sha1_file.c - jrn/git - Git at Google

 /*
  * GIT - The information manager from hell
  *
  * Copyright (C) Linus Torvalds, 2005
  *
  * This handles basic git sha1 object files - packing, unpacking,
  * creation etc.
  */
 #include <stdarg.h>
 #include "cache.h"

 const char *sha1_file_directory = NULL;

 #ifndef O_NOATIME
 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
 #define O_NOATIME 01000000
 #else
 #define O_NOATIME 0
 #endif
 #endif

 static unsigned int sha1_file_open_flag = O_NOATIME;

 static unsigned hexval(char c)
 {
 	if (c >= '0' && c <= '9')
 		return c - '0';
 	if (c >= 'a' && c <= 'f')
 		return c - 'a' + 10;
 	if (c >= 'A' && c <= 'F')
 		return c - 'A' + 10;
 	return ~0;
 }

 int get_sha1_hex(const char *hex, unsigned char *sha1)
 {
 	int i;
 	for (i = 0; i < 20; i++) {
 		unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
 		if (val & ~0xff)
 			return -1;
 		*sha1++ = val;
 		hex += 2;
 	}
 	return 0;
 }

 char * sha1_to_hex(const unsigned char *sha1)
 {
 	static char buffer[50];
 	static const char hex[] = "0123456789abcdef";
 	char *buf = buffer;
 	int i;

 	for (i = 0; i < 20; i++) {
 		unsigned int val = *sha1++;
 		*buf++ = hex[val >> 4];
 		*buf++ = hex[val & 0xf];
 	}
 	return buffer;
 }

 /*
  * NOTE! This returns a statically allocated buffer, so you have to be
  * careful about using it. Do a "strdup()" if you need to save the
  * filename.
  */
 char *sha1_file_name(const unsigned char *sha1)
 {
 	int i;
 	static char *name, *base;

 	if (!base) {
 		char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
 		int len = strlen(sha1_file_directory);
 		base = xmalloc(len + 60);
 		memcpy(base, sha1_file_directory, len);
 		memset(base+len, 0, 60);
 		base[len] = '/';
 		base[len+3] = '/';
 		name = base + len + 1;
 	}
 	for (i = 0; i < 20; i++) {
 		static char hex[] = "0123456789abcdef";
 		unsigned int val = sha1[i];
 		char *pos = name + i*2 + (i > 0);
 		*pos++ = hex[val >> 4];
 		*pos = hex[val & 0xf];
 	}
 	return base;
 }

 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
 {
 	char header[100];
 	unsigned char real_sha1[20];
 	SHA_CTX c;

 	SHA1_Init(&c);
 	SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 	SHA1_Update(&c, map, size);
 	SHA1_Final(real_sha1, &c);
 	return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 }

 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 {
 	char *filename = sha1_file_name(sha1);
 	struct stat st;
 	void *map;
 	int fd;

 	fd = open(filename, O_RDONLY | sha1_file_open_flag);
 	if (fd < 0) {
 		/* See if it works without O_NOATIME */
 		switch (sha1_file_open_flag) {
 		default:
 			fd = open(filename, O_RDONLY);
 			if (fd >= 0)
 				break;
 		/* Fallthrough */
 		case 0:
 			perror(filename);
 			return NULL;
 		}

 		/* If it failed once, it will probably fail again. Stop using O_NOATIME */
 		sha1_file_open_flag = 0;
 	}
 	if (fstat(fd, &st) < 0) {
 		close(fd);
 		return NULL;
 	}
 	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 	close(fd);
 	if (-1 == (int)(long)map)
 		return NULL;
 	*size = st.st_size;
 	return map;
 }

 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 {
 	int ret, bytes;
 	z_stream stream;
 	char buffer[8192];
 	char *buf;

 	/* Get the data stream */
 	memset(&stream, 0, sizeof(stream));
 	stream.next_in = map;
 	stream.avail_in = mapsize;
 	stream.next_out = buffer;
 	stream.avail_out = sizeof(buffer);

 	inflateInit(&stream);
 	ret = inflate(&stream, 0);
 	if (ret < Z_OK)
 		return NULL;
 	if (sscanf(buffer, "%10s %lu", type, size) != 2)
 		return NULL;

 	bytes = strlen(buffer) + 1;
 	buf = xmalloc(*size);

 	memcpy(buf, buffer + bytes, stream.total_out - bytes);
 	bytes = stream.total_out - bytes;
 	if (bytes < *size && ret == Z_OK) {
 		stream.next_out = buf + bytes;
 		stream.avail_out = *size - bytes;
 		while (inflate(&stream, Z_FINISH) == Z_OK)
 			/* nothing */;
 	}
 	inflateEnd(&stream);
 	return buf;
 }

