pidstat: Now handle processes with spaces in their name properly

pidstat had a bug which made it unable to handle processes with spaces
in their name, eg:

$ cat /proc/5768/stat
5768 (Plex New Transc) S 1264 1252 1252 0 -1 1077960704 17317 0 18 0
9260 137 0 0 15 -5 8 0 1430749 186589184 16704 18446744073709551615 1 1
0 0 0 0 0 0 8404998 18446744073709551615 0 0 17 1 0 0 22 0 0 0 0 0 0 0 0
0 0

This patch fixes the problem.

Reported by Chris Grindstaff (@cgrinds).

Signed-off-by: Sebastien GODARD <sysstat@users.noreply.github.com>

diff --git a/pidstat.c b/pidstat.c
index 28c8cba5851a2369f1359921d236b02ff97109a6..6be149e08fe38061c3b3e9cfc6f7bbf25fa61d22 100644 (file)
--- a/pidstat.c
+++ b/pidstat.c
@@ -23,6 +23,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <fcntl.h>
 #include <signal.h>
 #include <dirent.h>
 #include <ctype.h>
@@ -310,10 +311,10 @@ void read_proc_meminfo(void)
 int read_proc_pid_stat(unsigned int pid, struct pid_stats *pst,
                       unsigned int *thread_nr, unsigned int tgid)
 {
-       FILE *fp;
-       char filename[128], format[256], comm[MAX_COMM_LEN + 1];
-       size_t len;
-       int rc;
+       int fd, sz, rc, commsz;
+       char filename[128];
+       static char buffer[1024 + 1];
+       char *start, *end;
 
        if (tgid) {
                sprintf(filename, TASK_STAT, tgid, pid);
@@ -322,40 +323,46 @@ int read_proc_pid_stat(unsigned int pid, struct pid_stats *pst,
                sprintf(filename, PID_STAT, pid);
        }
 
-       if ((fp = fopen(filename, "r")) == NULL)
+       if ((fd = open(filename, O_RDONLY)) < 0)
                /* No such process */
                return 1;
 
-       sprintf(format, "%%*d (%%%ds %%*s %%*d %%*d %%*d %%*d %%*d %%*u %%llu %%llu"
-               " %%llu %%llu %%llu %%llu %%lld %%lld %%*d %%*d %%u %%*u %%*d %%llu %%llu"
-               " %%*u %%*u %%*u %%*u %%*u %%*u %%*u %%*u %%*u %%*u %%*u %%*u %%*u"
-               " %%*u %%u %%u %%u %%llu %%llu %%lld\\n", MAX_COMM_LEN);
+       sz = read(fd, buffer, 1024);
+       close(fd);
+       if (sz <= 0)
+               return 1;
+       buffer[sz] = '\0';
 
-       rc = fscanf(fp, format, comm,
+       if ((start = strchr(buffer, '(')) == NULL)
+               return 1;
+       start += 1;
+       if ((end = strrchr(start, ')')) == NULL)
+               return 1;
+       commsz = end - start;
+       if (commsz >= MAX_COMM_LEN)
+               return 1;
+       memcpy(pst->comm, start, commsz);
+       pst->comm[commsz] = '\0';
+       start = end + 2;
+
+       rc = sscanf(start,
+                   "%*s %*d %*d %*d %*d %*d %*u %llu %llu"
+                   " %llu %llu %llu %llu %lld %lld %*d %*d %u %*u %*d %llu %llu"
+                   " %*u %*u %*u %*u %*u %*u %*u %*u %*u %*u %*u %*u %*u"
+                   " %*u %u %u %u %llu %llu %lld\n",
                    &pst->minflt, &pst->cminflt, &pst->majflt, &pst->cmajflt,
                    &pst->utime,  &pst->stime, &pst->cutime, &pst->cstime,
                    thread_nr, &pst->vsz, &pst->rss, &pst->processor,
                    &pst->priority, &pst->policy,
                    &pst->blkio_swapin_delays, &pst->gtime, &pst->cgtime);
 
-       fclose(fp);
-
-       if (rc < 18)
+       if (rc < 17)
                return 1;
 
        /* Convert to kB */
        pst->vsz >>= 10;
        pst->rss = PG_TO_KB(pst->rss);
 
-       strncpy(pst->comm, comm, MAX_COMM_LEN);
-       pst->comm[MAX_COMM_LEN - 1] = '\0';
-
-       /* Remove trailing ')' */
-       len = strlen(pst->comm);
-       if (len && (pst->comm[len - 1] == ')')) {
-               pst->comm[len - 1] = '\0';
-       }
-
        pst->pid = pid;
        pst->tgid = tgid;
        return 0;