| Message ID | 20190805001541.8096-1-peter@lekensteyn.nl |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | tools: bpftool: fix reading from /proc/config.gz | expand |
Hi Peter, Thanks for looking into this (and for the fixes)! Some comments below. 2019-08-05 01:15 UTC+0100 ~ Peter Wu <peter@lekensteyn.nl> > /proc/config has never existed as far as I can see, but /proc/config.gz As far as I understood (from examining Cilium [0]), /proc/config _is_ used by some distributions, such as CoreOS. This is why we look at that location in bpftool. [0] https://github.com/cilium/cilium/blob/master/bpf/run_probes.sh#L42 > is present on Arch Linux. Execute an external gunzip program to avoid > linking to zlib and rework the option scanning code since a pipe is not > seekable. This also fixes a file handle leak on some error paths. > > Fixes: 4567b983f78c ("tools: bpftool: add probes for kernel configuration options") > Cc: Quentin Monnet <quentin.monnet@netronome.com> > Signed-off-by: Peter Wu <peter@lekensteyn.nl> > --- > tools/bpf/bpftool/feature.c | 92 +++++++++++++++++++++---------------- > 1 file changed, 52 insertions(+), 40 deletions(-) > > diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c > index d672d9086fff..e9e10f582047 100644 > --- a/tools/bpf/bpftool/feature.c > +++ b/tools/bpf/bpftool/feature.c > @@ -284,34 +284,34 @@ static void probe_jit_limit(void) > } > } > > -static char *get_kernel_config_option(FILE *fd, const char *option) > +static bool get_kernel_config_option(FILE *fd, char **buf_p, size_t *n_p, > + char **value) Maybe we could rename this function, and have "next" appear in it somewhere? After your changes, it does not return the value for a specific option anymore. > { > - size_t line_n = 0, optlen = strlen(option); > - char *res, *strval, *line = NULL; > - ssize_t n; > + char *sep; > + ssize_t linelen; Please order the declarations in reverse-Christmas tree style. > > - rewind(fd); > - while ((n = getline(&line, &line_n, fd)) > 0) { > - if (strncmp(line, option, optlen)) > + while ((linelen = getline(buf_p, n_p, fd)) > 0) { > + char *line = *buf_p; Please leave a blank line after declarations. > + if (strncmp(line, "CONFIG_", 7)) > continue; > - /* Check we have at least '=', value, and '\n' */ > - if (strlen(line) < optlen + 3) > - continue; > - if (*(line + optlen) != '=') > + > + sep = memchr(line, '=', linelen); > + if (!sep) > continue; > > /* Trim ending '\n' */ > - line[strlen(line) - 1] = '\0'; > + line[linelen - 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) > @@ -386,31 +386,34 @@ static void probe_kernel_image_config(void) > /* test_bpf module for BPF tests */ > "CONFIG_TEST_BPF", > }; > + char *values[ARRAY_SIZE(options)] = { }; > char *value, *buf = NULL; > struct utsname utsn; > char path[PATH_MAX]; > size_t i, n; > ssize_t ret; > - FILE *fd; > + FILE *fd = NULL; > + bool is_pipe = false; Reverse-Christmas-tree style please. > > if (uname(&utsn)) > - goto no_config; > + goto end_parse; Just thinking, maybe if uname() fails we can skip /boot/config-$(uname -r) but still attempt to parse /proc/config{,.gz} instead of printing only NULL options? > > snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); > > 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. > + /* Some distributions build with CONFIG_IKCONFIG=y and put the > + * config file at /proc/config.gz. We try to invoke an external > + * gzip program to avoid linking to libz. > + * Hide stderr to avoid interference with the JSON output. Because some distributions do use /proc/config, we should keep this. You can probably add /proc/config.gz as another attempt below (or even above) the current case? > */ > - fd = fopen("/proc/config", "r"); > + fd = popen("gunzip -c /proc/config.gz 2>/dev/null", "r"); > + is_pipe = true; > } > if (!fd) { > 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); > @@ -418,27 +421,36 @@ static void probe_kernel_image_config(void) > if (!buf || !ret) { > 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; > + } > + > + while (get_kernel_config_option(fd, &buf, &n, &value))> + for (i = 0; i < ARRAY_SIZE(options); i++) { > + if (values[i] || strcmp(buf, options[i])) Can we have an option set multiple times in the config file? If so, maybe have a p_info() if values are different to warn users that conflicting values were found? (Reading the file just once is a nice improvement over my version, by the way, thanks!) > + continue; > + > + values[i] = strdup(value); > + } > + } > + > +end_parse: > + if (fd) { > + if (is_pipe) { > + if (pclose(fd)) > + p_info("failed to read /proc/config.gz"); > + } else > + fclose(fd); Please use braces on all branches of the conditional statement (else). Thanks, Quentin
On 08/05, Peter Wu wrote: > /proc/config has never existed as far as I can see, but /proc/config.gz > is present on Arch Linux. Execute an external gunzip program to avoid > linking to zlib and rework the option scanning code since a pipe is not > seekable. This also fixes a file handle leak on some error paths. Thanks for doing that! One question: why not link against -lz instead? With fork/execing gunzip you're just hiding this dependency. You can add something like this to the Makefile: ifeq ($(feature-zlib),1) CLFAGS += -DHAVE_ZLIB endif And then conditionally add support for config.gz. Thoughts? > > Fixes: 4567b983f78c ("tools: bpftool: add probes for kernel configuration options") > Cc: Quentin Monnet <quentin.monnet@netronome.com> > Signed-off-by: Peter Wu <peter@lekensteyn.nl> > --- > tools/bpf/bpftool/feature.c | 92 +++++++++++++++++++++---------------- > 1 file changed, 52 insertions(+), 40 deletions(-) > > diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c > index d672d9086fff..e9e10f582047 100644 > --- a/tools/bpf/bpftool/feature.c > +++ b/tools/bpf/bpftool/feature.c > @@ -284,34 +284,34 @@ static void probe_jit_limit(void) > } > } > > -static char *get_kernel_config_option(FILE *fd, const char *option) > +static bool get_kernel_config_option(FILE *fd, char **buf_p, size_t *n_p, > + char **value) > { > - size_t line_n = 0, optlen = strlen(option); > - char *res, *strval, *line = NULL; > - ssize_t n; > + char *sep; > + ssize_t linelen; > > - rewind(fd); > - while ((n = getline(&line, &line_n, fd)) > 0) { > - if (strncmp(line, option, optlen)) > + while ((linelen = getline(buf_p, n_p, fd)) > 0) { > + char *line = *buf_p; > + if (strncmp(line, "CONFIG_", 7)) > continue; > - /* Check we have at least '=', value, and '\n' */ > - if (strlen(line) < optlen + 3) > - continue; > - if (*(line + optlen) != '=') > + > + sep = memchr(line, '=', linelen); > + if (!sep) > continue; > > /* Trim ending '\n' */ > - line[strlen(line) - 1] = '\0'; > + line[linelen - 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) > @@ -386,31 +386,34 @@ static void probe_kernel_image_config(void) > /* test_bpf module for BPF tests */ > "CONFIG_TEST_BPF", > }; > + char *values[ARRAY_SIZE(options)] = { }; > char *value, *buf = NULL; > struct utsname utsn; > char path[PATH_MAX]; > size_t i, n; > ssize_t ret; > - FILE *fd; > + FILE *fd = NULL; > + bool is_pipe = false; > > if (uname(&utsn)) > - goto no_config; > + goto end_parse; > > snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); > > 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. > + /* Some distributions build with CONFIG_IKCONFIG=y and put the > + * config file at /proc/config.gz. We try to invoke an external > + * gzip program to avoid linking to libz. > + * Hide stderr to avoid interference with the JSON output. > */ > - fd = fopen("/proc/config", "r"); > + fd = popen("gunzip -c /proc/config.gz 2>/dev/null", "r"); > + is_pipe = true; > } > if (!fd) { > 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); > @@ -418,27 +421,36 @@ static void probe_kernel_image_config(void) > if (!buf || !ret) { > 