Merge remote-tracking branch 'lenormf/command-force-write'

README.asciidoc

@@ -676,8 +676,10 @@ command `q!` has to be used).
  * `e[dit][!] <filename> [<line> [<column>]]`: open buffer on file, go to given
      line and column. If file is already opened, just switch to this file.
      use edit! to force reloading.
- * `w[rite] [<filename>]`: write buffer to <filename> or use it's name if
+ * `w[rite][!] [<filename>]`: write buffer to <filename> or use it's name if
-     filename is not given.
+     filename is not given. If the file is write-protected, its
+     permissions are temporarily changed to allow saving the buffer and
+     restored afterwards when the write! command is used.
  * `w[rite]a[ll]`: write all buffers that are associated to a file.
  * `q[uit][!]`: exit Kakoune, use quit! to force quitting even if there is some
      unsaved buffers remaining.

doc/manpages/commands.asciidoc

@@ -24,8 +24,11 @@ command *q!* has to be used).
 	open buffer on file, go to given line and column. If file is already
 	opened, just switch to this file. Use edit! to force reloading
 
-*w[rite]* [<filename>]::
+*w[rite][!]* [<filename>]::
-	write buffer to <filename> or use it's name if filename is not given
+	write buffer to <filename> or use it's name if filename is not
+	given. If the file is write-protected, its permissions are temporarily
+	changed to allow saving the buffer and restored afterwards when
+	the write! command is used.
 
 *w[rite]a[ll]*::
 	write all buffers that are associated to a file

src/commands.cc

@@ -309,6 +309,7 @@ const CommandDesc force_edit_cmd = {
     edit<true>
 };
 
+template<bool force = false>
 void write_buffer(const ParametersParser& parser, Context& context, const ShellContext&)
 {
     Buffer& buffer = context.buffer();
@@ -326,7 +327,7 @@ void write_buffer(const ParametersParser& parser, Context& context, const ShellC
                     buffer.name() : parse_filename(parser[0]);
 
     context.hooks().run_hook("BufWritePre", filename, context);
-    write_buffer_to_file(buffer, filename);
+    write_buffer_to_file(buffer, filename, force);
     context.hooks().run_hook("BufWritePost", filename, context);
 }
 
@@ -342,6 +343,18 @@ const CommandDesc write_cmd = {
     write_buffer,
 };
 
+const CommandDesc force_write_cmd = {
+    "write!",
+    "w!",
+    "write [filename]: write the current buffer to its file "
+    "or to [filename] if specified, even when the file is write protected",
+    single_optional_param,
+    CommandFlags::None,
+    CommandHelper{},
+    filename_completer,
+    write_buffer<true>,
+};
+
 void write_all_buffers(Context& context)
 {
     // Copy buffer list because hooks might be creating/deleting buffers
@@ -2102,6 +2115,7 @@ void register_commands()
     register_command(edit_cmd);
     register_command(force_edit_cmd);
     register_command(write_cmd);
+    register_command(force_write_cmd);
     register_command(write_all_cmd);
     register_command(write_all_quit_cmd);
     register_command(kill_cmd);

src/file.cc

@@ -278,9 +278,27 @@ void write_buffer_to_fd(Buffer& buffer, int fd)
     }
 }
 
-void write_buffer_to_file(Buffer& buffer, StringView filename)
+void write_buffer_to_file(Buffer& buffer, StringView filename, bool force)
 {
-    int fd = open(filename.zstr(), O_CREAT | O_WRONLY | O_TRUNC, 0644);
+    struct stat st;
+    auto zfilename = filename.zstr();
+
+    if (force)
+    {
+        if (::stat(zfilename, &st) == 0)
+        {
+            if (::chmod(zfilename, st.st_mode | S_IWUSR) < 0)
+                throw runtime_error("couldn't change file permissions");
+        }
+        else
+            force = false;
+    }
+    auto restore_mode = on_scope_end([&]{
+        if (force and ::chmod(zfilename, st.st_mode) < 0)
+            throw runtime_error("couldn't restore file permissions");
+    });
+
+    int fd = open(zfilename, O_CREAT | O_WRONLY | O_TRUNC, 0644);
     if (fd == -1)
         throw file_access_error(filename, strerror(errno));
 

src/file.hh

@@ -49,7 +49,7 @@ struct MappedFile
     struct stat st {};
 };
 
-void write_buffer_to_file(Buffer& buffer, StringView filename);
+void write_buffer_to_file(Buffer& buffer, StringView filename, bool force = false);
 void write_buffer_to_fd(Buffer& buffer, int fd);
 void write_buffer_to_backup_file(Buffer& buffer);