I have a project with files in different directories. Directory A contains two directories B and C, and C contains a directory D. Files are in B, C and D. I have written makefiles to compile that, with the main makefile in C.
C Makefile contains the following line :
export LDFLAGS = -I ../B -I . -I ../C/D -lm
(At first instead of "../C/D" I had written just "./D" but then I changed because of the error I got, just to be sure the path is valid also for B. However it doesn't changed anything)
The makefile in B contains the following rule :
%.o : %.c
$(CC) $(CFLAGS) -o $# -c $< $(LDFLAGS)
When I run "make", there is an error because a file in B has an include of a file in D, and it doesn't find this file. Why ? Thanks for your help !
edit : As I got exactly the same error (same missing file included on the same B header file) when I added the directory with the -I option, and then when I had the LDFLAGS on my B makefile, I didn't notice the file generating this error change : Now it is a .cpp file that include the B header including the D header that provoke the error.
(Don't ask me why there is one cpp file among c files by the way, it's not me that developed that...)
The lines for the cpp file in the B makefile are :
%.o : %.cpp
g++ $(CFLAGS) -o $# -c $< $(LDFLAGS)
But the .o of this .cpp file is not on the all rule (it call $(OBJS), define as OBJS = $(SRC:.c=.o)). I guess this is my mistake. Because when I run make, it first go on B directory and compile my c file with the options, and then leave directory, because of the rule :
b :
#(cd $(BDIR) && $(MAKE))
So, when make realise that myccpfile.o is needed, he magically call the line
g++ -c -o ../B/myccpfile.o ../B/mycppfile.cpp
So now I really don't understand where this call come from, that's really odd because the only rule using g++ have the CFLAGS and LDFLAGS, I don't understand why they disappeared...
Its CFLAGS that requires the -I options for the compilation phase of the build. Check the B makefile has CFLAGS set with the appropriate -I options.
LDFLAGS will only affect linker options.
Related
Automate the compilation of auto-generated C files with regular C files
We have developed a program "cperformer" that is able to generate a C file from a text file (to keep it simple).
It is a kind of "meta-compiler" that generates C file as output. Thus, we would like to improve the usage of this "C generator" by automating the generation of each C file as a first step of a makefile, and then compile and link together all of these generated C files with other C files already present with GCC in the same makefile.
Makefile 1
C_GEN :=./cperformer -n
CC :=gcc
CFLAGS :=-I.
#List all .c files generated from .text files
AUTO_SRCS = $(wildcard *.text)
AUTO_OBJS_C := $(patsubst %.text,%_alg.c,$(AUTO_SRCS))
$(info *INFO* Text files = $(AUTO_SRCS))
#List all .c files to compile (auto-generated or not)
SRCS = $(AUTO_OBJS_C)
SRCS += $(wildcard *.c)
OBJS := $(patsubst %.c,%.o,$(SRCS))
$(info *INFO* C files = $(SRCS))
# Main target rule
target : $(OBJS)
$(CC) -o $# $(OBJS) $(CFLAGS)
# Pre-compilation step (some C files generation)
prelim $(AUTO_OBJS_C): $(AUTO_SRCS)
$(C_GEN) $<
# Pre-compilation step (object files generation)
%.o: %.c
$(CC) -c -o $# $< $(CFLAGS)
all: prelim target
clean :
rm -f TARGET $(OBJS) *_alg*
Error 1
$ make all
*INFO* Text files = file3.text file2.text file1.text
*INFO* C files = file3_alg.c file2_alg.c file1_alg.c linked_list.c main.c
./cperformer -n file3.text
Compiling: file3.text ...
No error.
Done.
gcc -c -o file3_alg.o file3_alg.c -I.
./cperformer -n file3.text
Compiling: file3.text ...
No error.
Done.
gcc -c -o file2_alg.o file2_alg.c -I.
gcc: error: file2_alg.c: No such file or directory
gcc: fatal error: no input files
compilation terminated.
make: *** [Makefile:29: file2_alg.o] Error 1
It fails because the "cperformer" program is asked to generate the same C file each time "file3.c" so GCC don't find "file2.c" as expected and it aborts the compilation.
Makefile 2
Replace the C generative rule of the above makefile with the use of "%" :
# Pre-compilation step (some C files generation)
%.c: %.text
$(C_GEN) $<
Error 2
make: *** No rule to make target 'file3_alg.o', needed by 'target'. Stop.
Nothing compiles here.
Makefile 3
The dirty fix
batch_c_generation :
#$(foreach TXT_FILE, $(AUTO_SRCS), $(C_GEN) $(TXT_FILE);)
This is kind of working but remains very dirty because it re-generates all C files at each build and some duplication errors appear when it is not properly cleared between each make.
