Re: How to calculate MD5 of huge files?
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- Subject: Re: How to calculate MD5 of huge files?
- From: Joshua Jensen <jjensen@...>
- Date: 2010年4月26日 09:33:38 -0600
----- Original Message -----
From: Luiz Henrique de Figueiredo
Date: 4/26/2010 6:12 AM
-- using LHF's previous version of lmd5, the one before it was married to openssl :D
My version of lmd5 has this useful function. It calculates the MD5 of
an entire file and does so from C code. This means the garbage
collector isn't pegged heavily during a read of a large file.
/**
**/
static int Lupdatefile(lua_State *L)
{
MD5_CTX *c=Pget(L,1);
const char *fileName=luaL_checkstring(L,2);
const size_t BLOCK_SIZE = 32768;
unsigned char* buffer;
size_t fileLen;
size_t bytesToDo;
FILE* file = fopen(fileName, "rb");
if (!file)
return 0;
buffer = malloc(BLOCK_SIZE);
fseek(file, 0, SEEK_END);
fileLen = ftell(file);
fseek(file, 0, SEEK_SET);
bytesToDo = fileLen;
while (bytesToDo > 0)
{
size_t bytesToRead = bytesToDo < BLOCK_SIZE ? bytesToDo :
BLOCK_SIZE;
fread(buffer, bytesToRead, 1, file);
bytesToDo -= bytesToRead;
MD5Update(c, buffer, bytesToRead);
}
fseek(file, 0, SEEK_SET);
fclose(file);
free(buffer);
return 0;
}
-Josh