How to get the full path of a file in C?

Basel · 10-28-2010, 05:59 PM

Is there a way to get the full path of a file in C? I have a method that accepts a file name as an argument and is supposed to read the content of the file. The file name might include "../" so this might lead to accessing files outside of the current directory. I tried to use fstat but I could not figure out how to get the full path.

Code:

void readFile(char *filename) {
	FILE *fp;
	//char filename[] = "../../debug.log";
	fp = fopen(filename, "r");
	if (fp == NULL){
		printf("Cannot open file[%s]\n", filename);
		return;
	}
	// read the file
	fclose(fp);
}

UPDATE: follow-up posted on post #4

eSelix · 10-28-2010, 06:14 PM

"realpath()" can do it.

Basel · 10-28-2010, 06:42 PM

Thanks

Here is an example

Code:

char filename[] = "../../../../usr/include/stdio.h";
char *path = realpath(filename, NULL);
if(path == NULL){
	printf("cannot find file with name[%s]\n", filename);
} else{
	printf("path[%s]\n", path);
	free(path);
}
// output
path[/usr/include/stdio.h]
cannot find file with name[../../../usr/include/stdio.h]

Basel · 10-30-2010, 10:52 PM

Is there a method that would resolve a file name into a full path?
realpath works for existing files but I need to resolve a file name to a full path even if the file does not exist.