From 398cbfdcda21f349d9d7413fe3060c7abaf475bc Mon Sep 17 00:00:00 2001
From: JustAnotherArchivist <JustAnotherArchivist@users.noreply.github.com>
Date: Sat, 26 Sep 2020 17:41:19 +0000
Subject: [PATCH] Add s3-bucket-list-qwarc, rewritten s3-bucket-list on top of
 qwarc

---
 s3-bucket-list-qwarc | 241 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 241 insertions(+)
 create mode 100755 s3-bucket-list-qwarc

diff --git a/s3-bucket-list-qwarc b/s3-bucket-list-qwarc
new file mode 100755
index 0000000..dcfae80
--- /dev/null
+++ b/s3-bucket-list-qwarc
@@ -0,0 +1,241 @@
+#!/bin/bash
+format='{url}'
+
+function usage_exit {
+	echo 's3-bucket-list-qwarc [options] BUCKETURL [MARKER...]' >&2
+	echo >&2
+	echo 'List the contents of an open S3 (or S3-like) bucket, possibly in parallel using multiple markers' >&2
+	echo >&2
+	echo 'Options:' >&2
+	echo '  --concurrency N    Start qwarc with a concurrency of N; the default is to run all markers at once' >&2
+	echo "  --format FORMAT    Modify the output format; FORMAT defaults to '${format}'; available fields: url, key, size, and all fields returned by S3 (e.g. LastModified)" >&2
+	echo '  --no-start-marker  Disable the automatic marker to start from the beginning of the list' >&2
+	echo '  --no-end-marker    Disable the automatic marker to scan to the end of the list' >&2
+	echo '  --with-list-urls   Enables printing the list URLs retrieved to FD 3' >&2
+	exit $1
+}
+
+concurrency=
+listUrls=
+noStartMarker=
+noEndMarker=
+
+cmd="$(printf '%q ' 's3-bucket-list-qwarc' "$@" | sed 's, $,,')"
+while [[ $# -gt 0 ]]
+do
+	if [[ "$1" == '--help' || "$1" == '-h' ]]
+	then
+		usage_exit 0
+	elif [[ "$1" == '--concurrency' ]]
+	then
+		declare -i concurrency="$2"
+		shift
+	elif [[ "$1" == '--format' ]]
+	then
+		format="$2"
+		shift
+	elif [[ "$1" == '--no-start-marker' ]]
+	then
+		noStartMarker=1
+	elif [[ "$1" == '--no-end-marker' ]]
+	then
+		noEndMarker=1
+	elif [[ "$1" == '--with-list-urls' ]]
+	then
+		listUrls='yes'
+	else
+		break
+	fi
+	shift
+done
+
+bucketUrl="$1"
+shift
+
+# Remaining arguments are markers
+
+if [[ -z "${concurrency}" ]]
+then
+	declare -i concurrency=$#
+	if [[ -z "${noStartMarker}" ]]; then concurrency+=1; fi
+	if [[ -z "${noEndMarker}" ]]; then concurrency+=1; fi
+	concurrency+=-1 # Because the obvious -= doesn't work...
+fi
+
+if [[ "${listUrls}" ]] && ! { command >&3; } 2>/dev/null
+then
+	echo 'Error: --with-list-urls requires FD 3 to be open' >&2
+	exit 1
+fi
+
+# Validate and process bucket URL
+if [[ "${bucketUrl}" != http://* && "${bucketUrl}" != https://* ]]
+then
+	echo 'Invalid bucket URL: must be HTTP or HTTPS' >&2
+	exit 1
+fi
+if [[ "${bucketUrl}" == *'?'* ]]
+then
+	echo 'Invalid bucket URL: must not have a query' >&2
+	exit 1
+fi
+if [[ "${bucketUrl}" != *://*/* || "${bucketUrl}" != */ ]]
+then
+	bucketUrl="${bucketUrl}/"
+fi
+
+# Construct prefix for files and output
+prefix="${bucketUrl#*://}" # Remove protocol
+while [[ "${prefix}" == */ ]]; do prefix="${prefix%/}"; done # Remove trailing slashes
+prefix="${prefix//\//_}" # Replace slashes with underscores
+
+# Ensure no collisions
+if [[ "$(shopt -s nullglob; echo "${prefix}"*)" ]]
+then
+	echo "Error: there already exist files with the prefix '${prefix}' in this directory." >&2
+	exit 1
+fi
+
+# Write the qwarc spec file
+# Indentation... Inspired by https://stackoverflow.com/a/33817423
+readarray code <<EOF
+	#!/usr/bin/env python3
+	import html
+	import json
+	import logging
+	import os
+	import qwarc
+	import qwarc.utils
+	import shlex
+	import urllib.parse
+	import yarl
+
+
+	format = os.environ['S3_FORMAT']
+	bucketUrl = yarl.URL(os.environ['S3_BUCKET_URL'])
+	withListUrls = bool(os.environ.get('S3_WITH_LIST_URLS')) # True if present and non-empty
+	markersFilename = os.environ['S3_MARKERS_FILENAME']
+	if withListUrls:
+		try:
+			listUrlsFD = os.fdopen(3, 'w')
+		except OSError:
+			logging.critical('FD 3 is not open')
+			raise
+
+
+	class S3ListBucket(qwarc.Item):
+		itemType = 's3listbucket'
+		# itemValue = ('marker1', 'marker2') encoded as JSON
+
+		@classmethod
+		def generate(cls):
+			yield from map(lambda x: json.dumps(x, separators = (',', ':')), cls._generate())
+
+		@classmethod
+		def _generate(cls):
+			with open(markersFilename, 'r') as fp:
+				it = iter(fp)
+				lastLine = next(it).strip() or None
+				for line in it:
+					line = line.strip() or None
+					yield (lastLine, line)
+					lastLine = line
+
+		async def process(self):
+			marker1, marker2 = json.loads(self.itemValue)
+			marker = marker1
+			while True:
+				url = bucketUrl.with_query({'marker': marker} if marker is not None else {})
+				if withListUrls:
+					self.logger.info(f'List URL: {str(url)!r}')
+					print(f'{url}', file = listUrlsFD)
+				response = await self.fetch(url)
+				if response.status != 200:
+					self.logger.error(f'Could not fetch page on marker {marker!r}')
+					break
+				body = await response.read()
+				# Isn't this a 503?