How can I fix the makefile ?
You were close -- simply fix your pattern rule to look like this:
%_alg.c : %.text
$(C_GEN) $<
As #tripleee mentioned, the reason your makefile1 rule failed was that it expands to something like:
file2_alg.c file1_alg.c: file2.text file1.text
$(CGEN) $<
In this case $< expands to the first dependency which will always be file2.text...
In your makefile2 example, you used %.c instead of %_alg.c (and hence there's no rule to build file2_alg.c, and therefore no rule to build file2_alg.o)
I am working on project, where i use couple of .c and .h files.
I created Makefile where i actualize executable program based on changes in all of these files.
Problem is, when i use make, program is compiled, but when i execute program, it runs without any change. I need to save ( working in vim so :w ) all included files, even when i changed only one.
If i don't save all these files, program is compiled, but executes the same thing as it did before change.
Could someone explain me why is that ?
Makefile code :
CC=gcc
CFLAGS=-WALL
execFile: execFile.o functions.h newDataTypes.h
Thank you.
The reason you are not getting execFile updated is because you're NOT updating it. Or at least you don't seem to be in this particular case.
There are many ways to get about doing this. However since you are using gcc and I assume you're using gnu make the following is probably the best solution you can execute1.
Given the files:
-rw-r--r-- 1 user sudo 73 Nov 4 22:54 exeFile.c
-rw-r--r-- 1 user sudo 74 Nov 4 22:54 exeFile.h
-rw-r--r-- 1 user sudo 90 Nov 4 22:55 hello_world.c
-rw-r--r-- 1 user sudo 888 Nov 4 23:03 Makefile
cat exeFile.c
#include <stdio.h>
#include "exeFile.h"
int main()
{
hello_world();
}
exeFile.h
#ifndef _EXEFILE_H
#define _EXEFILE_H
extern void hello_world();
#endif
hello_world.c
#include <stdio.h>
#include "exeFile.h"
void hello_world()
{
printf("Hello World\n");
}
you can set up a make file that generates dependencies and ensures that the program will always be compiled correctly:
CC=gcc
CFLAGS=-Wall
SOURCES=exeFile.c hello_world.c
EXE=exeFile
OBJ=$(SOURCES:%.c=%.o)
DEPDIR := .deps
$(shell mkdir -p $(DEPDIR) >/dev/null)
DEPFLAGS = -MT $# -MMD -MP -MF $(DEPDIR)/$*.Td
COMPILE.c = $(CC) $(DEPFLAGS) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
COMPILE.cc = $(CXX) $(DEPFLAGS) $(CXXFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
POSTCOMPILE = #mv -f $(DEPDIR)/$*.Td $(DEPDIR)/$*.d && touch $#
%.o: %.c
%.o: %.c $(DEPDIR)/%.d
$(COMPILE.c) $(OUTPUT_OPTION) $<
$(POSTCOMPILE)
%.o : %.cc
%.o : %.cc $(DEPDIR)/%.d
$(COMPILE.cc) $(OUTPUT_OPTION) $<
$(POSTCOMPILE)
%.o : %.cxx
%.o : %.cxx $(DEPDIR)/%.d
$(COMPILE.cc) $(OUTPUT_OPTION) $<
$(POSTCOMPILE)
$(DEPDIR)/%.d: ;
.PRECIOUS: $(DEPDIR)/%.d
$(EXE): $(OBJ)
$(CC) -o $# $(OBJ) $(LDFLAGS)
clean:
$(RM) $(OBJ) $(EXE)
dev-clean: clean
$(RM) -r $(DEPDIR)
include $(wildcard $(patsubst %,$(DEPDIR)/%.d,$(basename $(SOURCES))))
Let's go over the relevant parts about dependencies
DEPDIR =
This implementation places dependency files into a subdirectory named .deps .
$(shell mkdir -p $(DEPDIR) 2>/dev/null)
GCC does not create subdirectories for output, this line ensures that the DEPDIR directory always exists.
DEPFLAGS = ...
These are GCC-specific flags which tell the compiler to generate dependency info.
-MT $#
Set the name of the target in the generated dependency file.
-MMD
Generate dependency information in addition to compiling. -MMD omits system headers from the generated dependencies: if you prefer to preserve system headers as prerequisites, use -MD instead.
-MP
Adds a make target for each prerequisite in the list, this avoids errors when deleting files.
-MF $(DEPDIR)/$*.Td
Write the generated dependency file to a temporary file $(DEPDIR)/$*.Td e.g. hello_world.c will generate hello_world.Td as temp dependency content for use in Makefile.
