librsync  2.3.2
mksum.c
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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 #include "config.h"
31 #include <assert.h>
32 #include <stdlib.h>
33 #include "librsync.h"
34 #include "job.h"
35 #include "sumset.h"
36 #include "stream.h"
37 #include "netint.h"
38 #include "trace.h"
39 #include "util.h"
40 
41 /* Possible state functions for signature generation. */
44 
45 /** State of trying to send the signature header. \private */
47 {
48  rs_signature_t *sig = job->signature;
49  rs_result result;
50 
51  if ((result =
52  rs_signature_init(sig, job->sig_magic, job->sig_block_len,
53  job->sig_strong_len, 0)) != RS_DONE)
54  return result;
55  rs_squirt_n4(job, sig->magic);
56  rs_squirt_n4(job, sig->block_len);
57  rs_squirt_n4(job, sig->strong_sum_len);
58  rs_trace("sent header (magic %#x, block len = %d, strong sum len = %d)",
59  sig->magic, sig->block_len, sig->strong_sum_len);
60  job->stats.block_len = sig->block_len;
61 
63  return RS_RUNNING;
64 }
65 
66 /** Generate the checksums for a block and write it out. Called when we
67  * already know we have enough data in memory at \p block. \private */
68 static rs_result rs_sig_do_block(rs_job_t *job, const void *block, size_t len)
69 {
70  rs_signature_t *sig = job->signature;
71  rs_weak_sum_t weak_sum;
72  rs_strong_sum_t strong_sum;
73 
74  weak_sum = rs_signature_calc_weak_sum(sig, block, len);
75  rs_signature_calc_strong_sum(sig, block, len, &strong_sum);
76  rs_squirt_n4(job, weak_sum);
77  rs_tube_write(job, strong_sum, sig->strong_sum_len);
78  if (rs_trace_enabled()) {
79  char strong_sum_hex[RS_MAX_STRONG_SUM_LENGTH * 2 + 1];
80  rs_hexify(strong_sum_hex, strong_sum, sig->strong_sum_len);
81  rs_trace("sent block: weak=" FMT_WEAKSUM ", strong=%s", weak_sum,
82  strong_sum_hex);
83  }
84  job->stats.sig_blocks++;
85  return RS_RUNNING;
86 }
87 
88 /** State of reading a block and trying to generate its sum. \private */
90 {
91  rs_result result;
92  size_t len;
93  void *block;
94 
95  /* must get a whole block, otherwise try again */
96  len = job->signature->block_len;
97  result = rs_scoop_read(job, len, &block);
98  /* If we are near EOF, get whatever is left. */
99  if (result == RS_INPUT_ENDED)
100  result = rs_scoop_read_rest(job, &len, &block);
101  if (result == RS_INPUT_ENDED) {
102  return RS_DONE;
103  } else if (result != RS_DONE) {
104  rs_trace("generate stopped: %s", rs_strerror(result));
105  return result;
106  }
107  rs_trace("got " FMT_SIZE " byte block", len);
108  return rs_sig_do_block(job, block, len);
109 }
110 
111 rs_job_t *rs_sig_begin(size_t block_len, size_t strong_len,
112  rs_magic_number sig_magic)
113 {
114  rs_job_t *job;
115 
116  job = rs_job_new("signature", rs_sig_s_header);
117  job->signature = rs_alloc_struct(rs_signature_t);
118  job->job_owns_sig = 1;
119  job->sig_magic = sig_magic;
120  job->sig_block_len = (int)block_len;
121  job->sig_strong_len = (int)strong_len;
122  return job;
123 }
Public header for librsync.
LIBRSYNC_EXPORT char const * rs_strerror(rs_result r)
Return an English description of a rs_result value.
Definition: msg.c:46
rs_result
Return codes from nonblocking rsync operations.
Definition: librsync.h:180
@ RS_RUNNING
The job is still running, and not yet finished or blocked.
Definition: librsync.h:183
@ RS_DONE
Completed successfully.
Definition: librsync.h:181
@ RS_INPUT_ENDED
Unexpected end of input file, perhaps due to a truncated file or dropped network connection.
Definition: librsync.h:190
rs_magic_number
A uint32 magic number, emitted in bigendian/network order at the start of librsync files.
Definition: librsync.h:65
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
static rs_result rs_sig_s_generate(rs_job_t *)
State of reading a block and trying to generate its sum.
Definition: mksum.c:89
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:111
static rs_result rs_sig_s_header(rs_job_t *)
State of trying to send the signature header.
Definition: mksum.c:46
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
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
Manage librsync streams of IO.
void rs_tube_write(rs_job_t *job, void const *buf, size_t len)
Push some data into the tube for storage.
Definition: tube.c:214
The contents of this structure are private.
Definition: job.h:26
int job_owns_sig
Flag indicating signature should be destroyed with the job.
Definition: job.h:54
rs_result(* statefn)(rs_job_t *)
Callback for each processing step.
Definition: job.h:35
rs_signature_t * signature
Pointer to the signature that's being used by the operation.
Definition: job.h:51
rs_stats_t stats
Encoding statistics.
Definition: job.h:72
Signature of a whole file.
Definition: sumset.h:37
int magic
The signature magic value.
Definition: sumset.h:38
int block_len
The block length.
Definition: sumset.h:39
int strong_sum_len
The block strong sum length.
Definition: sumset.h:40
rs_long_t sig_blocks
Number of blocks described by the signature.
Definition: librsync.h:222
logging functions.
#define rs_trace_enabled()
Call this before putting too much effort into generating trace messages.
Definition: trace.h:69