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/*
* Common eBPF ELF object loading operations.
*
* Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
* Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
* Copyright (C) 2015 Huawei Inc.
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <asm/unistd.h>
#include <linux/bpf.h>
#include <libelf.h>
#include <gelf.h>
#include "libbpf.h"
#define __printf(a, b) __attribute__((format(printf, a, b)))
__printf(1, 2)
static int __base_pr(const char *format, ...)
{
va_list args;
int err;
va_start(args, format);
err = vfprintf(stderr, format, args);
va_end(args);
return err;
}
static __printf(1, 2) libbpf_print_fn_t __pr_warning = __base_pr;
static __printf(1, 2) libbpf_print_fn_t __pr_info = __base_pr;
static __printf(1, 2) libbpf_print_fn_t __pr_debug;
#define __pr(func, fmt, ...) \
do { \
if ((func)) \
(func)("libbpf: " fmt, ##__VA_ARGS__); \
} while (0)
#define pr_warning(fmt, ...) __pr(__pr_warning, fmt, ##__VA_ARGS__)
#define pr_info(fmt, ...) __pr(__pr_info, fmt, ##__VA_ARGS__)
#define pr_debug(fmt, ...) __pr(__pr_debug, fmt, ##__VA_ARGS__)
void libbpf_set_print(libbpf_print_fn_t warn,
libbpf_print_fn_t info,
libbpf_print_fn_t debug)
{
__pr_warning = warn;
__pr_info = info;
__pr_debug = debug;
}
/* Copied from tools/perf/util/util.h */
#ifndef zfree
# define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
#endif
#ifndef zclose
# define zclose(fd) ({ \
int ___err = 0; \
if ((fd) >= 0) \
___err = close((fd)); \
fd = -1; \
___err; })
#endif
#ifdef HAVE_LIBELF_MMAP_SUPPORT
# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP
#else
# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
#endif
struct bpf_object {
/*
* Information when doing elf related work. Only valid if fd
* is valid.
*/
struct {
int fd;
Elf *elf;
GElf_Ehdr ehdr;
} efile;
char path[];
};
#define obj_elf_valid(o) ((o)->efile.elf)
static struct bpf_object *bpf_object__new(const char *path)
{
struct bpf_object *obj;
obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
if (!obj) {
pr_warning("alloc memory failed for %s\n", path);
return NULL;
}
strcpy(obj->path, path);
obj->efile.fd = -1;
return obj;
}
static void bpf_object__elf_finish(struct bpf_object *obj)
{
if (!obj_elf_valid(obj))
return;
if (obj->efile.elf) {
elf_end(obj->efile.elf);
obj->efile.elf = NULL;
}
zclose(obj->efile.fd);
}
static int bpf_object__elf_init(struct bpf_object *obj)
{
int err = 0;
GElf_Ehdr *ep;
if (obj_elf_valid(obj)) {
pr_warning("elf init: internal error\n");
return -EEXIST;
}
obj->efile.fd = open(obj->path, O_RDONLY);
if (obj->efile.fd < 0) {
pr_warning("failed to open %s: %s\n", obj->path,
strerror(errno));
return -errno;
}
obj->efile.elf = elf_begin(obj->efile.fd,
LIBBPF_ELF_C_READ_MMAP,
NULL);
if (!obj->efile.elf) {
pr_warning("failed to open %s as ELF file\n",
obj->path);
err = -EINVAL;
goto errout;
}
if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
pr_warning("failed to get EHDR from %s\n",
obj->path);
err = -EINVAL;
goto errout;
}
ep = &obj->efile.ehdr;
if ((ep->e_type != ET_REL) || (ep->e_machine != 0)) {
pr_warning("%s is not an eBPF object file\n",
obj->path);
err = -EINVAL;
goto errout;
}
return 0;
errout:
bpf_object__elf_finish(obj);
return err;
}
static struct bpf_object *
__bpf_object__open(const char *path)
{
struct bpf_object *obj;
if (elf_version(EV_CURRENT) == EV_NONE) {
pr_warning("failed to init libelf for %s\n", path);
return NULL;
}
obj = bpf_object__new(path);
if (!obj)
return NULL;
if (bpf_object__elf_init(obj))
goto out;
bpf_object__elf_finish(obj);
return obj;
out:
bpf_object__close(obj);
return NULL;
}
struct bpf_object *bpf_object__open(const char *path)
{
/* param validation */
if (!path)
return NULL;
pr_debug("loading %s\n", path);
return __bpf_object__open(path);
}
void bpf_object__close(struct bpf_object *obj)
{
if (!obj)
return;
bpf_object__elf_finish(obj);
free(obj);
}
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