Efficient linking and loading for late binding and platform retargeting

• US 20050223018A1
• Filed: 05/23/2005
• Published: 10/06/2005
• Est. Priority Date: 09/09/1998
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Forin, Alessandro, Helander, Johannes V.
• Granted Patent: US 8,434,099 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 8/41 Compilation
• CPC Class Codes: G06F 9/4411 Configuring for operating with peripheral devices; Loading of device drivers
• CPC Class Codes: G06F 9/4413 Plug-and-play [PnP]
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading
• CPC Class Codes: G06Q 10/10 Office automation; Time management
• CPC Class Codes: G06Q 40/00 Finance; Insurance; Tax strategies; Processing of corporate or income taxes

Abstract

A method of producing an executable image from an object file without shared library support from the operating system, wherein the executable image requires a shared library file in order to resolve at least one of the symbols called for in the object file. A method of optimizing the loading of a previously linked file into working memory in a computer for executing in a single address space of the working memory, the file containing an instruction to make an indirect jump to a location in a shared library through an import section of the file. A method for optimizing the loading of a previously linked file into working memory in a computer for executing in a single address space of the working memory, the file containing plural sections with number-filled padding between the end of each section and a succeeding page boundary. A method of optimizing the loading of a previously linked file into working memory in a computer for executing in a memory sharable with other executables. This method includes selecting a portion of code in the previously linked file, removing the portion of code from the previously linked file, and constructing a dynamically linked library file containing the portion of the code, the dynamically linked library file being available to plural files including the previously linked-file. A method of converting an image which has been previously linked for executing in an unshared memory into an image optimized for use with virtual memory.

Claims

1. In a computer with an operating system, a method of producing an executable image from an object file without shared library support from said operating system, wherein the executable image requires a shared library file in order to resolve at least one of the symbols called for in said object file, said method comprising:

permitting said operating system to link said object file, whereby at least one symbol remains unresolved after linking of the object file;

performing a post-link time link process comprising;

(a) constructing an import table;

(b) copying from a record in a definition file information pointing to the definition of said at least one symbol in said shared library file and writing at least some of said information as an entry in said import table;

(c) altering a relocation entry in said object file naming said at least one symbol so that said relocation entry both;

(i) names said at least one symbol and

(ii) points to said entry in said import table; and

(d) putting said import table into said executable image, whereby said at least one symbol is resolved through said relocation entry to a definition of said symbol exported by said shared library file.

2. The method of claim 1 wherein said information comprises:

a name of said shared library file;

an index specifying said entry in said import table;

an ordinal specifying an entry in an export table of said shared library file.

3. The method of claim 2 wherein said index is the index of said record of said definition file.

4. The method of claim 3 wherein said information further comprises:

a unique identifier number of a particular export table of said shared library file.

5. The method of claim 2 wherein the step of altering comprises:

inserting into said relocation entry a reference to said ordinal and said index.

6. The method of claim 5 wherein said reference is a pointer to an entry in a symbol section of said object file, said entry correlating said at least one symbol with said ordinal and said index.

7. The method of claim 6, wherein said writing step comprises writing said index and said file name in said import table entry, said method further comprising:

writing said ordinal and index into said entry in said symbol section, whereby said relation entry points to said entry in said symbol section containing said ordinal and index.

8. The method of claim 1 further comprising the step of producing said shared library file from a library object file containing said at least one symbol without shared library support from said operating system.

9-12. -12. (canceled)

13. A computer, comprising:

an object file requiring a shared library in order to resolve at least one of the symbols called for in said object file, said object file having been compiled and linked in an operating system without provision for a shared library whereby at least one symbol is unresolved in a symbol entry of said object file, said object file having a relocation entry pointing to said symbol;

a shared library file containing said definition of said at least one symbol;

a definition file containing a record having information pointing to the definition of said at least one symbol in said shared library;

a post-link time linker containing computer executable instructions, said computer carrying out said instructions by performing the steps of;

(a) constructing an import table;

(b) copying from said record in said definition file said information and writing at least some of said information as an entry in said import table;

(c) altering said relocation entry so that said relocation entry both;

(i) names said at least one symbol and

(ii) points to said entry in said import table; and

(d) putting said import table into an image file, whereby said at least one symbol is resolved through said relocation entry to a definition of said at least one symbol exported by said shared library file.

14. The computer of claim 13 wherein said information comprises:

the name of said shared library file;

an index specifying said entry in said import table;

an ordinal specifying an entry in an export table of said shared library file.

21. The computer of claim 14 wherein said computer carries out said instructions by performing the further steps of:

producing said shared library file from a library object file containing said at least one symbol without shared library support from said operating system, wherein the step of producing said shared library comprises;

permitting said operating system to link said library object file, whereby said library object file lacks said export table after the linking;

performing a post-link time link process on said library object file comprising;

(a) constructing an export table;

(b) writing the location of said at least one symbol in said library object file into a position in said export table corresponding to the value of said ordinal as said entry in said export table; and

(c) putting said export table into said library object file, whereby said library object file becomes said shared library file.

22. The computer of claim 21, wherein said computer carries out said instructions by performing the further steps of:

copying from said record in said definition file said identifier; and

labeling said export table with said identifier.

23. The computer of claim 21 wherein the step of writing the location of said at least one symbol as said entry in said export table is preceded by the step of copying said location of said at least one symbol from a symbol section of said library object file.

24. The computer of claim 21 wherein the step of writing the location of said at least one symbol as said entry in said export table is preceded by the step of copying said location from said record of said definition file.

25. The computer of claim 22 wherein said shared library file comprises plural export tables, each labeled with a unique identifier.

26. The computer of claim 25, wherein said unique identifier facilitates version control of different versions of a shared library, each such export table representing one previous version of the shared library.

27. The computer of claim 26, wherein such plural export tables are searchable at run-time for a specific Interface requested by an application via a call to the QueryInterface method.

15-20. -20. (canceled)

28-45. -45. (canceled)

46. A method of converting an image which has been previously linked for executing in an unshared memory into an image optimized for use with virtual memory, comprising:

selecting a portion of code in said previously linked file;

removing said portion of code from said previously linked file; and

constructing a dynamically linked library file containing said portion of said code, said dynamically linked library file being available to plural files including said previously linked file.

47. The method of claim 46 wherein said virtual memory is sharable with plural images including said previously linked image.

48. The method of claim 46 further comprising modifying said previously linked file to refer to said dynamically linked file.