rred: truncate result file before writing to it

[apt.git] / methods / rred.cc

diff --git a/methods/rred.cc b/methods/rred.cc
index 79ab8cb5282f00e6d94bbaf176793db0c555a70e..2d2333f9125179b23c2e01366e7f562e1fe97f28 100644 (file)
--- a/methods/rred.cc
+++ b/methods/rred.cc
@@ -10,7 +10,6 @@
 #include <apt-pkg/init.h>
 #include <apt-pkg/fileutl.h>
 #include <apt-pkg/error.h>
-#include <apt-pkg/acquire-method.h>
 #include <apt-pkg/strutl.h>
 #include <apt-pkg/hashes.h>
 #include <apt-pkg/configuration.h>
@@ -336,26 +335,30 @@ class Patch {
    FileChanges filechanges;
    MemBlock add_text;
 
-   static bool retry_fwrite(char *b, size_t l, FileFd &f, Hashes *hash)
+   static bool retry_fwrite(char *b, size_t l, FileFd &f, Hashes * const start_hash, Hashes * const end_hash = nullptr)
    {
       if (f.Write(b, l) == false)
         return false;
-      if (hash)
-        hash->Add((unsigned char*)b, l);
+      if (start_hash)
+        start_hash->Add((unsigned char*)b, l);
+      if (end_hash)
+        end_hash->Add((unsigned char*)b, l);
       return true;
    }
 
-   static void dump_rest(FileFd &o, FileFd &i, Hashes *hash)
+   static void dump_rest(FileFd &o, FileFd &i,
+        Hashes * const start_hash, Hashes * const end_hash)
    {
       char buffer[BLOCK_SIZE];
       unsigned long long l = 0;
       while (i.Read(buffer, sizeof(buffer), &l)) {
-        if (l ==0  || !retry_fwrite(buffer, l, o, hash))
+        if (l ==0  || !retry_fwrite(buffer, l, o, start_hash, end_hash))
            break;
       }
    }
 
-   static void dump_lines(FileFd &o, FileFd &i, size_t n, Hashes *hash)
+   static void dump_lines(FileFd &o, FileFd &i, size_t n,
+        Hashes * const start_hash, Hashes * const end_hash)
    {
       char buffer[BLOCK_SIZE];
       while (n > 0) {
@@ -364,11 +367,11 @@ class Patch {
         size_t const l = strlen(buffer);
         if (l == 0 || buffer[l-1] == '\n')
            n--;
-        retry_fwrite(buffer, l, o, hash);
+        retry_fwrite(buffer, l, o, start_hash, end_hash);
       }
    }
 
-   static void skip_lines(FileFd &i, int n)
+   static void skip_lines(FileFd &i, int n, Hashes * const start_hash)
    {
       char buffer[BLOCK_SIZE];
       while (n > 0) {
@@ -377,6 +380,8 @@ class Patch {
         size_t const l = strlen(buffer);
         if (l == 0 || buffer[l-1] == '\n')
            n--;
+        if (start_hash)
+           start_hash->Add((unsigned char*)buffer, l);
       }
    }
 
@@ -526,15 +531,16 @@ class Patch {
       }
    }
 
-   void apply_against_file(FileFd &out, FileFd &in, Hashes *hash = NULL)
+   void apply_against_file(FileFd &out, FileFd &in,
+        Hashes * const start_hash = nullptr, Hashes * const end_hash = nullptr)
    {
       std::list<struct Change>::iterator ch;
       for (ch = filechanges.begin(); ch != filechanges.end(); ++ch) {
-        dump_lines(out, in, ch->offset, hash);
-        skip_lines(in, ch->del_cnt);
-        dump_mem(out, ch->add, ch->add_len, hash);
+        dump_lines(out, in, ch->offset, start_hash, end_hash);
+        skip_lines(in, ch->del_cnt, start_hash);
+        dump_mem(out, ch->add, ch->add_len, end_hash);
       }
-      dump_rest(out, in, hash);
+      dump_rest(out, in, start_hash, end_hash);
       out.Flush();
    }
 };
@@ -582,6 +588,16 @@ class RredMethod : public aptMethod {
         std::vector<PDiffFile> patchfiles;
         Patch patch;
 
+        HashStringList StartHashes;
+        for (char const * const * type = HashString::SupportedHashes(); *type != nullptr; ++type)
+        {
+           std::string tagname;
+           strprintf(tagname, "Start-%s-Hash", *type);
+           std::string const hashsum = LookupTag(Message, tagname.c_str());
+           if (hashsum.empty() == false)
+              StartHashes.push_back(HashString(*type, hashsum));
+        }
+
         if (FileExists(Path + ".ed") == true)
         {
            HashStringList const ExpectedHashes = ReadExpectedHashesForPatch(0, Message);
@@ -648,14 +664,22 @@ class RredMethod : public aptMethod {
            std::cerr << "FAILED to open inp " << Path << std::endl;
            return _error->Error("Failed to open inp %s", Path.c_str());
         }
-        if (out.Open(Itm->DestFile, FileFd::WriteOnly | FileFd::Create | FileFd::BufferedWrite, FileFd::Extension) == false)
+        if (out.Open(Itm->DestFile, FileFd::WriteOnly | FileFd::Create | FileFd::Empty | FileFd::BufferedWrite, FileFd::Extension) == false)
         {
            std::cerr << "FAILED to open out " << Itm->DestFile << std::endl;
            return _error->Error("Failed to open out %s", Itm->DestFile.c_str());
         }
 
-        Hashes hash(Itm->ExpectedHashes);
-        patch.apply_against_file(out, inp, &hash);
+        Hashes end_hash(Itm->ExpectedHashes);
+        if (StartHashes.usable())
+        {
+           Hashes start_hash(StartHashes);
+           patch.apply_against_file(out, inp, &start_hash, &end_hash);
+           if (start_hash.GetHashStringList() != StartHashes)
+              _error->Error("The input file hadn't the expected hash!");
+        }
+        else
+           patch.apply_against_file(out, inp, nullptr, &end_hash);
 
         out.Close();
         inp.Close();
@@ -686,7 +710,7 @@ class RredMethod : public aptMethod {
 
         Res.LastModified = bufbase.st_mtime;
         Res.Size = bufbase.st_size;
-        Res.TakeHashes(hash);
+        Res.TakeHashes(end_hash);
         URIDone(Res);
 
         return true;
@@ -704,8 +728,7 @@ int main(int argc, char **argv)
    Patch patch;
 
    if (argc <= 1) {
-      RredMethod Mth;
-      return Mth.Run();
+      return RredMethod().Run();
    }
 
    // Usage: rred -t input output diff ...
@@ -739,7 +762,7 @@ int main(int argc, char **argv)
       FileFd out, inp;
       std::cerr << "Patching " << argv[2] << " into " << argv[3] << "\n";
       inp.Open(argv[2], FileFd::ReadOnly,FileFd::Extension);
-      out.Open(argv[3], FileFd::WriteOnly | FileFd::Create | FileFd::BufferedWrite, FileFd::Extension);
+      out.Open(argv[3], FileFd::WriteOnly | FileFd::Create | FileFd::Empty | FileFd::BufferedWrite, FileFd::Extension);
       patch.apply_against_file(out, inp);
       out.Close();
    } else if (just_diff) {