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git-pack-objects: write the pack files with a SHA1 csum

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We want to be able to check their integrity later, and putting the
sha1-sum of the contents at the end is a good thing.  The writing
routines are generic, so we could try to re-use them for the index file,
instead of having the same logic duplicated.

Update unpack-objects to know about the extra 20 bytes at the end
of the index.
This commit is contained in:
Linus Torvalds 2005-06-26 20:27:56 -07:00
parent 9b66ec0474
commit c38138cd78
5 changed files with 158 additions and 62 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Makefile
View File

@ -45,9 +45,9 @@ install: $(PROG) $(SCRIPTS)
LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o \
tag.o delta.o date.o index.o diff-delta.o patch-delta.o entry.o \
epoch.o refs.o
epoch.o refs.o csum-file.o
LIB_FILE=libgit.a
LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h epoch.h
LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h epoch.h csum-file.h
LIB_H += strbuf.h
LIB_OBJS += strbuf.o

120
csum-file.c Normal file
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@ -0,0 +1,120 @@
/*
* csum-file.c
*
* Copyright (C) 2005 Linus Torvalds
*
* Simple file write infrastructure for writing SHA1-summed
* files. Useful when you write a file that you want to be
* able to verify hasn't been messed with afterwards.
*/
#include "cache.h"
#include "csum-file.h"
static int sha1flush(struct sha1file *f, unsigned int count)
{
void *buf = f->buffer;
for (;;) {
int ret = write(f->fd, buf, count);
if (ret > 0) {
buf += ret;
count -= ret;
if (count)
continue;
return 0;
}
if (!ret)
die("sha1 file write error. Out of diskspace");
if (errno == EAGAIN || errno == EINTR)
continue;
die("sha1 file write error (%s)", strerror(errno));
}
}
int sha1close(struct sha1file *f)
{
unsigned offset = f->offset;
if (offset) {
SHA1_Update(&f->ctx, f->buffer, offset);
sha1flush(f, offset);
}
SHA1_Final(f->buffer, &f->ctx);
sha1flush(f, 20);
return 0;
}
int sha1write(struct sha1file *f, void *buf, unsigned int count)
{
while (count) {
unsigned offset = f->offset;
unsigned left = sizeof(f->buffer) - offset;
unsigned nr = count > left ? left : count;
memcpy(f->buffer + offset, buf, nr);
count -= nr;
offset += nr;
left -= nr;
if (!left) {
SHA1_Update(&f->ctx, f->buffer, offset);
sha1flush(f, offset);
offset = 0;
}
f->offset = offset;
}
return 0;
}
struct sha1file *sha1create(const char *fmt, ...)
{
static char filename[PATH_MAX];
struct sha1file *f;
unsigned len;
va_list arg;
int fd;
va_start(arg, fmt);
len = vsnprintf(filename, PATH_MAX, fmt, arg);
va_end(arg);
if (len >= PATH_MAX)
die("you wascally wabbit, you");
fd = open(filename, O_CREAT | O_EXCL | O_WRONLY, 0644);
if (fd < 0)
die("unable to open %s (%s)", filename, strerror(errno));
f = xmalloc(sizeof(*f));
f->fd = fd;
f->error = 0;
f->offset = 0;
SHA1_Init(&f->ctx);
return f;
}
int sha1write_compressed(struct sha1file *f, void *in, unsigned int size)
{
z_stream stream;
unsigned long maxsize;
void *out;
memset(&stream, 0, sizeof(stream));
deflateInit(&stream, Z_DEFAULT_COMPRESSION);
maxsize = deflateBound(&stream, size);
out = xmalloc(maxsize);
/* Compress it */
stream.next_in = in;
stream.avail_in = size;
stream.next_out = out;
stream.avail_out = maxsize;
while (deflate(&stream, Z_FINISH) == Z_OK)
/* nothing */;
deflateEnd(&stream);
size = stream.total_out;
sha1write(f, out, size);
free(out);
return size;
}

17
csum-file.h Normal file
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@ -0,0 +1,17 @@
#ifndef CSUM_FILE_H
#define CSUM_FILE_H
/* A SHA1-protected file */
struct sha1file {
int fd, error;
unsigned long offset;
SHA_CTX ctx;
unsigned char buffer[8192];
};
extern struct sha1file *sha1create(const char *fmt, ...);
extern int sha1close(struct sha1file *);
extern int sha1write(struct sha1file *, void *, unsigned int);
extern int sha1write_compressed(struct sha1file *, void *, unsigned int);
#endif

