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git/archive-tar.c
Glen Choo a4e7e317f8 config: add ctx arg to config_fn_t 
Add a new "const struct config_context *ctx" arg to config_fn_t to hold
additional information about the config iteration operation.
config_context has a "struct key_value_info kvi" member that holds
metadata about the config source being read (e.g. what kind of config
source it is, the filename, etc). In this series, we're only interested
in .kvi, so we could have just used "struct key_value_info" as an arg,
but config_context makes it possible to add/adjust members in the future
without changing the config_fn_t signature. We could also consider other
ways of organizing the args (e.g. moving the config name and value into
config_context or key_value_info), but in my experiments, the
incremental benefit doesn't justify the added complexity (e.g. a
config_fn_t will sometimes invoke another config_fn_t but with a
different config value).

In subsequent commits, the .kvi member will replace the global "struct
config_reader" in config.c, making config iteration a global-free
operation. It requires much more work for the machinery to provide
meaningful values of .kvi, so for now, merely change the signature and
call sites, pass NULL as a placeholder value, and don't rely on the arg
in any meaningful way.

Most of the changes are performed by
contrib/coccinelle/config_fn_ctx.pending.cocci, which, for every
config_fn_t:

- Modifies the signature to accept "const struct config_context *ctx"
- Passes "ctx" to any inner config_fn_t, if needed
- Adds UNUSED attributes to "ctx", if needed

Most config_fn_t instances are easily identified by seeing if they are
called by the various config functions. Most of the remaining ones are
manually named in the .cocci patch. Manual cleanups are still needed,
but the majority of it is trivial; it's either adjusting config_fn_t
that the .cocci patch didn't catch, or adding forward declarations of
"struct config_context ctx" to make the signatures make sense.

The non-trivial changes are in cases where we are invoking a config_fn_t
outside of config machinery, and we now need to decide what value of
"ctx" to pass. These cases are:

- trace2/tr2_cfg.c:tr2_cfg_set_fl()

  This is indirectly called by git_config_set() so that the trace2
  machinery can notice the new config values and update its settings
  using the tr2 config parsing function, i.e. tr2_cfg_cb().

- builtin/checkout.c:checkout_main()

  This calls git_xmerge_config() as a shorthand for parsing a CLI arg.
  This might be worth refactoring away in the future, since
  git_xmerge_config() can call git_default_config(), which can do much
  more than just parsing.

Handle them by creating a KVI_INIT macro that initializes "struct
key_value_info" to a reasonable default, and use that to construct the
"ctx" arg.

Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-28 14:06:39 -07:00

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/*
* Copyright (c) 2005, 2006 Rene Scharfe
*/
#include "git-compat-util.h"
#include "alloc.h"
#include "config.h"
#include "gettext.h"
#include "git-zlib.h"
#include "hex.h"
#include "tar.h"
#include "archive.h"
#include "object-store.h"
#include "streaming.h"
#include "run-command.h"
#include "write-or-die.h"
#define RECORDSIZE (512)
#define BLOCKSIZE (RECORDSIZE * 20)
static char block[BLOCKSIZE];
static unsigned long offset;
static int tar_umask = 002;
static int write_tar_filter_archive(const struct archiver *ar,
struct archiver_args *args);
/*
* This is the max value that a ustar size header can specify, as it is fixed
* at 11 octal digits. POSIX specifies that we switch to extended headers at
* this size.
*
* Likewise for the mtime (which happens to use a buffer of the same size).
*/
#if ULONG_MAX == 0xFFFFFFFF
#define USTAR_MAX_SIZE ULONG_MAX
#else
#define USTAR_MAX_SIZE 077777777777UL
#endif
#if TIME_MAX == 0xFFFFFFFF
#define USTAR_MAX_MTIME TIME_MAX
#else
#define USTAR_MAX_MTIME 077777777777ULL
#endif
static void tar_write_block(const void *buf)
{
write_or_die(1, buf, BLOCKSIZE);
}
static void (*write_block)(const void *) = tar_write_block;
/* writes out the whole block, but only if it is full */
static void write_if_needed(void)
{
if (offset == BLOCKSIZE) {
write_block(block);
offset = 0;
}
}
/*
* queues up writes, so that all our write(2) calls write exactly one
* full block; pads writes to RECORDSIZE
*/
static void do_write_blocked(const void *data, unsigned long size)
{
const char *buf = data;
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_block(buf);
size -= BLOCKSIZE;
buf += BLOCKSIZE;
}
if (size) {
memcpy(block + offset, buf, size);
offset += size;
}
}
static void finish_record(void)
{
unsigned long tail;
tail = offset % RECORDSIZE;
if (tail) {
memset(block + offset, 0, RECORDSIZE - tail);
offset += RECORDSIZE - tail;
}
write_if_needed();
}
static void write_blocked(const void *data, unsigned long size)
{
do_write_blocked(data, size);
finish_record();
}
/*
* 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_block(block);
if (tail < 2 * RECORDSIZE) {
memset(block, 0, offset);
write_block(block);
}
}
/*
* queues up writes, so that all our write(2) calls write exactly one
* full block; pads writes to RECORDSIZE
*/
static int stream_blocked(struct repository *r, const struct object_id *oid)
{
struct git_istream *st;
enum object_type type;
unsigned long sz;
char buf[BLOCKSIZE];
ssize_t readlen;
st = open_istream(r, oid, &type, &sz, NULL);
if (!st)
return error(_("cannot stream blob %s"), oid_to_hex(oid));
for (;;) {
readlen = read_istream(st, buf, sizeof(buf));
if (readlen <= 0)
break;
do_write_blocked(buf, readlen);
}
close_istream(st);
if (!readlen)
finish_record();
return readlen;
}
/*
* 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, size_t valuelen)
{
size_t orig_len = sb->len;
size_t len, tmp;
/* "%u %s=%s\n" */
len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
for (tmp = 1; len / 10 >= tmp; tmp *= 10)
len++;
strbuf_grow(sb, len);
strbuf_addf(sb, "%"PRIuMAX" %s=", (uintmax_t)len, keyword);
strbuf_add(sb, value, valuelen);
strbuf_addch(sb, '\n');
if (len != sb->len - orig_len)
BUG("pax extended header length miscalculated as %"PRIuMAX
", should be %"PRIuMAX,
(uintmax_t)len, (uintmax_t)(sb->len - orig_len));
}
/*
* Like strbuf_append_ext_header, but for numeric values.
*/
static void strbuf_append_ext_header_uint(struct strbuf *sb,
const char *keyword,
uintmax_t value)
{
char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
int len;
len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
strbuf_append_ext_header(sb, keyword, buf, len);
}
static unsigned int ustar_header_chksum(const struct ustar_header *header)
{
const unsigned char *p = (const unsigned char *)header;
unsigned int chksum = 0;
while (p < (const unsigned char *)header->chksum)
chksum += *p++;
chksum += sizeof(header->chksum) * ' ';
p += sizeof(header->chksum);
while (p < (const unsigned char *)header + sizeof(struct ustar_header))
chksum += *p++;
return chksum;
}
