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Replace per-byte partial-boundary scan with rfind lookbehind#300

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Merged
Kludex merged 1 commit into from
Jun 4, 2026
+55 −11
Merged

Replace per-byte partial-boundary scan with rfind lookbehind #300

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23 changes: 12 additions & 11 deletions python_multipart/multipart.py
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -1361,18 +1361,19 @@ def data_callback(name: CallbackName, end_i: int, remaining: bool = False) -> No
# We matched the whole boundary string.
index = boundary_length - 1
i = i0 + boundary_length - 1
c = data[i]
else:
# No match found for whole string.
# There may be a partial boundary at the end of the
# data, which the find will not match.
# Since the length to be searched is limited to the
# boundary length, scan the tail for boundary[0] via
# bytes.find (C-level) to keep cost off the Python loop.
i = max(i, length - boundary_length)
j = data.find(boundary[:1], i, length - 1)
i = j if j >= 0 else length - 1

c = data[i]
# No whole boundary, but the tail may hold a partial one
# that completes in the next chunk. Boundary starts with
# CR, which an RFC boundary contains nowhere else, so the
# last CR in the tail is the only candidate prefix start.
k = data.rfind(boundary[:1], max(i, length - boundary_length + 1), length)
if k != -1 and boundary.startswith(data[k:length]):
index = length - k
# Carry the partial via index; the end-of-chunk flush
# emits the data before it and re-marks the lookbehind.
i = length
continue

# Now, we have a couple of cases here. If our index is before
# the end of the boundary...
Expand Down
34 changes: 34 additions & 0 deletions tests/test_data/http/crlf_dense_part_data.http
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
--boundary
Content-Disposition: form-data; name="file"; filename="crlf.bin"
Content-Type: application/octet-stream






















--boundar





--bound

--boundary--
8 changes: 8 additions & 0 deletions tests/test_data/http/crlf_dense_part_data.yaml
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
boundary: boundary
expected:
- name: file
type: file
file_name: crlf.bin
content_type: 'application/octet-stream'
data: !!binary |
DQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KLS1ib3VuZGFyDQoNCg0KDQoNCg0KLS1ib3VuZA0K
1 change: 1 addition & 0 deletions tests/test_multipart.py
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -779,6 +779,7 @@ def test_not_aligned(self) -> None:
"almost_match_boundary_without_LF",
"almost_match_boundary_without_final_hyphen",
"single_field_single_file",
"crlf_dense_part_data",
]

EPILOGUE_TEST_HEAD = (
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Replace per-byte partial-boundary scan with rfind lookbehind by Kludex · Pull Request #300 · Kludex/python-multipart · GitHub
Skip to content
Replace per-byte partial-boundary scan with rfind lookbehind#300

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to your account

 Merged

Kludex
merged 1 commit into

from

Jun 4, 2026

+55

−11

 Merged


Replace per-byte partial-boundary scan with rfind lookbehind
#300
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23 changes: 12 additions & 11 deletions
python_multipart/multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1361,18 +1361,19 @@ def data_callback(name: CallbackName, end_i: int, remaining: bool = False) -> No
 # We matched the whole boundary string.
 index = boundary_length - 1
 i = i0 + boundary_length - 1
 c = data[i]
 else:
 # No match found for whole string.
 # There may be a partial boundary at the end of the
 # data, which the find will not match.
 # Since the length to be searched is limited to the
# boundary length, scan the tail for boundary[0] via
# bytes.find (C-level) to keep cost off the Python loop.
i = max(i, length - boundary_length)
j = data.find(boundary[:1], i, length - 1)
i = j if j >= 0 else length - 1

c = data[i]
 # No whole boundary, but the tail may hold a partial one
 # that completes in the next chunk. Boundary starts with
 # CR, which an RFC boundary contains nowhere else, so the
 # last CR in the tail is the only candidate prefix start.
k = data.rfind(boundary[:1], max(i, length - boundary_length + 1), length)
if k != -1 and boundary.startswith(data[k:length]):
 index = length - k
# Carry the partial via index; the end-of-chunk flush
# emits the data before it and re-marks the lookbehind.
 i = length
 continue

