resize.js
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import { encodeU32 } from "@webassemblyjs/wasm-gen";
import { getSectionMetadata, traverse, shiftSection } from "@webassemblyjs/ast";
import { overrideBytesInBuffer } from "@webassemblyjs/helper-buffer";
export function resizeSectionByteSize(ast, uint8Buffer, section, deltaBytes) {
var sectionMetadata = getSectionMetadata(ast, section);
if (typeof sectionMetadata === "undefined") {
throw new Error("Section metadata not found");
}
if (typeof sectionMetadata.size.loc === "undefined") {
throw new Error("SectionMetadata " + section + " has no loc");
} // keep old node location to be overriden
var start = sectionMetadata.size.loc.start.column;
var end = sectionMetadata.size.loc.end.column;
var newSectionSize = sectionMetadata.size.value + deltaBytes;
var newBytes = encodeU32(newSectionSize);
/**
* update AST
*/
sectionMetadata.size.value = newSectionSize;
var oldu32EncodedLen = end - start;
var newu32EncodedLen = newBytes.length; // the new u32 has a different encoded length
if (newu32EncodedLen !== oldu32EncodedLen) {
var deltaInSizeEncoding = newu32EncodedLen - oldu32EncodedLen;
sectionMetadata.size.loc.end.column = start + newu32EncodedLen;
deltaBytes += deltaInSizeEncoding; // move the vec size pointer size the section size is now smaller
sectionMetadata.vectorOfSize.loc.start.column += deltaInSizeEncoding;
sectionMetadata.vectorOfSize.loc.end.column += deltaInSizeEncoding;
} // Once we hit our section every that is after needs to be shifted by the delta
var encounteredSection = false;
traverse(ast, {
SectionMetadata: function SectionMetadata(path) {
if (path.node.section === section) {
encounteredSection = true;
return;
}
if (encounteredSection === true) {
shiftSection(ast, path.node, deltaBytes);
}
}
});
return overrideBytesInBuffer(uint8Buffer, start, end, newBytes);
}
export function resizeSectionVecSize(ast, uint8Buffer, section, deltaElements) {
var sectionMetadata = getSectionMetadata(ast, section);
if (typeof sectionMetadata === "undefined") {
throw new Error("Section metadata not found");
}
if (typeof sectionMetadata.vectorOfSize.loc === "undefined") {
throw new Error("SectionMetadata " + section + " has no loc");
} // Section has no vector
if (sectionMetadata.vectorOfSize.value === -1) {
return uint8Buffer;
} // keep old node location to be overriden
var start = sectionMetadata.vectorOfSize.loc.start.column;
var end = sectionMetadata.vectorOfSize.loc.end.column;
var newValue = sectionMetadata.vectorOfSize.value + deltaElements;
var newBytes = encodeU32(newValue); // Update AST
sectionMetadata.vectorOfSize.value = newValue;
sectionMetadata.vectorOfSize.loc.end.column = start + newBytes.length;
return overrideBytesInBuffer(uint8Buffer, start, end, newBytes);
}