From 74beff80ff3624761ecd20fafac0485f48c9c873 Mon Sep 17 00:00:00 2001
From: Jim Warner <james.warner@comcast.net>
Date: Sun, 28 Jun 2015 00:00:00 -0500
Subject: [PATCH] library: make reads & unref logic a little more robust

Since we are not using a higher level standard C fopen
all of the read requests were made signal sensitive as
that can result in a 'temporarily' failed i/o request.

Also, protection against some user calling the 'unref'
function on already free memory has been incorporated.
This will protect us from some nasty 'Abort' surprise.

Signed-off-by: Jim Warner <james.warner@comcast.net>
---
 proc/meminfo.c  | 15 +++++++++++----
 proc/readstat.c | 15 +++++++++++----
 proc/vmstat.c   | 15 +++++++++++----
 3 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/proc/meminfo.c b/proc/meminfo.c
index 7ab1cc9e..6cfe808c 100644
--- a/proc/meminfo.c
+++ b/proc/meminfo.c
@@ -110,9 +110,16 @@ PROCPS_EXPORT int procps_meminfo_read (
     if (lseek(info->meminfo_fd, 0L, SEEK_SET) == -1) {
         return -errno;
     }
-    if ((size = read(info->meminfo_fd, buf, sizeof(buf)-1)) < 0) {
-        return -1;
+    for (;;) {
+        if ((size = read(info->meminfo_fd, buf, sizeof(buf)-1)) < 0) {
+            if (errno == EINTR || errno == EAGAIN)
+                continue;
+            return -errno;
+        }
+        break;
     }
+    if (size == 0)
+        return 0;
     buf[size] = '\0';
 
     /* Scan the file */
@@ -219,11 +226,11 @@ PROCPS_EXPORT struct procps_meminfo *procps_meminfo_ref (
 PROCPS_EXPORT struct procps_meminfo *procps_meminfo_unref (
         struct procps_meminfo *info)
 {
-    if (info == NULL)
+    if (info == NULL || info->refcount == 0)
         return NULL;
     info->refcount--;
     if (info->refcount > 0)
-        return NULL;
+        return info;
     free(info);
     return NULL;
 }
diff --git a/proc/readstat.c b/proc/readstat.c
index c8873e77..16322ad3 100644
--- a/proc/readstat.c
+++ b/proc/readstat.c
@@ -90,9 +90,16 @@ PROCPS_EXPORT int procps_stat_read (
     if (lseek(info->stat_fd, 0L, SEEK_SET) == -1) {
         return -errno;
     }
-    if ((size = read(info->stat_fd, buf, sizeof(buf)-1)) < 0) {
-        return -1;
+    for (;;) {
+        if ((size = read(info->stat_fd, buf, sizeof(buf)-1)) < 0) {
+            if (errno == EINTR || errno == EAGAIN)
+                continue;
+            return -errno;
+        }
+        break;
     }
+    if (size == 0)
+        return 0;
     buf[size] = '\0';
 
     /* Scan the file */
@@ -155,11 +162,11 @@ PROCPS_EXPORT struct procps_statinfo *procps_stat_ref (
 PROCPS_EXPORT struct procps_statinfo *procps_stat_unref (
         struct procps_statinfo *info)
 {
-    if (info == NULL)
+    if (info == NULL || info->refcount == 0)
         return NULL;
     info->refcount--;
     if (info->refcount > 0)
-        return NULL;
+        return info;
     free(info);
     return NULL;
 }
diff --git a/proc/vmstat.c b/proc/vmstat.c
index 8f9f1f6f..953c8b6a 100644
--- a/proc/vmstat.c
+++ b/proc/vmstat.c
@@ -83,9 +83,16 @@ PROCPS_EXPORT int procps_vmstat_read (
     if (lseek(info->vmstat_fd, 0L, SEEK_SET) == -1) {
         return -errno;
     }
-    if ((size = read(info->vmstat_fd, buf, sizeof(buf)-1)) < 0) {
-        return -1;
+    for (;;) {
+        if ((size = read(info->vmstat_fd, buf, sizeof(buf)-1)) < 0) {
+            if (errno == EINTR || errno == EAGAIN)
+                continue;
+            return -errno;
+        }
+        break;
     }
+    if (size == 0)
+        return 0;
     buf[size] = '\0';
 
     /* Scan the file */
@@ -130,11 +137,11 @@ PROCPS_EXPORT struct procps_vmstat *procps_vmstat_ref (
 PROCPS_EXPORT struct procps_vmstat *procps_vmstat_unref (
         struct procps_vmstat *info)
 {
-    if (info == NULL)
+    if (info == NULL || info->refcount == 0)
         return NULL;
     info->refcount--;
     if (info->refcount > 0)
-        return NULL;
+        return info;
     free(info);
     return NULL;
 }