static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
{
size_t i = pathlen;
if (i > 1 && path[i - 1] == '/')
i--;
if (i > maxlen)
i = maxlen;
do {
i--;
} while (i > 0 && path[i] != '/');
return i;
}
static void prepare_header(struct archiver_args *args,
struct ustar_header *header,
unsigned int mode, unsigned long size)
{
xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
xsnprintf(header->size, sizeof(header->size), "%011"PRIoMAX , S_ISREG(mode) ? (uintmax_t)size : (uintmax_t)0);
xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
strlcpy(header->uname, "root", sizeof(header->uname));
strlcpy(header->gname, "root", sizeof(header->gname));
xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
memcpy(header->magic, "ustar", 6);
memcpy(header->version, "00", 2);
xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
}
static void write_extended_header(struct archiver_args *args,
const struct object_id *oid,
const void *buffer, unsigned long size)
{
struct ustar_header header;
unsigned int mode;
memset(&header, 0, sizeof(header));
*header.typeflag = TYPEFLAG_EXT_HEADER;
mode = 0100666;
xsnprintf(header.name, sizeof(header.name), "%s.paxheader", oid_to_hex(oid));
prepare_header(args, &header, mode, size);
write_blocked(&header, sizeof(header));
write_blocked(buffer, size);
}
static int write_tar_entry(struct archiver_args *args,
const struct object_id *oid,
const char *path, size_t pathlen,
unsigned int mode,
void *buffer, unsigned long size)
{
struct ustar_header header;
struct strbuf ext_header = STRBUF_INIT;
unsigned long size_in_header;
int err = 0;
memset(&header, 0, sizeof(header));
if (S_ISDIR(mode) || S_ISGITLINK(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 {
return error(_("unsupported file mode: 0%o (SHA1: %s)"),
mode, oid_to_hex(oid));
}
if (pathlen > sizeof(header.name)) {
size_t plen = get_path_prefix(path, pathlen,
sizeof(header.prefix));
size_t rest = pathlen - plen - 1;
if (plen > 0 && rest <= sizeof(header.name)) {
memcpy(header.prefix, path, plen);
memcpy(header.name, path + plen + 1, rest);
} else {
xsnprintf(header.name, sizeof(header.name), "%s.data",
oid_to_hex(oid));
strbuf_append_ext_header(&ext_header, "path",
path, pathlen);
}
} else
memcpy(header.name, path, pathlen);
if (S_ISLNK(mode)) {
if (size > sizeof(header.linkname)) {
xsnprintf(header.linkname, sizeof(header.linkname),
"see %s.paxheader", oid_to_hex(oid));
strbuf_append_ext_header(&ext_header, "linkpath",
buffer, size);
} else
memcpy(header.linkname, buffer, size);
}
size_in_header = size;
if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
size_in_header = 0;
strbuf_append_ext_header_uint(&ext_header, "size", size);
}
prepare_header(args, &header, mode, size_in_header);
if (ext_header.len > 0) {
write_extended_header(args, oid, ext_header.buf,
ext_header.len);
}
strbuf_release(&ext_header);
write_blocked(&header, sizeof(header));
if (S_ISREG(mode) && size > 0) {
if (buffer)
write_blocked(buffer, size);
else
err = stream_blocked(args->repo, oid);
}
return err;
}
static void write_global_extended_header(struct archiver_args *args)
{
const struct object_id *oid = args->commit_oid;
struct strbuf ext_header = STRBUF_INIT;
struct ustar_header header;
unsigned int mode;
if (oid)
strbuf_append_ext_header(&ext_header, "comment",
oid_to_hex(oid),
the_hash_algo->hexsz);
if (args->time > USTAR_MAX_MTIME) {
strbuf_append_ext_header_uint(&ext_header, "mtime",
args->time);
args->time = USTAR_MAX_MTIME;
}
if (!ext_header.len)
return;
memset(&header, 0, sizeof(header));
*header.typeflag = TYPEFLAG_GLOBAL_HEADER;
mode = 0100666;
xsnprintf(header.name, sizeof(header.name), "pax_global_header");
prepare_header(args, &header, mode, ext_header.len);
write_blocked(&header, sizeof(header));
write_blocked(ext_header.buf, ext_header.len);
strbuf_release(&ext_header);
}
static struct archiver **tar_filters;
static int nr_tar_filters;
static int alloc_tar_filters;
static struct archiver *find_tar_filter(const char *name, size_t len)
{
int i;
for (i = 0; i < nr_tar_filters; i++) {
struct archiver *ar = tar_filters[i];
if (!strncmp(ar->name, name, len) && !ar->name[len])
return ar;
}
return NULL;
}
