Make/CVS example 1 - Revision history

Root at 19:24, 3 May 2023

2023-05-03T19:24:30Z

← Older revision		Revision as of 19:24, 3 May 2023
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	{{TOCright}}		{{TOCright}}
			'''<font color="red">THIS PAGE IS OBSOLETE</font>'''

	== The Problem (in Portuguese) ==		== The Problem (in Portuguese) ==

Root at 14:44, 6 April 2015

2015-04-06T14:44:27Z

← Older revision		Revision as of 14:44, 6 April 2015
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	new revision: 1.3; previous revision: 1.2		new revision: 1.3; previous revision: 1.2

	[[category:~~Teaching~~]]		[[category:Ensino]]

Root: /* Step 5: User Control on Dynamic Linking */

2008-03-09T18:37:38Z

Step 5: User Control on Dynamic Linking

← Older revision		Revision as of 18:37, 9 March 2008
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	This is the new <tt>main.cpp</tt> file (note the name of the symbol corresponding to the "fact" function name in C++). A better style would perhaps be to use the <tt>extern "C"</tt> declaration.		This is the new <tt>main.cpp</tt> file (note the name of the symbol corresponding to the "fact" function name in C++). A better style would perhaps be to use the <tt>extern "C"</tt> declaration.
	<~~text~~>		<cpp>
	#include <iostream>		#include <iostream>
	#include <dlfcn.h>		#include <dlfcn.h>
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	((int(*)(int))fun)(5); // call function for 5!		((int(*)(int))fun)(5); // call function for 5!
	}		}
	</~~text~~>		</cpp>

	The Makefile is the following:		The Makefile is the following:

Root at 18:37, 9 March 2008

2008-03-09T18:37:14Z

← Older revision		Revision as of 18:37, 9 March 2008
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	/cvs/factorial/main.cpp,v <-- main.cpp		/cvs/factorial/main.cpp,v <-- main.cpp
	new revision: 1.3; previous revision: 1.2		new revision: 1.3; previous revision: 1.2

			[[category:Teaching]]

