[RFC PATCH bpf-next 3/7] libbpf: factor out common logic of testing and closing FD

[Andrii Nakryiko]

Factor out common piece of logic that detects support for a feature based on
successfully created FD. Also take care of closing FD, if it was created.

Signed-off-by: Andrii Nakryiko <andr...@fb.com>
---
 tools/lib/bpf/libbpf.c | 70 ++++++++++--------------------------------
 1 file changed, 17 insertions(+), 53 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8e329c57be51..24c806559867 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3427,6 +3427,13 @@ bpf_object__probe_loading(struct bpf_object *obj)
        return 0;
 }
 
+static int probe_fd(int fd)
+{
+       if (fd >= 0)
+               close(fd);
+       return fd >= 0;
+}
+
 static int probe_kern_prog_name(void)
 {
        struct bpf_load_program_attr attr;
@@ -3445,12 +3452,7 @@ static int probe_kern_prog_name(void)
        attr.license = "GPL";
        attr.name = "test";
        ret = bpf_load_program_xattr(&attr, NULL, 0);
-       if (ret >= 0) {
-               close(ret);
-               return 1;
-       }
-
-       return 0;
+       return probe_fd(ret);
 }
 
 static int probe_kern_global_data(void)
@@ -3490,12 +3492,7 @@ static int probe_kern_global_data(void)
 
        ret = bpf_load_program_xattr(&prg_attr, NULL, 0);
        close(map);
-       if (ret >= 0) {
-               close(ret);
-               return 1;
-       }
-
-       return 0;
+       return probe_fd(ret);
 }
 
 static int probe_kern_btf_func(void)
@@ -3511,16 +3508,9 @@ static int probe_kern_btf_func(void)
                /* FUNC x */                                    /* [3] */
                BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
        };
-       int btf_fd;
 
-       btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
-                                     strs, sizeof(strs));
-       if (btf_fd >= 0) {
-               close(btf_fd);
-               return 1;
-       }
-
-       return 0;
+       return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+                                            strs, sizeof(strs)));
 }
 
 static int probe_kern_btf_func_global(void)
@@ -3536,16 +3526,9 @@ static int probe_kern_btf_func_global(void)
                /* FUNC x BTF_FUNC_GLOBAL */                    /* [3] */
                BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 
BTF_FUNC_GLOBAL), 2),
        };
-       int btf_fd;
 
-       btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
-                                     strs, sizeof(strs));
-       if (btf_fd >= 0) {
-               close(btf_fd);
-               return 1;
-       }
-
-       return 0;
+       return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+                                            strs, sizeof(strs)));
 }
 
 static int probe_kern_btf_datasec(void)
@@ -3562,16 +3545,9 @@ static int probe_kern_btf_datasec(void)
                BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
                BTF_VAR_SECINFO_ENC(2, 0, 4),
        };
-       int btf_fd;
 
-       btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
-                                     strs, sizeof(strs));
-       if (btf_fd >= 0) {
-               close(btf_fd);
-               return 1;
-       }
-
-       return 0;
+       return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+                                            strs, sizeof(strs)));
 }
 
 static int probe_kern_array_mmap(void)
@@ -3583,14 +3559,8 @@ static int probe_kern_array_mmap(void)
                .value_size = sizeof(int),
                .max_entries = 1,
        };
-       int fd;
 
-       fd = bpf_create_map_xattr(&attr);
-       if (fd >= 0) {
-               close(fd);
-               return 1;
-       }
-       return 0;
+       return probe_fd(bpf_create_map_xattr(&attr));
 }
 
 static int probe_kern_exp_attach_type(void)
@@ -3600,7 +3570,6 @@ static int probe_kern_exp_attach_type(void)
                BPF_MOV64_IMM(BPF_REG_0, 0),
                BPF_EXIT_INSN(),
        };
-       int fd;
 
        memset(&attr, 0, sizeof(attr));
        /* use any valid combination of program type and (optional)
@@ -3614,12 +3583,7 @@ static int probe_kern_exp_attach_type(void)
        attr.insns_cnt = ARRAY_SIZE(insns);
        attr.license = "GPL";
 
-       fd = bpf_load_program_xattr(&attr, NULL, 0);
-       if (fd >= 0) {
-               close(fd);
-               return 1;
-       }
-       return 0;
+       return probe_fd(bpf_load_program_xattr(&attr, NULL, 0));
 }
 
 enum kern_feature_result {
-- 
2.24.1