Creation Zone

  • Subscribe to our RSS feed.
  • Twitter
  • StumbleUpon
  • Reddit
  • Facebook
  • Digg

Wednesday, 15 September 2004

Solaris/S1S9: Scope of Symbols: Default scope contd.,

Posted on 18:12 by Unknown
[Updated: 04/07/2006] Much accurate information is available in a better format at:
Reducing Symbol Scope with Sun Studio C/C++
__________________

Lets add one more local method called "addtentomyage()" in hidden.h

hidden.h
---------
bpte4500s001:/sunbuild1/giri/testcases/symbol-hiding/%cat hidden.c
#include
#include "hidden.h"

int age = 25;

int addtentomyage(int age)
{
return ((int) age + 10);
}

char *lastname(char *firstname)
{
return ((char *)"mandalika");
}

char firstchar(char *strings)
{
return (*strings);
}

int agefunc()
{
int finalage = 0;

finalage = addtentomyage(age);
return (finalage);
}


Create libhidden.so and run the driver program

bpte4500s001:/sunbuild1/giri/testcases/symbol-hiding/% CC -c hidden.c ; CC -G -o libhidden.so hidden.o ; CC -lhidden -o driver driver.c

bpte4500s001:/sunbuild1/giri/testcases/symbol-hiding/%./driver

lname = mandalika
age = 35
first char = c
Cool; got the expected result

Now lets introduce one more library called "libgeneric" with a buggy implementation for addtentomyage()

bpte4500s001:/sunbuild1/giri/testcases/symbol-hiding/%cat generic.c
#include "hidden.h"

int addtentomyage(int age)
{
return ((int) age + 100);
}
Compile & create a new library called "libgeneric"

bpte4500s001:/sunbuild1/giri/testcases/symbol-hiding/%CC -c generic.c ; CC -G -o libgeneric.so generic.o

Now link the new library (libgeneric) with the driver executable as follows (observe that libgeneric is placed before libhidden in the compile line):

bpte4500s001:/sunbuild1/giri/testcases/symbol-hiding/%CC -o driver -lgeneric -lhidden driver.c

Run the driver program and observe the result:
bpte4500s001:/sunbuild1/giri/testcases/symbol-hiding/%./driver

lname = mandalika
age = 125
first char = c
That's not good; the expected age was 35, but got 125! What's wrong?

Even though there is an implementation available inside the libhidden module itself, linker picked up the implementation from libgeneric by blindly following the left to right rule (ref: Linker & Libraries guide by Sun Microsystems). And in general references to global symbols within shared objects are not bound until runtime, even if definitions are available, so that definitions of the same symbol in an executable or other shared object can override the object's own definition

The tool "ldd" will be useful for dumping the dependency ordering
bpte4500s001:/sunbuild1/giri/testcases/symbol-hiding/%ldd driver
libgeneric.so => /sunbuild1/giri/testcases/symbol-hiding/libgeneric.so
libhidden.so => /sunbuild1/giri/testcases/symbol-hiding/libhidden.so
libCstd.so.1 => /usr/lib/libCstd.so.1
libCrun.so.1 => /usr/lib/libCrun.so.1
libm.so.1 => /usr/lib/libm.so.1
libw.so.1 => /usr/lib/libw.so.1
libc.so.1 => /usr/lib/libc.so.1
libdl.so.1 => /usr/lib/libdl.so.1
/usr/lib/cpu/sparcv8plus/libCstd_isa.so.1
/usr/platform/SUNW,Ultra-Enterprise/lib/libc_psr.so.1
Advantage:
The application can take advantage of interposing libraries i.e., if needed, the application can enjoy an alternate implementation for the same set of interfaces if available

Disadvantage:
Name collisions (just like the one shown in the example); due to the collision the application may break (our example shows that broken part - expected value: 35, but the returned value is: 125)

How to override this default behavior and make it pick the right implementation?

