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-rw-r--r--libstore/gunzip.c277
1 files changed, 277 insertions, 0 deletions
diff --git a/libstore/gunzip.c b/libstore/gunzip.c
new file mode 100644
index 00000000..230ce1b0
--- /dev/null
+++ b/libstore/gunzip.c
@@ -0,0 +1,277 @@
+/* Decompressing store backend
+
+ Copyright (C) 1997 Free Software Foundation, Inc.
+ Written by Miles Bader <miles@gnu.ai.mit.edu>
+ 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 <stdio.h>
+#include <string.h>
+#include <setjmp.h>
+#include <cthreads.h>
+
+#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 };
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