Cygwin: option to convert symlinks to hardlinks

3 files changed, 66 insertions, 9 deletions

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 509f0b4..b30d245 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -15,6 +15,7 @@ jobs:
       matrix:
         platform: [x86, x64]
         cygwin: [0, 1]
+        hardlinks: [0, 1]
         os: [ubuntu-18.04, windows-2019]
 
         include:
@@ -27,10 +28,12 @@ jobs:
           # This action is not suitable for Windows hosts, use setup-mingw for
           # that.
           - {os: windows-2019, cygwin: 0}
+          # Only test hardlinks on Cygwin.
+          - {cygwin: 0, hardlinks: 1}
 
     runs-on: '${{ matrix.os }}'
 
-    name: '${{ matrix.name }} / ${{ matrix.platform }}'
+    name: '${{ matrix.name }} / ${{ matrix.platform }} / Hardlinks: ${{ matrix.hardlinks }}'
 
     defaults:
       run:
@@ -56,6 +59,7 @@ jobs:
           platform: '${{ matrix.platform }}'
           cygwin: '${{ matrix.cygwin }}'
           cc: 1
+          hardlinks: '${{ matrix.hardlinks }}'
 
       - name: Build foo.exe
         run: |
@@ -68,6 +72,15 @@ jobs:
               $flags += '-lpthread'
           }
           g++ $flags
+        if: '!matrix.cygwin || matrix.hardlinks'
+
+      - name: Build foo.exe on Cygwin
+        run: |
+          $cwd = cygpath.exe -ua (Get-Location)
+          $arch = if ('${{ matrix.platform }}' -eq 'x64') { '-m64' } else { '-m32' }
+          $cmd = printf.exe -- 'cd %q && g++ %q -std=c++14 -o foo foo.cpp' $cwd $arch
+          bash.exe --login -o errexit -c $cmd
+        if: matrix.cygwin && !matrix.hardlinks
 
       - name: Run foo.exe
         run: |
@@ -88,9 +101,22 @@ jobs:
       # Is this really the most stable piece of `gcc --version` output?
       - name: Check cc/c++
         run: |
+          echo (Get-Command cc).Path
           $cc = & cc --version
           echo $cc
           $($cc | Select-String -Pattern "This is free software; see the source for copying conditions." -SimpleMatch -Quiet) -or $(throw "Unexpected `cc --version` output")
+          echo (Get-Command c++).Path
           $cxx = & c++ --version
           echo $cxx
           $($cxx | Select-String -Pattern "This is free software; see the source for copying conditions." -SimpleMatch -Quiet) -or $(throw "Unexpected `c++ --version` output")
+        if: '!matrix.cygwin || matrix.hardlinks'
+
+      - name: Check cc/c++ on Cygwin
+        run: |
+          $cc = bash.exe --login -o errexit -c 'cc --version'
+          echo $cc
+          $($cc | Select-String -Pattern "This is free software; see the source for copying conditions." -SimpleMatch -Quiet) -or $(throw "Unexpected `cc --version` output")
+          $cxx = bash.exe --login -o errexit -c 'c++ --version'
+          echo $cxx
+          $($cxx | Select-String -Pattern "This is free software; see the source for copying conditions." -SimpleMatch -Quiet) -or $(throw "Unexpected `c++ --version` output")
+        if: matrix.cygwin && !matrix.hardlinks
diff --git a/README.md b/README.md
index 882b4be..8cb7796 100644
--- a/README.md
+++ b/README.md
@@ -30,14 +30,16 @@ Disable this by setting the `cc` parameter to `0`.
 API
 ---
 
-| Input    | Value   | Default | Description
-| -------- | ------- | ------- | -----------
-| platform | x64     | Yes     | Install the x86_64 toolchain.
-|          | *Other* | No      | Install the i686 toolchain.
-| cygwin   | 1       | No      | Install Cygwin packages.
-|          | *Other* | Yes     | Install native binaries.
-| cc       | 1       | Yes     | Set up `cc`/`c++` executables.
-|          | *Other* | No      | Don't set up `cc`/`c++`.
+| Input     | Value   | Default | Description
+| --------- | ------- | ------- | -----------
+| platform  | x64     | Yes     | Install the x86_64 toolchain.
+|           | *Other* | No      | Install the i686 toolchain.
+| cygwin    | 1       | No      | Install Cygwin packages.
+|           | *Other* | Yes     | Install native binaries.
+| cc        | 1       | Yes     | Set up `cc`/`c++` executables.
+|           | *Other* | No      | Don't set up `cc`/`c++`.
+| hardlinks | *Other* | Yes     | Cygwin: don't convert any symlinks.
+|           | 1       | No      | Cygwin: convert symlinks in /usr/bin to hardlinks.
 
 License
 -------
diff --git a/action.yml b/action.yml
index ec7170c..acc886e 100644
--- a/action.yml
+++ b/action.yml
@@ -14,6 +14,10 @@ inputs:
     description: Set up cc/c++ executables
     required: false
     default: 1
+  hardlinks:
+    description: On Cygwin, replace executable symlinks with hardlinks
+    required: false
+    default: 0
 
 runs:
   using: composite
@@ -120,6 +124,31 @@ runs:
         }
       shell: pwsh
 
+    - run: |
+        New-Variable cygwin_host -Value ('${{ inputs.cygwin }}' -eq '1') -Option Constant
+        New-Variable hardlinks -Value ('${{ inputs.hardlinks }}' -eq '1') -Option Constant
+
+        if ($cygwin_host -and $hardlinks) {
+            echo @'
+        while IFS= read -d '' -r link_path; do
+            dest_path="$( readlink --canonicalize-existing -- "$link_path" )"
+            dest_ext=".${dest_path##*.}"
+            [ "$dest_ext" == ".$dest_path" ] && dest_ext=
+            link_ext=".${link_path##*.}"
+            [ "$link_ext" == ".$link_path" ] && link_ext=
+            echo "Removing symlink $link_path" && rm -f -- "$link_path"
+            [ "$link_ext" != "$dest_ext" ] && echo "${PATHEXT//\;/
+        }" | grep -q --ignore-case --line-regexp -F -- "$dest_ext" && link_path="$link_path$dest_ext"
+            echo "Creating hardlink $link_path -> $dest_path" && ln -- "$dest_path" "$link_path"
+        done < <( find /usr/local/bin /usr/bin \
+                       -type l '-(' \
+                       -path /usr/local/bin/cc -o \
+                       -path /usr/local/bin/c++ \
+                       '-)' -print0 )
+        '@ | & bash.exe --login -o errexit -o nounset -o pipefail -o igncr
+        }
+      shell: pwsh
+
 branding:
   icon: star
   color: green