1 files changed, 93 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index b07317d2842f..e8daf963ecef 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -21,6 +21,7 @@
 #include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/vfs.h>
+#include <sys/utsname.h>
 
 #include <linux/filter.h>
 #include <linux/limits.h>
@@ -31,6 +32,7 @@
 #include <bpf/hashmap.h>
 #include <bpf/libbpf.h> /* libbpf_num_possible_cpus */
 #include <bpf/btf.h>
+#include <zlib.h>
 
 #include "main.h"
 
@@ -1208,3 +1210,94 @@ int pathname_concat(char *buf, int buf_sz, const char *path,
 
 	return 0;
 }
+
+static bool read_next_kernel_config_option(gzFile file, char *buf, size_t n,
+					   char **value)
+{
+	char *sep;
+
+	while (gzgets(file, buf, n)) {
+		if (strncmp(buf, "CONFIG_", 7))
+			continue;
+
+		sep = strchr(buf, '=');
+		if (!sep)
+			continue;
+
+		/* Trim ending '\n' */
+		buf[strlen(buf) - 1] = '\0';
+
+		/* Split on '=' and ensure that a value is present. */
+		*sep = '\0';
+		if (!sep[1])
+			continue;
+
+		*value = sep + 1;
+		return true;
+	}
+
+	return false;
+}
+
+int read_kernel_config(const struct kernel_config_option *requested_options,
+		       size_t num_options, char **out_values,
+		       const char *define_prefix)
+{
+	struct utsname utsn;
+	char path[PATH_MAX];
+	gzFile file = NULL;
+	char buf[4096];
+	char *value;
+	size_t i;
+	int ret = 0;
+
+	if (!requested_options || !out_values || num_options == 0)
+		return -1;
+
+	if (!uname(&utsn)) {
+		snprintf(path, sizeof(path), "/boot/config-%s", utsn.release);
+
+		/* gzopen also accepts uncompressed files. */
+		file = gzopen(path, "r");
+	}
+
+	if (!file) {
+		/* Some distributions build with CONFIG_IKCONFIG=y and put the
+		 * config file at /proc/config.gz.
+		 */
+		file = gzopen("/proc/config.gz", "r");
+	}
+
+	if (!file) {
+		p_info("skipping kernel config, can't open file: %s",
+			strerror(errno));
+		return -1;
+	}
+
+	if (!gzgets(file, buf, sizeof(buf)) || !gzgets(file, buf, sizeof(buf))) {
+		p_info("skipping kernel config, can't read from file: %s",
+			strerror(errno));
+		ret = -1;
+		goto end_parse;
+	}
+
+	if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) {
+		p_info("skipping kernel config, can't find correct file");
+		ret = -1;
+		goto end_parse;
+	}
+
+	while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) {
+		for (i = 0; i < num_options; i++) {
+			if ((define_prefix && !requested_options[i].macro_dump) ||
+			     out_values[i] || strcmp(buf, requested_options[i].name))
+				continue;
+
+			out_values[i] = strdup(value);
+		}
+	}
+
+end_parse:
+	gzclose(file);
+	return ret;
+}