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/* Generic CommonDigest wrappers to match the semantics of libmd. */
#include <dispatch/dispatch.h>
#include <os/assumes.h>
#include <errno.h>
#include <fcntl.h>
#include "commoncrypto.h"
#define CHUNK_SIZE (10 * 1024 * 1024)
char *
Digest_End(CCDigestRef ctx, char *buf)
{
static const char hex[] = "0123456789abcdef";
uint8_t digest[32]; // SHA256 is the biggest
size_t i, length;
(void)os_assumes_zero(CCDigestFinal(ctx, digest));
length = CCDigestOutputSize(ctx);
os_assert(length <= sizeof(digest));
for (i = 0; i < length; i++) {
buf[i+i] = hex[digest[i] >> 4];
buf[i+i+1] = hex[digest[i] & 0x0f];
}
buf[i+i] = '\0';
return buf;
}
char *
Digest_Data(CCDigestAlg algorithm, const void *data, size_t len, char *buf)
{
CCDigestCtx ctx;
(void)os_assumes_zero(CCDigestInit(algorithm, &ctx));
(void)os_assumes_zero(CCDigestUpdate(&ctx, data, len));
return Digest_End(&ctx, buf);
}
char *
Digest_File(CCDigestAlg algorithm, const char *filename, char *buf)
{
int fd;
__block CCDigestCtx ctx;
dispatch_queue_t queue;
dispatch_semaphore_t sema;
dispatch_io_t io;
__block int s_error = 0;
__block bool eof = false;
off_t chunk_offset;
/* dispatch_io_create_with_path requires an absolute path */
fd = open(filename, O_RDONLY);
if (fd < 0) {
return NULL;
}
(void)fcntl(fd, F_NOCACHE, 1);
(void)os_assumes_zero(CCDigestInit(algorithm, &ctx));
queue = dispatch_queue_create("com.apple.mtree.io", NULL);
os_assert(queue);
sema = dispatch_semaphore_create(0);
os_assert(sema);
io = dispatch_io_create(DISPATCH_IO_STREAM, fd, queue, ^(int error) {
if (error != 0) {
s_error = error;
}
(void)close(fd);
(void)dispatch_semaphore_signal(sema);
});
os_assert(io);
for (chunk_offset = 0; eof == false && s_error == 0; chunk_offset += CHUNK_SIZE) {
dispatch_io_read(io, chunk_offset, CHUNK_SIZE, queue, ^(bool done, dispatch_data_t data, int error) {
if (data != NULL) {
(void)dispatch_data_apply(data, ^(__unused dispatch_data_t region, __unused size_t offset, const void *buffer, size_t size) {
(void)os_assumes_zero(CCDigestUpdate(&ctx, buffer, size));
return (bool)true;
});
}
if (error != 0) {
s_error = error;
}
if (done) {
eof = (data == dispatch_data_empty);
dispatch_semaphore_signal(sema);
}
});
dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
}
dispatch_release(io); // it will close on its own
(void)dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
dispatch_release(queue);
dispatch_release(sema);
if (s_error != 0) {
errno = s_error;
return NULL;
}
return Digest_End(&ctx, buf);
}
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