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

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.
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1 parent 9b66ec0 commit c38138cd78f284b261a02323e8f18a1dee87c7fa Linus Torvalds committed Jun 26, 2005
Showing with 158 additions and 62 deletions.
  1. +2 −2 Makefile
  2. +120 −0 csum-file.c
  3. +17 −0 csum-file.h
  4. +11 −55 pack-objects.c
  5. +8 −5 unpack-objects.c
View
4 Makefile
@@ -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
View
120 csum-file.c
@@ -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;
+}
+
+
View
17 csum-file.h
@@ -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
View
66 pack-objects.c
@@ -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];
@@ -121,16 +77,16 @@ 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;
}
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;
@@ -139,15 +95,15 @@ static void write_pack_file(void)
entry->offset = offset;
offset += write_object(f, entry);
}
- fclose(f);
+ sha1close(f);
mb = offset >> 20;
offset &= 0xfffff;
}
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)
View
13 unpack-objects.c
@@ -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 *));

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