In x86-64 LineageOS Termux why `libopenconnect.so` is *not found* while present?

```bash
./openconnect
```
```
CANNOT LINK EXECUTABLE "./openconnect": library "libopenconnect.so" not found: needed by main executable
```

```bash
ldd openconnect
```
```
libopenconnect.so => not found
libz.so => /system/lib64/libz.so
libm.so => /system/lib64/libm.so
liblog.so => /system/lib64/liblog.so
libdl.so => /system/lib64/libdl.so
libc.so => /system/lib64/libc.so
ld-android.so => /system/lib64/ld-android.so
libc++.so => /system/lib64/libc++.so
```

```bash
file libopenconnect.so
```
```
libopenconnect.so: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, for Android 23, built by NDK r27c (12479018), with debug_info, not stripped
```
Yesterday 4:50pm

The error CANNOT LINK EXECUTABLE "./openconnect": library "libopenconnect.so" not found on x86-64 LineageOS Termux—despite the file libopenconnect.so being present—is a classic dynamic linker issue. Here’s a structured breakdown of the problem and how to resolve it:



Root Cause: Dynamic Linker Search Path

The dynamic linker (ld) cannot find libopenconnect.so because:

  • It is not in a standard library search path (e.g., /system/lib64, /vendor/lib64, or Termux’s $PREFIX/lib).
  • The library is likely in the current directory or a custom path, but the linker does not search the current directory by default for security reasons.

Why ldd Fails to Find It

  • ldd uses the same search paths as the dynamic linker.
  • If libopenconnect.so is in the same directory as the openconnect binary, the linker will not look there unless explicitly told to do so.

Solutions

1. Set LD_LIBRARY_PATH

Temporarily tell the linker where to find the library:

bash
export LD_LIBRARY_PATH=$(pwd):$LD_LIBRARY_PATH
./openconnect
  • This adds the current directory to the linker’s search path.
  • Note: This is temporary and only affects the current shell session.

2. Use -rpath During Compilation

If you compiled openconnect yourself, ensure the library path is embedded in the binary:

bash
gcc -o openconnect openconnect.c -lopenconnect -Wl,-rpath=$(pwd)
  • -rpath embeds the library path into the executable, so the linker will look there at runtime.

3. Copy the Library to a Standard Path

Copy libopenconnect.so to a directory in the default linker search path:

bash
cp libopenconnect.so $PREFIX/lib
  • In Termux, $PREFIX is usually /data/data/com.termux/files/usr.
  • After copying, run ldconfig (if available) to update the linker cache:
    bash
    ldconfig

4. Use Absolute Path for the Library

If you don’t want to move the library, you can symlink it to a standard path:

bash
ln -s $(pwd)/libopenconnect.so $PREFIX/lib/libopenconnect.so

5. Check Library Permissions

Ensure the library is readable:

bash
chmod +r libopenconnect.so

6. Verify Architecture Compatibility

  • Your libopenconnect.so is x86-64 (as per file output).
  • Ensure your Termux environment and the openconnect binary are also x86-64.
  • If your device is ARM64, you cannot use x86-64 libraries. You need an ARM64 build of libopenconnect.so.

7. Check for Missing Dependencies

Even if libopenconnect.so is found, it may depend on other libraries. Use:

bash
ldd libopenconnect.so
  • If other libraries are missing, you’ll need to install them (e.g., via pkg install in Termux).

Termux-Specific Notes

  • Termux uses a custom prefix ($PREFIX). Libraries should ideally be placed in $PREFIX/lib.
  • If you installed openconnect via pkg install openconnect, the package should have placed the library in the correct location. If not, reinstall it:
    bash
    pkg reinstall openconnect

Debugging Steps

  1. Check where the linker looks for libraries:

    bash
    getconf -a | grep LD_LIBRARY_PATH

    or

    bash
    env | grep LD_LIBRARY_PATH
  2. List all library paths:

    bash
    cat /etc/ld.so.conf
    ldconfig -p
  3. Run with verbose linker output:

    bash
    LD_DEBUG=libs ./openconnect
    • This will show exactly where the linker is searching for libopenconnect.so.

Summary Table

Library not in search path
Set LD_LIBRARY_PATH or use -rpath
Library in current directory
export LD_LIBRARY_PATH=$(pwd):$LD_LIBRARY_PATH
Wrong architecture
Rebuild library for ARM64 if device is ARM64
Missing dependencies
Install missing libraries via pkg install
Library not in $PREFIX/lib
Copy or symlink to $PREFIX/lib


Next Step:
Try export LD_LIBRARY_PATH=$(pwd):$LD_LIBRARY_PATH and rerun ./openconnect. If that works, you can make it permanent by adding it to your ~/.bashrc. If not, let me know the output of LD_DEBUG=libs ./openconnect for further debugging.

Yesterday 4:50pm

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