diff options
Diffstat (limited to 'src/H5FDint.c')
-rw-r--r-- | src/H5FDint.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/src/H5FDint.c b/src/H5FDint.c index 2d1fc09..9f02a25 100644 --- a/src/H5FDint.c +++ b/src/H5FDint.c @@ -103,6 +103,70 @@ H5FD_int_init_interface(void) /*------------------------------------------------------------------------- + * Function: H5FD_locate_signature + * + * Purpose: Finds the HDF5 superblock signature in a file. The + * signature can appear at address 0, or any power of two + * beginning with 512. + * + * Return: Success: SUCCEED + * Failure: FAIL + * + * Programmer: Robb Matzke + * Friday, November 7, 1997 + * + *------------------------------------------------------------------------- + */ +herr_t +H5FD_locate_signature(H5FD_t *file, const H5P_genplist_t *dxpl, haddr_t *sig_addr) +{ + haddr_t addr, eoa; + uint8_t buf[H5F_SIGNATURE_LEN]; + unsigned n, maxpow; + herr_t ret_value = SUCCEED; /* Return value */ + + FUNC_ENTER_NOAPI_NOINIT + + /* Find the least N such that 2^N is larger than the file size */ + if(HADDR_UNDEF == (addr = H5FD_get_eof(file)) || HADDR_UNDEF == (eoa = H5FD_get_eoa(file, H5FD_MEM_SUPER))) + HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to obtain EOF/EOA value") + for(maxpow = 0; addr; maxpow++) + addr >>= 1; + maxpow = MAX(maxpow, 9); + + /* + * Search for the file signature at format address zero followed by + * powers of two larger than 9. + */ + for(n = 8; n < maxpow; n++) { + addr = (8 == n) ? 0 : (haddr_t)1 << n; + if(H5FD_set_eoa(file, H5FD_MEM_SUPER, addr + H5F_SIGNATURE_LEN) < 0) + HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to set EOA value for file signature") + if(H5FD_read(file, dxpl, H5FD_MEM_SUPER, addr, (size_t)H5F_SIGNATURE_LEN, buf) < 0) + HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to read file signature") + if(!HDmemcmp(buf, H5F_SIGNATURE, (size_t)H5F_SIGNATURE_LEN)) + break; + } /* end for */ + + /* + * If the signature was not found then reset the EOA value and return + * HADDR_UNDEF. + */ + if(n >= maxpow) { + if(H5FD_set_eoa(file, H5FD_MEM_SUPER, eoa) < 0) + HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to reset EOA value") + *sig_addr = HADDR_UNDEF; + } /* end if */ + else + /* Set return value */ + *sig_addr = addr; + +done: + FUNC_LEAVE_NOAPI(ret_value) +} /* end H5FD_locate_signature() */ + + +/*------------------------------------------------------------------------- * Function: H5FD_read * * Purpose: Private version of H5FDread() |