mercurial/bitmanipulation.h
author Anton Shestakov <av6@dwimlabs.net>
Mon, 31 Jan 2022 18:13:00 +0300
changeset 48789 ef50a62eec40
parent 48274 d86908050375
permissions -rw-r--r--
obsolete: don't use os.stat in repo.obsstore.__nonzero__ if it's static HTTP If a repo is accessed via static HTTP, then we obviously can't use os.stat() to just peek at the file size. Let's download the entire file to check its size. Yes, this feels wasteful, but: 1. If we're cloning or pulling a repo from a static HTTP server, we need the contents of the obsstore anyway. 2. Implementing statichttpvfs.stat() that uses HEAD will result in one more request to a static-only HTTP server, which is already slow. Also parsing a response to a HEAD request to construct os.stat_result is pretty hacky. There's also a question of the remote server properly supporting HEAD method and reporting at least file size. 3. Implementing statichttpvfs.stat() that uses GET is pretty much the same thing as we do here, except we can't even cache the response easily, unlike simply accessing obsstore._data, which is @propertycache'd. Importing statichttprepo locally to avoid circular import. See also: 4507bc001365 and commit message of f8f2ecdde4b5. Differential Revision: https://phab.mercurial-scm.org/D12195

#ifndef HG_BITMANIPULATION_H
#define HG_BITMANIPULATION_H

#include <string.h>

#include "compat.h"

/* Reads a 64 bit integer from big-endian bytes. Assumes that the data is long
 enough */
static inline uint64_t getbe64(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((((uint64_t)d[0]) << 56) | (((uint64_t)d[1]) << 48) |
	        (((uint64_t)d[2]) << 40) | (((uint64_t)d[3]) << 32) |
	        (((uint64_t)d[4]) << 24) | (((uint64_t)d[5]) << 16) |
	        (((uint64_t)d[6]) << 8) | (d[7]));
}

static inline uint32_t getbe32(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((((uint32_t)d[0]) << 24) | (((uint32_t)d[1]) << 16) |
	        (((uint32_t)d[2]) << 8) | (d[3]));
}

static inline int16_t getbeint16(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((d[0] << 8) | (d[1]));
}

static inline uint16_t getbeuint16(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((d[0] << 8) | (d[1]));
}

/* Writes a 64 bit integer to bytes in a big-endian format.
 Assumes that the buffer is long enough */
static inline void putbe64(uint64_t x, char *c)
{
	c[0] = (x >> 56) & 0xff;
	c[1] = (x >> 48) & 0xff;
	c[2] = (x >> 40) & 0xff;
	c[3] = (x >> 32) & 0xff;
	c[4] = (x >> 24) & 0xff;
	c[5] = (x >> 16) & 0xff;
	c[6] = (x >> 8) & 0xff;
	c[7] = (x)&0xff;
}

static inline void putbe32(uint32_t x, char *c)
{
	c[0] = (x >> 24) & 0xff;
	c[1] = (x >> 16) & 0xff;
	c[2] = (x >> 8) & 0xff;
	c[3] = (x)&0xff;
}

static inline double getbefloat64(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;
	double ret;
	int i;
	uint64_t t = 0;
	for (i = 0; i < 8; i++) {
		t = (t << 8) + d[i];
	}
	memcpy(&ret, &t, sizeof(t));
	return ret;
}

#endif