 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 {
 	unsigned long mapsize;
 	void *map, *buf;

 	map = map_sha1_file(sha1, &mapsize);
 	if (map) {
 		buf = unpack_sha1_file(map, mapsize, type, size);
 		munmap(map, mapsize);
 		return buf;
 	}
 	return NULL;
 }

 void *read_tree_with_tree_or_commit_sha1(const unsigned char *sha1,
 					 unsigned long *size,
 					 unsigned char *tree_sha1_return)
 {
 	char type[20];
 	void *buffer;
 	unsigned long isize;
 	int was_commit = 0;
 	unsigned char tree_sha1[20];

 	buffer = read_sha1_file(sha1, type, &isize);

 	/*
 	 * We might have read a commit instead of a tree, in which case
 	 * we parse out the tree_sha1 and attempt to read from there.
 	 * (buffer + 5) is because the tree sha1 is always at offset 5
 	 * in a commit record ("tree ").
 	 */
 	if (buffer &&
 	    !strcmp(type, "commit") &&
 	    !get_sha1_hex(buffer + 5, tree_sha1)) {
 		free(buffer);
 		buffer = read_sha1_file(tree_sha1, type, &isize);
 		was_commit = 1;
 	}

 	/*
 	 * Now do we have something and if so is it a tree?
 	 */
 	if (!buffer || strcmp(type, "tree")) {
 		free(buffer);
 		return NULL;
 	}

 	*size = isize;
 	if (tree_sha1_return)
 		memcpy(tree_sha1_return, was_commit ? tree_sha1 : sha1, 20);
 	return buffer;
 }

 int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 {
 	int size;
 	char *compressed;
 	z_stream stream;
 	unsigned char sha1[20];
 	SHA_CTX c;
 	char *filename;
 	char hdr[50];
 	int fd, hdrlen;

 	/* Generate the header */
 	hdrlen = sprintf(hdr, "%s %lu", type, len)+1;

 	/* Sha1.. */
 	SHA1_Init(&c);
 	SHA1_Update(&c, hdr, hdrlen);
 	SHA1_Update(&c, buf, len);
 	SHA1_Final(sha1, &c);

 	if (returnsha1)
 		memcpy(returnsha1, sha1, 20);

 	filename = sha1_file_name(sha1);
 	fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 	if (fd < 0) {
 		if (errno != EEXIST)
 			return -1;

 		/*
 		 * We might do collision checking here, but we'd need to
 		 * uncompress the old file and check it. Later.
 		 */
 		return 0;
 	}

 	/* Set it up */
 	memset(&stream, 0, sizeof(stream));
 	deflateInit(&stream, Z_BEST_COMPRESSION);
 	size = deflateBound(&stream, len+hdrlen);
 	compressed = xmalloc(size);

 	/* Compress it */
 	stream.next_out = compressed;
 	stream.avail_out = size;

 	/* First header.. */
 	stream.next_in = hdr;
 	stream.avail_in = hdrlen;
 	while (deflate(&stream, 0) == Z_OK)
 		/* nothing */

 	/* Then the data itself.. */
 	stream.next_in = buf;
 	stream.avail_in = len;
 	while (deflate(&stream, Z_FINISH) == Z_OK)
 		/* nothing */;
 	deflateEnd(&stream);
 	size = stream.total_out;

 	if (write(fd, compressed, size) != size)
 		die("unable to write file");
 	close(fd);

 	return 0;
 }

 static inline int collision_check(char *filename, void *buf, unsigned int size)
 {
 #ifdef COLLISION_CHECK
 	void *map;
 	int fd = open(filename, O_RDONLY);
 	struct stat st;
 	int cmp;

 	/* Unreadable object, or object went away? Strange. */
 	if (fd < 0)
 		return -1;

 	if (fstat(fd, &st) < 0 || size != st.st_size)
 		return -1;

