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feat: add Go HTTP server example
Minimal Go net/http server running on Hyperlight with host-proxied async networking via hostsock. Includes Dockerfile for cross-platform rootfs builds. Signed-off-by: danbugs <danilochiarlone@gmail.com>
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‎examples/go-http/Dockerfile‎

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FROM golang:1.21.3-bookworm AS build
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WORKDIR /src
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COPY ./main.go /src/main.go
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RUN set -xe; \
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CGO_ENABLED=0 \
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GOARCH=amd64 \
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go build \
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-buildmode=pie \
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-ldflags="-linkmode=internal" \
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-o /server main.go \
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;
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# Strip PT_INTERP from the static PIE binary: Go's internal linker adds
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# /lib64/ld-linux-x86-64.so.2 as interpreter for PIE on Linux, but the
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# binary is fully self-contained and does not need a dynamic linker.
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# Unikraft's elfloader fails when the interpreter is listed but absent.
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# Patch the program header: change PT_INTERP (type=3) -> PT_NULL (type=0).
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COPY patch_interp.py /patch_interp.py
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RUN python3 /patch_interp.py /server
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FROM scratch AS rootfs
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COPY --from=build /server /bin/server
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# --- CPIO rootfs builder (used by: docker build --target cpio) ---
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FROM alpine:3.20 AS cpio
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RUN apk add --no-cache cpio findutils
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COPY --from=rootfs / /rootfs/
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RUN cd /rootfs && find . | cpio -o -H newc > /output.cpio 2>/dev/null

‎examples/go-http/Justfile‎

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# go-http on Hyperlight
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#
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# just run - Run the HTTP server (--port implies --net)
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# just rootfs - Build rootfs via Docker (cross-platform)
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# just build - Build/pull kernel
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# just clean - Remove build artifacts
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set windows-shell := ["powershell.exe", "-NoLogo", "-Command"]
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export DOCKER_BUILDKIT := "0"
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kernel := ".unikraft/build/go-http-hyperlight_hyperlight-x86_64"
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initrd := "initrd.cpio"
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memory := "32Mi"
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image := "go-http-hyperlight"
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# Run the HTTP server (curl http://localhost:8080 to test)
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run:
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hyperlight-unikraft {{kernel}} --initrd {{initrd}} --memory {{memory}} --port 8080 -- /bin/server
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# Build rootfs via Docker (cross-platform)
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rootfs:
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docker build --platform linux/amd64 --target cpio -t {{image}}-cpio .
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- docker rm -f {{image}}-tmp
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docker create --name {{image}}-tmp {{image}}-cpio /bin/true
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docker cp {{image}}-tmp:/output.cpio ./{{initrd}}
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docker rm -f {{image}}-tmp
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# Build kernel via kraft (Linux)
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[unix]
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build:
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-kraft-hyperlight build --plat hyperlight --arch x86_64
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# Pull pre-built kernel from GHCR (Windows — no kernel published yet)
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[windows]
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build:
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Write-Host "No pre-built kernel for go-http yet. Build on Linux first."
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# Clean + rebuild everything
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rebuild: clean build rootfs
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# Clean build artifacts
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[unix]
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clean:
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rm -rf .unikraft {{initrd}}
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[windows]
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clean:
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if (Test-Path .unikraft) { Remove-Item -Recurse -Force .unikraft }
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if (Test-Path {{initrd}}) { Remove-Item -Force {{initrd}} }

