code segment
{{Short description|Portion of an object file containing executable instructions}}
File:Program memory layout.svg and heap sections.]]
In computing, a code segment, also known as a text segment or simply as text, is a portion of an object file or the corresponding section of the program's virtual address space that contains executable instructions.{{Cite web
| url = http://www.cs.uwm.edu/classes/cs315/Bacon/Lecture/HTML/ch10s04.html
| title = Chapter 10. Subprogram Calls and the Stack
| at = Section 10.4. Memory Segments
| date = 2012-03-13
| accessdate = 2014-05-02
| author = Jason W. Bacon
| website = cs.uwm.edu
| archive-date = 2014-05-02
| archive-url = https://web.archive.org/web/20140502115622/http://www.cs.uwm.edu/classes/cs315/Bacon/Lecture/HTML/ch10s04.html
| url-status = dead
}}
Segment
The term "segment" comes from the memory segment, which is a historical approach to memory management that has been succeeded by paging. When a program is stored in an object file, the code segment is a part of this file; when the loader places a program into memory so that it may be executed, various memory regions are allocated (in particular, as pages), corresponding to both the segments in the object files and to segments only needed at run time. For example, the code segment of an object file is loaded into a corresponding code segment in memory.
The code segment in memory is typically read-only and has a fixed size, so on embedded systems it can usually be placed in read-only memory (ROM), without the need for loading. If the code segment is not read-only, then the particular architecture allows self-modifying code. Fixed-position or position-independent code may be shared in memory by several processes in segmented or paged memory systems.{{Cite web
| url = http://www.beingdeveloper.com/memory-layout-of-a-program/
| title = Code Segment and Data Segment: Memory Layout of a Program
| date = 2012-09-20
| accessdate = 2014-05-02
| author = Kai Wang
| website = beingdeveloper.com
| archive-date = 2014-05-02
| archive-url = https://web.archive.org/web/20140502121214/http://www.beingdeveloper.com/memory-layout-of-a-program/
| url-status = dead
}} As a memory region, the code segment may be placed below the heap or stack in order to prevent heap and stack overflows from overwriting it.{{Cite conference
| doi = 10.1109/ISCIT.2005.1567023
| title = Buffer overflow protection based on adjusting code segment limit
| conference = IEEE International Symposium on Communications and Information Technology
| date = October 2005
| author1 = Yu-An Tan | author2 = Ji-yan Zheng | author3 = Yuan-Da Cao | author4 = Xue-lan Zhang
| publisher = IEEE
}}
See also
{{Portal|Computer programming}}