/* Store I/O Copyright (C) 1995-1999,2001,2002,2003 Free Software Foundation, Inc. Written by Miles Bader This file is part of the GNU Hurd. The GNU Hurd is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. The GNU Hurd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */ #include #include #include "store.h" /* Returns in RUN the tail of STORE's run list, who's first run contains ADDR, and is not a hole, and in RUNS_END a pointer pointing at the end of the run list. Returns the offset within it at which ADDR occurs. Also returns BASE, which should be added to offsets from RUNS. */ static inline store_offset_t store_find_first_run (struct store *store, store_offset_t addr, struct store_run **run, struct store_run **runs_end, store_offset_t *base, size_t *index) { struct store_run *tail = store->runs, *tail_end = tail + store->num_runs; store_offset_t wrap_src = store->wrap_src; if (addr >= wrap_src && addr < store->end) /* Locate the correct position within a repeating pattern of runs. */ { *base = addr / store->wrap_dst; addr %= wrap_src; } else *base = 0; /* XXX: this isn't going to be very efficient if RUNS is very complex... But it should do dandy if it's short. For long run lists, we could do a binary search or something. */ while (tail < tail_end) { store_offset_t run_blocks = tail->length; if (run_blocks > addr) { *run = tail; *runs_end = tail_end; *index = tail - store->runs; return addr; } /* Not to the right place yet, move on... */ addr -= run_blocks; tail++; } return -1; } /* Update RUN, BASE, & INDEX to point to the next elemement in the runs array. RUNS_END is the point where RUNS will wrap. Returns true if things are still kosher. */ static inline int store_next_run (struct store *store, struct store_run *runs_end, struct store_run **run, store_offset_t *base, size_t *index) { (*run)++; (*index)++; if (*run == runs_end) /* Wrap around in a repeating RUNS. */ { *run = store->runs; *base += store->wrap_dst; *index = 0; return (*base < store->end); } else return 1; } /* Write LEN bytes from BUF to STORE at ADDR. Returns the amount written in AMOUNT. ADDR is in BLOCKS (as defined by STORE->block_size). */ error_t store_write (struct store *store, store_offset_t addr, const void *buf, size_t len, size_t *amount) { error_t err; size_t index; store_offset_t base; struct store_run *run, *runs_end; int block_shift = store->log2_block_size; store_write_meth_t write = store->class->write; if (store->flags & STORE_READONLY) return EROFS; /* XXX */ if ((addr << block_shift) + len > store->size) return EIO; if (store->block_size != 0 && (len & (store->block_size - 1)) != 0) return EINVAL; addr = store_find_first_run (store, addr, &run, &runs_end, &base, &index); if (addr < 0) err = EIO; else if ((len >> block_shift) <= run->length - addr) /* The first run has it all... */ err = (*write)(store, base + run->start + addr, index, buf, len, amount); else /* ARGH, we've got to split up the write ... */ { mach_msg_type_number_t try, written; /* Write the initial bit in the first run. Errors here are returned. */ try = (run->length - addr) << block_shift; err = (*write) (store, base + run->start + addr, index, buf, try, &written); if (!err && written == try) /* Wrote the first bit successfully, now do the rest. Any errors will just result in a short write. */ { buf += written; len -= written; while (store_next_run (store, runs_end, &run, &base, &index) && run->start >= 0) /* Check for holes. */ /* Ok, we can write in this run, at least a bit. */ { mach_msg_type_number_t seg_written; if ((len >> block_shift) <= run->length) try = len; else try = run->length << block_shift; err = (*write)(store, base + run->start, index, buf, try, &seg_written); if (err) break; /* Ack */ written += seg_written; if (seg_written < try) break; /* Didn't use up the run, we're done. */ len -= seg_written; if (len == 0) break; /* Nothing left to write! */ buf += seg_written; } } *amount = written; } return err; } /* Read AMOUNT bytes from STORE at ADDR into BUF & LEN (which follows the usual mach buffer-return semantics) to STORE at ADDR. ADDR is in BLOCKS (as defined by STORE->block_size). */ error_t store_read (struct store *store, store_offset_t addr, size_t amount, void **buf, size_t *len) { size_t index; store_offset_t base; struct store_run *run, *runs_end; int block_shift = store->log2_block_size; store_read_meth_t read = store->class->read; addr = store_find_first_run (store, addr, &run, &runs_end, &base, &index); if (addr < 0 || run->start < 0) return EIO; /* Reading from a hole. */ if ((addr << block_shift) + amount > store->size) amount = store->size - (addr << block_shift); if (store->block_size != 0 && (amount & (store->block_size - 1)) != 0) return EINVAL; if ((amount >> block_shift) <= run->length - addr) /* The first run has it all... */ return (*read) (store, base + run->start + addr, index, amount, buf, len); else /* ARGH, we've got to split up the read ... This isn't fun. */ { error_t err; int all; /* WHOLE_BUF and WHOLE_BUF_LEN will point to a buff that's large enough to hold the entire request. This is initially whatever the user passed in, but we'll change it as necessary. */ void *whole_buf = *buf, *buf_end; size_t whole_buf_len = *len; /* Read LEN bytes from the store address ADDR into BUF_END. BUF_END and AMOUNT are adjusted by the amount actually read. Whether or not the amount read is the same as what was request is returned in ALL. */ inline error_t seg_read (store_offset_t addr, size_t len, int *all) { /* SEG_BUF and SEG_LEN are the buffer for a particular bit of the whole (within one run). */ void *seg_buf = buf_end; size_t seg_buf_len = len; error_t err = (*read)(store, addr, index, len, &seg_buf, &seg_buf_len); if (!err) { /* If for some bizarre reason, the underlying storage chose not to use the buffer space we so kindly gave it, copy it to that space. */ if (seg_buf != buf_end) { memcpy (buf_end, seg_buf, seg_buf_len); munmap (seg_buf, seg_buf_len); } buf_end += seg_buf_len; amount -= seg_buf_len; *all = (seg_buf_len == len); } return err; } if (whole_buf_len < amount) /* Not enough room in the user's buffer to hold everything, better make room. */ { whole_buf_len = amount; whole_buf = mmap (0, amount, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0); if (whole_buf == (void *) -1) return errno; /* Punt early, there's nothing to clean up. */ } buf_end = whole_buf; err = seg_read (base + run->start + addr, (run->length - addr) << block_shift, &all); while (!err && all && amount > 0 && store_next_run (store, runs_end, &run, &base, &index)) { if (run->start < 0) /* A hole! Can't read here. Must stop. */ break; else err = seg_read (base + run->start, (amount >> block_shift) <= run->length ? amount /* This run has the rest. */ : (run->length << block_shift), /* Whole run. */ &all); } /* The actual amount read. */ *len = buf_end - whole_buf; if (*len > 0) err = 0; /* Return a short read instead of an error. */ /* Deallocate any amount of WHOLE_BUF we didn't use. */ if (whole_buf != *buf) { if (err) munmap (whole_buf, whole_buf_len); else { vm_size_t unused = whole_buf_len - round_page (*len); if (unused) munmap (whole_buf + whole_buf_len - unused, unused); *buf = whole_buf; } } return err; } } /* Set STORE's size to NEWSIZE (in bytes). */ error_t store_set_size (struct store *store, size_t newsize) { error_t err; store_set_size_meth_t set_size = store->class->set_size; /* Updating the runs list is up to the class set_size method. */ err = (* set_size) (store, newsize); return err; }