Improve readability of commandrvf() by replacing bare int values for file descriptors with their symbolic names STD{IN,OUT,ERR}_FILENO. Also add PIPE_READ and PIPE_WRITE for referencing relevant ends of a pipe. --- daemon/guestfsd.c | 79 +++++++++++++++++++++++++++++-------------------------- 1 file changed, 42 insertions(+), 37 deletions(-) diff --git a/daemon/guestfsd.c b/daemon/guestfsd.c index 5c84849..4b3dd5f 100644 --- a/daemon/guestfsd.c +++ b/daemon/guestfsd.c @@ -66,6 +66,10 @@ static char *read_cmdline (void); # define O_CLOEXEC 0 #endif +/* For improved readability dealing with pipe arrays */ +#define PIPE_READ 0 +#define PIPE_WRITE 1 + /* If root device is an ext2 filesystem, this is the major and minor. * This is so we can ignore this device from the point of view of the * user, eg. in guestfs_list_devices and many other places. @@ -834,22 +838,22 @@ commandrvf (char **stdoutput, char **stderror, int flags, signal (SIGPIPE, SIG_DFL); close (0); if (flag_copy_stdin) { - dup2 (stdin_fd[0], 0); - close (stdin_fd[0]); - close (stdin_fd[1]); + dup2 (stdin_fd[PIPE_READ], STDIN_FILENO); + close (stdin_fd[PIPE_READ]); + close (stdin_fd[PIPE_WRITE]); } else { /* Set stdin to /dev/null (ignore failure) */ ignore_value (open ("/dev/null", O_RDONLY|O_CLOEXEC)); } - close (so_fd[0]); - close (se_fd[0]); + close (so_fd[PIPE_READ]); + close (se_fd[PIPE_READ]); if (!(flags & COMMAND_FLAG_FOLD_STDOUT_ON_STDERR)) - dup2 (so_fd[1], 1); + dup2 (so_fd[PIPE_WRITE], STDOUT_FILENO); else - dup2 (se_fd[1], 1); - dup2 (se_fd[1], 2); - close (so_fd[1]); - close (se_fd[1]); + dup2 (se_fd[PIPE_WRITE], STDOUT_FILENO); + dup2 (se_fd[PIPE_WRITE], STDERR_FILENO); + close (so_fd[PIPE_WRITE]); + close (se_fd[PIPE_WRITE]); execvp (argv[0], (void *) argv); perror (argv[0]); @@ -866,15 +870,15 @@ commandrvf (char **stdoutput, char **stderror, int flags, } if (stdin_pid == 0) { /* Child process copying stdin. */ - close (so_fd[0]); - close (so_fd[1]); - close (se_fd[0]); - close (se_fd[1]); + close (so_fd[PIPE_READ]); + close (so_fd[PIPE_WRITE]); + close (se_fd[PIPE_READ]); + close (se_fd[PIPE_WRITE]); - close (1); - dup2 (stdin_fd[1], 1); - close (stdin_fd[0]); - close (stdin_fd[1]); + close (STDOUT_FILENO); + dup2 (stdin_fd[PIPE_WRITE], STDOUT_FILENO); + close (stdin_fd[PIPE_READ]); + close (stdin_fd[PIPE_WRITE]); if (chroot (sysroot) == -1) { perror ("chroot"); @@ -884,7 +888,7 @@ commandrvf (char **stdoutput, char **stderror, int flags, ssize_t n; char buffer[BUFSIZ]; while ((n = read (fd, buffer, sizeof buffer)) > 0) { - if (xwrite (1, buffer, n) == -1) + if (xwrite (STDOUT_FILENO, buffer, n) == -1) /* EPIPE error indicates the command process has exited * early. If the command process fails that will be caught * by the daemon, and if not, then it's not an error. @@ -906,23 +910,24 @@ commandrvf (char **stdoutput, char **stderror, int flags, } close (fd); - close (stdin_fd[0]); - close (stdin_fd[1]); + close (stdin_fd[PIPE_READ]); + close (stdin_fd[PIPE_WRITE]); } /* Parent process. */ - close (so_fd[1]); - close (se_fd[1]); + close (so_fd[PIPE_WRITE]); + close (se_fd[PIPE_WRITE]); FD_ZERO (&rset); - FD_SET (so_fd[0], &rset); - FD_SET (se_fd[0], &rset); + FD_SET (so_fd[PIPE_READ], &rset); + FD_SET (se_fd[PIPE_READ], &rset); quit = 0; while (quit < 2) { again: rset2 = rset; - r = select (MAX (so_fd[0], se_fd[0]) + 1, &rset2, NULL, NULL, NULL); + r = select (MAX (so_fd[PIPE_READ], se_fd[PIPE_READ]) + 1, &rset2, + NULL, NULL, NULL); if (r == -1) { if (errno == EINTR) goto again; @@ -943,20 +948,20 @@ commandrvf (char **stdoutput, char **stderror, int flags, *stderror = strdup ("error running external command, " "see debug output for details"); } - close (so_fd[0]); - close (se_fd[0]); + close (so_fd[PIPE_READ]); + close (se_fd[PIPE_READ]); waitpid (pid, NULL, 0); if (stdin_pid >= 0) waitpid (stdin_pid, NULL, 0); return -1; } - if (FD_ISSET (so_fd[0], &rset2)) { /* something on stdout */ - r = read (so_fd[0], buf, sizeof buf); + if (FD_ISSET (so_fd[PIPE_READ], &rset2)) { /* something on stdout */ + r = read (so_fd[PIPE_READ], buf, sizeof buf); if (r == -1) { perror ("read"); goto quit; } - if (r == 0) { FD_CLR (so_fd[0], &rset); quit++; } + if (r == 0) { FD_CLR (so_fd[PIPE_READ], &rset); quit++; } if (r > 0 && stdoutput) { so_size += r; @@ -970,17 +975,17 @@ commandrvf (char **stdoutput, char **stderror, int flags, } } - if (FD_ISSET (se_fd[0], &rset2)) { /* something on stderr */ - r = read (se_fd[0], buf, sizeof buf); + if (FD_ISSET (se_fd[PIPE_READ], &rset2)) { /* something on stderr */ + r = read (se_fd[PIPE_READ], buf, sizeof buf); if (r == -1) { perror ("read"); goto quit; } - if (r == 0) { FD_CLR (se_fd[0], &rset); quit++; } + if (r == 0) { FD_CLR (se_fd[PIPE_READ], &rset); quit++; } if (r > 0) { if (verbose) - ignore_value (write (2, buf, r)); + ignore_value (write (STDERR_FILENO, buf, r)); if (stderror) { se_size += r; @@ -996,8 +1001,8 @@ commandrvf (char **stdoutput, char **stderror, int flags, } } - close (so_fd[0]); - close (se_fd[0]); + close (so_fd[PIPE_READ]); + close (se_fd[PIPE_READ]); /* Make sure the output buffers are \0-terminated. Also remove any * trailing \n characters from the error buffer (not from stdout). -- 1.7.11.7