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git/tar-tree.c

440 lines
11 KiB
C
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/*
* Copyright (c) 2005 Rene Scharfe
*/
#include <time.h>
#include "cache.h"
#define RECORDSIZE (512)
#define BLOCKSIZE (RECORDSIZE * 20)
#define TYPEFLAG_AUTO '\0'
#define TYPEFLAG_REG '0'
#define TYPEFLAG_LNK '2'
#define TYPEFLAG_DIR '5'
#define TYPEFLAG_GLOBAL_HEADER 'g'
#define TYPEFLAG_EXT_HEADER 'x'
#define EXT_HEADER_PATH 1
#define EXT_HEADER_LINKPATH 2
static const char *tar_tree_usage = "git-tar-tree <key> [basedir]";
static char block[BLOCKSIZE];
static unsigned long offset;
static const char *basedir;
static time_t archive_time;
struct path_prefix {
struct path_prefix *prev;
const char *name;
};
/* tries hard to write, either succeeds or dies in the attempt */
static void reliable_write(void *buf, unsigned long size)
{
while (size > 0) {
long ret = write(1, buf, size);
if (ret < 0) {
if (errno == EAGAIN)
continue;
if (errno == EPIPE)
exit(0);
die("git-tar-tree: %s", strerror(errno));
} else if (!ret) {
die("git-tar-tree: disk full?");
}
size -= ret;
buf += ret;
}
}
/* writes out the whole block, but only if it is full */
static void write_if_needed(void)
{
if (offset == BLOCKSIZE) {
reliable_write(block, BLOCKSIZE);
offset = 0;
}
}
/* acquire the next record from the buffer; user must call write_if_needed() */
static char *get_record(void)
{
char *p = block + offset;
memset(p, 0, RECORDSIZE);
offset += RECORDSIZE;
return p;
}
/*
* The end of tar archives is marked by 1024 nul bytes and after that
* follows the rest of the block (if any).
*/
static void write_trailer(void)
{
get_record();
write_if_needed();
get_record();
write_if_needed();
while (offset) {
get_record();
write_if_needed();
}
}
/*
* queues up writes, so that all our write(2) calls write exactly one
* full block; pads writes to RECORDSIZE
*/
static void write_blocked(void *buf, unsigned long size)
{
unsigned long tail;
if (offset) {
unsigned long chunk = BLOCKSIZE - offset;
if (size < chunk)
chunk = size;
memcpy(block + offset, buf, chunk);
size -= chunk;
offset += chunk;
buf += chunk;
write_if_needed();
}
while (size >= BLOCKSIZE) {
reliable_write(buf, BLOCKSIZE);
size -= BLOCKSIZE;
buf += BLOCKSIZE;
}
if (size) {
memcpy(block + offset, buf, size);
buf += size;
offset += size;
}
tail = offset % RECORDSIZE;
if (tail) {
memset(block + offset, 0, RECORDSIZE - tail);
offset += RECORDSIZE - tail;
}
write_if_needed();
}
static void append_string(char **p, const char *s)
{
unsigned int len = strlen(s);
memcpy(*p, s, len);
*p += len;
}
static void append_char(char **p, char c)
{
**p = c;
*p += 1;
}
static void append_path_prefix(char **buffer, struct path_prefix *prefix)
{
if (!prefix)
return;
append_path_prefix(buffer, prefix->prev);
append_string(buffer, prefix->name);
append_char(buffer, '/');
}
static unsigned int path_prefix_len(struct path_prefix *prefix)
{
if (!prefix)
return 0;
return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
}
static void append_path(char **p, int is_dir, const char *basepath,
struct path_prefix *prefix, const char *path)
{
if (basepath) {
append_string(p, basepath);
append_char(p, '/');
}
append_path_prefix(p, prefix);
append_string(p, path);
if (is_dir)
append_char(p, '/');
}
static unsigned int path_len(int is_dir, const char *basepath,
struct path_prefix *prefix, const char *path)