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; > + } > + > + while (get_kernel_config_option(fd, &buf, &n, &value)) { > + for (i = 0; i < ARRAY_SIZE(options); i++) { > + if (values[i] || strcmp(buf, options[i])) > + continue; > + > + values[i] = strdup(value); > + } > + } > + > +end_parse: > + if (fd) { > + if (is_pipe) { > + if (pclose(fd)) > + p_info("failed to read /proc/config.gz"); > + } else > + fclose(fd); > } > 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); > + print_kernel_option(options[i], values[i]); > + free(values[i]); > } > - fclose(fd); > - return; > - > -no_config: > - for (i = 0; i < ARRAY_SIZE(options); i++) > - print_kernel_option(options[i], NULL); > } > > static bool probe_bpf_syscall(const char *define_prefix) > -- > 2.22.0 >
On Mon, 5 Aug 2019 08:29:36 -0700, Stanislav Fomichev wrote: > On 08/05, Peter Wu wrote: > > /proc/config has never existed as far as I can see, but /proc/config.gz > > is present on Arch Linux. Execute an external gunzip program to avoid > > linking to zlib and rework the option scanning code since a pipe is not > > seekable. This also fixes a file handle leak on some error paths. > Thanks for doing that! One question: why not link against -lz instead? > With fork/execing gunzip you're just hiding this dependency. > > You can add something like this to the Makefile: > ifeq ($(feature-zlib),1) > CLFAGS += -DHAVE_ZLIB > endif > > And then conditionally add support for config.gz. Thoughts? +1
Hi all, Thank you for your quick feedback, I will address them in the next revision. On Mon, Aug 05, 2019 at 11:41:09AM +0100, Quentin Monnet wrote: > As far as I understood (from examining Cilium [0]), /proc/config _is_ > used by some distributions, such as CoreOS. This is why we look at that > location in bpftool. > > [0] https://github.com/cilium/cilium/blob/master/bpf/run_probes.sh#L42 This comment[1] says "CoreOS uses /proc/config", but I think that is a typo and is supposed to say "/proc/config.gz". The original feature request[2] uses "/boot/config" as example. [1]: https://github.com/cilium/cilium/pull/1065 [2]: https://github.com/cilium/cilium/issues/891 Given that "/proc/config.gz" is the standard since at least v2.6.12-rc2, and the official kernel has no mention of "/proc/config", I would like to skip the latter. If someone has a need for this and it is not covered by either /boot/config-$(uname -r) or /proc/config.gz, they could submit a patch for it with links to documentation. How about that? > > -static char *get_kernel_config_option(FILE *fd, const char *option) > > +static bool get_kernel_config_option(FILE *fd, char **buf_p, size_t *n_p, > > + char **value) > > Maybe we could rename this function, and have "next" appear in it > somewhere? After your changes, it does not return the value for a > specific option anymore. I have changed it to "read_next_kernel_config_option", let me know if you prefer an alternative. > > { > > - size_t line_n = 0, optlen = strlen(option); > > - char *res, *strval, *line = NULL; > > - ssize_t n; > > + char *sep; > > + ssize_t linelen; > > Please order the declarations in reverse-Christmas tree style. Does this refer to the type, name, or full line length? I did not find this in CodingStyle, the closest I could get is: https://lore.kernel.org/patchwork/patch/732076/ I will assume the line length for now. > > static void probe_kernel_image_config(void) > > @@ -386,31 +386,34 @@ static void probe_kernel_image_config(void) > > /* test_bpf module for BPF tests */ > > "CONFIG_TEST_BPF", > > }; > > + char *values[ARRAY_SIZE(options)] = { }; > > char *value, *buf = NULL; > > struct utsname utsn; > > char path[PATH_MAX]; > > size_t i, n; > > ssize_t ret; > > - FILE *fd; > > + FILE *fd = NULL; > > + bool is_pipe = false; > > Reverse-Christmas-tree style please. Even if that means moving lines? Something like this? char path[PATH_MAX]; + bool is_pipe = false; + FILE *fd = NULL; size_t i, n; ssize_t ret; - FILE *fd; > > if (uname(&utsn)) > > - goto no_config; > > + goto end_parse; > > Just thinking, maybe if uname() fails we can skip /boot/config-$(uname > -r) but still attempt to parse /proc/config{,.gz} instead of printing > only NULL options? Good idea, I'll try a bit harder if uname falls for whatever reason. > Because some distributions do use /proc/config, we should keep this. You > can probably add /proc/config.gz as another attempt below (or even > above) the current case? I doubt it is actually in use, it looks like a typo in the original PR. This post only lists /proc/config.gz, /boot/config and /boot/config-$(uname -r): https://superuser.com/questions/287371 > > + while (get_kernel_config_option(fd, &buf, &n, &value))> + for (i = 0; i < ARRAY_SIZE(options); i++) { > > + if (values[i] || strcmp(buf, options[i])) > > Can we have an option set multiple times in the config file? If so, > maybe have a p_info() if values are different to warn users that > conflicting values were found? scripts/kconfig/merge_config.sh seems to apply a merge strategy, overwriting earlier values and warning about it. However this should be rare given that it ended up at /proc/config.gz. For now I will favor simplicity over complexity and keep the old situation. Let me know if you prefer otherwise. On Mon, Aug 05, 2019 at 12:06:49PM -0700, Jakub Kicinski wrote: > On Mon, 5 Aug 2019 08:29:36 -0700, Stanislav Fomichev wrote: > > On 08/05, Peter Wu wrote: > > > /proc/config has never existed as far as I can see, but /proc/config.gz > > > is present on Arch Linux. Execute an external gunzip program to avoid > > > linking to zlib and rework the option scanning code since a pipe is not > > > seekable. This also fixes a file handle leak on some error paths. > > Thanks for doing that! One question: why not link against -lz instead? > > With fork/execing gunzip you're just hiding this dependency. > > > > You can add something like this to the Makefile: > > ifeq ($(feature-zlib),1) > > CLFAGS += -DHAVE_ZLIB > > endif > > > > And then conditionally add support for config.gz. Thoughts? > > +1 Given that the old code did not have this library dependency I did not add it (the program would otherwise fail to run). Executing an external process is similar to what tar does. I will look into linking directly to zlib, thanks!
Hi Peter, 2019-08-06 00:54 UTC+0100 ~ Peter Wu <peter@lekensteyn.nl> > Hi all, > > Thank you for your quick feedback, I will address them in the next > revision. > > On Mon, Aug 05, 2019 at 11:41:09AM +0100, Quentin Monnet wrote: > >> As far as I understood (from examining Cilium [0]), /proc/config _is_ >> used by some distributions, such as CoreOS. This is why we look at that >> location in bpftool. >> >> [0] https://github.com/cilium/cilium/blob/master/bpf/run_probes.sh#L42 > > This comment[1] says "CoreOS uses /proc/config", but I think that is a > typo and is supposed to say "/proc/config.gz". The original feature > request[2] uses "/boot/config" as example. > > [1]: https://github.com/cilium/cilium/pull/1065 > [2]: https://github.com/cilium/cilium/issues/891 > > Given that "/proc/config.gz" is the standard since at least v2.6.12-rc2, > and the official kernel has no mention of "/proc/config", I would like > to skip the latter. If someone has a need for this and it is not covered > by either /boot/config-$(uname -r) or /proc/config.gz, they could submit > a patch for it with links to documentation. How about that? Ok, did a bit of research on my side as well, and I couldn't find a solid reference to /proc/config either, so it seems you are correct. Let's drop /proc/config for now. Thanks for investigating that! > >>> -static char *get_kernel_config_option(FILE *fd, const char *option) >>> +static bool get_kernel_config_option(FILE *fd, char **buf_p, size_t *n_p, >>> + char **value) >> >> Maybe we could rename this function, and have "next" appear in it >> somewhere? After your changes, it