/*

 * Copyright (c) 2005, 2006 Rene Scharfe

 */

#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"

#include "config.h"

#include "gettext.h"

#include "git-zlib.h"

#include "hex.h"

#include "tar.h"

#include "archive.h"

#include "object-store-ll.h"

#include "strbuf.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 (!xstrncmpz(ar->name, 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, 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, ctx->kvi);

    }

    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]);

  }

}