Restore adler32, which is not deprecated

This reverts part of commit 0938aa15367caa3332d0b812b6e4514d14772e0d

Closes #27

1 files changed, 68 insertions, 0 deletions

diff --git a/client/adler32/adler32.c b/client/adler32/adler32.c
new file mode 100644
index 0000000..5dd7e4c
--- /dev/null
+++ b/client/adler32/adler32.c
@@ -0,0 +1,68 @@
+/*
+ * adler32.c (c) 2006 Bjorn Lindeijer
+ * License: GPL, v2 or later
+ *
+ * Calculates Adler-32 checksums for all files passed as argument.
+ *
+ *  Usage: adler32 [file]...
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <zlib.h>
+
+/**
+ * Calculates the Adler-32 checksum for the given file.
+ */
+unsigned long fadler32(FILE *file)
+{
+    // Obtain file size
+    fseek(file, 0, SEEK_END);
+    long fileSize = ftell(file);
+    rewind(file);
+
+    // Calculate Adler-32 checksum
+    char *buffer = (char*) malloc(fileSize);
+    fread(buffer, 1, fileSize, file);
+    unsigned long adler = adler32(0L, Z_NULL, 0);
+    adler = adler32(adler, (Bytef*) buffer, fileSize);
+    free(buffer);
+
+    return adler;
+}
+
+/**
+ * Prints out usage and exists.
+ */
+void print_usage()
+{
+    printf("Usage: adler32 [file]...\n");
+    exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+    int i;                            /**< Loops through arguments. */
+
+    if (argc == 1)
+    {
+        print_usage();
+    }
+
+    for (i = 1; i < argc; ++i)
+    {
+        FILE *file = fopen(argv[i], "r");
+
+        if (!file)
+        {
+            printf("Error while opening '%s' for reading!\n", argv[i]);
+            exit(1);
+        }
+
+        unsigned long adler = fadler32(file);
+        printf("%s %lx\n", argv[i], adler);
+        fclose(file);
+    }
+
+    return 0;
+}