Finally getting stuff to work again, NEXRAD Level II data needs to be

[grits] / opt / dec.c

diff --git a/opt/dec.c b/opt/dec.c
new file mode 100644 (file)
index 0000000..6126249
--- /dev/null
+++ b/opt/dec.c
@@ -0,0 +1,95 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <err.h>
+#include <arpa/inet.h>
+#include <bzlib.h>
+
+#define debug(...) fprintf(stderr, __VA_ARGS__);
+
+char *bunzip2(char *input, int input_len, int *output_len)
+{
+       bz_stream *stream = calloc(1, sizeof(bz_stream));
+
+       switch (BZ2_bzDecompressInit(stream, 0, 0)) {
+       case BZ_CONFIG_ERROR: err(1, "the library has been mis-compiled");
+       case BZ_PARAM_ERROR:  err(1, "Parameter error");
+       case BZ_MEM_ERROR:    err(1, "insufficient memory is available");
+       //case BZ_OK:           debug("success\n"); break;
+       //default:              debug("unknown\n"); break;
+       }
+
+       int   status;
+       int   output_size = 512;
+       char *output      = NULL;
+
+       do {
+               stream->next_in   = input       + stream->total_in_lo32;
+               stream->avail_in  = input_len   - stream->total_in_lo32;
+               output_size *= 2;
+               output       = realloc(output, output_size);
+               //debug("alloc %d\n", output_size);
+               stream->next_out  = output      + stream->total_out_lo32;
+               stream->avail_out = output_size - stream->total_out_lo32;
+               //debug("decompressing..\n"
+               //      "  next_in   = %p\n"
+               //      "  avail_in  = %u\n"
+               //      "  next_out  = %p\n"
+               //      "  avail_out = %u\n",
+               //      stream->next_in,
+               //      stream->avail_in,
+               //      stream->next_out,
+               //      stream->avail_out);
+       } while ((status = BZ2_bzDecompress(stream)) == BZ_OK && output_size < 1024*1024);
+
+       // debug("done with status %d = %d\n", status, BZ_STREAM_END);
+
+       *output_len = stream->total_out_lo32;
+       BZ2_bzDecompressEnd(stream);
+       return output;
+}
+
+int main(int argc, char **argv)
+{
+       if (argc != 3) {
+               printf("usage: ./dec <input> <output>\n");
+               return 0;
+       }
+
+       FILE *input  = fopen(argv[1], "r");
+       FILE *output = fopen(argv[2], "w+");
+       if (!input)  err(1, "error opening input");
+       if (!output) err(1, "error opening output");
+
+       int st;
+       int size = 0;
+       char *buf = malloc(24);
+
+       /* Clear header */
+       //debug("reading header\n");
+       fread (buf, 1, 24, input);
+       fwrite(buf, 1, 24, output);
+
+       //debug("reading body\n");
+       while ((st = fread(&size, 1, 4, input))) {
+               //debug("read %u bytes\n", st);
+               //fwrite(&size, 1, 4, output); // DEBUG
+               size = abs(ntohl(size));
+               if (size < 0)
+                       return 0;
+               //debug("size = %x\n", size);
+               if (size > 10*1024*1024)
+                       err(1, "sanity check failed, buf is to big: %d", size);
+               buf = realloc(buf, size);
+               fread (buf, 1, size, input);
+               //fwrite(buf, 1, size, output); // DEBUG
+
+               int dec_len;
+               char *dec = bunzip2(buf, size, &dec_len);
+               // debug("decompressed %u bytes\n", dec_len);
+               fwrite(dec, 1, dec_len, output);
+               free(dec);
+       }
+
+       return 0;
+}