diff options
Diffstat (limited to 'libio/fileops.c')
| -rw-r--r-- | libio/fileops.c | 304 |
1 files changed, 278 insertions, 26 deletions
diff --git a/libio/fileops.c b/libio/fileops.c index 2941296..979825e 100644 --- a/libio/fileops.c +++ b/libio/fileops.c @@ -601,42 +601,207 @@ _IO_new_file_underflow (fp) } INTDEF2(_IO_new_file_underflow, _IO_file_underflow) -/* Special callback replacing the underflow callbacks if we mmap the - file. */ -int -_IO_file_underflow_mmap (_IO_FILE *fp) +/* Guts of underflow callback if we mmap the file. This stats the file and + updates the stream state to match. In the normal case we return zero. + If the file is no longer eligible for mmap, its jump tables are reset to + the vanilla ones and we return nonzero. */ +static int +mmap_remap_check (_IO_FILE *fp) { - if (fp->_IO_read_end < fp->_IO_buf_end) + struct _G_stat64 st; + + if (_IO_SYSSTAT (fp, &st) == 0 + && S_ISREG (st.st_mode) && st.st_size != 0 + /* Limit the file size to 1MB for 32-bit machines. */ + && (sizeof (ptrdiff_t) > 4 || st.st_size < 1*1024*1024)) { - /* A stupid requirement in POSIX says that the first read on a - stream must update the atime. Just read a single byte. We - don't have to worry about repositioning the file descriptor - since the following seek defines its position anyway. */ - char ignore[1]; - read (fp->_fileno, ignore, 1); + const size_t pagesize = __getpagesize (); +# define ROUNDED(x) (((x) + pagesize - 1) & ~(pagesize - 1)) + if (ROUNDED (st.st_size) < ROUNDED (fp->_IO_buf_end + - fp->_IO_buf_base)) + { + /* We can trim off some pages past the end of the file. */ + (void) __munmap (fp->_IO_buf_base + ROUNDED (st.st_size), + ROUNDED (fp->_IO_buf_end - fp->_IO_buf_base) + - ROUNDED (st.st_size)); + fp->_IO_buf_end = fp->_IO_buf_base + st.st_size; + } + else if (ROUNDED (st.st_size) > ROUNDED (fp->_IO_buf_end + - fp->_IO_buf_base)) + { + /* The file added some pages. We need to remap it. */ + void *p; +#if defined __linux__ /* XXX */ + p = __mremap (fp->_IO_buf_base, ROUNDED (fp->_IO_buf_end + - fp->_IO_buf_base), + ROUNDED (st.st_size), MREMAP_MAYMOVE); + if (p == MAP_FAILED) + { + (void) __munmap (fp->_IO_buf_base, + fp->_IO_buf_end - fp->_IO_buf_base); + goto punt; + } +#else + (void) __munmap (fp->_IO_buf_base, + fp->_IO_buf_end - fp->_IO_buf_base); +# ifdef _G_MMAP64 + p = _G_MMAP64 (NULL, st.st_size, PROT_READ, MAP_SHARED, + fp->_fileno, 0); +# else + p = __mmap (NULL, st.st_size, PROT_READ, MAP_SHARED, + fp->_fileno, 0); +# endif + if (p == MAP_FAILED) + goto punt; +#endif + fp->_IO_buf_base = p; + fp->_IO_buf_end = fp->_IO_buf_base + st.st_size; + } + else + { + /* The number of pages didn't change. */ + fp->_IO_buf_end = fp->_IO_buf_base + st.st_size; + } +# undef ROUNDED + + fp->_offset -= fp->_IO_read_end - fp->_IO_read_ptr; + _IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base + fp->_offset, + fp->_IO_buf_end); if ( # ifdef _G_LSEEK64 - _G_LSEEK64 (fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base, - SEEK_SET) + _G_LSEEK64 # else - __lseek (fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base, SEEK_SET) + __lseek # endif + (fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base, SEEK_SET) != fp->_IO_buf_end - fp->_IO_buf_base) { fp->_flags |= _IO_ERR_SEEN; return EOF; } - fp->_offset = fp->_IO_buf_end - fp->_IO_buf_base; - fp->_IO_read_end = fp->_IO_buf_end; - return *(unsigned char *) fp->_IO_read_ptr; + + return 0; + } + else + { + /* Life is no longer good for mmap. Punt it. */ + (void) __munmap (fp->_IO_buf_base, + fp->_IO_buf_end - fp->_IO_buf_base); + punt: + fp->_IO_buf_base = fp->_IO_buf_end = NULL; + _IO_setg (fp, NULL, NULL, NULL); + if (fp->_mode <= 