POSTCOMPILE = ...
First rename the generated temporary dependency file to the real dependency file. We do this in a separate step to side-step compile errors. Next we explicitly touch the files to avoid a gcc bug.
%.o : %.c
Delete the built-in rules for building object files from .c files, so that our rule is used instead. Do the same for the other built-in rules.
... $(DEPDIR)/%.d
Declare the generated dependency file as a prerequisite of the target, so that if it’s missing the target will be rebuilt.
$(DEPDIR)/%.d: ;
Create a pattern rule with an empty recipe, so that make won’t fail if the dependency file doesn’t exist.
.PRECIOUS: $(DEPDIR)/%.d
Mark the dependency files precious to make, so they won’t be automatically deleted as intermediate files.
include ...
Include the dependency files that exist: translate each file listed in SOURCES into its dependency file. Use wildcard to avoid failing on non-existent files.
1 See Auto-Dependencies Generation for details.
Fix:
Tell make that the executable depends only on the object file and the object file depends on the header files:
execFile: execFile.o
execFile.o: functions.h newDataTypes.h
Explanation:
In order to build your executable two steps are needed:
compilation of C source files (that include header files) to produce object files,
linking of the object files to produce the executable.
So, when changing your header files you must re-compile, that is re-built the object files, not just re-link that would produce the same executable from the same object files.
In your Makefile the dependencies are not properly defined. You did not tell make that the object file (execFile.o) shall be rebuilt when your header files change. Instead, you told it that the executable (execFile) shall be rebuilt.
First of all, your dependencies are mistaken. Your executable does not depend on the .h header files, as they are using only at compilation time. The dependencies are normally between .o files and .h files, as when you modify one .h file, the including .c file must be compiled to generate the .o file. so in case you have execFile.o (which, on lack of complete information, I'll suppose it depends on execFile.c, which #includes functions.h and newDataTypes.h, the rule should be:
execFile.o: execFile.c functions.h newDataTypes.h
As it has been pointed out in other responses, there's no need to write the command to build the .o file, as there is a default rule like this:
.c.o:
$(CC) $(CFLAGS) -o $# -c $<
(observe there's a -c option to the compiler indicating to compile only and don't link, we'll return here below) which means that once you detect the .o is outdated (as the dependencies on .c and .hs mark) it will be compiled with the above command, which result in:
gcc -Wall -o execFile.o -c execFile.c
making the appropiate compilation.
Other thing is the dependencies of the executable file. These have to be included, as make(1) doesn't know which object files form your final executable. In this case, assuming you have your program execFile depend on execFile.o and a.o, b.o and c.o, I normally use to write:
execFile_objs = execFile.o a.o b.o c.o
execFile: $(execFile_objs)
$(CC) $(LDFLAGS) -o $# $(execFile_objs)
so any of the .os is changed (because an indirect change in a source file) the whole program is linked again (but only the touched files are compiled)
NOTE
In the case (not normal) that you have a Makefile to create a program that has only one source file and several include files you can compile each time the whole thing each time you modify one source file, in this way:
execFile: execFile.c functions.h newDataTypes.h
$(CC) $(CFLAGS) $(LDFLAGS) -o $# execFile.c
This will execute
gcc -Wall -o execFile execFile.c
Observe that there is no -c (compile only, don't link) option in this command.
There's no mention of the include files (they are included because of the #include directives in the code... and you only state here that the executable depends also (and have to be built) in case any of the .h files are modified.
Automatic dependency rules are a little confusing at first, as they induce you to think there are such rules to make any kind of file from any other kind of file (well, there are for .c -> .o files, and .c -> <nothing> to compile directly to an executable) normally you have to include dependencies in such cases when your target depends on more files than the automatic rule states. In such cases, it is very important not to include any command, so the compiler selects the automatic rule (when you don't include a command to generate the target, the make(1) program tries to use a default rule for it, or nothing at all if you have not included commands, it only assumes your dependencies are indirect through this fake target --- and, as this fake target is not built in the process, it will fail always and be followed)
I'm trying to create a Makefile for my C program in Raspbian (Raspberry Pi).
My program consists of a bunch of .c and .h Files. I've looked at countless Makefiles, but I just don't unterstand how it works with multiple files. There are always .o files in the Makefile but as I understand object files are the result of compiling, so I dont have any o. Files as I am trying to compile my .c Files.
Please explain to me how this works.
