Confused about compiler errors received using gcc - c

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