/* Decompressing store backend Copyright (C) 1997 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 #include #include "store.h" /* gzip.h makes several annoying defines & decls, which we have to work around. */ #define file_t gzip_file_t #include "gzip.h" #undef file_t #undef head #define IN_BUFFERING (256*1024) #define OUT_BUFFERING (512*1024) static struct mutex unzip_lock = MUTEX_INITIALIZER; /* Uncompress the contents of FROM, which should contain a valid gzip file, into memory, returning the result buffer in BUF & BUF_LEN. */ static error_t gunzip (struct store *from, void **buf, size_t *buf_len) { /* Entry points to unzip engine. */ int get_method (int); extern long int bytes_out; /* Callbacks from unzip for I/O and error interface. */ extern int (*unzip_read) (char *buf, size_t maxread); extern void (*unzip_write) (const char *buf, size_t nwrite); extern void (*unzip_read_error) (void); extern void (*unzip_error) (const char *msg); /* How we return errors from our hook functions. */ jmp_buf zerr_jmp_buf; error_t zerr; /* vm_alloced buffer for the input store. */ void *in_buf = 0; size_t in_buf_len = 0; size_t in_buf_offs = 0; /* Offset of read point in IN_BUF. */ off_t in_buf_addr = 0; /* Address in FROM of *next* IN_BUF. */ /* Buffer input in units that are least IN_BUFFERING bytes, but are also a multiple of FROM's block size. */ size_t in_addr_mask = ((1 << from->log2_block_size) - 1); size_t in_buffering = ((IN_BUFFERING + in_addr_mask) & ~in_addr_mask); /* Read at most MAXREAD (or 0 if eof) bytes into BUF from our current position in FROM. */ int zread (char *buf, size_t maxread) { size_t did_read = 0; while (maxread > 0) { size_t left = in_buf_len - in_buf_offs; if (left > 0) /* Fill BUF with what we can from IN_BUF. */ { if (left > maxread) left = maxread; bcopy (in_buf + in_buf_offs, buf, left); in_buf_offs += left; buf += left; maxread -= left; did_read += left; } /* Limit MAXREAD to the number of bytes left in the input. */ if (maxread > (from->size - (in_buf_addr << from->log2_block_size))) maxread = from->size - (in_buf_addr << from->log2_block_size); if (maxread > 0) /* Have to fill IN_BUF again. */ { void *new_in_buf = in_buf; size_t new_in_buf_len = in_buf_len; zerr = store_read (from, in_buf_addr, in_buffering, &new_in_buf, &new_in_buf_len); if (zerr) longjmp (zerr_jmp_buf, 1); in_buf_addr += (new_in_buf_len >> from->log2_block_size); if (new_in_buf != in_buf) { if (in_buf_len > 0) vm_deallocate (mach_task_self (), (vm_address_t)in_buf, in_buf_len); in_buf = new_in_buf; in_buf_len = new_in_buf_len; } in_buf_offs = 0; } } return did_read; } size_t out_buf_offs = 0; /* Position in the output buffer. */ /* Write compress data to our output buffer. */ void zwrite (const char *wbuf, size_t nwrite) { size_t old_buf_len = *buf_len; if (out_buf_offs + nwrite > old_buf_len) /* Have to grow the output buffer. */ { void *old_buf = *buf; void *new_buf = old_buf + old_buf_len; /* First try. */ size_t new_buf_len = round_page (old_buf_len + old_buf_len + nwrite); /* Try to grow the buffer. */ zerr = vm_allocate (mach_task_self (), (vm_address_t *)&new_buf, new_buf_len - old_buf_len, 0); if (zerr) /* Can't do that, try to make a bigger buffer elsewhere. */ { new_buf = old_buf; zerr = vm_allocate (mach_task_self (), (vm_address_t *)&new_buf, new_buf_len, 1); if (zerr) longjmp (zerr_jmp_buf, 1); if (out_buf_offs > 0) /* Copy the old buffer into the start of the new & free it. */ bcopy (old_buf, new_buf, out_buf_offs); vm_deallocate (mach_task_self (), (vm_address_t)old_buf, old_buf_len); *buf = new_buf; } *buf_len = new_buf_len; } bcopy (wbuf, *buf + out_buf_offs, nwrite); out_buf_offs += nwrite; } void zreaderr (void) { zerr = EIO; longjmp (zerr_jmp_buf, 1); } void zerror (const char *msg) { zerr = EINVAL; longjmp (zerr_jmp_buf, 2); } /* Try to guess a reasonable output buffer size. */ *buf_len = round_page (from->size * 2); zerr = vm_allocate (mach_task_self (), (vm_address_t *)buf, *buf_len, 1); if (zerr) return zerr; mutex_lock (&unzip_lock); unzip_read = zread; unzip_write = zwrite; unzip_read_error = zreaderr; unzip_error = zerror; if (! setjmp (zerr_jmp_buf)) { if (get_method (0) != 0) /* Not a happy gzip file. */ zerr = EINVAL; else /* Matched gzip magic number. Ready to unzip. Set up the output stream and let 'er rip. */ { /* Call the gunzip engine. */ bytes_out = 0; unzip (17, 23); /* Arguments ignored. */ zerr = 0; } } mutex_unlock (&unzip_lock); if (in_buf_len > 0) vm_deallocate (mach_task_self (), (vm_address_t)in_buf, in_buf_len); if (zerr) { if (*buf_len > 0) vm_deallocate (mach_task_self (), (vm_address_t)*buf, *buf_len); } else if (out_buf_offs < *buf_len) /* Trim the output buffer to be the right length. */ { size_t end = round_page (out_buf_offs); if (end < *buf_len) vm_deallocate (mach_task_self (), (vm_address_t)(*buf + end), *buf_len - end); *buf_len = out_buf_offs; } return zerr; } /* Return a new store in STORE which contains a snapshot of the uncompressed contents of the store FROM; FROM is consumed. */ error_t store_gunzip_create (struct store *from, int flags, struct store **store) { void *buf; size_t buf_len; error_t err = gunzip (from, &buf, &buf_len); if (! err) { err = store_buffer_create (buf, buf_len, flags, store); if (err) vm_deallocate (mach_task_self (), (vm_address_t)buf, buf_len); else store_free (from); } return err; } /* Open the gunzip NAME -- which consists of another store-class name, a ':', and a name for that store class to open -- and return the corresponding store in STORE. CLASSES is used to select classes specified by the type name; if it is 0, STORE_STD_CLASSES is used. */ error_t store_gunzip_open (const char *name, int flags, const struct store_class *const *classes, struct store **store) { struct store *from; error_t err = store_typed_open (name, flags | STORE_HARD_READONLY, classes, &from); if (! err) { err = store_gunzip_create (from, flags, store); if (err) store_free (from); } return err; } struct store_class store_gunzip_class = { -1, "gunzip", open: store_gunzip_open };