diff options
Diffstat (limited to 'examples/tiny.c')
| -rw-r--r-- | examples/tiny.c | 430 |
1 files changed, 430 insertions, 0 deletions
diff --git a/examples/tiny.c b/examples/tiny.c new file mode 100644 index 0000000..ff80f0c --- /dev/null +++ b/examples/tiny.c @@ -0,0 +1,430 @@ +int +save_bash_input (fd, new_fd) + int fd, new_fd; +{ + int nfd; + + /* Sync the stream so we can re-read from the new file descriptor. We + might be able to avoid this by copying the buffered stream verbatim + to the new file descriptor. */ + if (buffers[fd]) + sync_buffered_stream (fd); + + /* Now take care of duplicating the file descriptor that bash is + using for input, so we can reinitialize it later. */ + nfd = (new_fd == -1) ? fcntl (fd, F_DUPFD, 10) : new_fd; + if (nfd == -1) + { + if (fcntl (fd, F_GETFD, 0) == 0) + sys_error (_("cannot allocate new file descriptor for bash input from fd %d"), fd); + return -1; + } + + if (nfd < nbuffers && buffers[nfd]) + { + /* What's this? A stray buffer without an associated open file + descriptor? Free up the buffer and report the error. */ + internal_error (_("save_bash_input: buffer already exists for new fd %d"), nfd); + if (buffers[nfd]->b_flag & B_SHAREDBUF) + buffers[nfd]->b_buffer = (char *)NULL; + free_buffered_stream (buffers[nfd]); + } + + /* Reinitialize bash_input.location. */ + if (bash_input.type == st_bstream) + { + bash_input.location.buffered_fd = nfd; + fd_to_buffered_stream (nfd); + close_buffered_fd (fd); /* XXX */ + } + else + /* If the current input type is not a buffered stream, but the shell + is not interactive and therefore using a buffered stream to read + input (e.g. with an `eval exec 3>output' inside a script), note + that the input fd has been changed. pop_stream() looks at this + value and adjusts the input fd to the new value of + default_buffered_input accordingly. */ + bash_input_fd_changed++; + + if (default_buffered_input == fd) + default_buffered_input = nfd; + + SET_CLOSE_ON_EXEC (nfd); + return nfd; +} + +/* Check that file descriptor FD is not the one that bash is currently + using to read input from a script. FD is about to be duplicated onto, + which means that the kernel will close it for us. If FD is the bash + input file descriptor, we need to seek backwards in the script (if + possible and necessary -- scripts read from stdin are still unbuffered), + allocate a new file descriptor to use for bash input, and re-initialize + the buffered stream. Make sure the file descriptor used to save bash + input is set close-on-exec. Returns 0 on success, -1 on failure. This + works only if fd is > 0 -- if fd == 0 and bash is reading input from + fd 0, sync_buffered_stream is used instead, to cooperate with input + redirection (look at redir.c:add_undo_redirect()). */ +int +check_bash_input (fd) + int fd; +{ + if (fd_is_bash_input (fd)) + { + if (fd > 0) + return ((save_bash_input (fd, -1) == -1) ? -1 : 0); + else if (fd == 0) + return ((sync_buffered_stream (fd) == -1) ? -1 : 0); + } + return 0; +} + +/* This is the buffered stream analogue of dup2(fd1, fd2). The + BUFFERED_STREAM corresponding to fd2 is deallocated, if one exists. + BUFFERS[fd1] is copied to BUFFERS[fd2]. This is called by the + redirect code for constructs like 4<&0 and 3</etc/rc.local. */ +int +duplicate_buffered_stream (fd1, fd2) + int fd1, fd2; +{ + int is_bash_input, m; + + if (fd1 == fd2) + return 0; + + m = max (fd1, fd2); + ALLOCATE_BUFFERS (m); + + /* If FD2 is the file descriptor bash is currently using for shell input, + we need to do some extra work to make sure that the buffered stream + actually