Prevent zlib from being dynamically loaded

A pointer containing the dynamically loaded zlib library was not being properly cleaned up. This is picked up by our Coverity scans.

One solution to this would be to store the handle to the library alongside the function pointers to functoin within that library. Then, we can free the library whenever we call `inflateEnd` or `deflateEnd`. However, this solution ended up not being necessary.

Another solution (the one this commit implements) removes zlib from being dynamically loaded in the first place. This is possible since we already link zlib with the runtime during compilation, and so loading zlib dynamically is uncecessary.

This fixes the following Coverity issue:
```
lib/pkg_editor/src/zlib.c:119:1:
  Type: Resource leak (RESOURCE_LEAK)

lib/pkg_editor/src/zlib.c:98:3:
  1. path: Condition "zlib_interface.deflateInit_", taking false branch.
lib/pkg_editor/src/zlib.c:101:3:
  2. alloc_fn: Storage is returned from allocation function "zlib_load_library".
lib/pkg_editor/src/zlib.c:90:3:
  2.1. path: Condition "dlopen_handle", taking false branch.
lib/pkg_editor/src/zlib.c:93:3:
  2.2. alloc_fn: Storage is returned from allocation function "dlopen".
lib/pkg_editor/src/zlib.c:93:3:
  2.3. return_alloc_fn: Directly returning storage allocated by "dlopen".
lib/pkg_editor/src/zlib.c:101:3:
  3. var_assign: Assigning: "library" = storage returned from "zlib_load_library()".
lib/pkg_editor/src/zlib.c:102:3:
  4. path: Condition "library == NULL", taking false branch.
lib/pkg_editor/src/zlib.c:110:3:
  5. noescape: Resource "library" is not freed or pointed-to in "load_one_symbol".
lib/pkg_editor/src/zlib.c:39:36:
  5.1. noescape: "load_one_symbol(void *, char const *)" does not free or save its parameter "library".
lib/pkg_editor/src/zlib.c:111:3:
  6. noescape: Resource "library" is not freed or pointed-to in "load_one_symbol".
lib/pkg_editor/src/zlib.c:39:36:
  6.1. noescape: "load_one_symbol(void *, char const *)" does not free or save its parameter "library".
lib/pkg_editor/src/zlib.c:112:3:
  7. noescape: Resource "library" is not freed or pointed-to in "load_one_symbol".
lib/pkg_editor/src/zlib.c:39:36:
  7.1. noescape: "load_one_symbol(void *, char const *)" does not free or save its parameter "library".
lib/pkg_editor/src/zlib.c:113:3:
  8. noescape: Resource "library" is not freed or pointed-to in "load_one_symbol".
lib/pkg_editor/src/zlib.c:39:36:
  8.1. noescape: "load_one_symbol(void *, char const *)" does not free or save its parameter "library".
lib/pkg_editor/src/zlib.c:114:3:
  9. noescape: Resource "library" is not freed or pointed-to in "load_one_symbol".
lib/pkg_editor/src/zlib.c:39:36:
  9.1. noescape: "load_one_symbol(void *, char const *)" does not free or save its parameter "library".
lib/pkg_editor/src/zlib.c:115:3:
  10. noescape: Resource "library" is not freed or pointed-to in "load_one_symbol".
lib/pkg_editor/src/zlib.c:39:36:
  10.1. noescape: "load_one_symbol(void *, char const *)" does not free or save its parameter "library".
lib/pkg_editor/src/zlib.c:119:1:
  11. leaked_storage: Variable "library" going out of scope leaks the storage it points to.
```

Author: IlanTruanovsky

lib/pkg_editor/CMakeLists.txt

@@ -20,7 +20,6 @@ if(ZLIB_FOUND)
     target_compile_definitions(pkg_editor PRIVATE WINDOWS_ZLIB_PATH="${WINDOWS_ZLIB_DLL_PATH}")
   endif()
   target_link_libraries(pkg_editor PRIVATE ZLIB::ZLIB)
-  target_sources(pkg_editor PRIVATE src/zlib.c)
 endif()
 
 install(TARGETS pkg_editor

lib/pkg_editor/src/pkg_editor.c

@@ -39,9 +39,7 @@
 #endif
 
 #include "pkg_editor/pkg_editor.h"
-#if USE_ZLIB
-#include "zlib_interface.h"
-#endif
+#include "zlib.h"
 