 # Now, we have a couple of cases here. If our index is before
 # the end of the boundary...
Expand Down

34 changes: 34 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.http

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
--boundary
Content-Disposition: form-data; name="file"; filename="crlf.bin"
Content-Type: application/octet-stream






















--boundar





--bound

--boundary--

8 changes: 8 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.yaml

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
boundary: boundary
expected:
 - name: file
 type: file
 file_name: crlf.bin
 content_type: 'application/octet-stream'
 data: !!binary |
 DQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KLS1ib3VuZGFyDQoNCg0KDQoNCg0KLS1ib3VuZA0K

1 change: 1 addition & 0 deletions
tests/test_multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -779,6 +779,7 @@ def test_not_aligned(self) -> None:
 "almost_match_boundary_without_LF",
 "almost_match_boundary_without_final_hyphen",
 "single_field_single_file",
 "crlf_dense_part_data",
]

EPILOGUE_TEST_HEAD = (
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Replace per-byte partial-boundary scan with rfind lookbehind by Kludex · Pull Request #300 · Kludex/python-multipart · GitHub
Skip to content
Replace per-byte partial-boundary scan with rfind lookbehind#300

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

Kludex
merged 1 commit into

from

Jun 4, 2026

+55

−11

 Merged


Replace per-byte partial-boundary scan with rfind lookbehind
#300
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23 changes: 12 additions & 11 deletions
python_multipart/multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1361,18 +1361,19 @@ def data_callback(name: CallbackName, end_i: int, remaining: bool = False) -> No
 # We matched the whole boundary string.
 index = boundary_length - 1
 i = i0 + boundary_length - 1
 c = data[i]
 else:
 # No match found for whole string.
 # There may be a partial boundary at the end of the
 # data, which the find will not match.
 # Since the length to be searched is limited to the
# boundary length, scan the tail for boundary[0] via
# bytes.find (C-level) to keep cost off the Python loop.
i = max(i, length - boundary_length)
j = data.find(boundary[:1], i, length - 1)
i = j if j >= 0 else length - 1

c = data[i]
 # No whole boundary, but the tail may hold a partial one
 # that completes in the next chunk. Boundary starts with
 # CR, which an RFC boundary contains nowhere else, so the
 # last CR in the tail is the only candidate prefix start.
k = data.rfind(boundary[:1], max(i, length - boundary_length + 1), length)
if k != -1 and boundary.startswith(data[k:length]):
 index = length - k
# Carry the partial via index; the end-of-chunk flush
# emits the data before it and re-marks the lookbehind.
 i = length
 continue

 # Now, we have a couple of cases here. If our index is before
 # the end of the boundary...
Expand Down

34 changes: 34 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.http

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
--boundary
Content-Disposition: form-data; name="file"; filename="crlf.bin"
Content-Type: application/octet-stream






















--boundar





--bound

--boundary--

8 changes: 8 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.yaml

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
boundary: boundary
expected:
 - name: file
 type: file
 file_name: crlf.bin
 content_type: 'application/octet-stream'
 data: !!binary |
 DQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KLS1ib3VuZGFyDQoNCg0KDQoNCg0KLS1ib3VuZA0K

1 change: 1 addition & 0 deletions
tests/test_multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -779,6 +779,7 @@ def test_not_aligned(self) -> None:
 "almost_match_boundary_without_LF",
 "almost_match_boundary_without_final_hyphen",
 "single_field_single_file",
 "crlf_dense_part_data",
]

EPILOGUE_TEST_HEAD = (
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Replace per-byte partial-boundary scan with rfind lookbehind by Kludex · Pull Request #300 · Kludex/python-multipart · GitHub
Skip to content
Replace per-byte partial-boundary scan with rfind lookbehind#300

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

Kludex
merged 1 commit into

from

Jun 4, 2026

+55

−11

 Merged


Replace per-byte partial-boundary scan with rfind lookbehind
#300
Show file tree
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 Diff view

