librsync  2.3.0
mksum.c
Go to the documentation of this file.
1 /*= -*- c-basic-offset: 4; indent-tabs-mode: nil; -*-
2  *
3  * librsync -- library for network deltas
4  *
5  * Copyright 1999-2001, 2014, 2015 by Martin Pool <mbp@sourcefrog.net>
6  * Copyright (C) 1999 by Andrew Tridgell <tridge@samba.org>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU Lesser General Public License as published by
10  * the Free Software Foundation; either version 2.1 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21  */
22 
23 /** \file mksum.c
24  * Generate file signatures.
25  *
26  * Generating checksums is pretty easy, since we can always just process
27  * whatever data is available. When a whole block has arrived, or we've reached
28  * the end of the file, we write the checksum out.
29  *
30  * \todo Perhaps force blocks to be a multiple of 64 bytes, so that we can be
31  * sure checksum generation will be more efficient. I guess it will be OK at
32  * the moment, though, because tails are only used if necessary. */
33 
34 #include "config.h"
35 #include <assert.h>
36 #include <stdlib.h>
37 #include "librsync.h"
38 #include "job.h"
39 #include "sumset.h"
40 #include "stream.h"
41 #include "netint.h"
42 #include "trace.h"
43 #include "util.h"
44 
45 /* Possible state functions for signature generation. */
48 
49 /** State of trying to send the signature header. \private */
51 {
52  rs_signature_t *sig = job->signature;
53  rs_result result;
54 
55  if ((result =
56  rs_signature_init(sig, job->sig_magic, job->sig_block_len,
57  job->sig_strong_len, 0)) != RS_DONE)
58  return result;
59  rs_squirt_n4(job, sig->magic);
60  rs_squirt_n4(job, sig->block_len);
61  rs_squirt_n4(job, sig->strong_sum_len);
62  rs_trace("sent header (magic %#x, block len = %d, strong sum len = %d)",
63  sig->magic, sig->block_len, sig->strong_sum_len);
64  job->stats.block_len = sig->block_len;
65 
67  return RS_RUNNING;
68 }
69 
70 /** Generate the checksums for a block and write it out. Called when we
71  * already know we have enough data in memory at \p block. \private */
72 static rs_result rs_sig_do_block(rs_job_t *job, const void *block, size_t len)
73 {
74  rs_signature_t *sig = job->signature;
75  rs_weak_sum_t weak_sum;
76  rs_strong_sum_t strong_sum;
77 
78  weak_sum = rs_signature_calc_weak_sum(sig, block, len);
79  rs_signature_calc_strong_sum(sig, block, len, &strong_sum);
80  rs_squirt_n4(job, weak_sum);
81  rs_tube_write(job, strong_sum, sig->strong_sum_len);
82  if (rs_trace_enabled()) {
83  char strong_sum_hex[RS_MAX_STRONG_SUM_LENGTH * 2 + 1];
84  rs_hexify(strong_sum_hex, strong_sum, sig->strong_sum_len);
85  rs_trace("sent block: weak=" FMT_WEAKSUM ", strong=%s", weak_sum,
86  strong_sum_hex);
87  }
88  job->stats.sig_blocks++;
89  return RS_RUNNING;
90 }
91 
92 /** State of reading a block and trying to generate its sum. \private */
94 {
95  rs_result result;
96  size_t len;
97  void *block;
98 
99  /* must get a whole block, otherwise try again */
100  len = job->signature->block_len;
101  result = rs_scoop_read(job, len, &block);
102  /* If we are near EOF, get whatever is left. */
103  if (result == RS_INPUT_ENDED)
104  result = rs_scoop_read_rest(job, &len, &block);
105  if (result == RS_INPUT_ENDED) {
106  return RS_DONE;
107  } else if (result != RS_DONE) {
108  rs_trace("generate stopped: %s", rs_strerror(result));
109  return result;
110  }
111  rs_trace("got " FMT_SIZE " byte block", len);
112  return rs_sig_do_block(job, block, len);
113 }
114 
115 rs_job_t *rs_sig_begin(size_t block_len, size_t strong_len,
116  rs_magic_number sig_magic)
117 {
118  rs_job_t *job;
119 
120  job = rs_job_new("signature", rs_sig_s_header);
121  job->signature = rs_alloc_struct(rs_signature_t);
122  job->job_owns_sig = 1;
123  job->sig_magic = sig_magic;
124  job->sig_block_len = block_len;
125  job->sig_strong_len = strong_len;
126  return job;
127 }
LIBRSYNC_EXPORT rs_job_t * rs_sig_begin(size_t block_len, size_t strong_len, rs_magic_number sig_magic)
Start generating a signature.
Definition: mksum.c:115
#define rs_trace_enabled()
Call this before putting too much effort into generating trace messages.
Definition: trace.h:69
logging functions.
rs_result rs_scoop_read_rest(rs_job_t *job, size_t *len, void **ptr)
Read whatever data remains in the input stream.
Definition: scoop.c:212
int block_len
The block length.
Definition: sumset.h:39
rs_long_t sig_blocks
Number of blocks described by the signature.
Definition: librsync.h:222
rs_signature_t * signature
Pointer to the signature that&#39;s being used by the operation.
Definition: job.h:51
int job_owns_sig
Flag indicating signature should be destroyed with the job.
Definition: job.h:54
LIBRSYNC_EXPORT char const * rs_strerror(rs_result r)
Return an English description of a rs_result value.
Definition: msg.c:46
int strong_sum_len
The block strong sum length.
Definition: sumset.h:40
static rs_result rs_sig_s_generate(rs_job_t *)
State of reading a block and trying to generate its sum.
Definition: mksum.c:93
rs_stats_t stats
Encoding statistics.
Definition: job.h:72
Public header for librsync.
Signature of a whole file.
Definition: sumset.h:37
rs_result
Return codes from nonblocking rsync operations.
Definition: librsync.h:180
Unexpected end of input file, perhaps due to a truncated file or dropped network connection.
Definition: librsync.h:190
rs_result rs_scoop_read(rs_job_t *job, size_t len, void **ptr)
Read LEN bytes if possible, and remove them from the input scoop.
Definition: scoop.c:192
int magic
The signature magic value.
Definition: sumset.h:38
rs_magic_number
A uint32 magic number, emitted in bigendian/network order at the start of librsync files...
Definition: librsync.h:65
The job is still running, and not yet finished or blocked.
Definition: librsync.h:183
rs_result(* statefn)(rs_job_t *)
Callback for each processing step.
Definition: job.h:35
Completed successfully.
Definition: librsync.h:181
void rs_tube_write(rs_job_t *job, const void *buf, size_t len)
Push some data into the tube for storage.
Definition: tube.c:192
static rs_result rs_sig_s_header(rs_job_t *)
State of trying to send the signature header.
Definition: mksum.c:50
LIBRSYNC_EXPORT void rs_hexify(char *to_buf, void const *from_buf, int from_len)
Convert from_len bytes at from_buf into a hex representation in to_buf, which must be twice as long p...
Definition: hex.c:23
The contents of this structure are private.
Definition: job.h:26