 	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 	close(fd);
 	if (map == MAP_FAILED)
 		return -1;
 	cmp = memcmp(buf, map, size);
 	munmap(map, size);
 	if (cmp)
 		return -1;
 #endif
 	return 0;
 }

 int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
 {
 	char *filename = sha1_file_name(sha1);
 	int fd;

 	fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 	if (fd < 0) {
 		if (errno != EEXIST)
 			return -1;
 		if (collision_check(filename, buf, size))
 			return error("SHA1 collision detected!"
 					" This is bad, bad, BAD!\a\n");
 		return 0;
 	}
 	write(fd, buf, size);
 	close(fd);
 	return 0;
 }

 int write_sha1_from_fd(const unsigned char *sha1, int fd)
 {
 	char *filename = sha1_file_name(sha1);

 	int local;
 	z_stream stream;
 	unsigned char real_sha1[20];
 	char buf[4096];
 	char discard[4096];
 	int ret;
 	SHA_CTX c;

 	local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);

 	if (local < 0)
 		return error("Couldn't open %s\n", filename);

 	memset(&stream, 0, sizeof(stream));

 	inflateInit(&stream);

 	SHA1_Init(&c);

 	do {
 		ssize_t size;
 		size = read(fd, buf, 4096);
 		if (size <= 0) {
 			close(local);
 			unlink(filename);
 			if (!size)
 				return error("Connection closed?");
 			perror("Reading from connection");
 			return -1;
 		}
 		write(local, buf, size);
 		stream.avail_in = size;
 		stream.next_in = buf;
 		do {
 			stream.next_out = discard;
 			stream.avail_out = sizeof(discard);
 			ret = inflate(&stream, Z_SYNC_FLUSH);
 			SHA1_Update(&c, discard, sizeof(discard) -
 				    stream.avail_out);
 		} while (stream.avail_in && ret == Z_OK);

 	} while (ret == Z_OK);
 	inflateEnd(&stream);

 	close(local);
 	SHA1_Final(real_sha1, &c);
 	if (ret != Z_STREAM_END) {
 		unlink(filename);
 		return error("File %s corrupted", sha1_to_hex(sha1));
 	}
 	if (memcmp(sha1, real_sha1, 20)) {
 		unlink(filename);
 		return error("File %s has bad hash\n", sha1_to_hex(sha1));
 	}

 	return 0;
 }

 int has_sha1_file(const unsigned char *sha1)
 {
 	char *filename = sha1_file_name(sha1);
 	struct stat st;

 	if (!stat(filename, &st))
 		return 1;
 	return 0;
 }
	/*
	* GIT - The information manager from hell
	*
	* Copyright (C) Linus Torvalds, 2005
	*
	* This handles basic git sha1 object files - packing, unpacking,
	* creation etc.
	*/
	#include <stdarg.h>
	#include "cache.h"

	const char *sha1_file_directory = NULL;

	#ifndef O_NOATIME
	#if defined(__linux__) && (defined(__i386__) \|\| defined(__PPC__))
	#define O_NOATIME 01000000
	#else
	#define O_NOATIME 0
	#endif
	#endif

	static unsigned int sha1_file_open_flag = O_NOATIME;

	static unsigned hexval(char c)
	{
	if (c >= '0' && c <= '9')
	return c - '0';
	if (c >= 'a' && c <= 'f')
	return c - 'a' + 10;
	if (c >= 'A' && c <= 'F')
	return c - 'A' + 10;
	return ~0;
	}

	int get_sha1_hex(const char hex, unsigned char sha1)
	{
	int i;
	for (i = 0; i < 20; i++) {
	unsigned int val = (hexval(hex[0]) << 4) \| hexval(hex[1]);
	if (val & ~0xff)
	return -1;
	*sha1++ = val;
	hex += 2;
	}
	return 0;
	}

	char * sha1_to_hex(const unsigned char *sha1)
	{
	static char buffer[50];
	static const char hex[] = "0123456789abcdef";
	char *buf = buffer;
	int i;

	for (i = 0; i < 20; i++) {
	unsigned int val = *sha1++;
	*buf++ = hex[val >> 4];
	*buf++ = hex[val & 0xf];
	}
	return buffer;
	}

	/*
	* NOTE! This returns a statically allocated buffer, so you have to be
	* careful about using it. Do a "strdup()" if you need to save the
	* filename.
	*/
	char sha1_file_name(const unsigned char sha1)
	{
	int i;
	static char name, base;

	if (!base) {
	char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
	int len = strlen(sha1_file_directory);
	base = xmalloc(len + 60);
	memcpy(base, sha1_file_directory, len);
	memset(base+len, 0, 60);
	base[len] = '/';
	base[len+3] = '/';
	name = base + len + 1;
	}
	for (i = 0; i < 20; i++) {
	static char hex[] = "0123456789abcdef";
	unsigned int val = sha1[i];
	char pos = name + i2 + (i > 0);
	*pos++ = hex[val >> 4];
	*pos = hex[val & 0xf];
	}
	return base;
	}

	int check_sha1_signature(unsigned char sha1, void map, unsigned long size, const char *type)
	{
	char header[100];
	unsigned char real_sha1[20];
	SHA_CTX c;

