Re: [PATCH v2 2/2] pidfd: add tests for NSpid info in fdinfo
flat view
From: Jann Horn <jannh@google.com>
Date: 2019-10-11 15:09:58
Also in:
linux-kselftest, lkml
On Wed, Oct 9, 2019 at 6:10 PM Christian Kellner [off-list ref] wrote:
Add tests that check that if pid namespaces are configured the fdinfo file of a pidfd contains an NSpid: entry containing the process id in the current and additionally all nested namespaces.
[...]
quoted hunk ↗ jump to hunk
+static int compare_fdinfo_nspid(int pidfd, char *expect, size_t len) +{ + char path[512]; + FILE *f; + size_t n = 0; + ssize_t k; + char *line = NULL; + int r = -1; + + snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", pidfd);
(Maybe at some point the selftests code should add some more concise
alternative to snprintf() calls on separate lines. A macro or
something like that so that you can write stuff like `f =
fopen(tprintf("/proc/self/fdinfo/%d", pidfd), "re")`.)
quoted hunk ↗ jump to hunk
+ f = fopen(path, "re"); + if (!f) + return -1; + + while ((k = getline(&line, &n, f)) != -1) { + if (strncmp(line, "NSpid:", 6)) + continue; + + line[k - 1] = '\0'; + ksft_print_msg("Child: fdinfo NSpid line: '%s'.\n", line); + r = strncmp(line + 6, expect, len);
Wouldn't it be better to get rid of the nullbyte assignment and change the strncmp() into a strcmp() here... [...]
quoted hunk ↗ jump to hunk
+ /* The child will have pid 1 in the new pid namespace, + * so the line must be 'NSPid:\t<pid>\t1' + */ + n = snprintf(expect, sizeof(expect), "\t%d\t%d", pid, 1);
... and add a "\n" to the format string? It's shorter and doesn't silently ignore it if the line doesn't end at that point.