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lib/procfs: add function to parse /proc/#/stat 

Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2022-08-11 10:56:02 +02:00 committed by su-fang
parent 38835adcca
commit 2dab772cba
2 changed files with 58 additions and 1 deletions
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1
include/procfs.h
View File

@ -30,6 +30,7 @@ extern ssize_t procfs_process_get_cmdline(struct path_cxt *pc, char *buf, size_t
extern ssize_t procfs_process_get_cmdname(struct path_cxt *pc, char *buf, size_t bufsz);
extern ssize_t procfs_process_get_stat(struct path_cxt *pc, char *buf, size_t bufsz);
extern int procfs_process_get_stat_nth(struct path_cxt *pc, int n, uintmax_t *re);
static inline ssize_t procfs_process_get_exe(struct path_cxt *pc, char *buf, size_t bufsz)
{

58
lib/procfs.c
View File

@ -166,6 +166,35 @@ ssize_t procfs_process_get_stat(struct path_cxt *pc, char *buf, size_t bufsz)
return procfs_process_get_line_for(pc, buf, bufsz, "stat");
}
int procfs_process_get_stat_nth(struct path_cxt *pc, int n, uintmax_t *re)
{
ssize_t rc;
char *key = NULL, *tok, *p;
char buf[BUFSIZ];
int i;
if (n == 2 || n == 3) /* process name and status (strings) */
return -EINVAL;
rc = procfs_process_get_line_for(pc, buf, sizeof(buf), "stat");
if (rc < 0)
return rc;
for (i = 0, tok = strtok_r(buf, " ", &key); tok;
tok = strtok_r(NULL, " ", &key)) {
i++;
if (i == n)
return ul_strtou64(tok, re, 10);
/* skip rest of the process name */
if (i == 2 && (p = strchr(key, ')')))
key = p + 2;
}
return -EINVAL;
}
int procfs_process_get_uid(struct path_cxt *pc, uid_t *uid)
{
struct stat sb;
@ -536,6 +565,30 @@ static int test_isprocfs(int argc, char *argv[])
return is ? EXIT_SUCCESS : EXIT_FAILURE;
}
static int test_process_stat_nth(int argc, char *argv[])
{
pid_t pid;
struct path_cxt *pc;
uintmax_t num = 0;
int n;
if (argc != 3)
return EXIT_FAILURE;
pid = strtol(argv[1], (char **) NULL, 10);
n = strtol(argv[2], (char **) NULL, 10);
pc = ul_new_procfs_path(pid, NULL);
if (!pc)
err(EXIT_FAILURE, "cannot alloc procfs handler");
if (procfs_process_get_stat_nth(pc, n, &num) != 0)
err(EXIT_FAILURE, "read %dth number failed", n);
printf("%d: %dth %ju\n", (int) pid, n, num);
ul_unref_path(pc);
return EXIT_SUCCESS;
}
int main(int argc, char *argv[])
{
if (argc < 2) {
@ -543,7 +596,8 @@ int main(int argc, char *argv[])
" %1$s --fds <pid>\n"
" %1$s --is-procfs [<dir>]\n"
" %1$s --processes [---name <name>] [--uid <uid>]\n"
" %1$s --one <pid>\n",
" %1$s --one <pid>\n"
" %1$s --stat-nth <pid> <n>\n",
program_invocation_short_name);
return EXIT_FAILURE;
}
@ -558,6 +612,8 @@ int main(int argc, char *argv[])
return test_isprocfs(argc - 1, argv + 1);
if (strcmp(argv[1], "--one") == 0)
return test_one_process(argc - 1, argv + 1);
if (strcmp(argv[1], "--stat-nth") == 0)
return test_process_stat_nth(argc - 1, argv + 1);
return EXIT_FAILURE;
}