	SHA1_Init(&c);
	SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
	SHA1_Update(&c, map, size);
	SHA1_Final(real_sha1, &c);
	return memcmp(sha1, real_sha1, 20) ? -1 : 0;
	}

	void map_sha1_file(const unsigned char sha1, unsigned long *size)
	{
	char *filename = sha1_file_name(sha1);
	struct stat st;
	void *map;
	int fd;

	fd = open(filename, O_RDONLY \| sha1_file_open_flag);
	if (fd < 0) {
	/* See if it works without O_NOATIME */
	switch (sha1_file_open_flag) {
	default:
	fd = open(filename, O_RDONLY);
	if (fd >= 0)
	break;
	/* Fallthrough */
	case 0:
	perror(filename);
	return NULL;
	}

	/* If it failed once, it will probably fail again. Stop using O_NOATIME */
	sha1_file_open_flag = 0;
	}
	if (fstat(fd, &st) < 0) {
	close(fd);
	return NULL;
	}
	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	close(fd);
	if (-1 == (int)(long)map)
	return NULL;
	*size = st.st_size;
	return map;
	}

	void * unpack_sha1_file(void map, unsigned long mapsize, char type, unsigned long *size)
	{
	int ret, bytes;
	z_stream stream;
	char buffer[8192];
	char *buf;

	/* Get the data stream */
	memset(&stream, 0, sizeof(stream));
	stream.next_in = map;
	stream.avail_in = mapsize;
	stream.next_out = buffer;
	stream.avail_out = sizeof(buffer);

	inflateInit(&stream);
	ret = inflate(&stream, 0);
	if (ret < Z_OK)
	return NULL;
	if (sscanf(buffer, "%10s %lu", type, size) != 2)
	return NULL;

	bytes = strlen(buffer) + 1;
	buf = xmalloc(*size);

	memcpy(buf, buffer + bytes, stream.total_out - bytes);
	bytes = stream.total_out - bytes;
	if (bytes < *size && ret == Z_OK) {
	stream.next_out = buf + bytes;
	stream.avail_out = *size - bytes;
	while (inflate(&stream, Z_FINISH) == Z_OK)
	/* nothing */;
	}
	inflateEnd(&stream);
	return buf;
	}

	void * read_sha1_file(const unsigned char sha1, char type, unsigned long *size)
	{
	unsigned long mapsize;
	void map, buf;

	map = map_sha1_file(sha1, &mapsize);
	if (map) {
	buf = unpack_sha1_file(map, mapsize, type, size);
	munmap(map, mapsize);
	return buf;
	}
	return NULL;
	}

	void read_tree_with_tree_or_commit_sha1(const unsigned char sha1,
	unsigned long *size,
	unsigned char *tree_sha1_return)
	{
	char type[20];
	void *buffer;
	unsigned long isize;
	int was_commit = 0;
	unsigned char tree_sha1[20];

	buffer = read_sha1_file(sha1, type, &isize);

	/*
	* We might have read a commit instead of a tree, in which case
	* we parse out the tree_sha1 and attempt to read from there.
	* (buffer + 5) is because the tree sha1 is always at offset 5
	* in a commit record ("tree ").
	*/
	if (buffer &&
	!strcmp(type, "commit") &&
	!get_sha1_hex(buffer + 5, tree_sha1)) {
	free(buffer);
	buffer = read_sha1_file(tree_sha1, type, &isize);
	was_commit = 1;
	}

	/*
	* Now do we have something and if so is it a tree?
	*/
	if (!buffer \|\| strcmp(type, "tree")) {
	free(buffer);
	return NULL;
	}

	*size = isize;
	if (tree_sha1_return)
	memcpy(tree_sha1_return, was_commit ? tree_sha1 : sha1, 20);
	return buffer;
	}

	int write_sha1_file(char buf, unsigned long len, const char type, unsigned char *returnsha1)
	{
	int size;
	char *compressed;
	z_stream stream;
	unsigned char sha1[20];
	SHA_CTX c;
	char *filename;
	char hdr[50];
	int fd, hdrlen;