{
unsigned int len = 0;
if (basepath)
len += strlen(basepath) + 1;
len += path_prefix_len(prefix) + strlen(path);
if (is_dir)
len++;
return len;
}
static void append_extended_header_prefix(char **p, unsigned int size,
const char *keyword)
{
int len = sprintf(*p, "%u %s=", size, keyword);
*p += len;
}
static unsigned int extended_header_len(const char *keyword,
unsigned int valuelen)
{
/* "%u %s=%s\n" */
unsigned int len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
if (len > 9)
len++;
if (len > 99)
len++;
return len;
}
static void append_extended_header(char **p, const char *keyword,
const char *value, unsigned int len)
{
unsigned int size = extended_header_len(keyword, len);
append_extended_header_prefix(p, size, keyword);
memcpy(*p, value, len);
*p += len;
append_char(p, '\n');
}
static void write_header(const unsigned char *, char, const char *, struct path_prefix *,
const char *, unsigned int, void *, unsigned long);
/* stores a pax extended header directly in the block buffer */
static void write_extended_header(const char *headerfilename, int is_dir,
unsigned int flags, const char *basepath,
struct path_prefix *prefix,
const char *path, unsigned int namelen,
void *content, unsigned int contentsize)
{
char *buffer, *p;
unsigned int pathlen, size, linkpathlen = 0;
size = pathlen = extended_header_len("path", namelen);
if (flags & EXT_HEADER_LINKPATH) {
linkpathlen = extended_header_len("linkpath", contentsize);
size += linkpathlen;
}
write_header(NULL, TYPEFLAG_EXT_HEADER, NULL, NULL, headerfilename,
0100600, NULL, size);
buffer = p = malloc(size);
if (!buffer)
die("git-tar-tree: %s", strerror(errno));
append_extended_header_prefix(&p, pathlen, "path");
append_path(&p, is_dir, basepath, prefix, path);
append_char(&p, '\n');
if (flags & EXT_HEADER_LINKPATH)
append_extended_header(&p, "linkpath", content, contentsize);
write_blocked(buffer, size);
free(buffer);
}
static void write_global_extended_header(const unsigned char *sha1)
{
char *p;
unsigned int size;
size = extended_header_len("comment", 40);
write_header(NULL, TYPEFLAG_GLOBAL_HEADER, NULL, NULL,
"pax_global_header", 0100600, NULL, size);
p = get_record();
append_extended_header(&p, "comment", sha1_to_hex(sha1), 40);
write_if_needed();
}
/* stores a ustar header directly in the block buffer */
static void write_header(const unsigned char *sha1, char typeflag, const char *basepath,
struct path_prefix *prefix, const char *path,
unsigned int mode, void *buffer, unsigned long size)
{
unsigned int namelen;
char *header = NULL;
unsigned int checksum = 0;
int i;
unsigned int ext_header = 0;
if (typeflag == TYPEFLAG_AUTO) {
if (S_ISDIR(mode))
typeflag = TYPEFLAG_DIR;
else if (S_ISLNK(mode))
typeflag = TYPEFLAG_LNK;
else
typeflag = TYPEFLAG_REG;
}
namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
if (namelen > 100)
ext_header |= EXT_HEADER_PATH;
if (typeflag == TYPEFLAG_LNK && size > 100)
ext_header |= EXT_HEADER_LINKPATH;
/* the extended header must be written before the normal one */
if (ext_header) {
char headerfilename[51];
sprintf(headerfilename, "%s.paxheader", sha1_to_hex(sha1));
write_extended_header(headerfilename, S_ISDIR(mode),
ext_header, basepath, prefix, path,
namelen, buffer, size);
}
header = get_record();
if (ext_header) {
sprintf(header, "%s.data", sha1_to_hex(sha1));
} else {
char *p = header;
append_path(&p, S_ISDIR(mode), basepath, prefix, path);