Root at 18:27, 9 March 2008

2008-03-09T18:27:37Z

← Older revision		Revision as of 18:27, 9 March 2008
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	# Construa uma <tt><span style="color: #990000">Makefile</span></tt> para gerar o executável <tt><span style="color: #990000">fact</span></tt>, a partir dos ficheiros anteriores. Indique os comandos necessários para colocar a <tt><span style="color: #990000">Makefile</span></tt> no repositório CVS.		# Construa uma <tt><span style="color: #990000">Makefile</span></tt> para gerar o executável <tt><span style="color: #990000">fact</span></tt>, a partir dos ficheiros anteriores. Indique os comandos necessários para colocar a <tt><span style="color: #990000">Makefile</span></tt> no repositório CVS.
	# Considere agora que vai ter dois executáveis, cada um invocando a sua função. Indique as alterações Ã <span style="color: #990000"> <tt>Makefile</tt></span> para que passe a gerar os executáveis <tt><span style="color: #990000">recurs</span></tt> e <tt><span style="color: #990000">iter</span></tt>, utilizando ambos o mesmo ficheiro <tt><span style="color: #990000">main.cpp</span></tt> (mas diferentes implementações do factorial). Indique as operações do CVS para criar a nova versão do projecto, assumindo que o projecto está checked-out no directório corrente.		# Considere agora que vai ter dois executáveis, cada um invocando a sua função. Indique as alterações Ã <span style="color: #990000"> <tt>Makefile</tt></span> para que passe a gerar os executáveis <tt><span style="color: #990000">recurs</span></tt> e <tt><span style="color: #990000">iter</span></tt>, utilizando ambos o mesmo ficheiro <tt><span style="color: #990000">main.cpp</span></tt> (mas diferentes implementações do factorial). Indique as operações do CVS para criar a nova versão do projecto, assumindo que o projecto está checked-out no directório corrente.
	# Considere uma nova versão do projecto: pretende-se construir um único executável <span style="color: #990000"> <tt>fact</tt></span>, mas a escolha da implementação do factorial é efectuada em tempo de execução. Considere que os ficheiros <tt><span style="color: #990000">recurs.cpp</span></tt> e <tt><span style="color: #990000">recurs.h</span></tt> existem num subdirectório <tt><span style="color: #990000">recurs</span></tt> e, analogamente, existe um directório <tt><span style="color: #990000">iter</span></tt> para a outra versão. Cada um dos conjuntos apresenta agora a mesma interface para a função que calcula o factorial: <tt><span style="color: #990000">fact</span></tt>. Construa duas bibliotecas dinâmicas, ambas designadas por <span style="color: #990000"><tt>~~fact~~.so</tt></span>, cada uma em seu directório (<tt><span style="color: #990000">recurs/~~fact~~.so</span></tt> e <tt><span style="color: #990000">iter/~~fact~~.so</span></tt>). A selecção da variante a utilizar faz-se definindo a variável de ambiente <tt><span style="color: #990000">LD_LIBRARY_PATH</span></tt> com o directório apropriado. Indique quais os ficheiros iniciais modificados, face Ã alÃnea anterior, a nova <tt><span style="color: #990000">Makefile</span></tt> e os comandos CVS necessários para que o repositório passe a conter a nova versão.		# Considere uma nova versão do projecto: pretende-se construir um único executável <span style="color: #990000"> <tt>fact</tt></span>, mas a escolha da implementação do factorial é efectuada em tempo de execução. Considere que os ficheiros <tt><span style="color: #990000">recurs.cpp</span></tt> e <tt><span style="color: #990000">recurs.h</span></tt> existem num subdirectório <tt><span style="color: #990000">recurs</span></tt> e, analogamente, existe um directório <tt><span style="color: #990000">iter</span></tt> para a outra versão. Cada um dos conjuntos apresenta agora a mesma interface para a função que calcula o factorial: <tt><span style="color: #990000">fact</span></tt>. Construa duas bibliotecas dinâmicas, ambas designadas por <span style="color: #990000"><tt>libfact.so</tt></span>, cada uma em seu directório (<tt><span style="color: #990000">recurs/libfact.so</span></tt> e <tt><span style="color: #990000">iter/libfact.so</span></tt>). A selecção da variante a utilizar faz-se definindo a variável de ambiente <tt><span style="color: #990000">LD_LIBRARY_PATH</span></tt> com o directório apropriado. Indique quais os ficheiros iniciais modificados, face Ã alÃnea anterior, a nova <tt><span style="color: #990000">Makefile</span></tt> e os comandos CVS necessários para que o repositório passe a conter a nova versão.
	# Modifique a alÃnea anterior para que o utilizador possa escolher a variante a utilizar através de um argumento na linha do comando <tt><span style="color: #990000">fact</span></tt>, respectivamente <tt><span style="color: #990000">recurs</span></tt> ou <tt><span style="color: #990000">iter</span></tt>. Indique quais os ficheiros iniciais modificados, a nova <tt><span style="color: #990000">Makefile</span></tt> e os comandos CVS necessários para registar a nova versão.		# Modifique a alÃnea anterior para que o utilizador possa escolher a variante a utilizar através de um argumento na linha do comando <tt><span style="color: #990000">fact</span></tt>, respectivamente <tt><span style="color: #990000">recurs</span></tt> ou <tt><span style="color: #990000">iter</span></tt>. Indique quais os ficheiros iniciais modificados, a nova <tt><span style="color: #990000">Makefile</span></tt> e os comandos CVS necessários para registar a nova versão.