+				if b'<Error><Code>InternalError</Code><Message>We encountered an internal error. Please try again.</Message>' in body:
+					self.logger.error(f'Got internal error on {url} on attempt {attempt}; {"retrying" if attempt < 10 else "aborting"}')
+					if attempt >= 10:
+						if 'marker' in params:
+							self.logger.error(f'To retry, use marker {marker!r}')
+						break
+					attempt += 1
+					continue
+				if not body.startswith(b'<?xml version="1.0" encoding="UTF-8"?>\n<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">') and \
+				   not body.startswith(b"<?xml version='1.0' encoding='UTF-8'?><ListBucketResult xmlns='http://doc.s3.amazonaws.com/2006-03-01'>"):
+					self.logger.error(f'Invalid body on marker {marker!r}: {body[:200]}...')
+					break
+
+				if b'<Marker></Marker>' in body[:200] and marker is not None:
+					self.logger.error('Marker loop (empty marker in response despite providing one)')
+					break
+
+				# No risk, no fun!
+				contents = body.split(b'<Contents>')
+				assert all(content.startswith(b'<Key>') for content in contents[1:])
+				assert all(content.endswith(b'</Contents>') for content in contents[1:-1])
+				assert contents[-1].endswith(b'</Contents></ListBucketResult>')
+				contents[-1] = contents[-1][:-len('</ListBucketResult>')]
+				for content in contents[1:]:
+					key = html.unescape(content[5 : content.index(b'</Key>')].decode('utf-8')) # 5 = len(b'<Key>')
+					if marker2 is not None and key >= marker2:
+						break
+					url = f'{bucketUrl}{urllib.parse.quote(key)}'
+
+					tags = content.split(b'>')
+					assert len(tags) % 2 == 0
+					assert tags[-1] == b''
+					assert tags[-2] == b'</Contents'
+					openTags = [] # Current open tag hierarchy
+					fields = {}
+					for tag in tags[:-2]:
+						if tag.startswith(b'<'):
+							openTags.append(tag[1:])
+							continue
+						assert openTags
+						if tag.endswith(b'</' + openTags[-1]):
+							fields[b'>'.join(openTags).decode('utf-8')] = html.unescape(tag[:-(len(openTags[-1]) + 2)].decode('utf-8'))
+							openTags.pop()
+							continue
+						assert False
+
+					size = int(fields['Size']) if 'Size' in fields else None
+
+					s = format.format(**fields, key = key, url = url, size = size)
+					self.logger.info(f'Output: {s!r}')
+					print(s)
+				lastKey = key
+				if marker2 is not None and lastKey >= marker2:
+					break
+
+				truncated = True if b'<IsTruncated>true</IsTruncated>' in body else (False if b'<IsTruncated>false</IsTruncated>' in body else None)
+				assert truncated in (True, False)
+
+				if not truncated:
+					break
+				if marker is not None and marker == lastKey:
+					self.logger.error('Marker loop (same last key as previous marker)')
+					break
+				marker = lastKey
+				attempt = 1
+
+
+	specDependencies = qwarc.utils.SpecDependencies(
+		files = [os.environ['S3_MARKERS_FILENAME']],
+		extra = {'env': {k: os.environ.get(k) for k in ('S3BL_CMD', 'S3_FORMAT', 'S3_BUCKET_URL', 'S3_MARKERS_FILENAME', 'S3_WITH_LIST_URLS')}}
+	)
+EOF
+printf '%s' "${code[@]#	}" >"${prefix}.py"  # That's a tab character after the hash.
+
+# Generate the markers file
+{ if [[ -z "${noStartMarker}" ]]; then echo; fi; printf '%s\n' "$@"; if [[ -z "${noEndMarker}" ]]; then echo; fi; } >"${prefix}-markers"
+
+# Lift-off!
+S3BL_CMD="${cmd}" \
+  S3_FORMAT="${format}" \
+  S3_BUCKET_URL="${bucketUrl}" \
+  S3_MARKERS_FILENAME="${prefix}-markers" \
+  S3_WITH_LIST_URLS="${listUrls}" \
+  qwarc --concurrency "${concurrency}" --database "${prefix}.db" --log "${prefix}.log" --warc "${prefix}" "${prefix}.py"