A debug program to help diagnose data-transfer corruption problems.

diff --git a/support/savetransfer.c b/support/savetransfer.c
new file mode 100644 (file)
index 0000000..bec6c06
--- /dev/null
+++ b/support/savetransfer.c
@@ -0,0 +1,178 @@
+/* This program can record the stream of data flowing to or from a program.
+ * This allows it to be used to check that rsync's data that is flowing
+ * through a remote shell is not being corrupted (for example).
+ *
+ * Usage: savetransfer [-i|-o] OUTPUT_FILE PROGRAM [ARGS...]
+ * -i  Save the input going to PROGRAM to the OUTPUT_FILE
+ * -o  Save the output coming from PROGRAM to the OUTPUT_FILE
+ *
+ * If you want to capture the flow of data for an rsync command, use one of
+ * the following commands (the first two are push commands, the last two are
+ * pull commands):
+ *
+ * rsync -av --rsh="savetransfer -i /tmp/from.sender ssh"
+ *   --rsync-path="savetransfer -i /tmp/to.receiver rsync" FILES HOST:DEST
+ *
+ * rsync -av --rsh="savetransfer -o /tmp/to.sender ssh"
+ *   --rsync-path="savetransfer -o /tmp/from.generator rsync" FILES HOST:DEST
+ *
+ * rsync -av --rsh="savetransfer -i /tmp/from.generator ssh"
+ *   --rsync-path="savetransfer -i /tmp/to.sender rsync" HOST:FILES DEST
+ *
+ * rsync -av --rsh="savetransfer -o /tmp/to.receiver ssh"
+ *   --rsync-path="savetransfer -o /tmp/from.sender rsync" HOST:FILES DEST
+ *
+ * Note that this program aborts after 30 seconds of inactivity, so you'll need
+ * to change it if that is not enough dead time for your transfer.  Also, some
+ * of the above commands will not notice that the transfer is done (if we're
+ * saving the input to a PROGRAM and the PROGRAM goes away:  we won't notice
+ * that it's gone unless more data comes in) -- when this happens it will delay
+ * at the end of the transfer until the timeout period expires.
+ */
+
+#include "../rsync.h"
+
+#define TIMEOUT_SECONDS 30
+
+void run_program(char **command);
+
+char buf[4096];
+int save_data_from_program = 0;
+
+int
+main(int argc, char *argv[])
+{
+    int fd_file, len;
+    struct timeval tv;
+    fd_set fds;
+
+    argv++;
+    if (--argc && argv[0][0] == '-') {
+       if (argv[0][1] == 'o')
+           save_data_from_program = 1;
+       else if (argv[0][1] == 'i')
+           save_data_from_program = 0;
+       else {
+           fprintf(stderr, "Unknown option: %s\n", argv[0]);
+           exit(1);
+       }
+       argv++;
+       argc--;
+    }
+    if (argc < 2) {
+       fprintf(stderr, "Usage: savetransfer [-i|-o] OUTPUT_FILE PROGRAM [ARGS...]\n");
+       fprintf(stderr, "-i  Save the input going to PROGRAM to the OUTPUT_FILE\n");
+       fprintf(stderr, "-o  Save the output coming from PROGRAM to the OUTPUT_FILE\n");
+       exit(1);
+    }
+    if ((fd_file = open(*argv, O_WRONLY|O_TRUNC|O_CREAT|O_BINARY, 0644)) < 0) {
+       fprintf(stderr, "Unable to write to `%s': %s\n", *argv, strerror(errno));
+       exit(1);
+    }
+    set_blocking(fd_file);
+
+    signal(SIGPIPE, SIG_IGN);
+
+    run_program(argv + 1);
+
+#if HAVE_SETMODE && O_BINARY
+    setmode(STDIN_FILENO, O_BINARY);
+    setmode(STDOUT_FILENO, O_BINARY);
+#endif
+    set_nonblocking(STDIN_FILENO);
+    set_blocking(STDOUT_FILENO);
+
+    while (1) {
+       FD_ZERO(&fds);
+       FD_SET(STDIN_FILENO, &fds);
+       tv.tv_sec = TIMEOUT_SECONDS;
+       tv.tv_usec = 0;
+       if (!select(STDIN_FILENO+1, &fds, NULL, NULL, &tv))
+           break;
+       if (!FD_ISSET(STDIN_FILENO, &fds))
+           break;
+       if ((len = read(STDIN_FILENO, buf, sizeof buf)) <= 0)
+           break;
+       if (write(STDOUT_FILENO, buf, len) != len) {
+           fprintf(stderr, "Failed to write data to stdout: %s\n", strerror(errno));
+           exit(1);
+       }
+       if (write(fd_file, buf, len) != len) {
+           fprintf(stderr, "Failed to write data to fd_file: %s\n", strerror(errno));
+           exit(1);
+       }
+    }
+    return 0;
+}
+
+void
+run_program(char **command)
+{
+    int pipe_fds[2], ret;
+    pid_t pid;
+
+    if (pipe(pipe_fds) < 0) {
+       fprintf(stderr, "pipe failed: %s\n", strerror(errno));
+       exit(1);
+    }
+
+    if ((pid = fork()) < 0) {
+       fprintf(stderr, "fork failed: %s\n", strerror(errno));
+       exit(1);
+    }
+
+    if (pid == 0) {
+       if (save_data_from_program)
+           ret = dup2(pipe_fds[1], STDOUT_FILENO);
+       else
+           ret = dup2(pipe_fds[0], STDIN_FILENO);
+       if (ret < 0) {
+           fprintf(stderr, "Failed to dup (in child): %s\n", strerror(errno));
+           exit(1);
+       }
+       close(pipe_fds[0]);
+       close(pipe_fds[1]);
+       set_blocking(STDIN_FILENO);
+       set_blocking(STDOUT_FILENO);
+       execvp(command[0], command);
+       fprintf(stderr, "Failed to exec %s: %s\n", command[0], strerror(errno));
+       exit(1);
+    }
+
+    if (save_data_from_program)
+       ret = dup2(pipe_fds[0], STDIN_FILENO);
+    else
+       ret = dup2(pipe_fds[1], STDOUT_FILENO);
+    if (ret < 0) {
+       fprintf(stderr, "Failed to dup (in parent): %s\n", strerror(errno));
+       exit(1);
+    }
+    close(pipe_fds[0]);
+    close(pipe_fds[1]);
+}
+
+void
+set_nonblocking(int fd)
+{
+    int val;
+
+    if ((val = fcntl(fd, F_GETFL, 0)) == -1)
+       return;
+    if (!(val & NONBLOCK_FLAG)) {
+       val |= NONBLOCK_FLAG;
+       fcntl(fd, F_SETFL, val);
+    }
+}
+
+void
+set_blocking(int fd)
+{
+    int val;
+
+    if ((val = fcntl(fd, F_GETFL, 0)) < 0)
+       return;
+    if (val & NONBLOCK_FLAG) {
+       val &= ~NONBLOCK_FLAG;
+       fcntl(fd, F_SETFL, val);
+    }
+}