exists (it might not if fd1 was not active, and the copy + didn't actually do anything). */ + is_bash_input = (bash_input.type == st_bstream) && + (bash_input.location.buffered_fd == fd2); + + if (buffers[fd2]) + { + /* If the two objects share the same b_buffer, don't free it. */ + if (buffers[fd1] && buffers[fd1]->b_buffer && buffers[fd1]->b_buffer == buffers[fd2]->b_buffer) + buffers[fd2] = (BUFFERED_STREAM *)NULL; + /* If this buffer is shared with another fd, don't free the buffer */ + else if (buffers[fd2]->b_flag & B_SHAREDBUF) + { + buffers[fd2]->b_buffer = (char *)NULL; + free_buffered_stream (buffers[fd2]); + } + else + free_buffered_stream (buffers[fd2]); + } + buffers[fd2] = copy_buffered_stream (buffers[fd1]); + if (buffers[fd2]) + buffers[fd2]->b_fd = fd2; + + if (is_bash_input) + { + if (!buffers[fd2]) + fd_to_buffered_stream (fd2); + buffers[fd2]->b_flag |= B_WASBASHINPUT; + } + + if (fd_is_bash_input (fd1) || (buffers[fd1] && (buffers[fd1]->b_flag & B_SHAREDBUF))) + buffers[fd2]->b_flag |= B_SHAREDBUF; + + return (fd2); +} + +/* Return 1 if a seek on FD will succeed. */ +#define fd_is_seekable(fd) (lseek ((fd), 0L, SEEK_CUR) >= 0) + +/* Take FD, a file descriptor, and create and return a buffered stream + corresponding to it. If something is wrong and the file descriptor + is invalid, return a NULL stream. */ +BUFFERED_STREAM * +fd_to_buffered_stream (fd) + int fd; +{ + char *buffer; + size_t size; + struct stat sb; + + if (fstat (fd, &sb) < 0) + { + close (fd); + return ((BUFFERED_STREAM *)NULL); + } + + size = (fd_is_seekable (fd)) ? min (sb.st_size, MAX_INPUT_BUFFER_SIZE) : 1; + if (size == 0) + size = 1; + buffer = (char *)xmalloc (size); + + return (make_buffered_stream (fd, buffer, size)); +} + +/* Return a buffered stream corresponding to FILE, a file name. */ +BUFFERED_STREAM * +open_buffered_stream (file) + char *file; +{ + int fd; + + fd = open (file, O_RDONLY); + return ((fd >= 0) ? fd_to_buffered_stream (fd) : (BUFFERED_STREAM *)NULL); +} + +/* Deallocate a buffered stream and free up its resources. Make sure we + zero out the slot in BUFFERS that points to BP. */ +void +free_buffered_stream (bp) + BUFFERED_STREAM *bp; +{ + int n; + + if (!bp) + return; + + n = bp->b_fd; + if (bp->b_buffer) + free (bp->b_buffer); + free (bp); + buffers[n] = (BUFFERED_STREAM *)NULL; +} + +/* Close the file descriptor associated with BP, a buffered stream, and free + up the stream. Return the status of closing BP's file descriptor. */ +int +close_buffered_stream (bp) + BUFFERED_STREAM *bp; +{ + int fd; + + if (!bp) + return (0); + fd = bp->b_fd; + if (bp->b_flag & B_SHAREDBUF) + bp->b_buffer = (char *)NULL; + free_buffered_stream (bp); + return (close (fd)); +} + +/* Deallocate the buffered stream associated with file descriptor FD, and + close FD. Return the status of the close on FD. */ +int +close_buffered_fd (fd) + int fd; +{ + if (fd < 0) + { + errno = EBADF; + return -1; + } + if (fd >= nbuffers || !buffers || !buffers[fd]) + return (close (fd)); + return (close_buffered_stream (buffers[fd])); +} + +/* Make the BUFFERED_STREAM associated with buffers[FD] be BP, and return + the old BUFFERED_STREAM. */ +BUFFERED_STREAM * +set_buffered_stream (fd, bp) + int fd; + BUFFERED_STREAM *bp; +{ + BUFFERED_STREAM *ret; + + ret = buffers[fd]; + buffers[fd] = bp; + return ret; +} + +/* Read a buffer full of characters from BP, a buffered stream. */ +static int +b_fill_buffer (bp) + BUFFERED_STREAM *bp; +{ + ssize_t nr; + off_t o; + + CHECK_TERMSIG; + /* In an environment where text and binary files are treated differently, + compensate