Why are these static functions working outside their file?

Question

I defined the next two static functions in a file named Grafico.h.

static inline interface_t * obtener_intf_por_nombre(nodo_t *nodo, char *nombre_if) {
    for (int i = 0; i < MAX_INTF_POR_NODO; ++i)
    {
        if(!nodo->intf[i]) return NULL;
        if(strncmp(nodo->intf[i]->nombre_if, nombre_if, TAM_NOMBRE_IF) == 0) {
            return nodo->intf[i];
        }
    }
    return NULL;
}

static inline nodo_t * obtener_nodo_por_nombre(grafico_t *topologia, char *nombre_nodo) {
    return obtener_elemento(topologia->lista_nodos, nombre_nodo);
}

In my main file I called these functions without remembering they were static, and I didn't get any warning or error from the compiler related to it.

#include <stdio.h>
#include "Net.h"
#include "Grafico.h"
#include "Topologias.h"
#include "CommandParser/libcli.h"
#include "clired.c"

extern grafico_t *const_primera_topo();
grafico_t *topo = NULL;


int main(void) {
    inic_cli_red();
    topo = const_primera_topo();

    sleep(2);
    nodo_t *nodo_trans = obtener_nodo_por_nombre(topo, "R0");
    interface_t *interface_trans = obtener_intf_por_nombre(nodo_trans, "ethR0/0");
    char *mensaje = "Este es un mensaje de prueba\0";
    printf("Llegamos hasta aquí señores. Fue un honor.\n");
    enviar_paquete(mensaje, strlen(mensaje), interface_trans);
    
    start_shell();
    return 0;
}

In case it's useful, here is my makefile.

TARGET = $(BIN_DIR)/sim_tcp_ip
LIBS = -lpthread -L ./CommandParser -lcli -lrt
OBJS = $(OBJ_DIR)/prueba.o \
       $(OBJ_DIR)/ListaEnlazadaGenerica.o \
       $(OBJ_DIR)/Grafico.o \
       $(OBJ_DIR)/Net.o \
       $(OBJ_DIR)/Topologias.o \
       $(OBJ_DIR)/Com.o \
       $(OBJ_DIR)/Utiles.o \
       $(OBJ_DIR)/Capa2.o
BIN_DIR = ./bin
OBJ_DIR = ./obj
INC_DIR = ./inc
SRC_DIR = ./src
CFLAGS = -g -lpthread -Wall -I$(INC_DIR)

$(TARGET): $(OBJS) CommandParser/libcli.a
    mkdir -p $(BIN_DIR)
    gcc $(CFLAGS) $(OBJS) -o $(TARGET) $(LIBS)
    
$(OBJ_DIR)/%.o : %.c
    mkdir -p $(OBJ_DIR)
    gcc -c -MD $(CFLAGS) $< -o $@
    
CommandParser/libcli.a:
    (cd CommandParser; make)

-include $(OBJ_DIR)/*.d
    
.PHONY: clean
clean:
    rm -rf $(OBJ_DIR) $(BIN_DIR)
    (cd CommandParser; make clean)
all:
    make

Is there something wrong with the definition of these static functions?

Answer 1

The problem is that you have declared them in your header file, Graphico.h!

The static keyword just means that if you compile a source C file prog.c into an object file prog.o, then any static functions in prog.c will be hard coded as memory addresses in prog.o. That is to say, whereas a normal function has an entry defined in the symbol table of prog.o, that is used when prog.o is linked with another object file, a static function does not.