[PATCH 1/2] util: Add virProcessGetStat
Martin Kletzander
mkletzan at redhat.com
Fri Nov 19 17:31:35 UTC 2021
This reads and separates all fields from /proc/<pid>/stat or
/proc/<pid>/task/<tid>/stat as there are easy mistakes to be done in the
implementation. Some tests are added to show it works correctly. No number
parsing is done as it would be unused for most of the fields most, if not all,
of the time. No struct is used for the result as the length can vary (new
fields can be added in the future).
Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
---
src/libvirt_linux.syms | 3 +
src/util/virprocess.c | 78 +++++++++++++++++++++++++
src/util/virprocess.h | 4 ++
tests/meson.build | 1 +
tests/virprocessstatdata/complex/stat | 2 +
tests/virprocessstatdata/simple/stat | 1 +
tests/virprocessstattest.c | 84 +++++++++++++++++++++++++++
7 files changed, 173 insertions(+)
create mode 100644 tests/virprocessstatdata/complex/stat
create mode 100644 tests/virprocessstatdata/simple/stat
create mode 100644 tests/virprocessstattest.c
diff --git a/src/libvirt_linux.syms b/src/libvirt_linux.syms
index 55649ae39cec..14422fae7286 100644
--- a/src/libvirt_linux.syms
+++ b/src/libvirt_linux.syms
@@ -10,6 +10,9 @@ virHostCPUGetSiblingsList;
virHostCPUGetSocket;
virHostCPUGetStatsLinux;
+# util/virprocess.h
+virProcessGetStat;
+
# Let emacs know we want case-insensitive sorting
# Local Variables:
# sort-fold-case: t
diff --git a/src/util/virprocess.c b/src/util/virprocess.c
index 6de3f36f529c..4325f5116e8d 100644
--- a/src/util/virprocess.c
+++ b/src/util/virprocess.c
@@ -1721,3 +1721,81 @@ virProcessSetScheduler(pid_t pid G_GNUC_UNUSED,
}
#endif /* !WITH_SCHED_SETSCHEDULER */
+
+#ifdef __linux__
+/*
+ * Get all stat fields for a process based on pid and tid:
+ * - pid == 0 && tid == 0 => /proc/self/stat
+ * - pid != 0 && tid == 0 => /proc/<pid>/stat
+ * - pid == 0 && tid != 0 => /proc/self/task/<tid>/stat
+ * - pid != 0 && tid != 0 => /proc/<pid>/task/<tid>/stat
+ * and return them as array of strings.
+ */
+GStrv
+virProcessGetStat(pid_t pid,
+ pid_t tid)
+{
+ size_t buflen = 0;
+ g_autofree char *buf = NULL;
+ g_autofree char *path = NULL;
+ GStrv rest = NULL;
+ GStrv ret = NULL;
+ char *comm = NULL;
+ char *rparen = NULL;
+ size_t nrest = 0;
+
+ if (pid) {
+ if (tid)
+ path = g_strdup_printf("/proc/%d/task/%d/stat", (int)pid, (int)tid);
+ else
+ path = g_strdup_printf("/proc/%d/stat", (int)pid);
+ } else {
+ if (tid)
+ path = g_strdup_printf("/proc/self/task/%d/stat", (int)tid);
+ else
+ path = g_strdup("/proc/self/stat");
+ }
+
+ if (!g_file_get_contents(path, &buf, &buflen, NULL))
+ return NULL;
+
+ /* eliminate trailing spaces */
+ while (g_ascii_isspace(buf[--buflen]))
+ buf[buflen] = '\0';
+
+ /* Find end of the first field */
+ if (!(comm = strchr(buf, ' ')))
+ return NULL;
+ *comm = '\0';
+
+ /* Check start of the second field (filename of the executable, in
+ * parentheses) */
+ comm++;
+ if (*comm != '(')
+ return NULL;
+ comm++;
+
+ /* Check end of the second field (last closing parenthesis) */
+ rparen = strrchr(comm, ')');
+ if (!rparen)
+ return NULL;
+ *rparen = '\0';
+
+ /* We need to check that the next char is not '\0', but why not just opt in
+ * for the safer way of checking whether it is ' ' (space) instead */
+ if (rparen[1] != ' ')
+ return NULL;
+
+ rest = g_strsplit(rparen + 2, " ", 0);
+ nrest = g_strv_length(rest);
+ ret = g_new0(char *, nrest + 3);
+ ret[0] = g_strdup(buf);
+ ret[1] = g_strdup(comm);
+ memcpy(ret + 2, rest, nrest * sizeof(char *));
+
+ /* Do not use g_strfreev() as individual elements they were moved to @ret. */
+ VIR_FREE(rest);
