Add compress and decompress examples

examples/compress.c

@@ -0,0 +1,92 @@
+#if 0
+/*─────────────────────────────────────────────────────────────────╗
+│ To the extent possible under law, Justine Tunney has waived      │
+│ all copyright and related or neighboring rights to this file,    │
+│ as it is written in the following disclaimers:                   │
+│   • http://unlicense.org/                                        │
+│   • http://creativecommons.org/publicdomain/zero/1.0/            │
+╚─────────────────────────────────────────────────────────────────*/
+#endif
+#include "libc/assert.h"
+#include "libc/errno.h"
+#include "libc/log/check.h"
+#include "libc/mem/mem.h"
+#include "libc/runtime/gc.internal.h"
+#include "libc/stdio/stdio.h"
+#include "libc/str/str.h"
+#include "third_party/zlib/zlib.h"
+
+#define CHUNK 4096
+
+// clang-format off
+// make -j8 o//examples && dd if=/dev/urandom count=100 | tee a | o//examples/compress.com | o//examples/decompress.com >b && sha1sum a b
+// clang-format on
+
+int compressor(int infd, int outfd) {
+  z_stream zs;
+  int rc, flush;
+  unsigned have;
+  unsigned char *inbuf;
+  unsigned char *outbuf;
+  inbuf = gc(valloc(CHUNK));
+  outbuf = gc(valloc(CHUNK));
+  zs.zalloc = 0;
+  zs.zfree = 0;
+  zs.opaque = 0;
+  rc = deflateInit2(&zs, Z_DEFAULT_COMPRESSION, Z_DEFLATED, MAX_WBITS,
+                    DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY);
+  if (rc != Z_OK) return rc;
+  do {
+    rc = read(infd, inbuf, CHUNK);
+    if (rc == -1) {
+      deflateEnd(&zs);
+      return Z_ERRNO;
+    }
+    zs.avail_in = rc;
+    flush = !rc ? Z_FINISH : Z_SYNC_FLUSH;
+    zs.next_in = inbuf;
+    do {
+      zs.avail_out = CHUNK;
+      zs.next_out = outbuf;
+      rc = deflate(&zs, flush);
+      assert(rc != Z_STREAM_ERROR);
+      have = CHUNK - zs.avail_out;
+      if (write(outfd, outbuf, have) != have) {
+        deflateEnd(&zs);
+        return Z_ERRNO;
+      }
+    } while (!zs.avail_out);
+    assert(!zs.avail_in);
+  } while (flush != Z_FINISH);
+  assert(rc == Z_STREAM_END);
+  deflateEnd(&zs);
+  return Z_OK;
+}
+
+const char *zerr(int rc) {
+  switch (rc) {
+    case Z_ERRNO:
+      return strerror(errno);
+    case Z_STREAM_ERROR:
+      return "invalid compression level";
+    case Z_DATA_ERROR:
+      return "invalid or incomplete deflate data";
+    case Z_MEM_ERROR:
+      return "out of memory";
+    case Z_VERSION_ERROR:
+      return "zlib version mismatch!";
+    default:
+      unreachable;
+  }
+}
+
+int main(int argc, char *argv[]) {
+  int rc;
+  rc = compressor(0, 1);
+  if (rc == Z_OK) {
+    return 0;
+  } else {
+    fprintf(stderr, "error: compressor: %s\n", zerr(rc));
+    return 1;
+  }
+}