Relative paths from binary file

问题

I have the following folder structure:

bin/ <-binary-file is in here
include/
src/
data/
Makefile

In my code, I use relative paths to my data. So "../data/xml/xmlFile.xml". This is fine if I were executing the binary file from the bin/ folder:

brandonto@computer:~/PATH-TO-PROJECT/bin$ ./binary-file 
argv[0] = ./binary-file
dirname(argv[0]) = .

But if I were executing the binary from the main folder (or any other folder that is not the bin/ folder):

brandonto@computer:~/PATH-TO-PROJECT$ bin/binary-file 
argv[0] = bin/binary-file
dirname(argv[0]) = bin

The xml files would not be found because "../data" would now go up one directory from the main folder (or whatever folder you are in when executing the program).

How could I make it so that the binary file could be executed from any directory on my system?

To make the question a little more clear:

brandonto@brandonto-Aspire-S3-391:~/cpp-workspace/sdl-projects/sdl-space-shooter/bin$ ~/cpp-workspace/sdl-projects/sdl-space-shooter/bin/SpaceShooter 
argv[0] = /home/brandonto/cpp-workspace/sdl-projects/sdl-space-shooter/bin/SpaceShooter
dirname(argv[0]) = /home/brandonto/cpp-workspace/sdl-projects/sdl-space-shooter/bin

brandonto@brandonto-Aspire-S3-391:~/cpp-workspace/sdl-projects/sdl-space-shooter/bin$ cd ..
brandonto@brandonto-Aspire-S3-391:~/cpp-workspace/sdl-projects/sdl-space-shooter$ ~/cpp-workspace/sdl-projects/sdl-space-shooter/bin/SpaceShooter 
argv[0] = /home/brandonto/cpp-workspace/sdl-projects/sdl-space-shooter/bin/SpaceShooter
dirname(argv[0]) = /home/brandonto/cpp-workspace/sdl-projects/sdl-space-shooter/bin
Unable to load image ../data/graphics/background/darkPurple.png! SDL_image Error: Couldn't open ../data/graphics/background/darkPurple.png
Unable to load image ../data/graphics/sprites/meteorBrown_big1.png! SDL_image Error: Couldn't open ../data/graphics/sprites/meteorBrown_big1.png

Here, I executed the binary file once from inside the bin/ folder, then once from inside the main folder. The binary ran fine from inside the bin/ folder, but could not find the relative paths to the .png files from inside the main folder.

回答1:

Probably you are asking a wrong question: the build system has nothing to do with program execution.

However, if you look for an answer, how to make my program to correctly use data, that is located relative to program installation, than here is an answer.

When you program main gets executed, it gets the binary path as the first parameter (index 0). That path can be relative or absolute, but in any case it allows you to find the base directory.

These are also useful links:

How do I find the location of the executable in C?
Finding current executable's path without /proc/self/exe

Here how you can use first argument:

#include <linux/limits.h>
#include <stdio.h>
#include <string.h>
#include <libgen.h>

int main(int argc, char *argv[])
{
  char datadir[PATH_MAX];
  strncpy(datadir, argv[0], sizeof(datadir));
  dirname(datadir);
  strncat(datadir, "/../data", sizeof(datadir));

  printf("Data dir: %s\n", datadir);

  return 0;
}

回答2:

I believe that you can find your process id (pid) using the getpid command and perform functions to extract the directory in a manner similar to this question on Ask Ubuntu.

回答3:

I would have the data associated in some way (organizationally) with the bin directory where the executable resides.

Then, when running the routine, if a complete path is provided (noted by checking arg[0]), then you can find the data directory. If a relative path is provided, then search the search path sequentially until you find the executable, and then you can therefore find the data directory.

No pids needed. (I think this is how Python finds its way, or at least how it used to do so.)

回答4:

I usually solve this with a program setting. In the good old days I would have these settings in a .ini file which would accompany the executable. Some settings would be configurable from within the program, and all could be edited with a text editor. If the file was missing, or any setting missing, they would be created by default.

For the location of the program's data I would use its full absolute path name. For example it might be

Datapath = D:\os50k

and the program then appends individual file names to the path as necessary.

These days in Windows the System Registry is used for this purpose. However your question is tagged Linux which stores settings in various places, including the program directory.

This question, and this question describe the process more fully.

来源：https://stackoverflow.com/questions/28549606/relative-paths-from-binary-file

标签

Linux

executable