/* Check if FILE_NAME already exists and make a backup of it right now.
Return success (nonzero) only if the backup is either unneeded, or
successful. For now, directories are considered to never need
backup. If THIS_IS_THE_ARCHIVE is nonzero, this is the archive and
so, we do not have to backup block or character devices, nor remote
entities. */
bool
maybe_backup_file (const char *file_name, bool this_is_the_archive)
{
struct stat file_stat;
assign_string (&before_backup_name, file_name);
/* A run situation may exist between Emacs or other GNU programs trying to
make a backup for the same file simultaneously. If theoretically
possible, real problems are unlikely. Doing any better would require a
convention, GNU-wide, for all programs doing backups. */
assign_string (&after_backup_name, 0);
/* Check if we really need to backup the file. */
if (this_is_the_archive && _remdev (file_name))
return true;
if (deref_stat (file_name, &file_stat) != 0)
{
if (errno == ENOENT)
return true;
stat_error (file_name);
return false;
}
if (S_ISDIR (file_stat.st_mode))
return true;
if (this_is_the_archive
&& (S_ISBLK (file_stat.st_mode) || S_ISCHR (file_stat.st_mode)))
return true;
after_backup_name = find_backup_file_name (file_name, backup_type);
if (! after_backup_name)
xalloc_die ();
if (renameat (chdir_fd, before_backup_name, chdir_fd, after_backup_name)
== 0)
{
if (verbose_option)
fprintf (stdlis, _("Renaming %s to %s\n"),
quote_n (0, before_backup_name),
quote_n (1, after_backup_name));
return true;
}
else
{
/* The backup operation failed. */
int e = errno;
ERROR ((0, e, _("%s: Cannot rename to %s"),
quotearg_colon (before_backup_name),
quote_n (1, after_backup_name)));
assign_string (&after_backup_name, 0);
return false;
}
}
int
maybe_backup_file (const char *path, int archive)
{
struct L_STAT file_stat;
/* Check if we really need to backup the file. */
if (archive && _remdev (path))
return 1;
if (L_STAT (path, &file_stat))
{
if (errno == ENOENT)
return 1;
ERROR ((0, errno, "%s", path));
return 0;
}
if (S_ISDIR (file_stat.st_mode))
return 1;
#ifdef S_ISBLK
if (archive && S_ISBLK (file_stat.st_mode))
return 1;
#endif
#ifdef S_ISCHR
if (archive && S_ISCHR (file_stat.st_mode))
return 1;
#endif
assign_string (&before_backup_name, path);
/* A run situation may exist between Emacs or other GNU programs trying to
make a backup for the same file simultaneously. If theoretically
possible, real problems are unlikely. Doing any better would require a
convention, GNU-wide, for all programs doing backups. */
assign_string (&after_backup_name, NULL);
after_backup_name = find_backup_file_name (path);
if (after_backup_name == NULL)
FATAL_ERROR ((0, 0, "Virtual memory exhausted"));
if (rename (before_backup_name, after_backup_name) == 0)
{
if (verbose_option)
fprintf (stdlis, _("Renaming previous `%s' to `%s'\n"),
before_backup_name, after_backup_name);
return 1;
}
/* The backup operation failed. */
ERROR ((0, errno, _("%s: Cannot rename for backup"), before_backup_name));
assign_string (&after_backup_name, NULL);
return 0;
}
/* Set ARCHIVE for uncompressing, then reading an archive. */
pid_t
sys_child_open_for_uncompress (void)
{
int parent_pipe[2];
int child_pipe[2];
pid_t grandchild_pid;
pid_t child_pid;
xpipe (parent_pipe);
child_pid = xfork ();
if (child_pid > 0)
{
/* The parent tar is still here! Just clean up. */
archive = parent_pipe[PREAD];
xclose (parent_pipe[PWRITE]);
return child_pid;
}
/* The newborn child tar is here! */
set_program_name (_("tar (child)"));
signal (SIGPIPE, SIG_DFL);
xdup2 (parent_pipe[PWRITE], STDOUT_FILENO);
xclose (parent_pipe[PREAD]);
/* Check if we need a grandchild tar. This happens only if either:
a) we're reading stdin: to force unblocking;
b) the file is to be accessed by rmt: compressor doesn't know how;
c) the file is not a plain file. */
if (strcmp (archive_name_array[0], "-") != 0
&& !_remdev (archive_name_array[0])
&& is_regular_file (archive_name_array[0]))
{
/* We don't need a grandchild tar. Open the archive and lauch the
uncompressor. */
archive = open (archive_name_array[0], O_RDONLY | O_BINARY, MODE_RW);
if (archive < 0)
open_fatal (archive_name_array[0]);
xdup2 (archive, STDIN_FILENO);
execlp (use_compress_program_option, use_compress_program_option,
"-d", (char *) 0);
exec_fatal (use_compress_program_option);
}
/* We do need a grandchild tar. */
xpipe (child_pipe);
grandchild_pid = xfork ();
if (grandchild_pid == 0)
{
