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/* SPDX-License-Identifier: GPL-2.0 */
/*
* bpf_glue.c: BPF code to call both legacy and libbpf code
* Authors: Hangbin Liu <haliu@redhat.com>
*
*/
#include <sys/syscall.h>
#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include "bpf_util.h"
#ifdef HAVE_LIBBPF
#include <bpf/bpf.h>
#endif
int bpf(int cmd, union bpf_attr *attr, unsigned int size)
{
#ifdef __NR_bpf
return syscall(__NR_bpf, cmd, attr, size);
#else
fprintf(stderr, "No bpf syscall, kernel headers too old?\n");
errno = ENOSYS;
return -1;
#endif
}
int bpf_program_attach(int prog_fd, int target_fd, enum bpf_attach_type type)
{
#ifdef HAVE_LIBBPF
return bpf_prog_attach(prog_fd, target_fd, type, 0);
#else
return bpf_prog_attach_fd(prog_fd, target_fd, type);
#endif
}
#ifdef HAVE_LIBBPF
static const char *_libbpf_compile_version = LIBBPF_VERSION;
static char _libbpf_version[10] = {};
const char *get_libbpf_version(void)
{
/* Start by copying compile-time version into buffer so we have a
* fallback value in case we are dynamically linked, or can't find a
* version in /proc/self/maps below.
*/
strncpy(_libbpf_version, _libbpf_compile_version,
sizeof(_libbpf_version)-1);
#ifdef LIBBPF_DYNAMIC
char buf[PATH_MAX], *s;
bool found = false;
FILE *fp;
/* When dynamically linking against libbpf, we can't be sure that the
* version we discovered at compile time is actually the one we are
* using at runtime. This can lead to hard-to-debug errors, so we try to
* discover the correct version at runtime.
*
* The simple solution to this would be if libbpf itself exported a
* version in its API. But since it doesn't, we work around this by
* parsing the mappings of the binary at runtime, looking for the full
* filename of libbpf.so and using that.
*/
fp = fopen("/proc/self/maps", "r");
if (fp == NULL)
goto out;
while (fgets(buf, sizeof(buf), fp) != NULL) {
if ((s = strstr(buf, "libbpf.so.")) != NULL) {
strncpy(_libbpf_version, s+10, sizeof(_libbpf_version)-1);
strtok(_libbpf_version, "\n");
found = true;
break;
}
}
fclose(fp);
out:
if (!found)
fprintf(stderr, "Couldn't find runtime libbpf version - falling back to compile-time value!\n");
#endif /* LIBBPF_DYNAMIC */
_libbpf_version[sizeof(_libbpf_version)-1] = '\0';
return _libbpf_version;
}
#else
const char *get_libbpf_version(void)
{
return NULL;
}
#endif /* HAVE_LIBBPF */
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