Root: /* Step 5: User Control on Dynamic Linking */

2008-03-09T17:34:18Z

Step 5: User Control on Dynamic Linking

← Older revision		Revision as of 17:34, 9 March 2008
Line 279:		Line 279:
	-include .makedeps		-include .makedeps
	</text>		</text>
			Regarding CVS, only the Makefile and the main file had to be changed: all there is to do is updating and commiting the changes:
			prompt% cvs update
			M Makefile
			M main.cpp

			prompt% cvs commit
			/cvs/factorial/Makefile,v <-- Makefile
			new revision: 1.2; previous revision: 1.1
			/cvs/factorial/main.cpp,v <-- main.cpp
			new revision: 1.3; previous revision: 1.2

Root: /* Step 5: User Control on Dynamic Linking */

2008-03-09T17:31:49Z

Step 5: User Control on Dynamic Linking

← Older revision		Revision as of 17:31, 9 March 2008
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	void *fun = dlsym(handle, "_Z4facti"); // this is "fact" in C++		void *fun = dlsym(handle, "_Z4facti"); // this is "fact" in C++

			// cast void pointer into the appropriate function pointer
	((int(*)(int))fun)(5); // call function for 5!		((int(*)(int))fun)(5); // call function for 5!
	}		}
	</text>		</text>

	The Makefile is ~~as shown below.~~		The Makefile is the following:
	<text>		<text>
	.PHONY: all depend		.PHONY: all depend

	CXXFLAGS = ~~-ggdb~~ -fPIC # use position independent code		CXXFLAGS = -fPIC # use position independent code
	CXXFILES = $(wildcard .cpp) $(wildcard iter/.cpp) $(wildcard recurs/*.cpp)		CXXFILES = $(wildcard .cpp) $(wildcard iter/.cpp) $(wildcard recurs/*.cpp)
	CXXHEADS = $(wildcard .h) $(wildcard iter/.h) $(wildcard recurs/*.h)		CXXHEADS = $(wildcard .h) $(wildcard iter/.h) $(wildcard recurs/*.h)

Root: /* Step 4: The New Project Organization */

2008-03-09T17:30:23Z

Step 4: The New Project Organization

← Older revision		Revision as of 17:30, 9 March 2008
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	A recurs/recurs.h		A recurs/recurs.h

	The contents of the Makefile are as follows (we link with the "iter" version, but this is actually irrelevant, since the choice will always be dependent on <tt>LD_LIBRARY_PATH</tt>:		The contents of the Makefile are as follows (we link with the "iter" version, but this is actually irrelevant, since the choice will always be dependent on <tt>LD_LIBRARY_PATH</tt>. Note the use of position-independent code, so that dynamic libraries do not cause problems (the linker will refuse to create the libraries if the code in the <tt>.o</tt> files is not position independent):
	<text>		<text>
	.PHONY: all depend		.PHONY: all depend

			CXXFLAGS = -fPIC # use position-independent code
	CXXFILES = $(wildcard .cpp) $(wildcard iter/.cpp) $(wildcard recurs/*.cpp)		CXXFILES = $(wildcard .cpp) $(wildcard iter/.cpp) $(wildcard recurs/*.cpp)
	CXXHEADS = $(wildcard .h) $(wildcard iter/.h) $(wildcard recurs/*.h)		CXXHEADS = $(wildcard .h) $(wildcard iter/.h) $(wildcard recurs/*.h)

Root: /* Step 4: The New Makefile */

2008-03-09T17:28:11Z

Step 4: The New Makefile

@@ Line 128: / Line 128: @@
 Regarding CVS, only updates and commits are needed at this stage (new versions of the files will be sent to the repository).
-=== Step 4: The New Makefile ===
+=== Step 4: The New Project Organization ===
-In this case, we will reorganize the project. Since CVS does not support changes in file names or locations we will have to remove them from the old location and add them from the new location.
+In this case, we will need to reorganize the project. Since CVS does not support changes in file names or locations we will have to remove them from the old location and add them from the new location.
    prompt% mkdir iter recurs
@@ Line 214: / Line 214: @@
          libc.so.6 => /lib64/libc.so.6 (0x00002b553e9d8000)
          /lib64/ld-linux-x86-64.so.2 (0x00002b553de21000)

Root: /* Implementation */

2008-03-09T17:05:44Z

Implementation

← Older revision		Revision as of 17:05, 9 March 2008
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	Regarding CVS, only updates and commits are needed at this stage (new versions of the files will be sent to the repository).		Regarding CVS, only updates and commits are needed at this stage (new versions of the files will be sent to the repository).

