2 files changed, 67 insertions(+), 3 deletions(-)

M README.md
M main.c

@@ 11,11 11,15 @@ after-the-fact via a Unix socket. Useful when trying to obtain data about a
 
 ## Usage
 
-    <program> 2>&1 | blackbox
+    blackbox -- <program>
 
 `<program>` can be used normally for extended periods of time. blackbox will
 print instructions that can be used to grab logs when the bug is reproduced.
 
+blackbox can also read from the standard input:
+
+    <program> 2>&1 | blackbox
+
 ## License
 
 AGPLv3, see LICENSE.

@@ 6,6 6,7 @@
 #include <stdlib.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
 struct ring_buffer {


@@ 76,12 77,71 @@ int main(int argc, char *argv[]) {
 		// TODO: add more useful options
 		switch (opt) {
 		default:
-			fprintf(stderr, "usage: blackbox\n");
+			fprintf(stderr, "usage: blackbox [command...]\n");
 			return 1;
 		}
 	}
 
-	int in_fd = STDIN_FILENO;
+	int in_fd;
+	if (optind < argc) {
+		char **cmd = &argv[optind];
+
+		int child_pipe[2];
+		if (pipe(child_pipe) != 0) {
+			perror("pipe failed");
+			return 1;
+		}
+
+		pid_t pid = fork();
+		if (pid < 0) {
+			perror("fork failed");
+			return 1;
+		} else if (pid == 0) {
+			close(child_pipe[0]);
+
+			// Redirect stdout to the pipe
+			if (dup2(child_pipe[1], STDOUT_FILENO) < 0) {
+				perror("dup2 failed");
+				_exit(1);
+			}
+			close(child_pipe[1]);
+
+			// Then redirect stderr to stdout
+			if (dup2(STDOUT_FILENO, STDERR_FILENO) < 0) {
+				perror("dup2 failed");
+				_exit(1);
+			}
+
+			// Fork again to avoid SIGCHLD
+			pid = fork();
+			if (pid < 0) {
+				perror("fork failed");
+				_exit(1);
+			} else if (pid == 0) {
+				execvp(cmd[0], cmd);
+				perror("execvp failed");
+				_exit(1);
+			}
+
+			_exit(0);
+		}
+
+		close(child_pipe[1]);
+		in_fd = child_pipe[0];
+
+		int stat;
+		if (waitpid(pid, &stat, 0) < 0) {
+			perror("waitpid failed");
+			return 1;
+		}
+		if (stat != 0) {
+			fprintf(stderr, "failed to spawn child process\n");
+			return 1;
+		}
+	} else {
+		in_fd = STDIN_FILENO;
+	}
+
 	if (set_nonblock(in_fd) != 0) {
 		return 1;
 	}