[RFC PATCH v6 19/32] bpf tools: Introduce accessors for struct bpf_program

Wang Nan
2015-06-09T05:56:15Z

This patch introduces accessors for user of libbpf to retrive section
name and fd of a opened/loaded eBPF program. 'struct bpf_prog_handler'
is used for that purpose. Accessors of programs section name and file
descriptor are provided. Set/get private data are also impelmented.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
---
tools/lib/bpf/libbpf.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 25 +++++++++++++++
2 files changed, 107 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 9b56832..acf9190 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -98,6 +98,10 @@ struct bpf_program {
int nr_reloc;

int fd;
+
+ struct bpf_object *obj;
+ void *priv;
+ bpf_program_clear_priv_t clear_priv;
};

struct bpf_object {
@@ -150,6 +154,12 @@ static void bpf_program__clear(struct bpf_program *prog)
if (!prog)
return;

+ if (prog->clear_priv)
+ prog->clear_priv(prog, prog->priv);
+
+ prog->priv = NULL;
+ prog->clear_priv = NULL;
+
bpf_program__unload(prog);
zfree(&prog->section_name);
zfree(&prog->insns);
@@ -211,6 +221,7 @@ bpf_program__new(struct bpf_object *obj, void *data, size_t size,
prog->insns_cnt * sizeof(struct bpf_insn));
prog->idx = idx;
prog->fd = -1;
+ prog->obj = obj;

return prog;
out:
@@ -912,3 +923,74 @@ void bpf_object__close(struct bpf_object *obj)

free(obj);
}
+
+struct bpf_program *
+bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
+{
+ size_t idx;
+
+ if (!obj->programs)
+ return NULL;
+ /* First handler */
+ if (prev == NULL)
+ return (&obj->programs[0]);
+
+ if (prev->obj != obj) {
+ pr_warning("error: program handler doesn't match object\n");
+ return NULL;
+ }
+
+ idx = (prev - obj->programs) + 1;
+ if (idx >= obj->nr_programs)
+ return NULL;
+ return &obj->programs[idx];
+}
+
+int bpf_program__set_private(struct bpf_program *prog,
+ void *priv,
+ bpf_program_clear_priv_t clear_priv)
+{
+ if (prog->priv && prog->clear_priv)
+ prog->clear_priv(prog, prog->priv);
+
+ prog->priv = priv;
+ prog->clear_priv = clear_priv;
+ return 0;
+}
+
+int bpf_program__get_private(struct bpf_program *prog, void **ppriv)
+{
+ *ppriv = prog->priv;
+ return 0;
+}
+
+int bpf_program__get_title(struct bpf_program *prog,
+ const char **ptitle, bool dup)
+{
+ const char *title;
+
+ if (!ptitle)
+ return -EINVAL;
+
+ title = prog->section_name;
+ if (dup) {
+ title = strdup(title);
+ if (!title) {
+ pr_warning("failed to strdup program title\n");
+ *ptitle = NULL;
+ return -ENOMEM;
+ }
+ }
+
+ *ptitle = title;
+ return 0;
+}
+
+int bpf_program__get_fd(struct bpf_program *prog, int *pfd)
+{
+ if (!pfd)
+ return -EINVAL;
+
+ *pfd = prog->fd;
+ return 0;
+}
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 3e69600..3c54558 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -9,6 +9,7 @@
#define __BPF_LIBBPF_H

#include <stdio.h>
+#include <stdbool.h>

/*
* In include/linux/compiler-gcc.h, __printf is defined. However
@@ -34,6 +35,30 @@ void bpf_object__close(struct bpf_object *object);
int bpf_object__load(struct bpf_object *obj);
int bpf_object__unload(struct bpf_object *obj);

+/* Accessors of bpf_program. */
+struct bpf_program;
+struct bpf_program *bpf_program__next(struct bpf_program *prog,
+ struct bpf_object *obj);
+
+#define bpf_object__for_each_program(pos, obj) \
+ for ((pos) = bpf_program__next(NULL, (obj)); \
+ (pos) != NULL; \
+ (pos) = bpf_program__next((pos), (obj)))
+
+typedef void (*bpf_program_clear_priv_t)(struct bpf_program *,
+ void *);
+
+int bpf_program__set_private(struct bpf_program *prog, void *priv,
+ bpf_program_clear_priv_t clear_priv);
+
+int bpf_program__get_private(struct bpf_program *prog,
+ void **ppriv);
+
+int bpf_program__get_title(struct bpf_program *prog,
+ const char **ptitle, bool dup);
+
+int bpf_program__get_fd(struct bpf_program *prog, int *pfd);
+
/*
* We don't need __attribute__((packed)) now since it is
* unnecessary for 'bpf_map_def' because they are all aligned.
--
1.8.3.4