+
+ return ret;
+}
+#endif
diff --git a/src/util/virprocess.h b/src/util/virprocess.h
index 9910331a0caa..74dad1f3b15e 100644
--- a/src/util/virprocess.h
+++ b/src/util/virprocess.h
@@ -117,6 +117,10 @@ int virProcessSetupPrivateMountNS(void);
int virProcessSetScheduler(pid_t pid,
virProcessSchedPolicy policy,
int priority);
+#ifdef __linux__
+GStrv virProcessGetStat(pid_t pid, pid_t tid);
+#endif
+
typedef enum {
VIR_PROCESS_NAMESPACE_MNT = (1 << 1),
VIR_PROCESS_NAMESPACE_IPC = (1 << 2),
diff --git a/tests/meson.build b/tests/meson.build
index 1948c07ae385..f75c24872086 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -347,6 +347,7 @@ if host_machine.system() == 'linux'
{ 'name': 'scsihosttest' },
{ 'name': 'vircaps2xmltest', 'link_whole': [ test_file_wrapper_lib ] },
{ 'name': 'virnetdevbandwidthtest' },
+ { 'name': 'virprocessstattest', 'link_whole': [ test_file_wrapper_lib ] },
{ 'name': 'virresctrltest', 'link_whole': [ test_file_wrapper_lib ] },
{ 'name': 'virscsitest' },
{ 'name': 'virusbtest' },
diff --git a/tests/virprocessstatdata/complex/stat b/tests/virprocessstatdata/complex/stat
new file mode 100644
index 000000000000..df0ecc149c6f
--- /dev/null
+++ b/tests/virprocessstatdata/complex/stat
@@ -0,0 +1,2 @@
+1 (this) is ( a weird )
+)( (command ( ) 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
diff --git a/tests/virprocessstatdata/simple/stat b/tests/virprocessstatdata/simple/stat
new file mode 100644
index 000000000000..97d68735370d
--- /dev/null
+++ b/tests/virprocessstatdata/simple/stat
@@ -0,0 +1 @@
+1 (command) 3 4 5
diff --git a/tests/virprocessstattest.c b/tests/virprocessstattest.c
new file mode 100644
index 000000000000..c973dbc629d7
--- /dev/null
+++ b/tests/virprocessstattest.c
@@ -0,0 +1,84 @@
+#include <config.h>
+
+#include "testutils.h"
+#include "virfilewrapper.h"
+#include "virprocess.h"
+
+
+struct testData {
+ const char *filename;
+ const char *command;
+ size_t count;
+ bool self;
+};
+
+
+static int
+test_virProcessGetStat(const void *opaque)
+{
+ struct testData *data = (struct testData *) opaque;
+ g_autofree char *data_dir = NULL;
+ g_auto(GStrv) proc_stat = NULL;
+ size_t len = 0;
+ id_t id = data->self ? 0 : -1;
+
+ data_dir = g_strdup_printf("%s/virprocessstatdata/%s/",
+ abs_srcdir, data->filename);
+
+ if (data->self)
+ virFileWrapperAddPrefix("/proc/self/", data_dir);
+ else
+ virFileWrapperAddPrefix("/proc/-1/task/-1/", data_dir);
+
+ proc_stat = virProcessGetStat(id, id);
+
+ virFileWrapperClearPrefixes();
+
+ if (!proc_stat) {
+ fprintf(stderr, "Could not get process stats\n");
+ return -1;
+ }
+
+ len = g_strv_length(proc_stat);
+ if (data->count != len) {
+ fprintf(stderr, "Count incorrect, expected %zu, got %zu\n",
+ data->count, len);
+ return -1;
+ }
+
+ if (!STREQ_NULLABLE(data->command, proc_stat[1])) {
+ fprintf(stderr, "Command incorrect, expected %s, got %s\n",
+ data->command, proc_stat[1]);
+ return -1;
+ }
+
+ return 0;
+}
+
+
+static int
+mymain(void)
+{
+ struct testData data = {0};
+ int ret = 0;
+
+#define DO_TEST(_filename, _command, _count, _self) \
+ do { \
+ data = (struct testData){ \
+ .filename = _filename, \
+ .command = _command, \
+ .count = _count, \
+ .self = _self, \
+ }; \
+ if (virTestRun("Reading process stat: " _filename, \
+ test_virProcessGetStat, &data) < 0) \
+ ret = -1; \
+ } while (0)
+
+ DO_TEST("simple", "command", 5, true);
+ DO_TEST("complex", "this) is ( a \t weird )\n)( (command ( ", 100, false);
+
+ return ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+
+VIR_TEST_MAIN(mymain)
--
2.34.0
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