git/archive-tar.c
René Scharfe f08b3b0e2e Set default "tar" umask to 002 and owner.group to root.root
In order to make the generated tar files more friendly to users who
extract them as root using GNU tar and its implied -p option, change
the default umask to 002 and change the owner name and group name to
root.  This ensures that a) the extracted files and directories are
not world-writable and b) that they belong to user and group root.

Before they would have been assigned to a user and/or group named
git if it existed.  This also answers the question in the removed
comment: uid=0, gid=0, uname=root, gname=root is exactly what we
want.

Normal users who let tar apply their umask while extracting are
only affected if their umask allowed the world to change their
files (e.g. a umask of zero).  This case is so unlikely and strange
that we don't need to support it.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-01-06 10:37:14 -08:00

324 lines
8.1 KiB
C

/*
* Copyright (c) 2005, 2006 Rene Scharfe
*/
#include "cache.h"
#include "commit.h"
#include "strbuf.h"
#include "tar.h"
#include "builtin.h"
#include "archive.h"
#define RECORDSIZE (512)
#define BLOCKSIZE (RECORDSIZE * 20)
static char block[BLOCKSIZE];
static unsigned long offset;
static time_t archive_time;
static int tar_umask = 002;
static int verbose;
/* writes out the whole block, but only if it is full */
static void write_if_needed(void)
{
if (offset == BLOCKSIZE) {
write_or_die(1, block, BLOCKSIZE);
offset = 0;
}
}
/*
* queues up writes, so that all our write(2) calls write exactly one
* full block; pads writes to RECORDSIZE
*/
static void write_blocked(const void *data, unsigned long size)
{
const char *buf = data;
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) {
write_or_die(1, buf, BLOCKSIZE);
size -= BLOCKSIZE;
buf += BLOCKSIZE;
}
if (size) {
memcpy(block + offset, buf, size);
offset += size;
}
tail = offset % RECORDSIZE;
if (tail) {
memset(block + offset, 0, RECORDSIZE - tail);
offset += RECORDSIZE - tail;
}
write_if_needed();
}
/*
* The end of tar archives is marked by 2*512 nul bytes and after that
* follows the rest of the block (if any).
*/
static void write_trailer(void)
{
int tail = BLOCKSIZE - offset;
memset(block + offset, 0, tail);
write_or_die(1, block, BLOCKSIZE);
if (tail < 2 * RECORDSIZE) {
memset(block, 0, offset);
write_or_die(1, block, BLOCKSIZE);
}
}
static void strbuf_append_string(struct strbuf *sb, const char *s)
{
int slen = strlen(s);
int total = sb->len + slen;
if (total > sb->alloc) {
sb->buf = xrealloc(sb->buf, total);
sb->alloc = total;
}
memcpy(sb->buf + sb->len, s, slen);
sb->len = total;
}
/*
* pax extended header records have the format "%u %s=%s\n". %u contains
* the size of the whole string (including the %u), the first %s is the
* keyword, the second one is the value. This function constructs such a
* string and appends it to a struct strbuf.
*/
static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
const char *value, unsigned int valuelen)
{
char *p;
int len, total, tmp;
/* "%u %s=%s\n" */
len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
for (tmp = len; tmp > 9; tmp /= 10)
len++;
total = sb->len + len;
if (total > sb->alloc) {
sb->buf = xrealloc(sb->buf, total);
sb->alloc = total;
}
p = sb->buf;
p += sprintf(p, "%u %s=", len, keyword);
memcpy(p, value, valuelen);
p += valuelen;
*p = '\n';
sb->len = total;
}
static unsigned int ustar_header_chksum(const struct ustar_header *header)
{
char *p = (char *)header;
unsigned int chksum = 0;
while (p < header->chksum)
chksum += *p++;
chksum += sizeof(header->chksum) * ' ';
p += sizeof(header->chksum);
while (p < (char *)header + sizeof(struct ustar_header))
chksum += *p++;
return chksum;
}
static int get_path_prefix(const struct strbuf *path, int maxlen)
{
int i = path->len;
if (i > maxlen)
i = maxlen;
do {
i--;
} while (i > 0 && path->buf[i] != '/');
return i;
}
static void write_entry(const unsigned char *sha1, struct strbuf *path,
unsigned int mode, void *buffer, unsigned long size)
{
struct ustar_header header;
struct strbuf ext_header;
memset(&header, 0, sizeof(header));
ext_header.buf = NULL;
ext_header.len = ext_header.alloc = 0;