(to be continued ..)
Email ThisBlogThis!Share to XShare to Facebook
Posted in | No comments
Newer Post Older Post Home

0 comments:

Post a Comment

Subscribe to: Post Comments (Atom)

Popular Posts

  • *nix: Workaround to cannot find zipfile directory in one of file.zip or file.zip.zip ..
    Symptom: You are trying to extract the archived files off of a huge (any file with size > 2 GB or 4GB, depending on the OS) ZIP file with...
  • C/C++: Printing Stack Trace with printstack() on Solaris
    libc on Solaris 9 and later, provides a useful function called printstack , to print a symbolic stack trace to the specified file descripto...
  • JDS: Installing Sun Java Desktop System 2.0
    This document will guide you through the process of installing JDS 2.0 on a PC from integrated CDROM images Requirements I...
  • Binary compatibility
    What's It? "Binary compatibility" (BC) is the ability of one machine to run software that was written for another without hav...
  • Solaris: NULL pointer bugs & /usr/lib/0@0.so.1 library
    Some programmers assume that a NULL character pointer is the same as a pointer to a NULL string. However de-referencing a NULL pointer (ie.,...
  • Database: Oracle Server Architecture (overview)
    Oracle server consists of the following core components: 1) database(s) & 2) instance(s) 1) database consists of: 1) datafil...
  • Sun: OpenJDK
    Open source JDK, that is. Sun Microsystems did it again -- As promised during JavaOne event back in May 2006, Sun made the implementation of...
  • Consolidating Siebel CRM 8.0 on a Single Sun SPARC Enterprise Server, T5440
    .. blueprint document is now available on wikis.sun.com . Here is the direct link to the blueprint:              Consolidating Oracle Siebel...
  • Oracle Internet Directory 11g Benchmark on SPARC T5
    SUMMARY System Under Test (SUT)     Oracle's SPARC T5-2 server Software     Oracle Internet Directory 11 g R1-PS6 Target Load     50...
  • Fix to Firefox 3 Crash on Solaris 10 x86
    Symptom : Firefox 3 crashes on Solaris 10 x86 when the web browser tries to render some of the HTML pages with SWF content in them. For exam...

Categories

  • 80s music playlist
  • bandwidth iperf network solaris
  • best
  • black friday
  • breakdown database groups locality oracle pmap sga solaris
  • buy
  • deal
  • ebiz ebs hrms oracle payroll
  • emca oracle rdbms database ORA-01034
  • friday
  • Garmin
  • generic+discussion software installer
  • GPS
  • how-to solaris mmap
  • impdp ora-01089 oracle rdbms solaris tips upgrade workarounds zombie
  • Magellan
  • music
  • Navigation
  • OATS Oracle
  • Oracle Business+Intelligence Analytics Solaris SPARC T4
  • oracle database flashback FDA
  • Oracle Database RDBMS Redo Flash+Storage
  • oracle database solaris
  • oracle database solaris resource manager virtualization consolidation
  • Oracle EBS E-Business+Suite SPARC SuperCluster Optimized+Solution
  • Oracle EBS E-Business+Suite Workaround Tip
  • oracle lob bfile blob securefile rdbms database tips performance clob
  • oracle obiee analytics presentation+services
  • Oracle OID LDAP ADS
  • Oracle OID LDAP SPARC T5 T5-2 Benchmark
  • oracle pls-00201 dbms_system
  • oracle siebel CRM SCBroker load+balancing
  • Oracle Siebel Sun SPARC T4 Benchmark
  • Oracle Siebel Sun SPARC T5 Benchmark T5-2
  • Oracle Solaris
  • Oracle Solaris Database RDBMS Redo Flash F40 AWR
  • oracle solaris rpc statd RPC troubleshooting
  • oracle solaris svm solaris+volume+manager
  • Oracle Solaris Tips
  • oracle+solaris
  • RDC
  • sale
  • Smartphone Samsung Galaxy S2 Phone+Shutter Tip Android ICS
  • solaris oracle database fmw weblogic java dfw
  • SuperCluster Oracle Database RDBMS RAC Solaris Zones
  • tee
  • thanksgiving sale
  • tips
  • TomTom
  • windows

