libcurl-build (prebuilt + build scripts)

This repository folder contains prebuilt libcurl binaries for Android ABIs and reproducible build scripts to (re)build libcurl yourself on Windows and Linux.

What this folder includes

• install/<BuildType>-<stripped|unstripped>/<abi>/ — prebuilt outputs organized by build type and strip state (shared libs + headers)
  • Examples (per-variant paths):
    • install/RelWithDebInfo-unstripped/arm64-v8a/
    • install/RelWithDebInfo-stripped/arm64-v8a/
    • install/Release-unstripped/arm64-v8a/
    • install/Release-stripped/arm64-v8a/
    • install/Debug-unstripped/arm64-v8a/
    • install/Debug-stripped/arm64-v8a/
• build_all.ps1 — PowerShell script to build libcurl for ABIs on Windows (uses CMake + Android NDK)
• build_all.sh — Bash script to build libcurl for ABIs on Linux/macOS/WSL
• openssl/ — helper folder with OpenSSL prebuilds and build helpers (used as TLS backend)

Quick summary

• Purpose: provide ready-to-use libcurl.so per ABI and a simple way to rebuild them (reproducible builds)
• Supported ABIs: arm64-v8a, armeabi-v7a, x86_64 (see install/)

Cloning the repository

There are two common ways to clone this repository depending on whether you want to build OpenSSL yourself or use the prebuilt OpenSSL provided as a submodule:

• If you plan to build OpenSSL yourself (you will build the openssl folder locally), do a normal clone:

git clone https://github.com/XDcobra/libcurl-android-prebuilt-and-buildscripts

Then build as described below.

• If you want to use the prebuilt OpenSSL libraries included as a submodule, clone with submodules so the openssl content is fetched automatically:

git clone --recurse-submodules https://github.com/XDcobra/libcurl-android-prebuilt-and-buildscripts

Or, if you already cloned without --recurse-submodules, initialize submodules afterward:

git submodule update --init --recursive

Note: The build scripts expect OpenSSL files to be present under a per-build install tree such as openssl/install/<BuildType>-<stripped|unstripped>/<abi>/. You can either set OPENSSL_ANDROID_INSTALL to a BuildType-specific path (for example openssl/install/RelWithDebInfo-unstripped) or copy the ABI folders into openssl/install/<abi>/ as needed.

Quick Start

Windows (PowerShell)

# set NDK path if not already
$env:ANDROID_NDK_HOME = 'C:\Users\<you>\AppData\Local\Android\Sdk\ndk\<version>'
# optionally set OpenSSL install base if you built OpenSSL into a custom location. Otherwise it defaults to /openssl/install
$env:OPENSSL_ANDROID_INSTALL = 'C:\path\to\openssl\install'

# Build Release, strip artifacts for arm64-v8a only
powershell -NoProfile -ExecutionPolicy Bypass -File build_all.ps1 -BuildType Release -Strip -ABIs @('arm64-v8a')

Linux / macOS / WSL

export ANDROID_NDK_HOME=/path/to/android-ndk
export OPENSSL_ANDROID_INSTALL=/path/to/openssl/install
# Build Release, prefer stripped OpenSSL installs and build (all ABIs by default)
export BUILD_TYPE=Release
export STRIP=1
bash ./build_all.sh

Note: both scripts build all supported ABIs by default. To target only arm64-v8a:

• with PowerShell use the -ABIs parameter: -ABIs @('arm64-v8a') (example shown above).
• with the Bash script edit the ABIS=(...) array near the top of build_all.sh and keep only arm64-v8a (or set up a wrapper that exports a custom ABIS value before invoking the script). You can also control the build type and whether the Bash script prefers stripped installs via environment variables:

# choose build type (RelWithDebInfo, Release, Debug)
export BUILD_TYPE=RelWithDebInfo
# prefer stripped OpenSSL installs (set to 1 to prefer `-stripped` folders)
export STRIP=0
bash ./build_all.sh

If OPENSSL_ANDROID_INSTALL is not supplied the script will look for per-build OpenSSL installs under openssl/install/<BUILD_TYPE>-<stripped|unstripped>/<abi>/ and fall back to the legacy openssl/install/<abi>/ layout.

BuildType and Strip flags

build_all.ps1 now supports two additional options to control build type and whether installed artifacts are stripped:

• -BuildType : one of RelWithDebInfo, Release, Debug. Default is Release. The value is passed to CMake as -DCMAKE_BUILD_TYPE.
• -Strip : switch. When specified, the script will attempt to strip installed shared libraries and binaries using the NDK's llvm-strip (or strip) tool.