if (!sha1) {
*header.typeflag = TYPEFLAG_GLOBAL_HEADER;
mode = 0100666;
strcpy(header.name, "pax_global_header");
} else if (!path) {
*header.typeflag = TYPEFLAG_EXT_HEADER;
mode = 0100666;
sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
} else {
if (verbose)
fprintf(stderr, "%.*s\n", path->len, path->buf);
if (S_ISDIR(mode)) {
*header.typeflag = TYPEFLAG_DIR;
mode = (mode | 0777) & ~tar_umask;
} else if (S_ISLNK(mode)) {
*header.typeflag = TYPEFLAG_LNK;
mode |= 0777;
} else if (S_ISREG(mode)) {
*header.typeflag = TYPEFLAG_REG;
mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
} else {
error("unsupported file mode: 0%o (SHA1: %s)",
mode, sha1_to_hex(sha1));
return;
}
if (path->len > sizeof(header.name)) {
int plen = get_path_prefix(path, sizeof(header.prefix));
int rest = path->len - plen - 1;
if (plen > 0 && rest <= sizeof(header.name)) {
memcpy(header.prefix, path->buf, plen);
memcpy(header.name, path->buf + plen + 1, rest);
} else {
sprintf(header.name, "%s.data",
sha1_to_hex(sha1));
strbuf_append_ext_header(&ext_header, "path",
path->buf, path->len);
}
} else
memcpy(header.name, path->buf, path->len);
}
if (S_ISLNK(mode) && buffer) {
if (size > sizeof(header.linkname)) {
sprintf(header.linkname, "see %s.paxheader",
sha1_to_hex(sha1));
strbuf_append_ext_header(&ext_header, "linkpath",
buffer, size);
} else
memcpy(header.linkname, buffer, size);
}
sprintf(header.mode, "%07o", mode & 07777);
sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
sprintf(header.mtime, "%011lo", archive_time);
sprintf(header.uid, "%07o", 0);
sprintf(header.gid, "%07o", 0);
strlcpy(header.uname, "root", sizeof(header.uname));
strlcpy(header.gname, "root", sizeof(header.gname));
sprintf(header.devmajor, "%07o", 0);
sprintf(header.devminor, "%07o", 0);
memcpy(header.magic, "ustar", 6);
memcpy(header.version, "00", 2);
sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
if (ext_header.len > 0) {
write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
free(ext_header.buf);
}
write_blocked(&header, sizeof(header));
if (S_ISREG(mode) && buffer && size > 0)
write_blocked(buffer, size);
}
static void write_global_extended_header(const unsigned char *sha1)
{
struct strbuf ext_header;
ext_header.buf = NULL;
ext_header.len = ext_header.alloc = 0;
strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
free(ext_header.buf);
}
static int git_tar_config(const char *var, const char *value)
{
if (!strcmp(var, "tar.umask")) {
if (!strcmp(value, "user")) {
tar_umask = umask(0);
umask(tar_umask);
} else {
tar_umask = git_config_int(var, value);
}
return 0;
}
return git_default_config(var, value);
}
static int write_tar_entry(const unsigned char *sha1,
const char *base, int baselen,
const char *filename, unsigned mode, int stage)
{
static struct strbuf path;
int filenamelen = strlen(filename);
void *buffer;
char type[20];
unsigned long size;
if (!path.alloc) {
path.buf = xmalloc(PATH_MAX);
path.alloc = PATH_MAX;
path.len = path.eof = 0;
}
if (path.alloc < baselen + filenamelen) {
free(path.buf);
path.buf = xmalloc(baselen + filenamelen);
path.alloc = baselen + filenamelen;
}
memcpy(path.buf, base, baselen);
memcpy(path.buf + baselen, filename, filenamelen);
path.len = baselen + filenamelen;
if (S_ISDIR(mode)) {
strbuf_append_string(&path, "/");
buffer = NULL;
size = 0;
} else {
buffer = read_sha1_file(sha1, type, &size);
if (!buffer)
die("cannot read %s", sha1_to_hex(sha1));
}
write_entry(sha1, &path, mode, buffer, size);
free(buffer);
return READ_TREE_RECURSIVE;
}
int write_tar_archive(struct archiver_args *args)
{
int plen = args->base ? strlen(args->base) : 0;
git_config(git_tar_config);
archive_time = args->time;
verbose = args->verbose;
if (args->commit_sha1)
write_global_extended_header(args->commit_sha1);
if (args->base && plen > 0 && args->base[plen - 1] == '/') {
char *base = xstrdup(args->base);
int baselen = strlen(base);
while (baselen > 0 && base[baselen - 1] == '/')
base[--baselen] = '\0';
write_tar_entry(args->tree->object.sha1, "", 0, base, 040777, 0);
free(base);
}
read_tree_recursive(args->tree, args->base, plen, 0,
args->pathspec, write_tar_entry);
write_trailer();
return 0;
}