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libbpf: Add elf_open/elf_close functions

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Adding elf_open/elf_close functions and using it in
elf_find_func_offset_from_file function. It will be
used in following changes to save some common code.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-10-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jiri Olsa
2023-08-09 10:34:21 +02:00
committed by Andrii Nakryiko
parent 0cd5b05f53
commit 1f8929293e
3 changed files with 57 additions and 42 deletions
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61
src/elf.c
View File

@@ -10,6 +10,42 @@
#define STRERR_BUFSIZE 128
int elf_open(const char *binary_path, struct elf_fd *elf_fd)
{
char errmsg[STRERR_BUFSIZE];
int fd, ret;
Elf *elf;
if (elf_version(EV_CURRENT) == EV_NONE) {
pr_warn("elf: failed to init libelf for %s\n", binary_path);
return -LIBBPF_ERRNO__LIBELF;
}
fd = open(binary_path, O_RDONLY | O_CLOEXEC);
if (fd < 0) {
ret = -errno;
pr_warn("elf: failed to open %s: %s\n", binary_path,
libbpf_strerror_r(ret, errmsg, sizeof(errmsg)));
return ret;
}
elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
if (!elf) {
pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
close(fd);
return -LIBBPF_ERRNO__FORMAT;
}
elf_fd->fd = fd;
elf_fd->elf = elf;
return 0;
}
void elf_close(struct elf_fd *elf_fd)
{
if (!elf_fd)
return;
elf_end(elf_fd->elf);
close(elf_fd->fd);
}
/* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn)
{
@@ -170,28 +206,13 @@ out:
*/
long elf_find_func_offset_from_file(const char *binary_path, const char *name)
{
char errmsg[STRERR_BUFSIZE];
struct elf_fd elf_fd;
long ret = -ENOENT;
Elf *elf;
int fd;
fd = open(binary_path, O_RDONLY | O_CLOEXEC);
if (fd < 0) {
ret = -errno;
pr_warn("failed to open %s: %s\n", binary_path,
libbpf_strerror_r(ret, errmsg, sizeof(errmsg)));
ret = elf_open(binary_path, &elf_fd);
if (ret)
return ret;
}
elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
if (!elf) {
pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
close(fd);
return -LIBBPF_ERRNO__FORMAT;
}
ret = elf_find_func_offset(elf, binary_path, name);
elf_end(elf);
close(fd);
ret = elf_find_func_offset(elf_fd.elf, binary_path, name);
elf_close(&elf_fd);
return ret;
}