summaryrefslogtreecommitdiffstats
path: root/meta/lib/oe/reproducible.py
blob: 04a1810d4f297332f1dc2dbbf2d147a11a7d3909 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
#
# Copyright OpenEmbedded Contributors
#
# SPDX-License-Identifier: GPL-2.0-only
#
import os
import subprocess
import bb

# For reproducible builds, this code sets the default SOURCE_DATE_EPOCH in each
# component's build environment. The format is number of seconds since the
# system epoch.
#
# Upstream components (generally) respect this environment variable,
# using it in place of the "current" date and time.
# See https://reproducible-builds.org/specs/source-date-epoch/
#
# The default value of SOURCE_DATE_EPOCH comes from the function
# get_source_date_epoch_value which reads from the SDE_FILE, or if the file
# is not available will use the fallback of SOURCE_DATE_EPOCH_FALLBACK.
#
# The SDE_FILE is normally constructed from the function
# create_source_date_epoch_stamp which is typically added as a postfuncs to
# the do_unpack task.  If a recipe does NOT have do_unpack, it should be added
# to a task that runs after the source is available and before the
# do_deploy_source_date_epoch task is executed.
#
# If a recipe wishes to override the default behavior it should set it's own
# SOURCE_DATE_EPOCH or override the do_deploy_source_date_epoch_stamp task
# with recipe-specific functionality to write the appropriate
# SOURCE_DATE_EPOCH into the SDE_FILE.
#
# SOURCE_DATE_EPOCH is intended to be a reproducible value.  This value should
# be reproducible for anyone who builds the same revision from the same
# sources.
#
# There are 4 ways the create_source_date_epoch_stamp function determines what
# becomes SOURCE_DATE_EPOCH:
#
# 1. Use the value from __source_date_epoch.txt file if this file exists.
#    This file was most likely created in the previous build by one of the
#    following methods 2,3,4.
#    Alternatively, it can be provided by a recipe via SRC_URI.
#
# If the file does not exist:
#
# 2. If there is a git checkout, use the last git commit timestamp.
#    Git does not preserve file timestamps on checkout.
#
# 3. Use the mtime of "known" files such as NEWS, CHANGLELOG, ...
#    This works for well-kept repositories distributed via tarball.
#
# 4. Use the modification time of the youngest file in the source tree, if
#    there is one.
#    This will be the newest file from the distribution tarball, if any.
#
# 5. Fall back to a fixed timestamp (SOURCE_DATE_EPOCH_FALLBACK).
#
# Once the value is determined, it is stored in the recipe's SDE_FILE.

def get_source_date_epoch_from_known_files(d, sourcedir):
    source_date_epoch = None
    newest_file = None
    known_files = set(["NEWS", "ChangeLog", "Changelog", "CHANGES"])
    for file in known_files:
        filepath = os.path.join(sourcedir, file)
        if os.path.isfile(filepath):
            mtime = int(os.lstat(filepath).st_mtime)
            # There may be more than one "known_file" present, if so, use the youngest one
            if not source_date_epoch or mtime > source_date_epoch:
                source_date_epoch = mtime
                newest_file = filepath
    if newest_file:
        bb.debug(1, "SOURCE_DATE_EPOCH taken from: %s" % newest_file)
    return source_date_epoch

def find_git_folder(d, sourcedir):
    # First guess: WORKDIR/git
    # This is the default git fetcher unpack path
    workdir = d.getVar('WORKDIR')
    gitpath = os.path.join(workdir, "git/.git")
    if os.path.isdir(gitpath):
        return gitpath

