mirror/git
1
0
Fork 0
mirror of https://github.com/git/git.git synced 2024-11-19 01:34:04 +01:00
Code
a5cd7e1620
git/sha1_file.c
Christopher Li 812666c8e6 [PATCH] introduce xmalloc and xrealloc 
Introduce xmalloc and xrealloc to die gracefully with a descriptive
message when out of memory, rather than taking a SIGSEGV. 

Signed-off-by: Christopher Li<chrislgit@chrisli.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-26 12:00:58 -07:00

416 lines
8.7 KiB
C
Raw Blame History

/*
* 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;
}
View Git Blame Copy Permalink