Confused about compiler errors received using gcc

Question

I'm trying to compile this assignment I'm doing and I'm running into errors I'm not sure how to fix. Esepcially for Here's my command line argument:

gcc HW3.c semaphore.o buffer.c -L. -lst -o test

The problem is that the semaphor.h file was given to us so there isn't anything inherently wrong in the class so it shouldn't be complaining there I don't think. I'm not sure how to reconcile the struct errors either. I'm not particularly proficient in C. Here's the error list:

    In file included from buffer.c:11:
semaphore.h:4: error: expected specifier-qualifier-list before ‘st_cond_t’
In file included from buffer.h:2,
                 from buffer.c:12:
semaphore.h:4: error: expected specifier-qualifier-list before ‘st_cond_t’
semaphore.h:5: error: conflicting types for ‘semaphore’
semaphore.h:5: note: previous declaration of ‘semaphore’ was here
semaphore.h:7: error: conflicting types for ‘down’
semaphore.h:7: note: previous declaration of ‘down’ was here
semaphore.h:8: error: conflicting types for ‘up’
semaphore.h:8: note: previous declaration of ‘up’ was here
semaphore.h:9: error: conflicting types for ‘createSem’
semaphore.h:9: note: previous declaration of ‘createSem’ was here
buffer.c: In function ‘init_buffer’:
buffer.c:20: error: incompatible type for argument 1 of ‘createSem’
semaphore.h:9: note: expected ‘struct semaphore *’ but argument is of type ‘semaphore’
buffer.c:21: error: incompatible types when assigning to type ‘semaphore’ from type ‘void *’
buffer.c:23: error: incompatible type for argument 1 of ‘createSem’
semaphore.h:9: note: expected ‘struct semaphore *’ but argument is of type ‘semaphore’
buffer.c:24: error: incompatible types when assigning to type ‘semaphore’ from type ‘void *’
buffer.c: In function ‘c_deposit’:
buffer.c:38: error: incompatible type for argument 1 of ‘down’
semaphore.h:7: note: expected ‘struct semaphore *’ but argument is of type ‘semaphore’
buffer.c:41: error: incompatible type for argument 1 of ‘up’
semaphore.h:8: note: expected ‘struct semaphore *’ but argument is of type ‘semaphore’
buffer.c: In function ‘c_remove’:
buffer.c:46: error: incompatible type for argument 1 of ‘down’
semaphore.h:7: note: expected ‘struct semaphore *’ but argument is of type ‘semaphore’
buffer.c:49: error: incompatible type for argument 1 of ‘up’
semaphore.h:8: note: expected ‘struct semaphore *’ but argument is of type ‘semaphore’

buffer.c:

#include <stdio.h>
#include <stdlib.h>
#include "semaphore.h"
#include "buffer.h"

buffer *init_buffer(int size)
{

    buffer *new_Buffer;
    new_Buffer=malloc((sizeof(buffer)));

    createSem(new_Buffer->emptyBuffer, size);
    new_Buffer->emptyBuffer=malloc(sizeof(semaphore));

    createSem(new_Buffer->fullBuffer, 0);
    new_Buffer->fullBuffer=malloc(sizeof(semaphore));

    new_Buffer->chars=malloc(sizeof(char)*size);

    new_Buffer->size=size;

    new_Buffer->nextIn=0;
    new_Buffer->nextOut=0;

    return new_Buffer;
}

void c_deposit(buffer *buffer, char c)
{
    down(buffer->emptyBuffer);
    buffer->chars[buffer->nextIn]=c;
    buffer->nextIn=(buffer->nextIn+1)%buffer->size;
    up(buffer->fullBuffer);
}
int c_remove(buffer *buffer)
{
    int c;
    down(buffer->fullBuffer);
    c=buffer->chars[buffer->nextOut];
    buffer->nextOut=(buffer->nextOut+1)%buffer->size;
    up(buffer->emptyBuffer);
    return c;
}

buffer.h:

#include <stdio.h>
#include "semaphore.h"

typedef struct{
    semaphore emptyBuffer;
    semaphore fullBuffer;
    int nextIn;
    int nextOut;
    int size;
    char *chars;
}buffer;

void c_deposit(buffer *buffer, char c);
int c_remove(buffer *buffer);

buffer *init_buffer(int size);

For good measure here's semaphore.h as well:

typedef struct
{
  int value;
  st_cond_t sem_queue;
} semaphore;

void down(semaphore *s);
void up(semaphore *s);
void createSem(semaphore *s, int value);

Answer 1

Seems like semaphore.h needs to do this:

#include <st.h>

Also, you are including semaphore.h twice which is confusing the compiler.

Try putting this in semaphore.h as well:

#pragma once    

See: http://en.wikipedia.org/wiki/Pragma_once