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

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/include/procfs.h b/include/procfs.h
index 5a730c94caf09ef218922abba18f2ae2788edd7a..825689bc2dc39335987173fd465c10b019e6d05c 100644 (file)
--- a/include/procfs.h
+++ b/include/procfs.h
@@ -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)
 {

diff --git a/lib/procfs.c b/lib/procfs.c
index 0d58857c83b378cb1cb3baf00f88f992ff8dce1e..1072a9a2ce90cdd20b1b0107f3457aa8d1266a5f 100644 (file)
--- a/lib/procfs.c
+++ b/lib/procfs.c
@@ -169,6 +169,35 @@ 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;
@@ -547,6 +576,30 @@ 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) {
@@ -554,7 +607,8 @@ 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;
        }
@@ -569,6 +623,8 @@ 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;
 }