Optional flags

.github/workflows/build.yml

@@ -1,5 +1,8 @@
 name: build
 
+permissions:
+  contents: read
+
 on: [push, pull_request]
 
 jobs:
@@ -72,3 +75,31 @@ jobs:
         run: |
           cd build
           ctest -VV -C "Debug" --output-on-failure
+
+  compile-flags:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: no-inflate
+            flags: -DZIP_ENABLE_INFLATE=OFF
+          - name: no-deflate
+            flags: -DZIP_ENABLE_DEFLATE=OFF
+          - name: no-symlink
+            flags: -DZIP_HAVE_SYMLINK=OFF
+          - name: no-inflate-no-deflate
+            flags: -DZIP_ENABLE_INFLATE=OFF -DZIP_ENABLE_DEFLATE=OFF
+          - name: no-inflate-no-symlink
+            flags: -DZIP_ENABLE_INFLATE=OFF -DZIP_HAVE_SYMLINK=OFF
+          - name: no-deflate-no-symlink
+            flags: -DZIP_ENABLE_DEFLATE=OFF -DZIP_HAVE_SYMLINK=OFF
+          - name: all-disabled
+            flags: -DZIP_ENABLE_INFLATE=OFF -DZIP_ENABLE_DEFLATE=OFF -DZIP_HAVE_SYMLINK=OFF
+    name: compile-flags (${{ matrix.name }})
+    steps:
+      - uses: actions/checkout@v2
+      - name: Configure
+        run: cmake -DCMAKE_DISABLE_TESTING=ON ${{ matrix.flags }} -S . -B build
+      - name: Build
+        run: cmake --build build

CMakeLists.txt

@@ -18,11 +18,15 @@ option(ZIP_STATIC_PIC "Build static zip with PIC" ON)
 option(ZIP_BUILD_DOCS "Generate API documentation with Doxygen" OFF)
 option(ZIP_BUILD_FUZZ "Build fuzz targets" OFF)
 option(ZIP_BUILD_TOOLS "Build command-line tools (zipcli, unzipcli)" OFF)
+option(ZIP_ENABLE_INFLATE "Enable decompression / extraction support" ON)
+option(ZIP_ENABLE_DEFLATE "Enable compression / archive creation support" ON)
+option(ZIP_HAVE_SYMLINK "Enable symlink support during extraction" ON)
 
 if(ZIP_ENABLE_SHARABLE_FILE_OPEN)
     add_definitions(-DZIP_ENABLE_SHARABLE_FILE_OPEN)
 endif()
 
+
 if(CMAKE_SIZEOF_VOID_P EQUAL 4)
     # large file support
     add_definitions(-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64)
@@ -50,6 +54,16 @@ target_include_directories(${PROJECT_NAME} PUBLIC
   $<INSTALL_INTERFACE:include>
 )
 
+if(NOT ZIP_ENABLE_INFLATE)
+    target_compile_definitions(${PROJECT_NAME} PUBLIC ZIP_ENABLE_INFLATE=0)
+endif()
+if(NOT ZIP_ENABLE_DEFLATE)
+    target_compile_definitions(${PROJECT_NAME} PUBLIC ZIP_ENABLE_DEFLATE=0)
+endif()
+if(NOT ZIP_HAVE_SYMLINK)
+    target_compile_definitions(${PROJECT_NAME} PUBLIC ZIP_HAVE_SYMLINK=0)
+endif()
+
 # test
 if (NOT CMAKE_DISABLE_TESTING)
     enable_testing()

README.md

@@ -189,7 +189,7 @@ zip_stream_close(zip);
 free(outbuf);
 ```
 
-* Extract a zip entry into a memory (stream API).
+* Extract a zip entry into memory (stream API).
 
 ```c
 char *buf = NULL;
@@ -225,8 +225,6 @@ struct zip_t *zip = zip_open("foo.zip", 0, 'r');
     zip_entry_close(zip);
 }
 zip_close(zip);
-
-free(buf);
 ```
 
 * List of all zip entries
@@ -756,21 +754,58 @@ data = zip.zip_stream_copy(z)
 zip.zip_close(z)
 ```
 
+### Optional features
+
+The library supports three compile-time flags to strip unused functionality and reduce binary size.
+All features are **enabled by default** -- if you just drop the source files into your project and compile, everything works as before.
+
+| Flag | Default | Effect when disabled (`=0`) |
+|---|---|---|
+| `ZIP_ENABLE_DEFLATE` | `1` | Removes compression / archive-writing APIs (`zip_entry_write`, `zip_entry_fwrite`, `zip_create`, `zip_entries_delete`, …). Write and append modes (`'w'`, `'a'`, `'d'`) return an error. |
+| `ZIP_ENABLE_INFLATE` | `1` | Removes decompression / extraction APIs (`zip_entry_read`, `zip_entry_fread`, `zip_entry_extract`, `zip_extract`, `zip_stream_extract`, …). Read mode (`'r'`) returns an error. |
+| `ZIP_HAVE_SYMLINK` | `1` (Unix/macOS), `0` (Windows) | When disabled, symlink entries are extracted as regular file copies instead of creating actual symlinks. |
+
+**With CMake:**
+
+```shell
+# Extract-only build (no compression)
+cmake .. -DZIP_ENABLE_DEFLATE=OFF
+
+# Compress-only build (no extraction)
+cmake .. -DZIP_ENABLE_INFLATE=OFF
+
+# Disable symlink support
+cmake .. -DZIP_HAVE_SYMLINK=OFF
+```
+
+**Without CMake** (compiler flags):
+
+```shell
+cc -DZIP_ENABLE_DEFLATE=0 -c zip.c
+```
+
+Or define before including the header:
+
+```c
+#define ZIP_ENABLE_DEFLATE 0
+#include "zip.h"
+```
+
 ### No ZIP64
 
-By default, opening an archive for writing with the literal mode character 'w' will enable ZIP64 output. 
-Internally the library sets a write flag when the mode equals the literal 'w':
+By default, opening an archive for writing with the literal mode character `'w'` will enable ZIP64 output.
+Internally the library sets a write flag when the mode equals the literal `'w'`:
 
-```zip/src/zip.c#L948-956
+```c
 mz_uint wflags = (mode == 'w') ? MZ_ZIP_FLAG_WRITE_ZIP64 : 0;
 ```
 
-To ensure the produced ZIP archive is _NOT ZIP64_, use the alternate mode value that selects the same semantic mode but does not compare equal to the literal 'w'. 
-The implementation accepts an alternate value in the switch labels (so the same behavior is selected), but only the literal 'w' triggers the automatic ZIP64 flag.
+To ensure the produced ZIP archive is _NOT ZIP64_, use the alternate mode value that selects the same semantic mode but does not compare equal to the literal `'w'`.
+The implementation accepts an alternate value in the switch labels (so the same behavior is selected), but only the literal `'w'` triggers the automatic ZIP64 flag.
 
 Convention:
-- Use 'w' - 64 (integer value 55) when calling zip_open, zip_stream_open, etc., to select write mode without enabling ZIP64.
-- The same pattern applies to other modes: use 'r' - 64, 'a' - 64, 'd' - 64 to pick the non-ZIP64 variants.
+- Use `'w' - 64` (integer value 55) when calling `zip_open`, `zip_stream_open`, etc., to select write mode without enabling ZIP64.
+- The same pattern applies to other modes: use `'r' - 64`, `'a' - 64`, `'d' - 64` to pick the non-ZIP64 variants.
 
 ### Check out more cool projects which use this library