}
if (typeflag == TYPEFLAG_LNK) {
if (ext_header & EXT_HEADER_LINKPATH) {
sprintf(&header[157], "see %s.paxheader",
sha1_to_hex(sha1));
} else {
if (buffer)
strncpy(&header[157], buffer, size);
}
}
if (S_ISDIR(mode))
mode |= 0755; /* GIT doesn't store permissions of dirs */
if (S_ISLNK(mode))
mode |= 0777; /* ... nor of symlinks */
sprintf(&header[100], "%07o", mode & 07777);
/* XXX: should we provide more meaningful info here? */
sprintf(&header[108], "%07o", 0); /* uid */
sprintf(&header[116], "%07o", 0); /* gid */
strncpy(&header[265], "git", 31); /* uname */
strncpy(&header[297], "git", 31); /* gname */
if (S_ISDIR(mode) || S_ISLNK(mode))
size = 0;
sprintf(&header[124], "%011lo", size);
sprintf(&header[136], "%011lo", archive_time);
header[156] = typeflag;
memcpy(&header[257], "ustar", 6);
memcpy(&header[263], "00", 2);
printf(&header[329], "%07o", 0); /* devmajor */
printf(&header[337], "%07o", 0); /* devminor */
memset(&header[148], ' ', 8);
for (i = 0; i < RECORDSIZE; i++)
checksum += header[i];
sprintf(&header[148], "%07o", checksum & 0x1fffff);
write_if_needed();
}
static void traverse_tree(void *buffer, unsigned long size,
struct path_prefix *prefix)
{
struct path_prefix this_prefix;
this_prefix.prev = prefix;
while (size) {
int namelen = strlen(buffer)+1;
void *eltbuf;
char elttype[20];
unsigned long eltsize;
unsigned char *sha1 = buffer + namelen;
char *path = strchr(buffer, ' ') + 1;
unsigned int mode;
if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1)
die("corrupt 'tree' file");
buffer = sha1 + 20;
size -= namelen + 20;
eltbuf = read_sha1_file(sha1, elttype, &eltsize);
if (!eltbuf)
die("cannot read %s", sha1_to_hex(sha1));
write_header(sha1, TYPEFLAG_AUTO, basedir, prefix, path,
mode, eltbuf, eltsize);
if (!strcmp(elttype, "tree")) {
this_prefix.name = path;
traverse_tree(eltbuf, eltsize, &this_prefix);
} else if (!strcmp(elttype, "blob") && !S_ISLNK(mode)) {
write_blocked(eltbuf, eltsize);
}
free(eltbuf);
}
}
/* get commit time from committer line of commit object */
static time_t commit_time(void * buffer, unsigned long size)
{
time_t result = 0;
char *p = buffer;
while (size > 0) {
char *endp = memchr(p, '\n', size);
if (!endp || endp == p)
break;
*endp = '\0';
if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
char *nump = strrchr(p, '>');
if (!nump)
break;
nump++;
result = strtoul(nump, &endp, 10);
if (*endp != ' ')
result = 0;
break;
}
size -= endp - p - 1;
p = endp + 1;
}
return result;
}
int main(int argc, char **argv)
{
unsigned char sha1[20];
unsigned char commit_sha1[20];
void *buffer;
unsigned long size;
switch (argc) {
case 3:
basedir = argv[2];
/* FALLTHROUGH */
case 2:
if (get_sha1(argv[1], sha1) < 0)
usage(tar_tree_usage);
break;
default:
usage(tar_tree_usage);
}
buffer = read_object_with_reference(sha1, "commit", &size, commit_sha1);
if (buffer) {
write_global_extended_header(commit_sha1);
archive_time = commit_time(buffer, size);
free(buffer);
}
buffer = read_object_with_reference(sha1, "tree", &size, NULL);
if (!buffer)
die("not a reference to a tag, commit or tree object: %s",
sha1_to_hex(sha1));
if (!archive_time)
archive_time = time(NULL);
if (basedir)
write_header((unsigned char *)"0", TYPEFLAG_DIR, NULL, NULL,
basedir, 040755, NULL, 0);
traverse_tree(buffer, size, NULL);
free(buffer);
write_trailer();
return 0;
}
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