for lseek() on text files returning an offset different from + the count of characters read() returns. Text-mode streams have to be + treated as unbuffered. */ + if ((bp->b_flag & (B_TEXT | B_UNBUFF)) == B_TEXT) + { + o = lseek (bp->b_fd, 0, SEEK_CUR); + nr = zread (bp->b_fd, bp->b_buffer, bp->b_size); + if (nr > 0 && nr < lseek (bp->b_fd, 0, SEEK_CUR) - o) + { + lseek (bp->b_fd, o, SEEK_SET); + bp->b_flag |= B_UNBUFF; + bp->b_size = 1; + nr = zread (bp->b_fd, bp->b_buffer, bp->b_size); + } + } + else + nr = zread (bp->b_fd, bp->b_buffer, bp->b_size); + if (nr <= 0) + { + bp->b_used = bp->b_inputp = 0; + bp->b_buffer[0] = 0; + if (nr == 0) + bp->b_flag |= B_EOF; + else + bp->b_flag |= B_ERROR; + return (EOF); + } + + bp->b_used = nr; + bp->b_inputp = 0; + return (bp->b_buffer[bp->b_inputp++] & 0xFF); +} + +/* Get a character from buffered stream BP. */ +#define bufstream_getc(bp) \ + (bp->b_inputp == bp->b_used || !bp->b_used) \ + ? b_fill_buffer (bp) \ + : bp->b_buffer[bp->b_inputp++] & 0xFF + +/* Push C back onto buffered stream BP. */ +static int +bufstream_ungetc(c, bp) + int c; + BUFFERED_STREAM *bp; +{ + if (c == EOF || bp == 0 || bp->b_inputp == 0) + return (EOF); + + bp->b_buffer[--bp->b_inputp] = c; + return (c); +} + +/* Seek backwards on file BFD to synchronize what we've read so far + with the underlying file pointer. */ +int +sync_buffered_stream (bfd) + int bfd; +{ + BUFFERED_STREAM *bp; + off_t chars_left; + + if (buffers == 0 || (bp = buffers[bfd]) == 0) + return (-1); + + chars_left = bp->b_used - bp->b_inputp; + if (chars_left) + lseek (bp->b_fd, -chars_left, SEEK_CUR); + bp->b_used = bp->b_inputp = 0; + return (0); +} + +int +buffered_getchar () +{ + CHECK_TERMSIG; + + if (bash_input.location.buffered_fd < 0 || buffers[bash_input.location.buffered_fd] == 0) + return EOF; + +#if !defined (DJGPP) + return (bufstream_getc (buffers[bash_input.location.buffered_fd])); +#else + /* On DJGPP, ignore \r. */ + int ch; + while ((ch = bufstream_getc (buffers[bash_input.location.buffered_fd])) == '\r') + ; + return ch; +#endif +} + +int +buffered_ungetchar (c) + int c; +{ + return (bufstream_ungetc (c, buffers[bash_input.location.buffered_fd])); +} + +/* Make input come from file descriptor BFD through a buffered stream. */ +void +with_input_from_buffered_stream (bfd, name) + int bfd; + char *name; +{ + INPUT_STREAM location; + BUFFERED_STREAM *bp; + + location.buffered_fd = bfd; + /* Make sure the buffered stream exists. */ + bp = fd_to_buffered_stream (bfd); + init_yy_io (bp == 0 ? return_EOF : buffered_getchar, + buffered_ungetchar, st_bstream, name, location); +} + +#if defined (TEST) +void * +xmalloc(s) +int s; +{ + return (malloc (s)); +} + +void * +xrealloc(s, size) +char *s; +int size; +{ + if (!s) + return(malloc (size)); + else + return(realloc (s, size)); +} + +void +init_yy_io () +{ +} + +process(bp) +BUFFERED_STREAM *bp; +{ + int c; + + while ((c = bufstream_getc(bp)) != EOF) + putchar(c); +} + +BASH_INPUT bash_input; + +struct stat dsb; /* can be used from gdb */ + +/* imitate /bin/cat */ +main(argc, argv) +int argc; +char **argv; +{ + register int i; + BUFFERED_STREAM *bp; + + if (argc == 1) { + bp = fd_to_buffered_stream (0); + process(bp); + exit(0); + } + for (i = 1; i < argc; i++) { + if (argv[i][0] == '-' && argv[i][1] == '\0') { + bp = fd_to_buffered_stream (0); + if (!bp) + continue; + process(bp); + free_buffered_stream (bp); + } else { + bp = open_buffered_stream (argv[i]); + if (!bp) + continue; + process(bp); + close_buffered_stream (bp); + } + } + exit(0); +} +#endif /* TEST */ +#endif /* BUFFERED_INPUT */ |