/* vi: set sw=4 ts=4: */ /* * Utility routines. * * Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org> * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ #include "libbb.h" #if ENABLE_FEATURE_USE_SENDFILE # include <sys/sendfile.h> #else # define sendfile(a,b,c,d) (-1) #endif /* * We were using 0x7fff0000 as sendfile chunk size, but it * was seen to cause largish delays when user tries to ^C a file copy. * Let's use a saner size. * Note: needs to be >= max(CONFIG_FEATURE_COPYBUF_KB), * or else "copy to eof" code will use neddlesly short reads. */ #define SENDFILE_BIGBUF (16*1024*1024) /* Used by NOFORK applets (e.g. cat) - must not use xmalloc. * size < 0 means "ignore write errors", used by tar --to-command * size = 0 means "copy till EOF" */ static off_t bb_full_fd_action(int src_fd, int dst_fd, off_t size) { int status = -1; off_t total = 0; bool continue_on_write_error = 0; ssize_t sendfile_sz; #if CONFIG_FEATURE_COPYBUF_KB > 4 char *buffer = buffer; /* for compiler */ int buffer_size = 0; #else char buffer[CONFIG_FEATURE_COPYBUF_KB * 1024]; enum { buffer_size = sizeof(buffer) }; #endif if (size < 0) { size = -size; continue_on_write_error = 1; } if (src_fd < 0) goto out; sendfile_sz = !ENABLE_FEATURE_USE_SENDFILE ? 0 : SENDFILE_BIGBUF; if (!size) { size = SENDFILE_BIGBUF; status = 1; /* copy until eof */ } while (1) { ssize_t rd; if (sendfile_sz) { rd = sendfile(dst_fd, src_fd, NULL, size > sendfile_sz ? sendfile_sz : size); if (rd >= 0) goto read_ok; sendfile_sz = 0; /* do not try sendfile anymore */ } #if CONFIG_FEATURE_COPYBUF_KB > 4 if (buffer_size == 0) { if (size > 0 && size <= 4 * 1024) goto use_small_buf; /* We want page-aligned buffer, just in case kernel is clever * and can do page-aligned io more efficiently */ buffer = mmap(NULL, CONFIG_FEATURE_COPYBUF_KB * 1024, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, /* ignored: */ -1, 0); buffer_size = CONFIG_FEATURE_COPYBUF_KB * 1024; if (buffer == MAP_FAILED) { use_small_buf: buffer = alloca(4 * 1024); buffer_size = 4 * 1024; } } #endif rd = safe_read(src_fd, buffer, size > buffer_size ? buffer_size : size); if (rd < 0) { bb_perror_msg(bb_msg_read_error); break; } read_ok: if (!rd) { /* eof - all done */ status = 0; break; } /* dst_fd == -1 is a fake, else... */ if (dst_fd >= 0 && !sendfile_sz) { ssize_t wr = full_write(dst_fd, buffer, rd); if (wr < rd) { if (!continue_on_write_error) { bb_perror_msg(bb_msg_write_error); break; } dst_fd = -1; } } total += rd; if (status < 0) { /* if we aren't copying till EOF... */ size -= rd; if (!size) { /* 'size' bytes copied - all done */ status = 0; break; } } } out: /* some environments don't have munmap(), hide it in #if */ #if CONFIG_FEATURE_COPYBUF_KB > 4 if (buffer_size > 4 * 1024) munmap(buffer, buffer_size); #endif return status ? -1 : total; } #if 0 void FAST_FUNC complain_copyfd_and_die(off_t sz) { if (sz != -1) bb_error_msg_and_die("short read"); /* if sz == -1, bb_copyfd_XX already complained */ xfunc_die(); } #endif off_t FAST_FUNC bb_copyfd_size(int fd1, int fd2, off_t size) { if (size) { return bb_full_fd_action(fd1, fd2, size); } return 0; } void FAST_FUNC bb_copyfd_exact_size(int fd1, int fd2, off_t size) { off_t sz = bb_copyfd_size(fd1, fd2, size); if (sz == (size >= 0 ? size : -size)) return; if (sz != -1) bb_error_msg_and_die("short read"); /* if sz == -1, bb_copyfd_XX already complained */ xfunc_die(); } off_t FAST_FUNC bb_copyfd_eof(int fd1, int fd2) { return bb_full_fd_action(fd1, fd2, 0); }