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23 changes: 12 additions & 11 deletions
python_multipart/multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1361,18 +1361,19 @@ def data_callback(name: CallbackName, end_i: int, remaining: bool = False) -> No
 # We matched the whole boundary string.
 index = boundary_length - 1
 i = i0 + boundary_length - 1
 c = data[i]
 else:
 # No match found for whole string.
 # There may be a partial boundary at the end of the
 # data, which the find will not match.
 # Since the length to be searched is limited to the
# boundary length, scan the tail for boundary[0] via
# bytes.find (C-level) to keep cost off the Python loop.
i = max(i, length - boundary_length)
j = data.find(boundary[:1], i, length - 1)
i = j if j >= 0 else length - 1

c = data[i]
 # No whole boundary, but the tail may hold a partial one
 # that completes in the next chunk. Boundary starts with
 # CR, which an RFC boundary contains nowhere else, so the
 # last CR in the tail is the only candidate prefix start.
k = data.rfind(boundary[:1], max(i, length - boundary_length + 1), length)
if k != -1 and boundary.startswith(data[k:length]):
 index = length - k
# Carry the partial via index; the end-of-chunk flush
# emits the data before it and re-marks the lookbehind.
 i = length
 continue

 # Now, we have a couple of cases here. If our index is before
 # the end of the boundary...
Expand Down

34 changes: 34 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.http

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
--boundary
Content-Disposition: form-data; name="file"; filename="crlf.bin"
Content-Type: application/octet-stream






















--boundar





--bound

--boundary--

8 changes: 8 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.yaml

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
boundary: boundary
expected:
 - name: file
 type: file
 file_name: crlf.bin
 content_type: 'application/octet-stream'
 data: !!binary |
 DQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KLS1ib3VuZGFyDQoNCg0KDQoNCg0KLS1ib3VuZA0K

1 change: 1 addition & 0 deletions
tests/test_multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -779,6 +779,7 @@ def test_not_aligned(self) -> None:
 "almost_match_boundary_without_LF",
 "almost_match_boundary_without_final_hyphen",
 "single_field_single_file",
 "crlf_dense_part_data",
]

EPILOGUE_TEST_HEAD = (
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Replace per-byte partial-boundary scan with rfind lookbehind by Kludex · Pull Request #300 · Kludex/python-multipart · GitHub
Skip to content
Replace per-byte partial-boundary scan with rfind lookbehind#300

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

Kludex
merged 1 commit into

from

Jun 4, 2026

+55

−11

 Merged


Replace per-byte partial-boundary scan with rfind lookbehind
#300
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


Select commit


File filter

Filter by extension
Filter by extension
Conversations

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Loading
Jump to

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Failed to load files. 
Loading
 Diff view

 Diff view


23 changes: 12 additions & 11 deletions
python_multipart/multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1361,18 +1361,19 @@ def data_callback(name: CallbackName, end_i: int, remaining: bool = False) -> No
 # We matched the whole boundary string.
 index = boundary_length - 1
 i = i0 + boundary_length - 1
 c = data[i]
 else:
 # No match found for whole string.
 # There may be a partial boundary at the end of the
 # data, which the find will not match.
 # Since the length to be searched is limited to the
# boundary length, scan the tail for boundary[0] via
# bytes.find (C-level) to keep cost off the Python loop.
i = max(i, length - boundary_length)
j = data.find(boundary[:1], i, length - 1)
i = j if j >= 0 else length - 1

c = data[i]
 # No whole boundary, but the tail may hold a partial one
 # that completes in the next chunk. Boundary starts with
 # CR, which an RFC boundary contains nowhere else, so the
 # last CR in the tail is the only candidate prefix start.
k = data.rfind(boundary[:1], max(i, length - boundary_length + 1), length)
if k != -1 and boundary.startswith(data[k:length]):
 index = length - k
# Carry the partial via index; the end-of-chunk flush
# emits the data before it and re-marks the lookbehind.
 i = length
 continue

 # Now, we have a couple of cases here. If our index is before
 # the end of the boundary...
Expand Down

34 changes: 34 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.http

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
--boundary
Content-Disposition: form-data; name="file"; filename="crlf.bin"
Content-Type: application/octet-stream






















--boundar





--bound

--boundary--

8 changes: 8 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.yaml

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
boundary: boundary
expected:
 - name: file
 type: file
 file_name: crlf.bin
 content_type: 'application/octet-stream'
 data: !!binary |
 DQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KLS1ib3VuZGFyDQoNCg0KDQoNCg0KLS1ib3VuZA0K

