[Tex/LaTex] Margins in section header

Question

I redefined some commands to meet my university requirements in my 'report' based class, and these commands basically work fine. Additionally, I need to change sections/subsections header margin rules.

Now I have:

    1.1 Very long section name Lorem ipsum dolor sit amet, consectetur adipisci veliturea
        adipiscing elit. Ut convallis pharetra augue at aliquet.

    Text text text Aliquam sem quam, euismod id consequat in, rutrum ac ipsum. Vestibulum 
pellentesque vitae lectus. Mauris feugiat lectus gravida nisi aliquam quis sodales eros. 

And what I need:

    1.1 Very long section name Lorem ipsum dolor sit amet, consectetur adipisci veliturea
adipiscing elit. Ut convallis pharetra augue at aliquet.

    Text text text Aliquam sem quam, euismod id consequat in, rutrum ac ipsum. Vestibulum 
pellentesque vitae lectus. Mauris feugiat lectus gravida nisi aliquam quis sodales eros.

Current 'section' command:

\newcommand\section{%
      \renewcommand{\@seccntformat}[1]{%
      %% custom section caption
      \csname thesection\endcsname\hspace{0.5em}}%
      %% custom first line indent
      \@startsection {section}{1}{10mm}%
      {3.5ex \@plus 1ex \@minus .2ex}%
      {2.3ex \@plus.2ex}%
      %% disable hyphenation 
      {\normalfont\bfseries\raggedright}}

In other words, I want to preserve the first line indent that I have set, but all other lines in section/subsection headers should be presented with zero margin, as in chapter header. How can I do that?

UPD. I think we can see it with standard 'report' class (the same behavior):

\documentclass{report}

\usepackage{indentfirst}

\begin{document}

\chapter{Very long chapter name Lorem ipsum dolor sit amet, consectetur adipisci veliturea
adipiscing elit. Ut convallis pharetra augue at aliquet.}

\section{Very long section name Lorem ipsum dolor sit amet, consectetur adipisci veliturea
adipiscing elit. Ut convallis pharetra augue at aliquet.}

Some text Lorem ipsum dolor sit amet, consectetur adipisci veliturea
adipiscing elit. Ut convallis pharetra augue at aliquet.

\end{document}

Answer 1

Another option, not requiring additional packages would be to use the TeX primitive \parshape:

\newcommand\section{%
      \renewcommand{\@seccntformat}[1]{%
      \csname thesection\endcsname\hspace{0.5em}}%
      \@startsection {section}{1}{10mm}%
      {3.5ex \@plus 1ex \@minus .2ex}%
      {2.3ex \@plus.2ex}%
      {\normalfont\bfseries\raggedright\parshape 1 0cm \textwidth}}

An example:

\documentclass{book}

\makeatletter
\renewcommand\section{%
      \renewcommand{\@seccntformat}[1]{%
      \csname thesection\endcsname\hspace{0.5em}}%
      \@startsection {section}{1}{10mm}%
      {3.5ex \@plus 1ex \@minus .2ex}%
      {2.3ex \@plus.2ex}%
      {\normalfont\bfseries\raggedright\parshape 1 0cm \textwidth}}
\makeatother

\begin{document}
\chapter{Test Chapter}

\section{Very long section name Lorem ipsum dolor sit amet, consectetur adipisci veliturea
adipiscing elit. Ut convallis pharetra augue at aliquet.}

Some text Lorem ipsum dolor sit amet, consectetur adipisci veliturea
adipiscing elit. Ut convallis pharetra augue at aliquet.

\end{document}