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#include <assert.h>
#include <dlfcn.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <errno.h>
#include "disp.h"
void
/* Internals of strbuild. */
__strbuild(char *buf, int size,
const char *file, int line,
const char *fmt, ...)
{
va_list ap;
int len;
va_start(ap, fmt);
len = vsnprintf(NULL, 0, fmt, ap);
va_end(ap);
if (len < 0)
{
fprintf(stderr, "%s:%d: ", file, line);
perror("");
exit(EXIT_FAILURE);
}
if (len >= size)
{
fprintf(stderr, "%s:%d: error: not enough space, "
"have %d, need at least %d\n",
file, line,
size, len + 1);
exit(EXIT_FAILURE);
}
va_start(ap, fmt);
len = vsnprintf(buf, size, fmt, ap);
va_end(ap);
assert(len >= 0);
}
/* Safely create a formatted string and write it to BUF. BUF shall be a buffer
* of size at least SIZE. BUF can be stack-allocated. If the formatting cannot
* be performed, exit(3) is called. This function is not meant to be called
* directly: the macro strbuild should be used. The code is adapted from the
* make_message function of the vsnprintf(3) manual page, section "examples". */
#define strbuild(buf, fmt, ...) \
__strbuild(buf, sizeof(buf), __FILE__, __LINE__, fmt, __VA_ARGS__)
#define strbuild_with_size(buf, size, fmt, ...) \
__strbuild(buf, size, __FILE__, __LINE__, fmt, __VA_ARGS__)
int
file_exists(const char *path)
{
struct stat statbuf __attribute__((unused));
int rc = stat(path, &statbuf);
if (rc == 0)
return 1;
else if ((rc == -1) && (errno == ENOENT))
return 0;
fprintf(stderr, "stat: \"%s\": ", path);
perror("");
exit(EXIT_FAILURE);
}
static void *
load_generic_symbol(struct disp *disp, char *base_name)
{
char full_name[64] = {0};
void *ptr;
strcpy(full_name, disp->name);
strcat(full_name, "_");
strcat(full_name, base_name);
ptr = dlsym(disp->dl_handle, full_name);
if (!ptr)
{
fprintf(stderr, "calculer: %s\n", dlerror());
destroy_disp(disp);
exit(1);
}
return ptr;
}
static void
load_symbols(struct disp *disp)
{
void *handle = dlopen(disp->so_path, RTLD_LAZY);
if (!handle)
{
fprintf(stderr, "calculer: %s\n", dlerror());
destroy_disp(disp);
exit(1);
}
disp->dl_handle = handle;
disp->init = load_generic_symbol(disp, "init");
disp->display_calc = load_generic_symbol(disp, "display_calc");
disp->read_input = load_generic_symbol(disp, "read_input");
disp->display_res = load_generic_symbol(disp, "display_res");
disp->destroy = load_generic_symbol(disp, "destroy");
disp->pre_reload = load_generic_symbol(disp, "pre_reload");
disp->post_reload = load_generic_symbol(disp, "post_reload");
printf("INFO: successfully loaded symbols from \"%s\"\n",
disp->so_path);
}
struct disp *
get_disp(char *disp_name)
{
char so_path[128];
/* local lookup, useful while developing */
strbuild(so_path, "./lib%s.so", disp_name);
if (!file_exists(so_path))
strbuild(so_path, "%s/lib/calculer/lib%s.so", CALCULER_PREFIX, disp_name);
struct disp *disp = malloc(sizeof(*disp));
disp->so_path = strdup(so_path);
disp->name = disp_name;
load_symbols(disp);
return disp;
}
void
destroy_disp(struct disp *disp)
{
if (disp->destroy)
disp->destroy();
if (disp->dl_handle)
dlclose(disp->dl_handle);
free(disp->so_path);
free(disp);
}
void
disp_reload(struct disp *disp)
{
printf("INFO: saving state\n");
void *state = disp->pre_reload();
printf("INFO: closing shared library\n");
dlclose(disp->dl_handle);
printf("INFO: reloading symbols\n");
load_symbols(disp);
printf("INFO: loading state\n");
disp->post_reload(state);
printf("INFO: reloading done\n");
}
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