Blog Archive

  • ►  2013 (16)
    • ►  December (3)
    • ►  November (2)
    • ►  October (1)
    • ►  September (1)
    • ►  August (1)
    • ►  July (1)
    • ►  June (1)
    • ►  May (1)
    • ►  April (1)
    • ►  March (1)
    • ►  February (2)
    • ►  January (1)
  • ►  2012 (14)
    • ►  December (1)
    • ►  November (1)
    • ►  October (1)
    • ►  September (1)
    • ►  August (1)
    • ►  July (1)
    • ►  June (2)
    • ►  May (1)
    • ►  April (1)
    • ►  March (1)
    • ►  February (1)
    • ►  January (2)
  • ►  2011 (15)
    • ►  December (2)
    • ►  November (1)
    • ►  October (2)
    • ►  September (1)
    • ►  August (2)
    • ►  July (1)
    • ►  May (2)
    • ►  April (1)
    • ►  March (1)
    • ►  February (1)
    • ►  January (1)
  • ►  2010 (19)
    • ►  December (3)
    • ►  November (1)
    • ►  October (2)
    • ►  September (1)
    • ►  August (1)
    • ►  July (1)
    • ►  June (1)
    • ►  May (5)
    • ►  April (1)
    • ►  March (1)
    • ►  February (1)
    • ►  January (1)
  • ►  2009 (25)
    • ►  December (1)
    • ►  November (2)
    • ►  October (1)
    • ►  September (1)
    • ►  August (2)
    • ►  July (2)
    • ►  June (1)
    • ►  May (2)
    • ►  April (3)
    • ►  March (1)
    • ►  February (5)
    • ►  January (4)
  • ►  2008 (34)
    • ►  December (2)
    • ►  November (2)
    • ►  October (2)
    • ►  September (1)
    • ►  August (4)
    • ►  July (2)
    • ►  June (3)
    • ►  May (3)
    • ►  April (2)
    • ►  March (5)
    • ►  February (4)
    • ►  January (4)
  • ►  2007 (33)
    • ►  December (2)
    • ►  November (4)
    • ►  October (2)
    • ►  September (5)
    • ►  August (3)
    • ►  June (2)
    • ►  May (3)
    • ►  April (5)
    • ►  March (3)
    • ►  February (1)
    • ►  January (3)
  • ►  2006 (40)
    • ►  December (2)
    • ►  November (6)
    • ►  October (2)
    • ►  September (2)
    • ►  August (1)
    • ►  July (2)
    • ►  June (2)
    • ►  May (4)
    • ►  April (5)
    • ►  March (5)
    • ►  February (3)
    • ►  January (6)
  • ►  2005 (72)
    • ►  December (5)
    • ►  November (2)
    • ►  October (6)
    • ►  September (5)
    • ►  August (5)
    • ►  July (10)
    • ►  June (8)
    • ►  May (9)
    • ►  April (6)
    • ►  March (6)
    • ►  February (5)
    • ►  January (5)
  • ▼  2004 (36)
    • ►  December (1)
    • ►  November (5)
    • ►  October (12)
    • ▼  September (18)
      • Solaris: Virtual Memory System
      • Linux: Installing Source RPM (SRPM) package
      • Linux: Installing Dynamic Fonts
      • UNIX/C: Program that prints Itself
      • SPARC: Position Independent Code (PIC)
      • Solaris/S1S9: Scope of Symbols IV - hidden scope
      • Solaris/S1S9: Scope of Symbols - Adv/Disadv of GLO...
      • Solaris/S1S9: Scope of Symbols :: III symbolic sco...
      • Solaris/S1S9: Scope of Symbols - III symbolic scope
      • Solaris/S1S9: Scope of Symbols: Default scope contd.,
      • Solaris/S1S9: Scope of Symbols - II :: Default scope
      • Solaris/S1S9: Scope of Symbols - I :: Source files
      • Solaris & UltraSPARC IV: Displaying processor info...
      • JDS: Installing Sun Java Desktop System 2.0
      • Solaris: malloc Vs mtmalloc
      • Solaris: Recovering from a Runtime Linker Failure
      • Linux: Finding out the amount of free & used memory
      • UNIX®: How to build a Shared Library (*.so file)
Powered by Blogger.

About Me

Unknown
View my complete profile