 typedef struct acl_pkg_file {
   const char *fname;
@@ -1194,7 +1192,7 @@ static int append_data(const void *data, size_t size, ZInfo *z_info, FILE *of,
       int ret;
       z_info->strm.avail_out = sizeof(z_info->buffer);
       z_info->strm.next_out = z_info->buffer;
-      ret = zlib_deflate(&z_info->strm, Z_FINISH);
+      ret = deflate(&z_info->strm, Z_FINISH);
       assert(ret != Z_STREAM_ERROR);
       output_size = sizeof(z_info->buffer) - z_info->strm.avail_out;
       if (output_size > 0) {
@@ -1206,7 +1204,7 @@ static int append_data(const void *data, size_t size, ZInfo *z_info, FILE *of,
   } else {
     // Only dump the output buffer when it is full.
     do {
-      int ret = zlib_deflate(&z_info->strm, Z_NO_FLUSH);
+      int ret = deflate(&z_info->strm, Z_NO_FLUSH);
       assert(ret != Z_STREAM_ERROR);
       if (z_info->strm.avail_out == 0) {
         if (fwrite(z_info->buffer, sizeof(z_info->buffer), 1, of) != 1) {
@@ -1476,7 +1474,8 @@ int acl_pkg_pack(const char *out_file, const char **input_files_dirs) {
   z_info.strm.opaque = Z_NULL;
   z_info.strm.avail_out = sizeof(z_info.buffer);
   z_info.strm.next_out = z_info.buffer;
-  ret = zlib_deflateInit(&z_info.strm, Z_BEST_COMPRESSION);
+  ret = deflateInit_(&z_info.strm, Z_BEST_COMPRESSION, ZLIB_VERSION,
+                     (int)sizeof(z_stream));
   if (ret != Z_OK) {
     fprintf(stderr, "acl_pkg_pack: Unable to initialize zlib for writing %s\n",
             out_file);
@@ -1491,7 +1490,7 @@ int acl_pkg_pack(const char *out_file, const char **input_files_dirs) {
     if (result == PACK_END) {
       // We had a failure; stop here.
       fclose(of);
-      zlib_deflateEnd(&z_info.strm);
+      deflateEnd(&z_info.strm);
       return 0;
     }
     input_files_dirs++;
@@ -1505,10 +1504,10 @@ int acl_pkg_pack(const char *out_file, const char **input_files_dirs) {
   if (fclose(of) != 0) {
     fprintf(stderr, "acl_pkg_pack: Write of %s failed: %s\n", out_file,
             strerror(errno));
-    zlib_deflateEnd(&z_info.strm);
+    deflateEnd(&z_info.strm);
     return 0;
   }
-  zlib_deflateEnd(&z_info.strm);
+  deflateEnd(&z_info.strm);
   return 1 /* success */;
 }
 
@@ -1534,7 +1533,7 @@ static int read_data(void *data, size_t size, ZInfo *z_info, FILE *in_fd) {
       z_info->strm.next_in = z_info->buffer;
     }
     // Grab the next chunk of data from the input buffer.
-    ret = zlib_inflate(&z_info->strm, Z_NO_FLUSH);
+    ret = inflate(&z_info->strm, Z_NO_FLUSH);
     assert(ret != Z_STREAM_ERROR);
     if (ret == Z_STREAM_END) {
       // Last bit of data.
@@ -1590,7 +1589,7 @@ static int acl_pkg_unpack_buffer_or_file(const char *buffer, size_t buffer_size,
     z_info.strm.avail_in = 0;
     z_info.strm.next_in = NULL;
   }
-  ret = zlib_inflateInit(&z_info.strm);
+  ret = inflateInit_(&z_info.strm, ZLIB_VERSION, (int)sizeof(z_stream));
   if (ret != Z_OK) {
     fprintf(stderr, "%s: Unable to initialize zlib for reading from buffer\n",
             routine_name);
@@ -1611,13 +1610,13 @@ static int acl_pkg_unpack_buffer_or_file(const char *buffer, size_t buffer_size,
     acl_pkg_pack_info info;
     if (!read_data(&info, sizeof(info), &z_info, input)) {
       fprintf(stderr, "%s: Error reading from buffer\n", routine_name);
-      zlib_inflateEnd(&z_info.strm);
+      inflateEnd(&z_info.strm);
       return 0;
     }
     if (info.magic != PACK_MAGIC) {
       fprintf(stderr, "%s: Incorrect magic number read from buffer\n",
               routine_name);
-      zlib_inflateEnd(&z_info.strm);
+      inflateEnd(&z_info.strm);
       return 0;
     }
 