1 change: 1 addition & 0 deletions
tests/test_multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -779,6 +779,7 @@ def test_not_aligned(self) -> None:
 "almost_match_boundary_without_LF",
 "almost_match_boundary_without_final_hyphen",
 "single_field_single_file",
 "crlf_dense_part_data",
]

EPILOGUE_TEST_HEAD = (
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Replace per-byte partial-boundary scan with rfind lookbehind by Kludex · Pull Request #300 · Kludex/python-multipart · GitHub
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Replace per-byte partial-boundary scan with rfind lookbehind#300

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 Merged

Kludex
merged 1 commit into

from

Jun 4, 2026

+55

−11

 Merged


Replace per-byte partial-boundary scan with rfind lookbehind
#300
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23 changes: 12 additions & 11 deletions
python_multipart/multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1361,18 +1361,19 @@ def data_callback(name: CallbackName, end_i: int, remaining: bool = False) -> No
 # We matched the whole boundary string.
 index = boundary_length - 1
 i = i0 + boundary_length - 1
 c = data[i]
 else:
 # No match found for whole string.
 # There may be a partial boundary at the end of the
 # data, which the find will not match.
 # Since the length to be searched is limited to the
# boundary length, scan the tail for boundary[0] via
# bytes.find (C-level) to keep cost off the Python loop.
i = max(i, length - boundary_length)
j = data.find(boundary[:1], i, length - 1)
i = j if j >= 0 else length - 1

c = data[i]
 # No whole boundary, but the tail may hold a partial one
 # that completes in the next chunk. Boundary starts with
 # CR, which an RFC boundary contains nowhere else, so the
 # last CR in the tail is the only candidate prefix start.
k = data.rfind(boundary[:1], max(i, length - boundary_length + 1), length)
if k != -1 and boundary.startswith(data[k:length]):
 index = length - k
# Carry the partial via index; the end-of-chunk flush
# emits the data before it and re-marks the lookbehind.
 i = length
 continue

 # Now, we have a couple of cases here. If our index is before
 # the end of the boundary...
Expand Down

34 changes: 34 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.http

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
--boundary
Content-Disposition: form-data; name="file"; filename="crlf.bin"
Content-Type: application/octet-stream






















--boundar





--bound

--boundary--

8 changes: 8 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.yaml

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
boundary: boundary
expected:
 - name: file
 type: file
 file_name: crlf.bin
 content_type: 'application/octet-stream'
 data: !!binary |
 DQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KLS1ib3VuZGFyDQoNCg0KDQoNCg0KLS1ib3VuZA0K

1 change: 1 addition & 0 deletions
tests/test_multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -779,6 +779,7 @@ def test_not_aligned(self) -> None:
 "almost_match_boundary_without_LF",
 "almost_match_boundary_without_final_hyphen",
 "single_field_single_file",
 "crlf_dense_part_data",
]

EPILOGUE_TEST_HEAD = (
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Replace per-byte partial-boundary scan with rfind lookbehind by Kludex · Pull Request #300 · Kludex/python-multipart · GitHub
Skip to content
Replace per-byte partial-boundary scan with rfind lookbehind#300

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Already on GitHub?
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to your account

 Merged

Kludex
merged 1 commit into

from

Jun 4, 2026

+55

−11

 Merged


Replace per-byte partial-boundary scan with rfind lookbehind
#300
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23 changes: 12 additions & 11 deletions
python_multipart/multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1361,18 +1361,19 @@ def data_callback(name: CallbackName, end_i: int, remaining: bool = False) -> No
 # We matched the whole boundary string.
 index = boundary_length - 1
 i = i0 + boundary_length - 1
 c = data[i]
 else:
 # No match found for whole string.
 # There may be a partial boundary at the end of the
 # data, which the find will not match.
 # Since the length to be searched is limited to the
# boundary length, scan the tail for boundary[0] via
# bytes.find (C-level) to keep cost off the Python loop.
i = max(i, length - boundary_length)
j = data.find(boundary[:1], i, length - 1)
i = j if j >= 0 else length - 1

c = data[i]
 # No whole boundary, but the tail may hold a partial one
 # that completes in the next chunk. Boundary starts with
 # CR, which an RFC boundary contains nowhere else, so the
 # last CR in the tail is the only candidate prefix start.
k = data.rfind(boundary[:1], max(i, length - boundary_length + 1), length)
if k != -1 and boundary.startswith(data[k:length]):
 index = length - k
# Carry the partial via index; the end-of-chunk flush
# emits the data before it and re-marks the lookbehind.
 i = length
 continue

