[Bug-wget] [PATCH v5 1/4] Make wget capable of starting downloads from a specified position.

[Yousong Zhou]

This patch adds an option `--start-pos' for specifying starting position
of a HTTP or FTP download.

Signed-off-by: Yousong Zhou <address@hidden>
---
 doc/ChangeLog |    4 ++++
 doc/wget.texi |   16 ++++++++++++++++
 src/ChangeLog |    7 +++++++
 src/ftp.c     |    2 ++
 src/http.c    |    2 ++
 src/init.c    |    4 ++++
 src/main.c    |   18 +++++++++++++++---
 src/options.h |    1 +
 8 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/doc/ChangeLog b/doc/ChangeLog
index 58d1439..68629c6 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,7 @@
+2014-02-10  Yousong Zhou  <address@hidden>
+
+       * wget.texi: Add documentation for --start-pos.
+
 2013-12-29  Giuseppe Scrivano  <address@hidden>
 
        * wget.texi: Update to GFDL 1.3.
diff --git a/doc/wget.texi b/doc/wget.texi
index 6a8c6a3..0b23bda 100644
--- a/doc/wget.texi
+++ b/doc/wget.texi
@@ -701,6 +701,22 @@ Another instance where you'll get a garbled file if you 
try to use
 Note that @samp{-c} only works with @sc{ftp} servers and with @sc{http}
 servers that support the @code{Range} header.
 
address@hidden offset
address@hidden continue retrieval
address@hidden incomplete downloads
address@hidden resume download
address@hidden start position
address@hidden address@hidden
+Start downloading at zero-based position @var{OFFSET}.  Offset may be expressed
+in bytes, kilobytes with the `k' suffix, or megabytes with the `m' suffix, etc.
+
address@hidden has higher precedence over @samp{--continue}. When
address@hidden and @samp{--continue} are both specified, wget will emit a
+warning then proceed as if @samp{--continue} was absent.
+
+Server support for continued download is required, otherwise @samp{--start-pos}
+cannot help.  See @samp{-c} for details.
+
 @cindex progress indicator
 @cindex dot style
 @item address@hidden
diff --git a/src/ChangeLog b/src/ChangeLog
index b7b6753..6615ad7 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2014-02-10  Yousong Zhou  <address@hidden>
+
+       * init.c, main.c, options.h: Add option --start-pos for specifying
+       start position of a download.
+       * http.c: Utilize opt.start_pos for HTTP download.
+       * ftp.c: Utilize opt.start_pos for FTP retrieval.
+
 2014-02-06  Giuseppe Scrivano  <address@hidden>
 
        * main.c (print_version): Move copyright year out of the localized
diff --git a/src/ftp.c b/src/ftp.c
index c2522ca..5282588 100644
--- a/src/ftp.c
+++ b/src/ftp.c
@@ -1632,6 +1632,8 @@ ftp_loop_internal (struct url *u, struct fileinfo *f, 
ccon *con, char **local_fi
       /* Decide whether or not to restart.  */
       if (con->cmd & DO_LIST)
         restval = 0;
+      else if (opt.start_pos >= 0)
+        restval = opt.start_pos;
       else if (opt.always_rest
           && stat (locf, &st) == 0
           && S_ISREG (st.st_mode))
diff --git a/src/http.c b/src/http.c
index 5715df6..0bede9d 100644
--- a/src/http.c
+++ b/src/http.c
@@ -3101,6 +3101,8 @@ Spider mode enabled. Check if remote file exists.\n"));
       /* Decide whether or not to restart.  */
       if (force_full_retrieve)
         hstat.restval = hstat.len;
+      else if (opt.start_pos >= 0)
+        hstat.restval = opt.start_pos;
       else if (opt.always_rest
           && got_name
           && stat (hstat.local_file, &st) == 0
diff --git a/src/init.c b/src/init.c
index 56fef50..9ed72b2 100644
--- a/src/init.c
+++ b/src/init.c
@@ -270,6 +270,7 @@ static const struct {
   { "showalldnsentries", &opt.show_all_dns_entries, cmd_boolean },
   { "spanhosts",        &opt.spanhost,          cmd_boolean },
   { "spider",           &opt.spider,            cmd_boolean },
+  { "startpos",         &opt.start_pos,         cmd_bytes },
   { "strictcomments",   &opt.strict_comments,   cmd_boolean },
   { "timeout",          NULL,                   cmd_spec_timeout },
   { "timestamping",     &opt.timestamping,      cmd_boolean },
@@ -406,6 +407,9 @@ defaults (void)
   opt.warc_cdx_dedup_filename = NULL;
   opt.warc_tempdir = NULL;
   opt.warc_keep_log = true;
+
+  /* Use a negative value to mark the absence of --start-pos option */
+  opt.start_pos = -1;
 }
 
 /* Return the user's home directory (strdup-ed), or NULL if none is
diff --git a/src/main.c b/src/main.c
index 3ce7583..39fcff4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -276,6 +276,7 @@ static struct cmdline_option option_data[] =
     { "server-response", 'S', OPT_BOOLEAN, "serverresponse", -1 },
     { "span-hosts", 'H', OPT_BOOLEAN, "spanhosts", -1 },
     { "spider", 0, OPT_BOOLEAN, "spider", -1 },
+    { "start-pos", 0, OPT_VALUE, "startpos", -1 },
     { "strict-comments", 0, OPT_BOOLEAN, "strictcomments", -1 },
     { "timeout", 'T', OPT_VALUE, "timeout", -1 },
     { "timestamping", 'N', OPT_BOOLEAN, "timestamping", -1 },
@@ -486,6 +487,8 @@ Download:\n"),
     N_("\
   -c,  --continue                resume getting a partially-downloaded 
file.\n"),
     N_("\
+       --start-pos=OFFSET        start downloading from zero-based position 
OFFSET.\n"),
+    N_("\
        --progress=TYPE           select progress gauge type.\n"),
     N_("\
   -N,  --timestamping            don't re-retrieve files unless newer than\n\
@@ -1323,12 +1326,13 @@ for details.\n\n"));
                    _("WARC output does not work with --spider.\n"));
           exit (1);
         }
-      if (opt.always_rest)
+      if (opt.always_rest || opt.start_pos >= 0)
         {
           fprintf (stderr,
-                   _("WARC output does not work with --continue, "
-                     "--continue will be disabled.\n"));
+                   _("WARC output does not work with --continue or"
+                     " --start-pos, they will be disabled.\n"));
           opt.always_rest = false;
+          opt.start_pos = -1;
         }
       if (opt.warc_cdx_dedup_filename != 0 && !opt.warc_digests_enabled)
         {
@@ -1350,6 +1354,14 @@ for details.\n\n"));
       exit (1);
     }
 
+  if (opt.start_pos >= 0 && opt.always_rest)
+    {
+      fprintf (stderr,
+               _("Specifying both --start-pos and --continue is not "
+                 "recommended; --continue will be disabled.\n"));
+      opt.always_rest = false;
+    }
+
   if (!nurl && !opt.input_filename)
     {
       /* No URL specified.  */
diff --git a/src/options.h b/src/options.h
index 06783cc..b527829 100644
--- a/src/options.h
+++ b/src/options.h
@@ -116,6 +116,7 @@ struct options
   bool ask_passwd;              /* Ask for password? */
 
   bool always_rest;            /* Always use REST. */
+  wgint start_pos;             /* Start position of a download. */
   char *ftp_user;              /* FTP username */
   char *ftp_passwd;            /* FTP password */
   bool netrc;                  /* Whether to read .netrc. */
-- 
1.7.2.5