strlen(buffer) on binary data

I wanted to write a function like this that would return a buffer containing a binary file:

Code:

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char *getbin (char *filename) {
        char *buffer;
        struct stat finfo;
        FILE *fstRO = fopen(filename, "rb");
        if (fstRO == NULL) return NULL;
        stat(filename,&finfo);
        buffer=ec_malloc(finfo.st_size);
        if (fread(buffer,1,finfo.st_size,fstRO) != finfo.st_size) {
                fclose(fstRO); return NULL;}
        fclose(fstRO); return buffer;
}

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It works fine -- the only problem is it's impossible to determine how big the returned buffer is! strlen() returns the wrong number (hitting a 0, i guess). Do I have to change the function to return a typedef struct containing the buffer and the size, or is there some way to measure a buffer containing binary data?

One way would be to "return" the size as well. This can be done by passing int *size or something like that into the function.

That said, I'm not sure I'm in love with passing allocated memory out of this thing like you are doing.

No you will have to pass a pointer as an additional parameter or else 'piggyback' it onto the buffer itself (I'd prefer the former, personally).

Quote:

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Originally Posted by FillYourBrain

One way would be to "return" the size as well. This can be done by passing int *size or something like that into the function.

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I like that suggestion, thanks.

Quote:

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Originally Posted by FillYourBrain

That said, I'm not sure I'm in love with passing allocated memory out of this thing like you are doing.

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Isn't that normal as long as I free it later? Is it better to pass a pointer to the function for allocation (why)?

yeah that part is what I'm not sure about... It seems you just want a quick single call for loading the file. Fine, but I would usually prefer to get the size of the file first and pass the buffer into a call like this. But then I'm weird like that.

I don't tell people that their approach is wrong though, and I'm not saying that here.

Incidentally, shouldn't you free the buffer if fread() returns something other than finfo.st_size? At the moment it seems to me that there is a memory leak there since only NULL is returned in that case, thus there is no way to free the buffer.

EDIT:
Oh, and are you sure you do not need to check if ec_malloc() returns a null pointer? The standard malloc() returns a null pointer if memory could not be allocated.

Quote:

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Originally Posted by laserlight

Incidentally, shouldn't you free the buffer if fread() returns something other than finfo.st_size?

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Yep. Thanks for noticing. And I should check buffer != NULL after the malloc...