Install layout

• Outputs are stored under install/<BuildType>-<stripLabel>/<abi>/... where stripLabel is stripped when -Strip is used and unstripped otherwise.

Examples

# RelWithDebInfo and stripped outputs
powershell -NoProfile -ExecutionPolicy Bypass -File build_all.ps1 -NDK 'C:\path\to\android-ndk' -BuildType RelWithDebInfo -Strip

# Debug unstripped
powershell -NoProfile -ExecutionPolicy Bypass -File build_all.ps1 -NDK 'C:\path\to\android-ndk' -BuildType Debug

See build_all.ps1 for details.

Only strip existing unstripped installs

If you already have unstripped outputs (for example install\RelWithDebInfo-unstripped), you can run the script in "strip-only" mode which copies the unstripped install tree to a -stripped variant and runs the NDK llvm-strip on .so and binaries.

Requirements:

• The source folder must exist: install\<BuildType>-unstripped\.
• ANDROID_NDK_HOME or -NDK must point to an NDK with toolchains\llvm\prebuilt\<host>.

Example (copy unstripped Release -> stripped and strip):

powershell -NoProfile -ExecutionPolicy Bypass -File build_all.ps1 -BuildType Release -OnlyStrip:$true -NDK 'C:\path\to\android-ndk'

After completion the stripped outputs are available under: install\<BuildType>-stripped\<abi>\...

What the scripts do

• Configure CMake with the Android toolchain file and point OPENSSL_ROOT_DIR / libs to per-ABI OpenSSL installs.
• Build with Ninja. -- Install libcurl.so into install/<BuildType>-<stripLabel>/<abi>/lib/ then copy the resulting libcurl.so (and libssl.so/libcrypto.so if using shared OpenSSL) into ../app/src/main/jniLibs/<abi>/ so your Android project can pick them up.

Prerequisites

Windows

• Android NDK (side-by-side or bundle). Set ANDROID_NDK_HOME to the NDK root. Install via Android Studio or check out here
• CMake (>= 3.15) and Ninja: add C:\Program Files\CMake\bin and Ninja to PATH.

choco install ninja

• Visual Studio (for general build tools) — the build scripts use CMake/Ninja and the NDK clang cross‑toolchain.
• (Optional) MSYS2 / Perl / Make if you plan to build OpenSSL with the included Windows helpers.

choco install msys2

Install/update in an MSYS2 shell:

pacman -Syu
# restart MSYS2 if it asks you to, then:
pacman -S --needed base-devel make perl git

Linux / WSL / macOS

• Android NDK. Set ANDROID_NDK_HOME.
• CMake, Ninja, clang, make, perl (for OpenSSL builds).

Environment variables used by the scripts

• ANDROID_NDK_HOME — path to the Android NDK (required)
• OPENSSL_ANDROID_INSTALL or OPENSSL_ROOT_DIR — path to the OpenSSL install base. If you built OpenSSL with build helpers in this repo the outputs are organized under openssl/install/<BuildType>-<stripped|unstripped>/ so point this variable to the desired build-type folder (e.g. openssl/install/RelWithDebInfo-unstripped).
• BUILD_TYPE (bash): controls -DCMAKE_BUILD_TYPE when running build_all.sh (default: Release).
• STRIP (bash): if set to 1, the bash script will prefer -stripped OpenSSL installs when resolving the OpenSSL ABI folder (default: 0).
• CURL_VERSION (optional) — override curl version the script downloads

Notes on OpenSSL

• The build scripts will prefer per-build OpenSSL install folders: openssl/install/<BuildType>-<stripped|unstripped>/<abi>/lib with headers under .../<abi>/include.
• If those are not present, the scripts will fall back to the legacy layout openssl/install/<abi>/lib and openssl/install/<abi>/include.
• This repository includes a submodule containing prebuilt OpenSSL libraries for the supported ABIs. If you want to build your own OpenSSL libraries, see openssl-android-prebuilt-and-buildscripts.

Support / Troubleshooting

• If CMake fails to find OpenSSL, make sure OPENSSL_ROOT_DIR and the include/lib paths exist for the ABI you're building.
• On Windows prefer running the build in a Developer PowerShell with NDK/Toolchain in PATH, or use WSL/Git-Bash for the OpenSSL build steps.

License

• This folder contains OpenSSL libraries which are licensed under the OpenSSL license. Keep LICENSE/LICENSE.txt with the distributed artifacts.