0) + _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_file_jumps; + else + _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_wfile_jumps; + fp->_wide_data->_wide_vtable = &_IO_wfile_jumps; + + return 1; } +} + +/* Special callback replacing the underflow callbacks if we mmap the file. */ +int +_IO_file_underflow_mmap (_IO_FILE *fp) +{ + if (fp->_IO_read_ptr < fp->_IO_read_end) + return *(unsigned char *) fp->_IO_read_ptr; + + if (__builtin_expect (mmap_remap_check (fp), 0)) + /* We punted to the regular file functions. */ + return _IO_UNDERFLOW (fp); + + if (fp->_IO_read_ptr < fp->_IO_read_end) + return *(unsigned char *) fp->_IO_read_ptr; fp->_flags |= _IO_EOF_SEEN; return EOF; } +static void +decide_maybe_mmap (_IO_FILE *fp) +{ + /* We use the file in read-only mode. This could mean we can + mmap the file and use it without any copying. But not all + file descriptors are for mmap-able objects and on 32-bit + machines we don't want to map files which are too large since + this would require too much virtual memory. */ + struct _G_stat64 st; + + if (_IO_SYSSTAT (fp, &st) == 0 + && S_ISREG (st.st_mode) && st.st_size != 0 + /* Limit the file size to 1MB for 32-bit machines. */ + && (sizeof (ptrdiff_t) > 4 || st.st_size < 1*1024*1024) + /* Sanity check. */ + && (fp->_offset == _IO_pos_BAD || fp->_offset <= st.st_size)) + { + /* Try to map the file. */ + void *p; + +# ifdef _G_MMAP64 + p = _G_MMAP64 (NULL, st.st_size, PROT_READ, MAP_SHARED, fp->_fileno, 0); +# else + p = __mmap (NULL, st.st_size, PROT_READ, MAP_SHARED, fp->_fileno, 0); +# endif + if (p != MAP_FAILED) + { + /* OK, we managed to map the file. Set the buffer up and use a + special jump table with simplified underflow functions which + never tries to read anything from the file. */ + + if ( +# ifdef _G_LSEEK64 + _G_LSEEK64 +# else + __lseek +# endif + (fp->_fileno, st.st_size, SEEK_SET) != st.st_size) + { + (void) __munmap (p, st.st_size); + fp->_offset = _IO_pos_BAD; + } + else + { + INTUSE(_IO_setb) (fp, p, (char *) p + st.st_size, 0); + + if (fp->_offset == _IO_pos_BAD) + fp->_offset = 0; + + _IO_setg (fp, p, p + fp->_offset, p + st.st_size); + fp->_offset = st.st_size; + + if (fp->_mode <= 0) + _IO_JUMPS ((struct _IO_FILE_plus *)fp) = &_IO_file_jumps_mmap; + else + _IO_JUMPS ((struct _IO_FILE_plus *)fp) = &_IO_wfile_jumps_mmap; + fp->_wide_data->_wide_vtable = &_IO_wfile_jumps_mmap; + + return; + } + } + } + + /* We couldn't use mmap, so revert to the vanilla file operations. */ + + if (fp->_mode <= 0) + _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_file_jumps; + else + _IO_JUMPS ((struct _IO_FILE_plus *) fp) = &_IO_wfile_jumps; + fp->_wide_data->_wide_vtable = &_IO_wfile_jumps; +} + +int +_IO_file_underflow_maybe_mmap (_IO_FILE *fp) +{ + /* This is the first read attempt. Choose mmap or vanilla operations + and then punt to the chosen underflow routine. */ + decide_maybe_mmap (fp); + return _IO_UNDERFLOW (fp); +} + + int _IO_new_file_overflow (f, ch) _IO_FILE *f; @@ -726,6 +891,34 @@ _IO_new_file_sync (fp) } INTDEF2(_IO_new_file_sync, _IO_file_sync) +static int +_IO_file_sync_mmap (_IO_FILE *fp) +{ + if (fp->_IO_read_ptr != fp->_IO_read_end) + { +#ifdef TODO + if (_IO_in_backup (fp)) + delta -= eGptr () - Gbase (); +#endif + if ( +# ifdef _G_LSEEK64 + _G_LSEEK64 +# else + __lseek +# endif + (fp->_fileno, fp->_IO_read_ptr - fp->_IO_buf_base, SEEK_SET) + != fp->_IO_read_ptr - fp->_IO_buf_base) + { + fp->_flags |= _IO_ERR_SEEN; + return EOF; + } + } + fp->_offset = fp->_IO_read_ptr - fp->_IO_buf_base; + fp->_IO_read_end = fp->_IO_read_ptr = fp->_IO_read_base; + return 0; +} + + _IO_off64_t _IO_new_file_seekoff (fp, offset, dir, mode) _IO_FILE *fp; @@ -968,6 +1161,25 @@ _IO_file_seekoff_mmap (fp, offset, dir, mode) return offset; } +_IO_off64_t +_IO_file_seekoff_maybe_mmap (fp, offset, dir, mode) + _IO_FILE *fp; + _IO_off64_t offset; + int dir; + int mode; +{ + /* We only get here when we haven't tried to read anything yet. + So there is nothing more useful for us to do here than just + the underlying lseek call. */ + + _IO_off64_t result = _IO_SYSSEEK (fp, offset, dir); + if (result < 0) + return EOF; + + fp->_offset = result; + return result; +} + _IO_ssize_t _IO_file_read (fp, buf, size) _IO_FILE *fp; @@ -1009,9 +1221,8 @@ int _IO_file_close_mmap (fp) _IO_FILE *fp; { - /* In addition to closing the file descriptor we have to unmap the - file. */ - (void) munmap (fp->_IO_buf_base, fp->_IO_buf_end - fp->_IO_buf_base); + /* In addition to closing the file descriptor we have to unmap the file. */ + (void) __munmap (fp->_IO_buf_base, fp->_IO_buf_end - fp->_IO_buf_base); fp->_IO_buf_base = fp->_IO_buf_end = NULL; return close (fp->_fileno); } @@ -1270,11 +1481,13 @@ _IO_file_xsgetn_mmap (fp, data, n) if (have < n) { - /* Maybe the read buffer is not yet fully set up. */ - fp->_IO_read_ptr = fp->_IO_read_end; - if (fp->_IO_read_end < fp->_IO_buf_end - && _IO_file_underflow_mmap (fp) != EOF) - have = fp->_IO_read_end - read_ptr; + /* Check that we are mapping all of the file, in case it grew. */ + if (__builtin_expect (mmap_remap_check (fp), 0)) + /* We punted mmap, so complete with the vanilla code. */ + return s - (char *) data + _IO_XSGETN (fp, data, n); + + read_ptr = fp->_IO_read_ptr; + have = fp->_IO_read_end - read_ptr; } } @@ -1296,6 +1509,21 @@ _IO_file_xsgetn_mmap (fp, data, n) return s - (char *) data; } +static _IO_size_t _IO_file_xsgetn_maybe_mmap __P ((_IO_FILE *, void *, + _IO_size_t)); +static _IO_size_t +_IO_file_xsgetn_maybe_mmap (fp, data, n) + _IO_FILE *fp; + void *data; + _IO_size_t n; +{ + /* We only get here if this is the first attempt to read something. + Decide which operations to use and then punt to the chosen one. */ + + decide_maybe_mmap (fp); + return _IO_XSGETN (fp, data, n); +} + struct _IO_jump_t _IO_file_jumps = { JUMP_INIT_DUMMY, @@ -1334,7 +1562,7 @@ struct _IO_jump_t _IO_file_jumps_mmap = JUMP_INIT(seekoff, _IO_file_seekoff_mmap), JUMP_INIT(seekpos, _IO_default_seekpos), JUMP_INIT(setbuf, (_IO_setbuf_t) _IO_file_setbuf_mmap), - JUMP_INIT(sync, _IO_new_file_sync), + JUMP_INIT(sync, _IO_file_sync_mmap), JUMP_INIT(doallocate, INTUSE(_IO_file_doallocate)), JUMP_INIT(read, INTUSE(_IO_file_read)), JUMP_INIT(write, _IO_new_file_write), @@ -1345,6 +1573,30 @@ struct _IO_jump_t _IO_file_jumps_mmap = JUMP_INIT(imbue, _IO_default_imbue) }; +struct _IO_jump_t _IO_file_jumps_maybe_mmap = +{ + JUMP_INIT_DUMMY, + JUMP_INIT(finish, INTUSE(_IO_file_finish)), + JUMP_INIT(overflow, INTUSE(_IO_file_overflow)), + JUMP_INIT(underflow, _IO_file_underflow_maybe_mmap), + JUMP_INIT(uflow, INTUSE(_IO_default_uflow)), + JUMP_INIT(pbackfail, INTUSE(_IO_default_pbackfail)), + JUMP_INIT(xsputn, _IO_new_file_xsputn), + JUMP_INIT(xsgetn, _IO_file_xsgetn_maybe_mmap), + JUMP_INIT(seekoff, _IO_file_seekoff_maybe_mmap), + JUMP_INIT(seekpos, _IO_default_seekpos), + JUMP_INIT(setbuf, (_IO_setbuf_t) _IO_file_setbuf_mmap), + JUMP_INIT(sync, _IO_new_file_sync), + JUMP_INIT(doallocate, INTUSE(_IO_file_doallocate)), + JUMP_INIT(read, INTUSE(_IO_file_read)), + JUMP_INIT(write, _IO_new_file_write), + JUMP_INIT(seek, INTUSE(_IO_file_seek)), + JUMP_INIT(close, _IO_file_close), + JUMP_INIT(stat, INTUSE(_IO_file_stat)), + JUMP_INIT(showmanyc, _IO_default_showmanyc), + JUMP_INIT(imbue, _IO_default_imbue) +}; + #ifdef _LIBC versioned_symbol (libc, _IO_new_do_write, _IO_do_write, GLIBC_2_1); versioned_symbol (libc, _IO_new_file_attach, _IO_file_attach, GLIBC_2_1); |