 # Now, we have a couple of cases here. If our index is before
 # the end of the boundary...
Expand Down

34 changes: 34 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.http

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
--boundary
Content-Disposition: form-data; name="file"; filename="crlf.bin"
Content-Type: application/octet-stream






















--boundar





--bound

--boundary--

8 changes: 8 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.yaml

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
boundary: boundary
expected:
 - name: file
 type: file
 file_name: crlf.bin
 content_type: 'application/octet-stream'
 data: !!binary |
 DQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KLS1ib3VuZGFyDQoNCg0KDQoNCg0KLS1ib3VuZA0K

1 change: 1 addition & 0 deletions
tests/test_multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -779,6 +779,7 @@ def test_not_aligned(self) -> None:
 "almost_match_boundary_without_LF",
 "almost_match_boundary_without_final_hyphen",
 "single_field_single_file",
 "crlf_dense_part_data",
]

EPILOGUE_TEST_HEAD = (
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
Replace per-byte partial-boundary scan with rfind lookbehind by Kludex · Pull Request #300 · Kludex/python-multipart · GitHub
Skip to content
Replace per-byte partial-boundary scan with rfind lookbehind#300

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

Kludex
merged 1 commit into

from

Jun 4, 2026

+55

−11

 Merged


Replace per-byte partial-boundary scan with rfind lookbehind
#300
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


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Failed to load files. 
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 Diff view


23 changes: 12 additions & 11 deletions
python_multipart/multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1361,18 +1361,19 @@ def data_callback(name: CallbackName, end_i: int, remaining: bool = False) -> No
 # We matched the whole boundary string.
 index = boundary_length - 1
 i = i0 + boundary_length - 1
 c = data[i]
 else:
 # No match found for whole string.
 # There may be a partial boundary at the end of the
 # data, which the find will not match.
 # Since the length to be searched is limited to the
# boundary length, scan the tail for boundary[0] via
# bytes.find (C-level) to keep cost off the Python loop.
i = max(i, length - boundary_length)
j = data.find(boundary[:1], i, length - 1)
i = j if j >= 0 else length - 1

c = data[i]
 # No whole boundary, but the tail may hold a partial one
 # that completes in the next chunk. Boundary starts with
 # CR, which an RFC boundary contains nowhere else, so the
 # last CR in the tail is the only candidate prefix start.
k = data.rfind(boundary[:1], max(i, length - boundary_length + 1), length)
if k != -1 and boundary.startswith(data[k:length]):
 index = length - k
# Carry the partial via index; the end-of-chunk flush
# emits the data before it and re-marks the lookbehind.
 i = length
 continue

 # Now, we have a couple of cases here. If our index is before
 # the end of the boundary...
Expand Down

34 changes: 34 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.http

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
--boundary
Content-Disposition: form-data; name="file"; filename="crlf.bin"
Content-Type: application/octet-stream






















--boundar





--bound

--boundary--

8 changes: 8 additions & 0 deletions
tests/test_data/http/crlf_dense_part_data.yaml

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
boundary: boundary
expected:
 - name: file
 type: file
 file_name: crlf.bin
 content_type: 'application/octet-stream'
 data: !!binary |
 DQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KDQoNCg0KLS1ib3VuZGFyDQoNCg0KDQoNCg0KLS1ib3VuZA0K

1 change: 1 addition & 0 deletions
tests/test_multipart.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -779,6 +779,7 @@ def test_not_aligned(self) -> None:
 "almost_match_boundary_without_LF",
 "almost_match_boundary_without_final_hyphen",
 "single_field_single_file",
 "crlf_dense_part_data",
]

EPILOGUE_TEST_HEAD = (
Expand Down
Loading