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/*
* 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;
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 = malloc(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);
int fd = open(filename, O_RDONLY);
struct stat st;
void *map;
if (fd < 0) {
perror(filename);
return NULL;
}
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 (sscanf(buffer, "%10s %lu", type, size) != 2)
return NULL;
bytes = strlen(buffer) + 1;
buf = malloc(*size);
if (!buf)
return NULL;
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;
}
int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
{
int size;
char *compressed;
z_stream stream;
unsigned char sha1[20];
SHA_CTX c;
/* Sha1.. */
SHA1_Init(&c);
SHA1_Update(&c, buf, len);
SHA1_Final(sha1, &c);
/* Set it up */
memset(&stream, 0, sizeof(stream));
deflateInit(&stream, Z_BEST_COMPRESSION);
size = deflateBound(&stream, len);
compressed = malloc(size);
/* Compress it */
stream.next_in = buf;
stream.avail_in = len;
stream.next_out = compressed;
stream.avail_out = size;
while (deflate(&stream, Z_FINISH) == Z_OK)
/* nothing */;
deflateEnd(&stream);
size = stream.total_out;
if (write_sha1_buffer(sha1, compressed, size) < 0)
return -1;
if (returnsha1)
memcpy(returnsha1, sha1, 20);
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;
}
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