Edit:
Thank you. So I tried this and it starts compiling but there are errors 'multiple definition'. Example:
These are my Files:
main.c main.h
calibration.c calibration.h
file.c file.h
frame.c frame.h
gamepad.c gamepad.h
gpio.c gpio.h
uart.c uart.h
types.h
this is my makefile:
all: main
main: main.o calibration.o file.o frame.o gamepad.o gpio.o uart.o
%.o: %.c
gcc -c -std=c99 -Wall $< -o $# -lncurses
Where can i put 'types.h'?
With every file I get errors 'multiple definitions'
A very simple but typical makefile could look like this
SOURCES = source1.c source2.c source3.c
OBJECTS = $(SOURCES:%.c=%.o)
TARGET = myExecutable
$(TARGET): $(OBJECTS)
gcc $^ -o $#
%.o: %.c
gcc -c $< -o $#
The complicated parts:
SOURCES = source1.c source2.c source3.c This is a variable definition, it assigns the string "source1.c source2.c source3.c to the variable SOURCES.
$(SOURCES:%.c=%.o) This is a shorthand for the patsubst text function. It takes all text from the $(SOUCES) variable, and replaces the pattern %.c with %.o, i.e. it takes e.g. the string source1.c and replace it with source1.o.
$(TARGET): $(OBJECTS) This makes myExecutable depend on all object files, meaning if one object file is modified then the command in the rule will be executed.
gcc $^ -o $# This calls the gcc command, passing all dependencies ($^) as arguments (that is, all object files), and tells gcc to output a file with the name of the target ($#).
%.o: %.c This is the rule that makes object files depend in their source file. So if you have source1.c then source1.o will depend on that source file.
gcc -c $< -o $# This is the command that compiles the source file (the first dependency, $<) to an object file (with the -c option) and name it as the target of the rule ($#).
Also note that if you invoke make without a specific target, then the first rule will be selected. In the case of the above makefile, it will be the $(TARGET): $(OBJECTS) rule which will make sure that all object files are build from the source files, and then link the object files into the resulting executable.
The basic syntax of a make rule is:
target … : prerequisites …
recipe
…
…
On the left of the semicolon are the targets. The targets are your object files(.o). On the right of the semicolon are the files that you will need to create this file. Those files are the source files(.c).
Lets give a basic example of what such a rule could look like.
%.o: %.c
gcc -c $< -o $#
The % sign is a wildcard. %.o means everything that ends with .o. So, if you want to make an object file, you can say make file.o, and make will try to find a rule with which it can make this target. This happens to be the rule I just showed as an example, because file.o matches %.o.
Then the recipe. This is what will be executed. Usually it's about invoking the compiler(gcc), and feeding it the source file to generate the object file. That's what we do with gcc -c $< -o $#. The $< and $# mean target and prerequisites respectively.
So, what happens when you 'just' want to build your program? You usually will type make, and it will build. The default rule that's used when you type make, is all. So, if you make a rule about all, then you can specify what files you want to create to build your program. Example of such a rule:
all: main
Then, when make is invoked, it will find that rule and finds out it needs main. To create main you need another rule:
main: file.o
This rule says that to build main, you need file.o. So, when you put all of the example rules together you get this:
all: main
main: file.o
%.o: %.c
gcc -c $< -o $#
Note that you can specify more than one file, so instead of file.o, you can say file.o main.o other_file.o etc. Every prerequisite that you specify will be made, if they can find a rule to make it.
I am modifying an old makefile in order to build a C extension for postgreSQL. The Makefile currently looks like this:
PGLIB = /usr/lib/postgresql/8.4/lib
PQINC = /usr/include/postgresql/8.4/server
CC=gcc
override CFLAGS+= $(CFLAGS_SL) -DPG_AGGREGATE
SHLIB = pg_myextlib
SRC = foo.c \
foobar.c
OBJS = foo.o \
foobar.o
all: $(OBJS)
$(CC) -shared -o $(SHLIB)$(DLSUFFIX) $(OBJS) -I$(PQINC)
cp *.so $(PGLIB)
clean:
rm -f $(SHLIB) $(OBJS)
The error I get when I run make is:
common.h:58:22: error: postgres.h: No such file or directory
Which suggests that the include path is not being added (the file exists in $PQINC).
Its a long time since I wrote the Makefile - and I haven't written many since. As an aside, I am pretty sure that 'shared' is not the gcc flag to build shared libs on Ubuntu (my current dev box) - I think the flag should be 'fPIC' - can someone confirm this?
I am runing gcc v4.4.3 on Ubuntu 10.0.4 and compiling for use with PG 8.4
Try moving the -I$(PQINC) from target all to the end of line that starts with override CFLAGS.
Placing -Isomething on the compiler line which turns object files, like those in $(OBJS), into executable will have no effect whatsoever.
You need to do it when you compile the source files.