66
pack-objects.c
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@ -2,6 +2,7 @@
#include "cache.h"
#include "object.h"
#include "delta.h"
#include "csum-file.h"
static const char pack_usage[] = "git-pack-objects [--window=N] [--depth=N] base-name < object-list";
@ -29,51 +30,6 @@ static struct object_entry *objects = NULL;
static int nr_objects = 0, nr_alloc = 0;
static const char *base_name;
struct myfile {
int fd;
unsigned long chars;
unsigned char buffer[8192];
};
static FILE *create_file(const char *suffix)
{
static char filename[PATH_MAX];
unsigned len;
len = snprintf(filename, PATH_MAX, "%s.%s", base_name, suffix);
if (len >= PATH_MAX)
die("you wascally wabbit, you");
return fopen(filename, "w");
}
static unsigned long fwrite_compressed(void *in, unsigned long size, FILE *f)
{
z_stream stream;
unsigned long maxsize;
void *out;
memset(&stream, 0, sizeof(stream));
deflateInit(&stream, Z_DEFAULT_COMPRESSION);
maxsize = deflateBound(&stream, size);
out = xmalloc(maxsize);
/* Compress it */
stream.next_in = in;
stream.avail_in = size;
stream.next_out = out;
stream.avail_out = maxsize;
while (deflate(&stream, Z_FINISH) == Z_OK)
/* nothing */;
deflateEnd(&stream);
size = stream.total_out;
fwrite(out, size, 1, f);
free(out);
return size;
}
static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
{
unsigned long othersize, delta_size;
@ -92,7 +48,7 @@ static void *delta_against(void *buf, unsigned long size, struct object_entry *e
return delta_buf;
}
static unsigned long write_object(FILE *f, struct object_entry *entry)
static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
{
unsigned long size;
char type[10];
@ -121,8 +77,8 @@ static unsigned long write_object(FILE *f, struct object_entry *entry)
}
datalen = htonl(size);
memcpy(header+1, &datalen, 4);
fwrite(header, hdrlen, 1, f);
datalen = fwrite_compressed(buf, size, f);
sha1write(f, header, hdrlen);
datalen = sha1write_compressed(f, buf, size);
free(buf);
return hdrlen + datalen;
}
@ -130,7 +86,7 @@ static unsigned long write_object(FILE *f, struct object_entry *entry)
static void write_pack_file(void)
{
int i;
FILE *f = create_file("pack");
struct sha1file *f = sha1create("%s.%s", base_name, "pack");
unsigned long offset = 0;
unsigned long mb;
@ -139,7 +95,7 @@ static void write_pack_file(void)
entry->offset = offset;
offset += write_object(f, entry);
}
fclose(f);
sha1close(f);
mb = offset >> 20;
offset &= 0xfffff;
}
@ -147,7 +103,7 @@ static void write_pack_file(void)
static void write_index_file(void)
{
int i;
FILE *f = create_file("idx");
struct sha1file *f = sha1create("%s.%s", base_name, "idx");
struct object_entry **list = sorted_by_sha;
struct object_entry **last = list + nr_objects;
unsigned int array[256];
@ -168,7 +124,7 @@ static void write_index_file(void)
array[i] = htonl(next - sorted_by_sha);
list = next;
}
fwrite(array, 256, sizeof(int), f);
sha1write(f, array, 256 * sizeof(int));
/*
* Write the actual SHA1 entries..
@ -177,10 +133,10 @@ static void write_index_file(void)
for (i = 0; i < nr_objects; i++) {
struct object_entry *entry = *list++;
unsigned int offset = htonl(entry->offset);
fwrite(&offset, 4, 1, f);
fwrite(entry->sha1, 20, 1, f);
sha1write(f, &offset, 4);
sha1write(f, entry->sha1, 20);
}
fclose(f);
sha1close(f);
}
static void add_object_entry(unsigned char *sha1, unsigned int hash)

13
unpack-objects.c
View File

@ -61,7 +61,7 @@ static int check_index(void)
unsigned int nr;
int i;
if (index_size < 4*256)
if (index_size < 4*256 + 20)
return error("index file too small");
nr = 0;
for (i = 0; i < 256; i++) {
@ -70,11 +70,14 @@ static int check_index(void)
return error("non-monotonic index");
nr = n;
}
if (index_size != 4*256 + nr * 24) {
printf("index_size=%lu, expected %u (%u)\n",
index_size, 4*256 + nr * 24, nr);
/*
* Total size:
* - 256 index entries 4 bytes each
* - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
* - 20-byte SHA1 file checksum
*/
if (index_size != 4*256 + nr * 24 + 20)
return error("wrong index file size");
}
nr_entries = nr;
pack_list = xmalloc(nr * sizeof(struct pack_entry *));