[libvirt PATCH v2 1/4] util: Try to get limits from /proc

[Andrea Bolognani]

On Mon, 2021-03-15 at 11:57 +0100, Andrea Bolognani wrote:
> The changes you're suggesting are not trivial enough for me to feel
> comfortable simply applying them locally and then pushing right away.
> Would the diff below look reasonable squashed in?
> 
> diff --git a/src/util/virprocess.c b/src/util/virprocess.c
> index 4fa854090d..cae0dabae3 100644
> --- a/src/util/virprocess.c
> +++ b/src/util/virprocess.c
> @@ -799,16 +799,17 @@ virProcessGetLimitFromProc(pid_t pid,
>      size_t i;
> 
>      if (!(label = virProcessLimitResourceToLabel(resource))) {
> +        virReportSystemError(EINVAL, "%s", _("Invalid resource"));
>          return -1;
>      }
> 
>      procfile = g_strdup_printf("/proc/%lld/limits", (long long)pid);
> 
>      if (virFileReadAllQuiet(procfile, 2048, &buf) < 0)
> -        return -1;
> +        goto error;
> 
[...]
> 
> + error:
> +    virReportSystemError(EIO, "%s", _("Input/output error"));
> +    return -1;
>  }
>  # else /* !defined(__linux__) */
>  static int
> @@ -846,6 +851,7 @@ virProcessGetLimitFromProc(pid_t pid G_GNUC_UNUSED,
>                             int resource G_GNUC_UNUSED,
>                             struct rlimit *limit G_GNUC_UNUSED)
>  {
> +    virReportSystemError(ENOSYS, "%s", _("Not supported on this platform"));
>      return -1;
>  }
>  # endif /* !defined(__linux__) */

This probably makes more sense:

diff --git a/src/util/virprocess.c b/src/util/virprocess.c
index 4fa854090d..b173856b7a 100644
--- a/src/util/virprocess.c
+++ b/src/util/virprocess.c
@@ -799,16 +799,17 @@ virProcessGetLimitFromProc(pid_t pid,
     size_t i;

     if (!(label = virProcessLimitResourceToLabel(resource))) {
+        errno = EINVAL;
         return -1;
     }

     procfile = g_strdup_printf("/proc/%lld/limits", (long long)pid);

     if (virFileReadAllQuiet(procfile, 2048, &buf) < 0)
-        return -1;
+        goto error;

     if (!(lines = g_strsplit(buf, "\n", 0)))
-        return -1;
+        goto error;

     for (i = 0; lines[i]; i++) {
         g_autofree char *softLimit = NULL;
@@ -820,25 +821,29 @@ virProcessGetLimitFromProc(pid_t pid,
             continue;
 
         if (sscanf(line, "%ms %ms %*s", &softLimit, &hardLimit) < 2)
-            return -1;
+            goto error;
 
         if (STREQ(softLimit, "unlimited")) {
             limit->rlim_cur = RLIM_INFINITY;
         } else {
             if (virStrToLong_ull(softLimit, NULL, 10, &tmp) < 0)
-                return -1;
+                goto error;
             limit->rlim_cur = tmp;
         }
         if (STREQ(hardLimit, "unlimited")) {
             limit->rlim_max = RLIM_INFINITY;
         } else {
             if (virStrToLong_ull(hardLimit, NULL, 10, &tmp) < 0)
-                return -1;
+                goto error;
             limit->rlim_max = tmp;
         }
     }
 
     return 0;
+
+ error:
+    errno = EIO;
+    return -1;
 }
 # else /* !defined(__linux__) */
 static int
@@ -846,6 +851,7 @@ virProcessGetLimitFromProc(pid_t pid G_GNUC_UNUSED,
                            int resource G_GNUC_UNUSED,
                            struct rlimit *limit G_GNUC_UNUSED)
 {
+    errno = ENOSYS;
     return -1;
 }
 # endif /* !defined(__linux__) */
-- 
Andrea Bolognani / Red Hat / Virtualization