static int tar_filter_config(const char *var, const char *value,
void *data UNUSED)
{
struct archiver *ar;
const char *name;
const char *type;
size_t namelen;
if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
return 0;
ar = find_tar_filter(name, namelen);
if (!ar) {
CALLOC_ARRAY(ar, 1);
ar->name = xmemdupz(name, namelen);
ar->write_archive = write_tar_filter_archive;
ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS |
ARCHIVER_HIGH_COMPRESSION_LEVELS;
ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
tar_filters[nr_tar_filters++] = ar;
}
if (!strcmp(type, "command")) {
if (!value)
return config_error_nonbool(var);
free(ar->filter_command);
ar->filter_command = xstrdup(value);
return 0;
}
if (!strcmp(type, "remote")) {
if (git_config_bool(var, value))
ar->flags |= ARCHIVER_REMOTE;
else
ar->flags &= ~ARCHIVER_REMOTE;
return 0;
}
return 0;
}
static int git_tar_config(const char *var, const char *value,
const struct config_context *ctx UNUSED, void *cb)
{
if (!strcmp(var, "tar.umask")) {
if (value && !strcmp(value, "user")) {
tar_umask = umask(0);
umask(tar_umask);
} else {
tar_umask = git_config_int(var, value);
}
return 0;
}
return tar_filter_config(var, value, cb);
}
static int write_tar_archive(const struct archiver *ar UNUSED,
struct archiver_args *args)
{
int err = 0;
write_global_extended_header(args);
err = write_archive_entries(args, write_tar_entry);
if (!err)
write_trailer();
return err;
}
static git_zstream gzstream;
static unsigned char outbuf[16384];
static void tgz_deflate(int flush)
{
while (gzstream.avail_in || flush == Z_FINISH) {
int status = git_deflate(&gzstream, flush);
if (!gzstream.avail_out || status == Z_STREAM_END) {
write_or_die(1, outbuf, gzstream.next_out - outbuf);
gzstream.next_out = outbuf;
gzstream.avail_out = sizeof(outbuf);
if (status == Z_STREAM_END)
break;
}
if (status != Z_OK && status != Z_BUF_ERROR)
die(_("deflate error (%d)"), status);
}
}
static void tgz_write_block(const void *data)
{
gzstream.next_in = (void *)data;
gzstream.avail_in = BLOCKSIZE;
tgz_deflate(Z_NO_FLUSH);
}
static const char internal_gzip_command[] = "git archive gzip";
static int write_tar_filter_archive(const struct archiver *ar,
struct archiver_args *args)
{
#if ZLIB_VERNUM >= 0x1221
struct gz_header_s gzhead = { .os = 3 }; /* Unix, for reproducibility */
#endif
struct strbuf cmd = STRBUF_INIT;
struct child_process filter = CHILD_PROCESS_INIT;
int r;
if (!ar->filter_command)
BUG("tar-filter archiver called with no filter defined");
if (!strcmp(ar->filter_command, internal_gzip_command)) {
write_block = tgz_write_block;
git_deflate_init_gzip(&gzstream, args->compression_level);
#if ZLIB_VERNUM >= 0x1221
if (deflateSetHeader(&gzstream.z, &gzhead) != Z_OK)
BUG("deflateSetHeader() called too late");
#endif
gzstream.next_out = outbuf;
gzstream.avail_out = sizeof(outbuf);
r = write_tar_archive(ar, args);
tgz_deflate(Z_FINISH);
git_deflate_end(&gzstream);
return r;
}
strbuf_addstr(&cmd, ar->filter_command);
if (args->compression_level >= 0)
strbuf_addf(&cmd, " -%d", args->compression_level);
strvec_push(&filter.args, cmd.buf);
filter.use_shell = 1;
filter.in = -1;
filter.silent_exec_failure = 1;
if (start_command(&filter) < 0)
die_errno(_("unable to start '%s' filter"), cmd.buf);
close(1);
if (dup2(filter.in, 1) < 0)
die_errno(_("unable to redirect descriptor"));
close(filter.in);
r = write_tar_archive(ar, args);
close(1);
if (finish_command(&filter) != 0)
die(_("'%s' filter reported error"), cmd.buf);
strbuf_release(&cmd);
return r;
}
static struct archiver tar_archiver = {
.name = "tar",
.write_archive = write_tar_archive,
.flags = ARCHIVER_REMOTE,
};
void init_tar_archiver(void)
{
int i;
register_archiver(&tar_archiver);
tar_filter_config("tar.tgz.command", internal_gzip_command, NULL);
tar_filter_config("tar.tgz.remote", "true", NULL);
tar_filter_config("tar.tar.gz.command", internal_gzip_command, NULL);
tar_filter_config("tar.tar.gz.remote", "true", NULL);
git_config(git_tar_config, NULL);
for (i = 0; i < nr_tar_filters; i++) {
/* omit any filters that never had a command configured */
if (tar_filters[i]->filter_command)
register_archiver(tar_filters[i]);
}
}
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