			=== Step 4: The New Makefile ===

			In this case, we will reorganize the project. Since CVS does not support changes in file names or locations we will have to remove them from the old location and add them from the new location.

			prompt% mkdir iter recurs
			prompt% mv iter.cpp iter.h iter
			prompt% mv recurs.cpp recurs.h recurs
			prompt% cvs remove iter.cpp iter.h recurs.cpp recurs.h
			cvs remove: use `cvs commit' to remove these files permanently
			prompt% cvs add iter recurs
			Directory /cvs/factorial/iter added to the repository
			Directory /cvs/factorial/recurs added to the repository
			prompt% cvs add iter/iter.cpp iter/iter.h recurs/recurs.cpp recurs/recurs.h
			cvs add: use `cvs commit' to add these files permanently

			After updating the main file and the Makefile, the project's status is as follows:

			prompt% cvs update
			M Makefile
			R iter.cpp
			R iter.h
			M main.cpp
			R recurs.cpp
			R recurs.h
			A iter/iter.cpp
			A iter/iter.h
			A recurs/recurs.cpp
			A recurs/recurs.h

			The contents of the Makefile are as follows (we link with the "iter" version, but this is actually irrelevant, since the choice will always be dependent on <tt>LD_LIBRARY_PATH</tt>:
			<text>
			.PHONY: all depend

			CXXFILES = $(wildcard .cpp) $(wildcard iter/.cpp) $(wildcard recurs/*.cpp)
			CXXHEADS = $(wildcard .h) $(wildcard iter/.h) $(wildcard recurs/*.h)
			LIBITER = iter/libfact.so
			LIBRECURS = recurs/libfact.so
			PROG = fact

			%.o: %.cpp
			$(CXX) $(CXXFLAGS) -c $< -o $@

			all: depend $(LIBITER) $(LIBRECURS) $(PROG)

			$(PROG): main.o
			$(CXX) -o $@ $^ -Liter -lfact

			$(LIBITER): iter/iter.o
			$(CXX) -shared -o $@ $^

			$(LIBRECURS): recurs/recurs.o
			$(CXX) -shared -o $@ $^

			depend: .makedeps

			.makedeps: $(CXXFILES) $(CXXHEADS)
			$(CXX) $(CXXFLAGS) -MM $(CXXFILES) > .makedeps

			-include .makedeps
			</text>

			Inpecting the produced executable (in a Linux machine), without specifying a value for <tt>LD_LIBRARY_PATH</tt> and specifying the two possibilities:

			prompt% ldd fact
			libfact.so => not found
			libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00002b5a6869c000)
			libm.so.6 => /lib64/libm.so.6 (0x00002b5a689a4000)
			libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00002b5a68bf8000)
			libc.so.6 => /lib64/libc.so.6 (0x00002b5a68e06000)
			/lib64/ld-linux-x86-64.so.2 (0x00002b5a6847f000)

			prompt% LD_LIBRARY_PATH=iter ldd fact
			libfact.so => iter/libfact.so (0x00002b804d64e000)
			libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00002b804d87e000)
			libm.so.6 => /lib64/libm.so.6 (0x00002b804db86000)
			libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00002b804ddd9000)
			libc.so.6 => /lib64/libc.so.6 (0x00002b804dfe8000)
			/lib64/ld-linux-x86-64.so.2 (0x00002b804d431000)

			prompt% LD_LIBRARY_PATH=recurs ldd fact
			libfact.so => recurs/libfact.so (0x00002b553e03e000)
			libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00002b553e26e000)
			libm.so.6 => /lib64/libm.so.6 (0x00002b553e576000)
			libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00002b553e7c9000)
			libc.so.6 => /lib64/libc.so.6 (0x00002b553e9d8000)
			/lib64/ld-linux-x86-64.so.2 (0x00002b553de21000)