‎examples/go-http/kraft.yaml‎

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specification: '0.6'
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name: go-http-hyperlight
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unikraft:
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source: https://github.com/unikraft/unikraft.git
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version: plat-hyperlight
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kconfig:
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# Platform
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CONFIG_PLAT_HYPERLIGHT: 'y'
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CONFIG_PAGING: 'n'
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CONFIG_LIBUKVMEM: 'n'
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CONFIG_LIBUKINTCTLR_HYPERLIGHT: 'y'
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CONFIG_HYPERLIGHT_MAX_GUEST_LOG_LEVEL: 0
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# Suppress kernel logging for performance
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CONFIG_LIBUKPRINT_KLVL_CRIT: 'y'
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CONFIG_LIBUKPRINT_PRINT_TIME: 'n'
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CONFIG_LIBUKPRINT_PRINT_SRCNAME: 'n'
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CONFIG_LIBUKBOOT_BANNER_NONE: 'y'
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# Size optimization
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CONFIG_OPTIMIZE_SIZE: 'y'
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CONFIG_OPTIMIZE_PIE: 'y'
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# VFS and initrd support
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CONFIG_LIBVFSCORE: 'y'
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CONFIG_LIBVFSCORE_AUTOMOUNT_CI: 'y'
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CONFIG_LIBVFSCORE_AUTOMOUNT_CI_CUSTOM: 'y'
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CONFIG_LIBVFSCORE_AUTOMOUNT_CI0_MP: '/'
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CONFIG_LIBVFSCORE_AUTOMOUNT_CI0_DRIVER: 'cpiovfs'
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CONFIG_LIBVFSCORE_AUTOMOUNT_CI0_UKOPTS_IFINITRD0: 'y'
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CONFIG_LIBCPIOVFS: 'y'
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CONFIG_LIBUKCPIO: 'y'
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# ELF loader - Go binary location
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CONFIG_APPELFLOADER: 'y'
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CONFIG_APPELFLOADER_VFSEXEC: 'y'
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CONFIG_APPELFLOADER_CUSTOMAPPNAME: 'n'
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CONFIG_APPELFLOADER_VFSEXEC_ENVPATH: 'n'
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CONFIG_APPELFLOADER_VFSEXEC_PATH: '/bin/server'
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CONFIG_LIBPOSIX_ENVIRON_ENVP0: '"PATH=/bin"'
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CONFIG_LIBPOSIX_ENVIRON_ENVP1: '"GOMEMLIMIT=64MiB"'
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CONFIG_LIBPOSIX_ENVIRON_ENVP2: '"GOMAXPROCS=1"'
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CONFIG_LIBELF: 'y'
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# Random number support
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CONFIG_LIBUKRANDOM_CMDLINE_SEED: 'y'
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CONFIG_LIBUKRANDOM_GETRANDOM: 'y'
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# Threading support
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CONFIG_LIBUKBOOT_MAINTHREAD: 'y'
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CONFIG_LIBPOSIX_PROCESS_ARCH_PRCTL: 'y'
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CONFIG_LIBPOSIX_PROCESS_MULTITHREADING: 'y'
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# Signal and futex support (needed for Go runtime)
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CONFIG_LIBPOSIX_PROCESS_SIGNAL: 'y'
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CONFIG_LIBPOSIX_FUTEX: 'y'
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# eventfd (needed by Go's epoll-based netpoller)
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CONFIG_LIBPOSIX_EVENTFD: 'y'
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# mmap needed by Go runtime (heap reservation + page summaries)
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CONFIG_LIBUKMPI: 'y'
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CONFIG_LIBUKMMAP: 'y'
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# devfs + /dev/hcall (required for host-proxied networking)
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CONFIG_LIBDEVFS: 'y'
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CONFIG_LIBDEVFS_AUTOMOUNT: 'y'
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CONFIG_HYPERLIGHT_HCALL: 'y'
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# Networking: host-proxied sockets
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CONFIG_LIBPOSIX_SOCKET: 'y'
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CONFIG_LIBHOSTSOCK: 'y'
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# FD infrastructure (required by posix-socket)
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CONFIG_LIBPOSIX_FDIO: 'y'
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CONFIG_LIBPOSIX_FDTAB: 'y'
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CONFIG_LIBUKFILE: 'y'
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libraries:
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app-elfloader:
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source: https://github.com/unikraft/app-elfloader.git
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version: plat-hyperlight
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libelf:
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source: https://github.com/unikraft/lib-libelf.git
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version: staging
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targets:
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- architecture: x86_64
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platform: hyperlight

‎examples/go-http/main.go‎

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package main
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import (
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"fmt"
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"log"
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"net/http"
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)
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func helloHandler(w http.ResponseWriter, r *http.Request) {
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fmt.Fprint(w, "Hello from Hyperlight-Unikraft!")
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}
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func main() {
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mux := http.NewServeMux()
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mux.HandleFunc("/", helloHandler)
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fmt.Println("Server is running on http://localhost:8080")
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log.Fatal(http.ListenAndServe(":8080", mux))
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}

‎examples/go-http/patch_interp.py‎

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#!/usr/bin/env python3
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"""Strip PT_INTERP from a static PIE binary.
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Go's internal linker adds /lib64/ld-linux-x86-64.so.2 as PT_INTERP for PIE
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binaries on Linux, but a CGO_ENABLED=0 binary is fully self-contained and
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does not need a dynamic linker. Patch PT_INTERP -> PT_NULL so elfloaders
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that reject missing interpreters will load the binary directly.
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"""
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import struct
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import sys
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path = sys.argv[1]
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with open(path, "rb") as f:
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data = bytearray(f.read())
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e_phoff, = struct.unpack_from("<Q", data, 32)
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e_phentsize, = struct.unpack_from("<H", data, 54)
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e_phnum, = struct.unpack_from("<H", data, 56)
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for i in range(e_phnum):
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off = e_phoff + i * e_phentsize
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p_type, = struct.unpack_from("<I", data, off)
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if p_type == 3: # PT_INTERP
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struct.pack_into("<I", data, off, 0) # PT_NULL
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print(f"Patched PT_INTERP -> PT_NULL at program header index {i}")
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with open(path, "wb") as f:
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f.write(data)

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