	/* Generate the header */
	hdrlen = sprintf(hdr, "%s %lu", type, len)+1;

	/* Sha1.. */
	SHA1_Init(&c);
	SHA1_Update(&c, hdr, hdrlen);
	SHA1_Update(&c, buf, len);
	SHA1_Final(sha1, &c);

	if (returnsha1)
	memcpy(returnsha1, sha1, 20);

	filename = sha1_file_name(sha1);
	fd = open(filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
	if (fd < 0) {
	if (errno != EEXIST)
	return -1;

	/*
	* We might do collision checking here, but we'd need to
	* uncompress the old file and check it. Later.
	*/
	return 0;
	}

	/* Set it up */
	memset(&stream, 0, sizeof(stream));
	deflateInit(&stream, Z_BEST_COMPRESSION);
	size = deflateBound(&stream, len+hdrlen);
	compressed = xmalloc(size);

	/* Compress it */
	stream.next_out = compressed;
	stream.avail_out = size;

	/* First header.. */
	stream.next_in = hdr;
	stream.avail_in = hdrlen;
	while (deflate(&stream, 0) == Z_OK)
	/* nothing */

	/* Then the data itself.. */
	stream.next_in = buf;
	stream.avail_in = len;
	while (deflate(&stream, Z_FINISH) == Z_OK)
	/* nothing */;
	deflateEnd(&stream);
	size = stream.total_out;

	if (write(fd, compressed, size) != size)
	die("unable to write file");
	close(fd);

	return 0;
	}

	static inline int collision_check(char filename, void buf, unsigned int size)
	{
	#ifdef COLLISION_CHECK
	void *map;
	int fd = open(filename, O_RDONLY);
	struct stat st;
	int cmp;

	/* Unreadable object, or object went away? Strange. */
	if (fd < 0)
	return -1;

	if (fstat(fd, &st) < 0 \|\| size != st.st_size)
	return -1;

	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	close(fd);
	if (map == MAP_FAILED)
	return -1;
	cmp = memcmp(buf, map, size);
	munmap(map, size);
	if (cmp)
	return -1;
	#endif
	return 0;
	}

	int write_sha1_buffer(const unsigned char sha1, void buf, unsigned int size)
	{
	char *filename = sha1_file_name(sha1);
	int fd;

	fd = open(filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
	if (fd < 0) {
	if (errno != EEXIST)
	return -1;
	if (collision_check(filename, buf, size))
	return error("SHA1 collision detected!"
	" This is bad, bad, BAD!\a\n");
	return 0;
	}
	write(fd, buf, size);
	close(fd);
	return 0;
	}

	int write_sha1_from_fd(const unsigned char *sha1, int fd)
	{
	char *filename = sha1_file_name(sha1);

	int local;
	z_stream stream;
	unsigned char real_sha1[20];
	char buf[4096];
	char discard[4096];
	int ret;
	SHA_CTX c;

	local = open(filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);

	if (local < 0)
	return error("Couldn't open %s\n", filename);

	memset(&stream, 0, sizeof(stream));

	inflateInit(&stream);

	SHA1_Init(&c);

	do {
	ssize_t size;
	size = read(fd, buf, 4096);
	if (size <= 0) {
	close(local);
	unlink(filename);
	if (!size)
	return error("Connection closed?");
	perror("Reading from connection");
	return -1;
	}
	write(local, buf, size);
	stream.avail_in = size;
	stream.next_in = buf;
	do {
	stream.next_out = discard;
	stream.avail_out = sizeof(discard);
	ret = inflate(&stream, Z_SYNC_FLUSH);
	SHA1_Update(&c, discard, sizeof(discard) -
	stream.avail_out);
	} while (stream.avail_in && ret == Z_OK);

	} while (ret == Z_OK);
	inflateEnd(&stream);

	close(local);
	SHA1_Final(real_sha1, &c);
	if (ret != Z_STREAM_END) {
	unlink(filename);
	return error("File %s corrupted", sha1_to_hex(sha1));
	}
	if (memcmp(sha1, real_sha1, 20)) {
	unlink(filename);
	return error("File %s has bad hash\n", sha1_to_hex(sha1));
	}

	return 0;
	}

	int has_sha1_file(const unsigned char *sha1)
	{
	char *filename = sha1_file_name(sha1);
	struct stat st;

	if (!stat(filename, &st))
	return 1;
	return 0;
	}