    # Second guess: ${S}
    gitpath = os.path.join(sourcedir, ".git")
    if os.path.isdir(gitpath):
        return gitpath

    # Perhaps there was a subpath or destsuffix specified.
    # Go looking in the WORKDIR
    exclude = set(["build", "image", "license-destdir", "patches", "pseudo",
                   "recipe-sysroot", "recipe-sysroot-native", "sysroot-destdir", "temp"])
    for root, dirs, files in os.walk(workdir, topdown=True):
        dirs[:] = [d for d in dirs if d not in exclude]
        if '.git' in dirs:
            return os.path.join(root, ".git")

    bb.warn("Failed to find a git repository in WORKDIR: %s" % workdir)
    return None

def get_source_date_epoch_from_git(d, sourcedir):
    if not "git://" in d.getVar('SRC_URI') and not "gitsm://" in d.getVar('SRC_URI'):
        return None

    gitpath = find_git_folder(d, sourcedir)
    if not gitpath:
        return None

    # Check that the repository has a valid HEAD; it may not if subdir is used
    # in SRC_URI
    p = subprocess.run(['git', '--git-dir', gitpath, 'rev-parse', 'HEAD'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    if p.returncode != 0:
        bb.debug(1, "%s does not have a valid HEAD: %s" % (gitpath, p.stdout.decode('utf-8')))
        return None

    bb.debug(1, "git repository: %s" % gitpath)
    p = subprocess.run(['git', '--git-dir', gitpath, 'log', '-1', '--pretty=%ct'], check=True, stdout=subprocess.PIPE)
    return int(p.stdout.decode('utf-8'))

def get_source_date_epoch_from_youngest_file(d, sourcedir):
    if sourcedir == d.getVar('WORKDIR'):
       # These sources are almost certainly not from a tarball
       return None

    # Do it the hard way: check all files and find the youngest one...
    source_date_epoch = None
    newest_file = None
    for root, dirs, files in os.walk(sourcedir, topdown=True):
        files = [f for f in files if not f[0] == '.']

        for fname in files:
            filename = os.path.join(root, fname)
            try:
                mtime = int(os.lstat(filename).st_mtime)
            except ValueError:
                mtime = 0
            if not source_date_epoch or mtime > source_date_epoch:
                source_date_epoch = mtime
                newest_file = filename

    if newest_file:
        bb.debug(1, "Newest file found: %s" % newest_file)
    return source_date_epoch

def fixed_source_date_epoch(d):
    bb.debug(1, "No tarball or git repo found to determine SOURCE_DATE_EPOCH")
    source_date_epoch = d.getVar('SOURCE_DATE_EPOCH_FALLBACK')
    if source_date_epoch:
        bb.debug(1, "Using SOURCE_DATE_EPOCH_FALLBACK")
        return int(source_date_epoch)
    return 0

def get_source_date_epoch(d, sourcedir):
    return (
        get_source_date_epoch_from_git(d, sourcedir) or
        get_source_date_epoch_from_youngest_file(d, sourcedir) or
        fixed_source_date_epoch(d)       # Last resort
    )

def epochfile_read(epochfile, d):
    cached, efile = d.getVar('__CACHED_SOURCE_DATE_EPOCH') or (None, None)
    if cached and efile == epochfile:
        return cached

    if cached and epochfile != efile:
        bb.debug(1, "Epoch file changed from %s to %s" % (efile, epochfile))

    source_date_epoch = int(d.getVar('SOURCE_DATE_EPOCH_FALLBACK'))
    try:
        with open(epochfile, 'r') as f:
            s = f.read()
            try:
                source_date_epoch = int(s)
            except ValueError:
                bb.warn("SOURCE_DATE_EPOCH value '%s' is invalid. Reverting to SOURCE_DATE_EPOCH_FALLBACK" % s)
                source_date_epoch = int(d.getVar('SOURCE_DATE_EPOCH_FALLBACK'))
        bb.debug(1, "SOURCE_DATE_EPOCH: %d" % source_date_epoch)
    except FileNotFoundError:
        bb.debug(1, "Cannot find %s. SOURCE_DATE_EPOCH will default to %d" % (epochfile, source_date_epoch))

    d.setVar('__CACHED_SOURCE_DATE_EPOCH', (str(source_date_epoch), epochfile))
    return str(source_date_epoch)

def epochfile_write(source_date_epoch, epochfile, d):

    bb.debug(1, "SOURCE_DATE_EPOCH: %d" % source_date_epoch)
    bb.utils.mkdirhier(os.path.dirname(epochfile))

    tmp_file = "%s.new" % epochfile
    with open(tmp_file, 'w') as f:
        f.write(str(source_date_epoch))
    os.rename(tmp_file, epochfile)