(seek_archive): New function

[chaz/tar] / src / buffer.c

diff --git a/src/buffer.c b/src/buffer.c
index 7fd43f647e694020fa82f35265416d2229c70926..80bbe829b4d031ed0ea7b47a527f818515550e4b 100644 (file)
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -75,7 +75,7 @@ static int checkpoint;
    Declared in update.c
 
    As least EXTERN like this one as possible. (?? --gray)
-   FIXME: Either eliminate it or move it to common.h. 
+   FIXME: Either eliminate it or move it to common.h.
 */
 extern bool time_to_start_writing;
 
@@ -109,7 +109,7 @@ static off_t real_s_sizeleft;
 /* Functions.  */
 
 void
-clear_read_error_count ()
+clear_read_error_count (void)
 {
   read_error_count = 0;
 }
@@ -599,7 +599,7 @@ archive_read_error (void)
 }
 
 static void
-short_read (ssize_t status)
+short_read (size_t status)
 {
   size_t left;                 /* bytes left */
   char *more;                  /* pointer to next byte to read */
@@ -611,23 +611,23 @@ short_read (ssize_t status)
         || (left && status && read_full_records_option))
     {
       if (status)
-       while ((status = rmtread (archive, more, left)) < 0)
+       while ((status = rmtread (archive, more, left)) == SAFE_READ_ERROR)
          archive_read_error ();
 
       if (status == 0)
        {
          char buf[UINTMAX_STRSIZE_BOUND];
-         
+
          WARN((0, 0, _("Read %s bytes from %s"),
                STRINGIFY_BIGINT (record_size - left, buf),
                *archive_name_cursor));
          break;
        }
-  
+
       if (! read_full_records_option)
        {
          unsigned long rest = record_size - left;
-         
+
          FATAL_ERROR ((0, 0,
                        ngettext ("Unaligned block (%lu byte) in archive",
                                  "Unaligned block (%lu bytes) in archive",
@@ -644,8 +644,8 @@ short_read (ssize_t status)
   /* FIXME: for size=0, multi-volume support.  On the first record, warn
      about the problem.  */
 
-  if (!read_full_records_option && verbose_option
-      && record_start_block == 0 && status > 0)
+  if (!read_full_records_option && verbose_option > 1
+      && record_start_block == 0 && status != 0)
     {
       unsigned long rsize = (record_size - left) / BLOCKSIZE;
       WARN ((0, 0,
@@ -663,7 +663,7 @@ short_read (ssize_t status)
 void
 flush_read (void)
 {
-  ssize_t status;              /* result from system call */
+  size_t status;               /* result from system call */
 
   if (checkpoint_option && !(++checkpoint % 10))
     WARN ((0, 0, _("Read checkpoint %d"), checkpoint));
@@ -710,9 +710,9 @@ flush_read (void)
      This is incorrect since even if new_volume() succeeds, the
      subsequent call to rmtread will overwrite the chunk of data
      already read in the buffer, so the processing will fail */
-        
+
   if ((status == 0
-       || (status < 0 && errno == ENOSPC))
+       || (status == SAFE_READ_ERROR && errno == ENOSPC))
       && multi_volume_option)
     {
       union block *cursor;
@@ -733,12 +733,12 @@ flush_read (void)
          break;
        }
 
-      while ((status =
-             rmtread (archive, record_start->buffer, record_size)) < 0)
+      while ((status = rmtread (archive, record_start->buffer, record_size))
+            == SAFE_READ_ERROR)
        archive_read_error ();
-      
+
       if (status != record_size)
-       short_read (status); 
+       short_read (status);
 
       cursor = record_start;
 
@@ -806,7 +806,7 @@ flush_read (void)
       records_read++;
       return;
     }
-  else if (status < 0)
+  else if (status == SAFE_READ_ERROR)
     {
       archive_read_error ();
       goto error_loop;         /* try again */
@@ -888,6 +888,42 @@ backspace_output (void)
   }
 }
 
+off_t
+seek_archive (off_t size)
+{
+  off_t start = current_block_ordinal ();
+  off_t offset;
+  off_t nrec, nblk;
+  off_t skipped = (blocking_factor - (current_block - record_start));
+  
+  size -= skipped * BLOCKSIZE;
+  
+  if (size < record_size)
+    return 0;
+  /* FIXME: flush? */
+  
+  /* Compute number of records to skip */
+  nrec = size / record_size;
+  offset = rmtlseek (archive, nrec * record_size, SEEK_CUR);
+  if (offset < 0)
+    return offset;
+
+  if (offset % record_size)
+    FATAL_ERROR ((0, 0, _("rmtlseek not stopped at a record boundary")));
+
+  /* Convert to number of records */
+  offset /= BLOCKSIZE;
+  /* Compute number of skipped blocks */
+  nblk = offset - start;
+
+  /* Update buffering info */
+  records_read += nblk / blocking_factor;
+  record_start_block = offset - blocking_factor;
+  current_block = record_end;
+ 
+  return nblk;
+}
+
 /* Close the archive file.  */
 void
 close_archive (void)
@@ -896,7 +932,7 @@ close_archive (void)
     flush_archive ();
 
   sys_drain_input_pipe ();
-  
+
   if (verify_option)
     verify_volume ();
 
@@ -904,7 +940,7 @@ close_archive (void)
     close_warn (*archive_name_cursor);
 
   sys_wait_for_child (child_pid);
-  
+
   tar_stat_destroy (&current_stat_info);
   if (save_name)
     free (save_name);
@@ -956,7 +992,7 @@ closeout_volume_number (void)
    Return nonzero on success.
 */
 static bool
-new_volume (enum access_mode access)
+new_volume (enum access_mode mode)
 {
   static FILE *read_file;
   static int looped;
@@ -1085,7 +1121,7 @@ new_volume (enum access_mode access)
     archive = rmtopen (*archive_name_cursor, O_RDWR | O_CREAT, MODE_RW,
                       rsh_command_option);
   else
-    switch (access)
+    switch (mode)
       {
       case ACCESS_READ:
        archive = rmtopen (*archive_name_cursor, O_RDONLY, MODE_RW,
@@ -1108,7 +1144,7 @@ new_volume (enum access_mode access)
   if (archive < 0)
     {
       open_warn (*archive_name_cursor);
-      if (!verify_option && access == ACCESS_WRITE && backup_option)
+      if (!verify_option && mode == ACCESS_WRITE && backup_option)
        undo_last_backup ();
       goto tryagain;
     }