From c38138cd78f284b261a02323e8f18a1dee87c7fa Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 26 Jun 2005 20:27:56 -0700 Subject: [PATCH] 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. --- Makefile | 4 +- csum-file.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++ csum-file.h | 17 +++++++ pack-objects.c | 66 +++++--------------------- unpack-objects.c | 13 +++-- 5 files changed, 158 insertions(+), 62 deletions(-) create mode 100644 csum-file.c create mode 100644 csum-file.h diff --git a/Makefile b/Makefile index e74b90bfe..e55d35214 100644 --- a/Makefile +++ b/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 diff --git a/csum-file.c b/csum-file.c new file mode 100644 index 000000000..98cb59ddd --- /dev/null +++ b/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; +} + + diff --git a/csum-file.h b/csum-file.h new file mode 100644 index 000000000..1086f04ca --- /dev/null +++ b/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 diff --git a/pack-objects.c b/pack-objects.c index bc8bb954b..f0c84c9a7 100644 --- a/pack-objects.c +++ b/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]; @@ -121,8 +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) diff --git a/unpack-objects.c b/unpack-objects.c index 9da3ac89a..91a71c55c 100644 --- a/unpack-objects.c +++ b/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 *)); -- 2.26.2