@@ -1630,7 +1629,7 @@ static int acl_pkg_unpack_buffer_or_file(const char *buffer, size_t buffer_size,
     if (!read_data(name, info.name_length, &z_info, input)) {
       fprintf(stderr, "%s: Error reading file name from buffer\n",
               routine_name);
-      zlib_inflateEnd(&z_info.strm);
+      inflateEnd(&z_info.strm);
       return 0;
     }
 
@@ -1656,7 +1655,7 @@ static int acl_pkg_unpack_buffer_or_file(const char *buffer, size_t buffer_size,
       if (out_file == NULL) {
         fprintf(stderr, "%s: Unable to open %s for writing: %s\n", routine_name,
                 full_name, strerror(errno));
-        zlib_inflateEnd(&z_info.strm);
+        inflateEnd(&z_info.strm);
         return 0;
       }
       if (info.file_length > 0) {
@@ -1666,14 +1665,14 @@ static int acl_pkg_unpack_buffer_or_file(const char *buffer, size_t buffer_size,
             fprintf(stderr, "%s: Error reading file data for %s from buffer\n",
                     routine_name, full_name);
             fclose(out_file);
-            zlib_inflateEnd(&z_info.strm);
+            inflateEnd(&z_info.strm);
             return 0;
           }
           if (fwrite(buf, info.file_length, 1, out_file) != 1) {
             fprintf(stderr, "%s: Failed to write to %s: %s\n", routine_name,
                     full_name, strerror(errno));
             fclose(out_file);
-            zlib_inflateEnd(&z_info.strm);
+            inflateEnd(&z_info.strm);
             return 0;
           }
         } else {
@@ -1683,23 +1682,23 @@ static int acl_pkg_unpack_buffer_or_file(const char *buffer, size_t buffer_size,
                     routine_name, full_name, strerror(errno));
             fclose(out_file);
             free(buf2);
-            zlib_inflateEnd(&z_info.strm);
+            inflateEnd(&z_info.strm);
             return PACK_END;
           }
           if (!read_data(buf2, info.file_length, &z_info, input)) {
             fprintf(stderr, "%s: Error reading file data for %s from buffer\n",
                     routine_name, full_name);
             fclose(out_file);
             free(buf2);
-            zlib_inflateEnd(&z_info.strm);
+            inflateEnd(&z_info.strm);
             return 0;
           }
           if (fwrite(buf2, info.file_length, 1, out_file) != 1) {
             fprintf(stderr, "%s: Failed to write to %s: %s\n", routine_name,
                     full_name, strerror(errno));
             fclose(out_file);
             free(buf2);
-            zlib_inflateEnd(&z_info.strm);
+            inflateEnd(&z_info.strm);
             return 0;
           }
           free(buf2);
@@ -1709,7 +1708,7 @@ static int acl_pkg_unpack_buffer_or_file(const char *buffer, size_t buffer_size,
     }
   }
 
-  zlib_inflateEnd(&z_info.strm);
+  inflateEnd(&z_info.strm);
   return 1;
 }
 
@@ -1744,22 +1743,4 @@ int acl_pkg_unpack(const char *in_file, const char *out_dir) {
   return ret;
 }
 
-#else // USE_ZLIB
-
-int acl_pkg_pack(const char *out_file, const char **input_files_dirs) {
-  // Not implemented if no ZLIB
-  return 0;
-}
-
-int acl_pkg_unpack(const char *in_file, const char *out_dir) {
-  // Not implemented if no ZLIB
-  return 0;
-}
-
-int acl_pkg_unpack_buffer(const char *buffer, size_t buffer_size,
-                          const char *out_dir) {
-  // Not implemented if no ZLIB
-  return 0;
-}
-
-#endif // USE_ZLIB
+#endif // USE_ZLIB