Since your makefile doesn't explicitly show the rule for processing source files, it may well be using a default one, which is incredibly unlikely to know about PQINC.
You seem to be using the default rules to build foo.o from foo.c, which doesn't have your -I. Try adding the following rule to your Makefile:
.c.o:
$(CC) $(CFLAGS) -c $< -o $# -I$(PQINC)
This makefile does not behave as I expect. I want it to build .o files for each .c file in the current directory and subdirectories, and put them in a static library. However, it stops applying my $(INCS) after the first or second file. When it tries to build the second .o file, I don't see the -I paths in the build line and it complains about not finding a header file therein. Names have been genericized to simplify things. I'm using cygwin on Windows XP. I'm using an ARM cross compiler that is not under the cygwin tree. I based this makefile off an answer here. There are only about two dozen .c files so the overhead of creating the dependency files this way isn't a big deal.
# Project specific options
CC = my-cross-gcc
INCS := -I. -Iinc
INCS += -Imy/inc/path
CFLAGS := -Wall -fPIC -static -cross-compiler-specific-options
OUT := bin/libmylib.a
MKDIR:=mkdir -p
### Generic C makefile items below:
# Add .d to Make's recognized suffixes.
SUFFIXES += .d
NODEPS:=clean
#Find all the C files in this directory, recursively
SOURCES:=$(shell find . -name "*.c")
#These are the dependency files
DEPFILES:=$(patsubst %.c,%.d,$(SOURCES))
OBJS:= $(patsubst %.c,%.o,$(SOURCES))
#Don't create dependencies when we're cleaning, for instance
ifeq (0, $(words $(findstring $(MAKECMDGOALS), $(NODEPS))))
-include $(DEPFILES)
endif
#This is the rule for creating the dependency files
%.d: %.c
$(CC) $(INCS) $(CFLAGS) -MM -MT '$(patsubst %.c, %.o,$(patsubst %.c,%.o,$<))' $< > $#
#This rule does the compilation
%.o: %.c %.d %.h
$(CC) $(INCS) $(CFLAGS) -o $# -c $<
# Now create a static library
all: $(OBJS)
#$(MKDIR) bin
ar rcsvq $(OUT) $(OBJS)
clean:
rm -rf $(OBJS) $(OUT) $(DEPFILES)
Why does this makefile not apply $(INCS) when building subsequent .o files? How do I fix it? Output resembles this:
$ make all
my-cross-gcc -I. -Iinc -Imy/inc/path -<compiler options> -o firstfile.o -c firstfile.c
my-cross-gcc -I. -Iinc -Imy/inc/path -<compiler options> -o secondfile.o -c secondfile.c
my-cross-gcc -<compiler flags> -o thirdfile.o -c thirdfile.c
thirdfile.c:23:18: fatal error: myinc.h: No such file or directory
compilation terminated.
When I go to the command line and type in the gcc line to build thirdfile.o and use the -I paths, the object file is successfully built.
There are two different mechanisms for handling header files at work here:
When the compiler is trying to build foo.o from foo.c, and in foo.c it encounters #include "foo.h", it goes looking for foo.h. The -I flags tell it where to look. If it is invoked without the flags it needs to find foo.h, it will complain and die.
When Make is trying to build foo.o, and considering which rule to use, it looks at the prerequisites. The prerequisites for your rule are foo.c foo.d foo.h, so it goes looking for those prerequisites. How is it to know where foo.h is? Note that the compiler flag inside one of its commands is of no use-- it won't make any deductions about that. If it can't find (and doesn't know how to make) a prerequisite, it will reject that rule and look for another one, such as the implicit %.o rule which knows nothing about your $(INCS) variable, and that leads you to the problem described above.
If this is the problem (and you can check by looking at the locations of the headers and doing some experiments) you have a couple of options:
A) You can use the implicit rule, and it's variables. Just add INCS to CFLAGS and you'll probably get the results you want. This tells the compiler what to do, but it still leaves Make in the dark about the dependencies, so you'll probably have to double-check that your dependency handling is correct.
B) You can tell Make where to find the header files:
vpath %.h inc my/inc/path
(You may notice that this is redundant with your INCS variable, and redundancy is bad-- you can eliminate this redundancy, but I urge you to get it working first.)
I'm going to guess that you have files named firstfile.h, secondfile.h, but no file named thirdfile.h?
I would then suppose that make cannot use the rule you gave it because and can't find or build the .h file. So it decides to use the default implicit rule instead.
All I can imagine is that for "thirdfile" your depfile is somehow out-of-date or corrupt. Perhaps it is bad enough that it's confusing make into calling some other default target.