pretend-git/archive-tar.c at master · submitgit/pretend-git · GitHub

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#include "cache.h"

#include "tar.h"

#include "archive.h"

#include "streaming.h"

#include "run-command.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);

/* 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 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_or_die(1, buf, BLOCKSIZE);

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_or_die(1, block, BLOCKSIZE);

if (tail < 2 * RECORDSIZE) {

memset(block, 0, offset);

write_or_die(1, block, BLOCKSIZE);

}

* queues up writes, so that all our write(2) calls write exactly one

* full block; pads writes to RECORDSIZE

static int stream_blocked(const unsigned char *sha1)

{

struct git_istream *st;

enum object_type type;

unsigned long sz;

char buf[BLOCKSIZE];

ssize_t readlen;

st = open_istream(sha1, &type, &sz, NULL);

if (!st)

return error("cannot stream blob %s", sha1_to_hex(sha1));

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, unsigned int valuelen)

{

int len, tmp;

/* "%u %s=%s\n" */

len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;

for (tmp = len; tmp > 9; tmp /= 10)

len++;

strbuf_grow(sb, len);

strbuf_addf(sb, "%u %s=", len, keyword);

strbuf_add(sb, value, valuelen);

strbuf_addch(sb, '\n');

}

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)

{

sprintf(header->mode, "%07o", mode & 07777);

sprintf(header->size, "%011lo", S_ISREG(mode) ? size : 0);

sprintf(header->mtime, "%011lo", (unsigned long) args->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));

}

static int write_extended_header(struct archiver_args *args,

const unsigned char *sha1,

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;

sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));

prepare_header(args, &header, mode, size);

write_blocked(&header, sizeof(header));

write_blocked(buffer, size);

return 0;

}

static int write_tar_entry(struct archiver_args *args,

const unsigned char *sha1,

const char *path, size_t pathlen,

unsigned int mode)

{

struct ustar_header header;

struct strbuf ext_header = STRBUF_INIT;

unsigned int old_mode = mode;

unsigned long size;

void *buffer;

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, sha1_to_hex(sha1));

}

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 {

sprintf(header.name, "%s.data",

sha1_to_hex(sha1));

strbuf_append_ext_header(&ext_header, "path",

path, pathlen);

}

} else

memcpy(header.name, path, pathlen);

if (S_ISREG(mode) && !args->convert &&

sha1_object_info(sha1, &size) == OBJ_BLOB &&

size > big_file_threshold)

buffer = NULL;

else if (S_ISLNK(mode) || S_ISREG(mode)) {

enum object_type type;

buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);

if (!buffer)

return error("cannot read %s", sha1_to_hex(sha1));

} else {

buffer = NULL;

size = 0;

}

if (S_ISLNK(mode)) {

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);

}

prepare_header(args, &header, mode, size);

if (ext_header.len > 0) {

err = write_extended_header(args, sha1, ext_header.buf,

ext_header.len);

if (err) {

free(buffer);

return err;

}

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(sha1);

}

free(buffer);

return err;

}

static int write_global_extended_header(struct archiver_args *args)

{

const unsigned char *sha1 = args->commit_sha1;

struct strbuf ext_header = STRBUF_INIT;

struct ustar_header header;

unsigned int mode;

int err = 0;

strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);

memset(&header, 0, sizeof(header));

*header.typeflag = TYPEFLAG_GLOBAL_HEADER;

mode = 0100666;

strcpy(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);

return err;

}

static struct archiver **tar_filters;

static int nr_tar_filters;

static int alloc_tar_filters;

static struct archiver *find_tar_filter(const char *name, int 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)

{

struct archiver *ar;

const char *name;

const char *type;

int namelen;

if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)

return 0;

ar = find_tar_filter(name, namelen);

if (!ar) {

ar = xcalloc(1, sizeof(*ar));

ar->name = xmemdupz(name, namelen);

ar->write_archive = write_tar_filter_archive;

ar->flags = ARCHIVER_WANT_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->data);

ar->data = 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, 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,

struct archiver_args *args)

{

int err = 0;

if (args->commit_sha1)

err = write_global_extended_header(args);

if (!err)

err = write_archive_entries(args, write_tar_entry);

if (!err)

write_trailer();

return err;

}

static int write_tar_filter_archive(const struct archiver *ar,

struct archiver_args *args)

{

struct strbuf cmd = STRBUF_INIT;

struct child_process filter = CHILD_PROCESS_INIT;

const char *argv[2];

int r;

if (!ar->data)

die("BUG: tar-filter archiver called with no filter defined");

strbuf_addstr(&cmd, ar->data);

if (args->compression_level >= 0)

strbuf_addf(&cmd, " -%d", args->compression_level);

argv[0] = cmd.buf;

argv[1] = NULL;

filter.argv = argv;

filter.use_shell = 1;

filter.in = -1;

if (start_command(&filter) < 0)

die_errno("unable to start '%s' filter", argv[0]);

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", argv[0]);

strbuf_release(&cmd);

return r;

}

static struct archiver tar_archiver = {

"tar",

write_tar_archive,

ARCHIVER_REMOTE

};

void init_tar_archiver(void)

{

int i;

register_archiver(&tar_archiver);

tar_filter_config("tar.tgz.command", "gzip -cn", NULL);

tar_filter_config("tar.tgz.remote", "true", NULL);

tar_filter_config("tar.tar.gz.command", "gzip -cn", 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]->data)

register_archiver(tar_filters[i]);

}

pretend-git/archive-tar.c at master · submitgit/pretend-git · GitHub

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