# nghttp2_hd_inflate_hd3

## Synopsis

#include <nghttp2/nghttp2.h>

nghttp2_ssize nghttp2_hd_inflate_hd3(nghttp2_hd_inflater *inflater, nghttp2_nv *nv_out, int *inflate_flags, const uint8_t *in, size_t inlen, int in_final)

  Inflates name/value block stored in in with length inlen. This function performs decompression. For each successful emission of header name/value pair, `nghttp2_hd_inflate_flag.NGHTTP2_HD_INFLATE_EMIT` is set in *inflate_flags and name/value pair is assigned to the nv_out and the function returns. The caller must not free the members of nv_out.

  The nv_out may include pointers to the memory region in the in. The caller must retain the in while the nv_out is used.

  The application should call this function repeatedly until the `(*inflate_flags) & NGHTTP2_HD_INFLATE_FINAL` is nonzero and return value is non-negative. If that happens, all given input data (inlen bytes) are processed successfully. Then the application must call `nghttp2_hd_inflate_end_headers()` to prepare for the next header block input.

  In other words, if in_final is nonzero, and this function returns inlen, you can assert that `nghttp2_hd_inflate_final.NGHTTP2_HD_INFLATE_FINAL` is set in *inflate_flags.

  The caller can feed complete compressed header block. It also can feed it in several chunks. The caller must set in_final to nonzero if the given input is the last block of the compressed header.

  This function returns the number of bytes processed if it succeeds, or one of the following negative error codes:

  `nghttp2_error.NGHTTP2_ERR_NOMEM`

    Out of memory.

  `nghttp2_error.NGHTTP2_ERR_HEADER_COMP`

    Inflation process has failed.

  `nghttp2_error.NGHTTP2_ERR_BUFFER_ERROR`

    The header field name or value is too large.

  Example follows:

      int inflate_header_block(nghttp2_hd_inflater *hd_inflater,
                               uint8_t *in, size_t inlen, int final)
      {
          nghttp2_ssize rv;

          for(;;) {
              nghttp2_nv nv;
              int inflate_flags = 0;

              rv = nghttp2_hd_inflate_hd3(hd_inflater, &nv, &inflate_flags,
                                          in, inlen, final);

              if(rv < 0) {
                  fprintf(stderr, "inflate failed with error code %td", rv);
                  return -1;
              }

              in += rv;
              inlen -= rv;

              if(inflate_flags & NGHTTP2_HD_INFLATE_EMIT) {
                  fwrite(nv.name, nv.namelen, 1, stderr);
                  fprintf(stderr, ": ");
                  fwrite(nv.value, nv.valuelen, 1, stderr);
                  fprintf(stderr, "\n");
              }
              if(inflate_flags & NGHTTP2_HD_INFLATE_FINAL) {
                  nghttp2_hd_inflate_end_headers(hd_inflater);
                  break;
              }
              if((inflate_flags & NGHTTP2_HD_INFLATE_EMIT) == 0 &&
                 inlen == 0) {
                 break;
              }
          }

          return 0;
      }