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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); }
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