From: Denis Vlasenko Date: Thu, 28 Feb 2008 10:10:10 +0000 (-0000) Subject: script: correctly handle buffered "tail" of output. +35 bytes. X-Git-Tag: 1_10_0~80 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=32fd76c1d5a2e430ecdbb84706dba410992c34d0;p=oweals%2Fbusybox.git script: correctly handle buffered "tail" of output. +35 bytes. --- diff --git a/util-linux/script.c b/util-linux/script.c index e6dbb1aa2..a4aaa422f 100644 --- a/util-linux/script.c +++ b/util-linux/script.c @@ -13,67 +13,38 @@ #include "libbb.h" -struct globals { - int child_pid; - int attr_ok; /* NB: 0: ok */ - struct termios tt; - const char *fname; -}; -#define G (*ptr_to_globals) -#define child_pid (G.child_pid) -#define attr_ok (G.attr_ok ) -#define tt (G.tt ) -#define fname (G.fname ) -#define INIT_G() do { \ - SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \ - fname = "typescript"; \ -} while (0) - -static void done(void) -{ - if (child_pid) { /* we are parent */ - if (attr_ok == 0) - tcsetattr(0, TCSAFLUSH, &tt); - if (!(option_mask32 & 8)) /* not -q */ - printf("Script done, file is %s\n", fname); - } - exit(0); -} +static smallint fd_count = 2; -#ifdef UNUSED static void handle_sigchld(int sig) { - /* wait for the exited child and exit */ - while (wait_any_nohang(&sig) > 0) - continue; - done(); + fd_count = 0; } -#endif - -#if ENABLE_GETOPT_LONG -static const char getopt_longopts[] ALIGN1 = - "append\0" No_argument "a" - "command\0" Required_argument "c" - "flush\0" No_argument "f" - "quiet\0" No_argument "q" - ; -#endif int script_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE; int script_main(int argc, char *argv[]) { - int opt, pty; - int winsz_ok; + int opt; int mode; - struct termios rtt; + int child_pid; + int attr_ok; /* NB: 0: ok */ + int winsz_ok; + int pty; + char pty_line[32]; + struct termios tt, rtt; struct winsize win; - char line[32]; + const char *fname = "typescript"; const char *shell; char shell_opt[] = "-i"; char *shell_arg = NULL; - INIT_G(); #if ENABLE_GETOPT_LONG + static const char getopt_longopts[] ALIGN1 = + "append\0" No_argument "a" + "command\0" Required_argument "c" + "flush\0" No_argument "f" + "quiet\0" No_argument "q" + ; + applet_long_options = getopt_longopts; #endif opt_complementary = "?1"; /* max one arg */ @@ -95,10 +66,10 @@ int script_main(int argc, char *argv[]) } shell = getenv("SHELL"); if (shell == NULL) { - shell = _PATH_BSHELL; + shell = DEFAULT_SHELL; } - pty = getpty(line, sizeof(line)); + pty = getpty(pty_line, sizeof(pty_line)); if (pty < 0) { bb_perror_msg_and_die("can't get pty"); } @@ -112,9 +83,12 @@ int script_main(int argc, char *argv[]) rtt.c_lflag &= ~ECHO; tcsetattr(0, TCSAFLUSH, &rtt); - /* We exit as soon as child exits */ - //signal(SIGCHLD, handle_sigchld); - signal(SIGCHLD, (void (*)(int)) done); + /* "script" from util-linux exits when child exits, + * we wouldn't wait for EOF from slave pty + * (output may be produced by grandchildren of child) */ + signal(SIGCHLD, handle_sigchld); + + /* TODO: SIGWINCH? pass window size changes down to slave? */ child_pid = vfork(); if (child_pid < 0) { @@ -123,11 +97,10 @@ int script_main(int argc, char *argv[]) if (child_pid) { /* parent */ - char buf[256]; +#define buf bb_common_bufsiz1 struct pollfd pfd[2]; - int outfd; - int fd_count = 2; struct pollfd *ppfd = pfd; + int outfd, count, loop; outfd = xopen(fname, mode); pfd[0].fd = 0; @@ -135,14 +108,16 @@ int script_main(int argc, char *argv[]) pfd[1].fd = pty; pfd[1].events = POLLIN; ndelay_on(pty); /* this descriptor is not shared, can do this */ - /* ndelay_on(0); - NO, stdin can be shared! */ + /* ndelay_on(0); - NO, stdin can be shared! Pity :( */ /* copy stdin to pty master input, * copy pty master output to stdout and file */ /* TODO: don't use full_write's, use proper write buffering */ - while (fd_count && safe_poll(ppfd, fd_count, -1) > 0) { + while (fd_count) { + /* not safe_poll! we want SIGCHLD to EINTR poll */ + poll(ppfd, fd_count, -1); if (pfd[0].revents) { - int count = safe_read(0, buf, sizeof(buf)); + count = safe_read(0, buf, sizeof(buf)); if (count <= 0) { /* err/eof: don't read anymore */ pfd[0].revents = 0; @@ -153,7 +128,6 @@ int script_main(int argc, char *argv[]) } } if (pfd[1].revents) { - int count; errno = 0; count = safe_read(pty, buf, sizeof(buf)); if (count <= 0 && errno != EAGAIN) { @@ -170,14 +144,32 @@ int script_main(int argc, char *argv[]) } } } - done(); /* does not return */ + /* If loop was exited because SIGCHLD handler set fd_count to 0, + * there still can be some buffered output. But not loop forever: + * we won't pump orphaned grandchildren's output indefinitely. + * Testcase: running this in script: + * exec dd if=/dev/zero bs=1M count=1 + * must have "1+0 records in, 1+0 records out" captured too. + * (util-linux's script doesn't do this. buggy :) */ + loop = 999; + /* pty is in O_NONBLOCK mode, we exit as soon as buffer is empty */ + while (--loop && (count = safe_read(pty, buf, sizeof(buf))) > 0) { + full_write(1, buf, count); + full_write(outfd, buf, count); + } + + if (attr_ok == 0) + tcsetattr(0, TCSAFLUSH, &tt); + if (!(opt & 8)) /* not -q */ + printf("Script done, file is %s\n", fname); + return EXIT_SUCCESS; } /* child: make pty slave to be input, output, error; run shell */ close(pty); /* close pty master */ /* open pty slave to fd 0,1,2 */ close(0); - xopen(line, O_RDWR); /* uses fd 0 */ + xopen(pty_line, O_RDWR); /* uses fd 0 */ xdup2(0, 1); xdup2(0, 2); /* copy our original stdin tty's parameters to pty */