This change splits the elf_find_func_offset() function in two:
elf_find_func_offset(), which now accepts an already opened Elf object
instead of a path to a file that is to be opened, as well as
elf_find_func_offset_from_file(), which opens a binary based on a
path and then invokes elf_find_func_offset() on the Elf object. Having
this split in responsibilities will allow us to call
elf_find_func_offset() from other code paths on Elf objects that did not
necessarily come from a file on disk.
Signed-off-by: Daniel Müller <deso@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 57 ++++++++++++++++++++++++++----------------
1 file changed, 36 insertions(+), 21 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 05c4db3..4543e9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -10531,32 +10531,19 @@ static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn)
return NULL;
}
-/* Find offset of function name in object specified by path. "name" matches
- * symbol name or name@@LIB for library functions.
+/* Find offset of function name in the provided ELF object. "binary_path" is
+ * the path to the ELF binary represented by "elf", and only used for error
+ * reporting matters. "name" matches symbol name or name@@LIB for library
+ * functions.
*/
-static long elf_find_func_offset(const char *binary_path, const char *name)
+static long elf_find_func_offset(Elf *elf, const char *binary_path, const char *name)
{
- int fd, i, sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
+ int i, sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
bool is_shared_lib, is_name_qualified;
- char errmsg[STRERR_BUFSIZE];
long ret = -ENOENT;
size_t name_len;
GElf_Ehdr ehdr;
- Elf *elf;
- 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)));
- 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;
- }
if (!gelf_getehdr(elf, &ehdr)) {
pr_warn("elf: failed to get ehdr from %s: %s\n", binary_path, elf_errmsg(-1));
ret = -LIBBPF_ERRNO__FORMAT;
@@ -10569,7 +10556,7 @@ static long elf_find_func_offset(const char *binary_path, const char *name)
/* Does name specify "@@LIB"? */
is_name_qualified = strstr(name, "@@") != NULL;
- /* Search SHT_DYNSYM, SHT_SYMTAB for symbol. This search order is used because if
+ /* Search SHT_DYNSYM, SHT_SYMTAB for symbol. This search order is used because if
* a binary is stripped, it may only have SHT_DYNSYM, and a fully-statically
* linked binary may not have SHT_DYMSYM, so absence of a section should not be
* reported as a warning/error.
@@ -10682,6 +10669,34 @@ static long elf_find_func_offset(const char *binary_path, const char *name)
}
}
out:
+ return ret;
+}
+
+/* Find offset of function name in ELF object specified by path. "name" matches
+ * symbol name or name@@LIB for library functions.
+ */
+static long elf_find_func_offset_from_file(const char *binary_path, const char *name)
+{
+ char errmsg[STRERR_BUFSIZE];
+ 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)));
+ 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);
return ret;
@@ -10805,7 +10820,7 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
if (func_name) {
long sym_off;
- sym_off = elf_find_func_offset(binary_path, func_name);
+ sym_off = elf_find_func_offset_from_file(binary_path, func_name);
if (sym_off < 0)
return libbpf_err_ptr(sym_off);
func_offset += sym_off;
--
2.30.2
