Commit a664a834 authored by Peter Wu's avatar Peter Wu Committed by Daniel Borkmann

tools: bpftool: fix reading from /proc/config.gz

/proc/config has never existed as far as I can see, but /proc/config.gz
is present on Arch Linux. Add support for decompressing config.gz using
zlib which is a mandatory dependency of libelf anyway. Replace existing
stdio functions with gzFile operations since the latter transparently
handles uncompressed and gzip-compressed files.

Cc: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: default avatarPeter Wu <peter@lekensteyn.nl>
Reviewed-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 9f30cd56
......@@ -52,7 +52,7 @@ ifneq ($(EXTRA_LDFLAGS),)
LDFLAGS += $(EXTRA_LDFLAGS)
endif
LIBS = -lelf $(LIBBPF)
LIBS = -lelf -lz $(LIBBPF)
INSTALL ?= install
RM ?= rm -f
......
......@@ -14,6 +14,7 @@
#include <bpf.h>
#include <libbpf.h>
#include <zlib.h>
#include "main.h"
......@@ -284,34 +285,32 @@ static void probe_jit_limit(void)
}
}
static char *get_kernel_config_option(FILE *fd, const char *option)
static bool read_next_kernel_config_option(gzFile file, char *buf, size_t n,
char **value)
{
size_t line_n = 0, optlen = strlen(option);
char *res, *strval, *line = NULL;
ssize_t n;
char *sep;
rewind(fd);
while ((n = getline(&line, &line_n, fd)) > 0) {
if (strncmp(line, option, optlen))
while (gzgets(file, buf, n)) {
if (strncmp(buf, "CONFIG_", 7))
continue;
/* Check we have at least '=', value, and '\n' */
if (strlen(line) < optlen + 3)
continue;
if (*(line + optlen) != '=')
sep = strchr(buf, '=');
if (!sep)
continue;
/* Trim ending '\n' */
line[strlen(line) - 1] = '\0';
buf[strlen(buf) - 1] = '\0';
/* Split on '=' and ensure that a value is present. */
*sep = '\0';
if (!sep[1])
continue;
/* Copy and return config option value */
strval = line + optlen + 1;
res = strdup(strval);
free(line);
return res;
*value = sep + 1;
return true;
}
free(line);
return NULL;
return false;
}
static void probe_kernel_image_config(void)
......@@ -386,59 +385,61 @@ static void probe_kernel_image_config(void)
/* test_bpf module for BPF tests */
"CONFIG_TEST_BPF",
};
char *value, *buf = NULL;
char *values[ARRAY_SIZE(options)] = { };
struct utsname utsn;
char path[PATH_MAX];
size_t i, n;
ssize_t ret;
FILE *fd;
gzFile file = NULL;
char buf[4096];
char *value;
size_t i;
if (uname(&utsn))
goto no_config;
if (!uname(&utsn)) {
snprintf(path, sizeof(path), "/boot/config-%s", utsn.release);
snprintf(path, sizeof(path), "/boot/config-%s", utsn.release);
/* gzopen also accepts uncompressed files. */
file = gzopen(path, "r");
}
fd = fopen(path, "r");
if (!fd && errno == ENOENT) {
/* Some distributions put the config file at /proc/config, give
* it a try.
* Sometimes it is also at /proc/config.gz but we do not try
* this one for now, it would require linking against libz.
if (!file) {
/* Some distributions build with CONFIG_IKCONFIG=y and put the
* config file at /proc/config.gz.
*/
fd = fopen("/proc/config", "r");
file = gzopen("/proc/config.gz", "r");
}
if (!fd) {
if (!file) {
p_info("skipping kernel config, can't open file: %s",
strerror(errno));
goto no_config;
goto end_parse;
}
/* Sanity checks */
ret = getline(&buf, &n, fd);
ret = getline(&buf, &n, fd);
if (!buf || !ret) {
if (!gzgets(file, buf, sizeof(buf)) ||
!gzgets(file, buf, sizeof(buf))) {
p_info("skipping kernel config, can't read from file: %s",
strerror(errno));
free(buf);
goto no_config;
goto end_parse;
}
if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) {
p_info("skipping kernel config, can't find correct file");
free(buf);
goto no_config;
goto end_parse;
}
free(buf);
for (i = 0; i < ARRAY_SIZE(options); i++) {
value = get_kernel_config_option(fd, options[i]);
print_kernel_option(options[i], value);
free(value);
while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) {
for (i = 0; i < ARRAY_SIZE(options); i++) {
if (values[i] || strcmp(buf, options[i]))
continue;
values[i] = strdup(value);
}
}
fclose(fd);
return;
no_config:
for (i = 0; i < ARRAY_SIZE(options); i++)
print_kernel_option(options[i], NULL);
end_parse:
if (file)
gzclose(file);
for (i = 0; i < ARRAY_SIZE(options); i++) {
print_kernel_option(options[i], values[i]);
free(values[i]);
}
}
static bool probe_bpf_syscall(const char *define_prefix)
......
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