/* The newborn grandchild tar is here! Launch the uncompressor. */
set_program_name (_("tar (grandchild)"));
xdup2 (child_pipe[PREAD], STDIN_FILENO);
xclose (child_pipe[PWRITE]);
execlp (use_compress_program_option, use_compress_program_option,
"-d", (char *) 0);
exec_fatal (use_compress_program_option);
}
/* The child tar is still here! */
/* Prepare for unblocking the data from the archive into the
uncompressor. */
xdup2 (child_pipe[PWRITE], STDOUT_FILENO);
xclose (child_pipe[PREAD]);
if (strcmp (archive_name_array[0], "-") == 0)
archive = STDIN_FILENO;
else
archive = rmtopen (archive_name_array[0], O_RDONLY | O_BINARY,
MODE_RW, rsh_command_option);
if (archive < 0)
open_fatal (archive_name_array[0]);
/* Let's read the archive and pipe it into stdout. */
while (1)
{
char *cursor;
size_t maximum;
size_t count;
size_t status;
clear_read_error_count ();
error_loop:
status = rmtread (archive, record_start->buffer, record_size);
if (status == SAFE_READ_ERROR)
{
archive_read_error ();
goto error_loop;
}
if (status == 0)
break;
cursor = record_start->buffer;
maximum = status;
while (maximum)
{
count = maximum < BLOCKSIZE ? maximum : BLOCKSIZE;
if (full_write (STDOUT_FILENO, cursor, count) != count)
write_error (use_compress_program_option);
cursor += count;
maximum -= count;
}
}
xclose (STDOUT_FILENO);
wait_for_grandchild (grandchild_pid);
}
/* Set ARCHIVE for writing, then compressing an archive. */
pid_t
sys_child_open_for_compress (void)
{
int parent_pipe[2];
int child_pipe[2];
pid_t grandchild_pid;
pid_t child_pid;
xpipe (parent_pipe);
child_pid = xfork ();
if (child_pid > 0)
{
/* The parent tar is still here! Just clean up. */
archive = parent_pipe[PWRITE];
xclose (parent_pipe[PREAD]);
return child_pid;
}
/* The new born child tar is here! */
set_program_name (_("tar (child)"));
signal (SIGPIPE, SIG_DFL);
xdup2 (parent_pipe[PREAD], STDIN_FILENO);
xclose (parent_pipe[PWRITE]);
/* Check if we need a grandchild tar. This happens only if either:
a) the file is to be accessed by rmt: compressor doesn't know how;
b) the file is not a plain file. */
if (!_remdev (archive_name_array[0])
&& is_regular_file (archive_name_array[0]))
{
if (backup_option)
maybe_backup_file (archive_name_array[0], 1);
/* We don't need a grandchild tar. Open the archive and launch the
compressor. */
if (strcmp (archive_name_array[0], "-"))
{
archive = creat (archive_name_array[0], MODE_RW);
if (archive < 0)
{
int saved_errno = errno;
if (backup_option)
undo_last_backup ();
errno = saved_errno;
open_fatal (archive_name_array[0]);
}
xdup2 (archive, STDOUT_FILENO);
}
execlp (use_compress_program_option, use_compress_program_option, NULL);
exec_fatal (use_compress_program_option);
}
/* We do need a grandchild tar. */
xpipe (child_pipe);
grandchild_pid = xfork ();
if (grandchild_pid == 0)
{
/* The newborn grandchild tar is here! Launch the compressor. */
set_program_name (_("tar (grandchild)"));
xdup2 (child_pipe[PWRITE], STDOUT_FILENO);
xclose (child_pipe[PREAD]);
execlp (use_compress_program_option, use_compress_program_option,
(char *) 0);
exec_fatal (use_compress_program_option);
}
/* The child tar is still here! */
/* Prepare for reblocking the data from the compressor into the archive. */
xdup2 (child_pipe[PREAD], STDIN_FILENO);
xclose (child_pipe[PWRITE]);
if (strcmp (archive_name_array[0], "-") == 0)
archive = STDOUT_FILENO;
else
{
archive = rmtcreat (archive_name_array[0], MODE_RW, rsh_command_option);
if (archive < 0)
open_fatal (archive_name_array[0]);
}
/* Let's read out of the stdin pipe and write an archive. */
while (1)
{
size_t status = 0;
char *cursor;
size_t length;
/* Assemble a record. */
for (length = 0, cursor = record_start->buffer;
length < record_size;
length += status, cursor += status)
{
size_t size = record_size - length;
status = safe_read (STDIN_FILENO, cursor, size);
if (status == SAFE_READ_ERROR)
read_fatal (use_compress_program_option);
if (status == 0)
break;
}
/* Copy the record. */
if (status == 0)
{
/* We hit the end of the file. Write last record at
full length, as the only role of the grandchild is
doing proper reblocking. */
if (length > 0)
{
memset (record_start->buffer + length, 0, record_size - length);
status = sys_write_archive_buffer ();
if (status != record_size)
archive_write_error (status);
}
/* There is nothing else to read, break out. */
break;
}
status = sys_write_archive_buffer ();
if (status != record_size)
archive_write_error (status);
}
wait_for_grandchild (grandchild_pid);
}