does not return the value for a >> specific option anymore. > > I have changed it to "read_next_kernel_config_option", let me know if > you prefer an alternative. > Sounds good to me. >>> { >>> - size_t line_n = 0, optlen = strlen(option); >>> - char *res, *strval, *line = NULL; >>> - ssize_t n; >>> + char *sep; >>> + ssize_t linelen; >> >> Please order the declarations in reverse-Christmas tree style. > > Does this refer to the type, name, or full line length? I did not find > this in CodingStyle, the closest I could get is: > https://lore.kernel.org/patchwork/patch/732076/ > > I will assume the line length for now. I am unsure this is in the CodingStyle, but fairly certain that this is a convention for at least network-related code. And yes, as I understand it refers to the length of the line. > >>> static void probe_kernel_image_config(void) >>> @@ -386,31 +386,34 @@ static void probe_kernel_image_config(void) >>> /* test_bpf module for BPF tests */ >>> "CONFIG_TEST_BPF", >>> }; >>> + char *values[ARRAY_SIZE(options)] = { }; >>> char *value, *buf = NULL; >>> struct utsname utsn; >>> char path[PATH_MAX]; >>> size_t i, n; >>> ssize_t ret; >>> - FILE *fd; >>> + FILE *fd = NULL; >>> + bool is_pipe = false; >> >> Reverse-Christmas-tree style please. > > Even if that means moving lines? Something like this? > > char path[PATH_MAX]; > + bool is_pipe = false; > + FILE *fd = NULL; > size_t i, n; > ssize_t ret; > - FILE *fd; Yes, that's the idea (although "is_pipe" should be at the top in that case, above "path" -- and this applies to your v2 patch, by the way). > >>> if (uname(&utsn)) >>> - goto no_config; >>> + goto end_parse; >> >> Just thinking, maybe if uname() fails we can skip /boot/config-$(uname >> -r) but still attempt to parse /proc/config{,.gz} instead of printing >> only NULL options? > > Good idea, I'll try a bit harder if uname falls for whatever reason. Thanks! > >> Because some distributions do use /proc/config, we should keep this. You >> can probably add /proc/config.gz as another attempt below (or even >> above) the current case? > > I doubt it is actually in use, it looks like a typo in the original PR. > This post only lists /proc/config.gz, /boot/config and > /boot/config-$(uname -r): https://superuser.com/questions/287371 > >>> + while (get_kernel_config_option(fd, &buf, &n, &value)) >>> + for (i = 0; i < ARRAY_SIZE(options); i++) { >>> + if (values[i] || strcmp(buf, options[i])) >> >> Can we have an option set multiple times in the config file? If so, >> maybe have a p_info() if values are different to warn users that >> conflicting values were found? > > scripts/kconfig/merge_config.sh seems to apply a merge strategy, > overwriting earlier values and warning about it. However this should be > rare given that it ended up at /proc/config.gz. For now I will favor > simplicity over complexity and keep the old situation. Let me know if > you prefer otherwise. Understood, let's keep it that way for now. Thanks, Quentin
On Tue, Aug 6, 2019 at 2:36 AM Quentin Monnet <quentin.monnet@netronome.com> wrote: > > >>> { > >>> - size_t line_n = 0, optlen = strlen(option); > >>> - char *res, *strval, *line = NULL; > >>> - ssize_t n; > >>> + char *sep; > >>> + ssize_t linelen; > >> > >> Please order the declarations in reverse-Christmas tree style. > > > > Does this refer to the type, name, or full line length? I did not find > > this in CodingStyle, the closest I could get is: > > https://lore.kernel.org/patchwork/patch/732076/ > > > > I will assume the line length for now. > > I am unsure this is in the CodingStyle, but fairly certain that this is > a convention for at least network-related code. And yes, as I understand > it refers to the length of the line. Let's not over focus on this. It's a preference, but not a strong requirement. There are plenty of cases where it shouldn't be followed. Like logical grouping of variables take precedence of xmas tree.
diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c index d672d9086fff..e9e10f582047 100644 --- a/tools/bpf/bpftool/feature.c +++ b/tools/bpf/bpftool/feature.c @@ -284,34 +284,34 @@ static void probe_jit_limit(void) } } -static char *get_kernel_config_option(FILE *fd, const char *option) +static bool get_kernel_config_option(FILE *fd, char **buf_p, size_t *n_p, + char **value) { - size_t line_n = 0, optlen = strlen(option); - char *res, *strval, *line = NULL; - ssize_t n; + char *sep; + ssize_t linelen; - rewind(fd); - while ((n = getline(&line, &line_n, fd)) > 0) { - if (strncmp(line, option, optlen)) + while ((linelen = getline(buf_p, n_p, fd)) > 0) { + char *line = *buf_p; + if (strncmp(line, "CONFIG_", 7)) continue; - /* Check we have at least '=', value, and '\n' */ - if (strlen(line) < optlen + 3) - continue; - if (*(line + optlen) != '=') + + sep = memchr(line, '=', linelen); + if (!sep) continue; /* Trim ending '\n' */ - line[strlen(line) - 1] = '\0'; + line[linelen - 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) @@ -386,31 +386,34 @@ static void probe_kernel_image_config(void) /* test_bpf module for BPF tests */ "CONFIG_TEST_BPF", }; + char *values[ARRAY_SIZE(options)] = { }; char *value, *buf = NULL; struct utsname utsn; char path[PATH_MAX]; size_t i, n; ssize_t ret; - FILE *fd; + FILE *fd = NULL; + bool is_pipe = false; if (uname(&utsn)) - goto no_config; + goto end_parse; snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); 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. + /* Some distributions build with CONFIG_IKCONFIG=y and put the + * config file at /proc/config.gz. We try to invoke an external + * gzip program to avoid linking to libz. + * Hide stderr to avoid interference with the JSON output. */ - fd = fopen("/proc/config", "r"); + fd = popen("gunzip -c /proc/config.gz 2>/dev/null", "r"); + is_pipe = true; } if (!fd) { 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); @@ -418,27 +421,36 @@ static void probe_kernel_image_config(void) if (!buf || !ret) { 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; + } + + while (get_kernel_config_option(fd, &buf, &n, &value)) { + for (i = 0; i < ARRAY_SIZE(options); i++) { + if (values[i] || strcmp(buf, options[i])) + continue; + + values[i] = strdup(value); + } + } + +end_parse: + if (fd) { + if (is_pipe) { + if (pclose(fd)) + p_info("failed to read /proc/config.gz"); + } else + fclose(fd); } 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); + print_kernel_option(options[i], values[i]); + free(values[i]); } - fclose(fd); - return; - -no_config: - for (i = 0; i < ARRAY_SIZE(options); i++) - print_kernel_option(options[i], NULL); } static bool probe_bpf_syscall(const char *define_prefix)
/proc/config has never existed as far as I can see, but /proc/config.gz is present on Arch Linux. Execute an external gunzip program to avoid linking to zlib and rework the option scanning code since a pipe is not seekable. This also fixes a file handle leak on some error paths. Fixes: 4567b983f78c ("tools: bpftool: add probes for kernel configuration options") Cc: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: Peter Wu <peter@lekensteyn.nl> --- tools/bpf/bpftool/feature.c | 92 +++++++++++++++++++++---------------- 1 file changed, 52 insertions(+), 40 deletions(-)