char *gdbEnv[] = { NULL };
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close(gdbPipe[1]); // No output to pipe
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dup2(gdbPipe[0], STDIN_FILENO); // STDIN from pipe
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dup2(dumpFile, STDOUT_FILENO); // STDOUT to dumpFile
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write(dumpFile, "GDB extended backtrace:\n",
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strlen("GDB extended backtrace:\n"));
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execve(gdbPath, (char **)gdbArgv, (char **)gdbEnv);
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}
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else if (pid > (pid_t)0)
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{
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// Retrieve a full stack backtrace
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static const char gdbCommands[] = "backtrace full\n"
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// Move to the stack frame where we triggered the crash
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"frame 4\n"
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// Show the assembly code associated with that stack frame
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"disassemble\n"
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// Show the content of all registers
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"info registers\n"
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"quit\n";
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close(gdbPipe[0]); // No input from pipe
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write(gdbPipe[1], gdbCommands,
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sizeof(gdbCommands));
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if (waitpid(pid, NULL, 0) < 0)
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{
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printf("GDB failed\n");
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}
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close(gdbPipe[1]);
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}
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else
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{
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printf("Fork failed\n");
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}
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}
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else
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{
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printf("Pipe failed\n");
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}
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}
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else
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/* Check if the "bare minimum" is available: GDB and an absolute path
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* to our program's binary.
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*/
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if (!programIsAvailable
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|| !gdbIsAvailable)
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{
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write(dumpFile, "No extended backtrace dumped:\n",
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strlen("No extended backtrace dumped:\n"));
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strlen("No extended backtrace dumped:\n"));
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if (!programIsAvailable)
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{
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write(dumpFile, "- Program path not available\n",
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strlen("- Program path not available\n"));
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strlen("- Program path not available\n"));
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}
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if (!gdbIsAvailable)
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{
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write(dumpFile, "- GDB not available\n",
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strlen("- GDB not available\n"));
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strlen("- GDB not available\n"));
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}
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return false;
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}
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// Create a pipe to use for communication with 'gdb'
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int gdbPipe[2];
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if (pipe(gdbPipe) == -1)
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{
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write(dumpFile, "Pipe failed\n",
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strlen("Pipe failed\n"));
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printf("Pipe failed\n");
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return false;
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}
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// Fork a new child process
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const pid_t pid = fork();
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if (pid == -1)
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{
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write(dumpFile, "Fork failed\n",
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strlen("Fork failed\n"));
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printf("Fork failed\n");
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// Clean up our pipe
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close(gdbPipe[0]);
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close(gdbPipe[1]);
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return false;
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}
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// Check to see if we're the child
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if (pid == 0)
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{
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char *gdbArgv[] = { gdbPath, programPath, programPID, NULL };
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char *gdbEnv[] = { NULL };
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close(gdbPipe[1]); // No output to pipe
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dup2(gdbPipe[0], STDIN_FILENO); // STDIN from pipe
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dup2(dumpFile, STDOUT_FILENO); // STDOUT to dumpFile
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write(dumpFile, "GDB extended backtrace:\n",
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strlen("GDB extended backtrace:\n"));
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/* If execve() is successful it effectively prevents further
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* execution of this code.
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*/
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execve(gdbPath, (char **)gdbArgv, (char **)gdbEnv);
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}
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// PARENT: If we get here we're the parent
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// Retrieve a full stack backtrace
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static const char gdbCommands[] = "backtrace full\n"
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// Move to the stack frame where we triggered the crash
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"frame 4\n"
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// Show the assembly code associated with that stack frame
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"disassemble\n"
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// Show the content of all registers
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"info registers\n"
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"quit\n";
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close(gdbPipe[0]); // No input from pipe
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write(gdbPipe[1], gdbCommands, sizeof(gdbCommands));
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/* Close our end of the pipe to force an EOF on GDB's side of the pipe.
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* This will prevent any kind of buffering on GDB's end from causing
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* infinite blocking on the next waitpid() call.
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*/
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close(gdbPipe[1]);
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if (waitpid(pid, NULL, 0) < 0)
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{
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printf("GDB failed\n");
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}
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return true;
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}
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