From b0c5e620359898f3c0f1c9fa92a6fd0e34b7b769 Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Sat, 2 Mar 2013 01:44:31 +0100
Subject: [PATCH] linux: make uv_cpu_info() handle absent procfs

Return an error when reading from /proc files fails because the procfs
isn't mounted.

This is a back-port of commit 7e59f9b from the master branch.
---
 src/unix/linux/linux-core.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/src/unix/linux/linux-core.c b/src/unix/linux/linux-core.c
index 4259d171..a2387dab 100644
--- a/src/unix/linux/linux-core.c
+++ b/src/unix/linux/linux-core.c
@@ -64,9 +64,9 @@ static struct {
   size_t len;
 } process_title;
 
-static void read_models(unsigned int numcpus, uv_cpu_info_t* ci);
+static int read_models(unsigned int numcpus, uv_cpu_info_t* ci);
+static int read_times(unsigned int numcpus, uv_cpu_info_t* ci);
 static void read_speeds(unsigned int numcpus, uv_cpu_info_t* ci);
-static void read_times(unsigned int numcpus, uv_cpu_info_t* ci);
 static unsigned long read_cpufreq(unsigned int cpunum);
 
 
@@ -325,10 +325,19 @@ uv_err_t uv_cpu_info(uv_cpu_info_t** cpu_infos, int* count) {
   if (ci == NULL)
     return uv__new_sys_error(ENOMEM);
 
-  read_models(numcpus, ci);
-  read_times(numcpus, ci);
+  if (read_models(numcpus, ci)) {
+    SAVE_ERRNO(free(ci));
+    return uv__new_sys_error(errno);
+  }
 
-  /* read_models() on x86 also reads the CPU speed from /proc/cpuinfo */
+  if (read_times(numcpus, ci)) {
+    SAVE_ERRNO(free(ci));
+    return uv__new_sys_error(errno);
+  }
+
+  /* read_models() on x86 also reads the CPU speed from /proc/cpuinfo.
+   * We don't check for errors here. Worst case, the field is left zero.
+   */
   if (ci[0].speed == 0)
     read_speeds(numcpus, ci);
 
@@ -350,7 +359,7 @@ static void read_speeds(unsigned int numcpus, uv_cpu_info_t* ci) {
 /* Also reads the CPU frequency on x86. The other architectures only have
  * a BogoMIPS field, which may not be very accurate.
  */
-static void read_models(unsigned int numcpus, uv_cpu_info_t* ci) {
+static int read_models(unsigned int numcpus, uv_cpu_info_t* ci) {
 #if defined(__i386__) || defined(__x86_64__)
   static const char model_marker[] = "model name\t: ";
   static const char speed_marker[] = "cpu MHz\t\t: ";
@@ -373,7 +382,7 @@ static void read_models(unsigned int numcpus, uv_cpu_info_t* ci) {
 
   fp = fopen("/proc/cpuinfo", "r");
   if (fp == NULL)
-    return;
+    return -1;
 
   model_idx = 0;
   speed_idx = 0;
@@ -398,10 +407,12 @@ static void read_models(unsigned int numcpus, uv_cpu_info_t* ci) {
     }
   }
   fclose(fp);
+
+  return 0;
 }
 
 
-static void read_times(unsigned int numcpus, uv_cpu_info_t* ci) {
+static int read_times(unsigned int numcpus, uv_cpu_info_t* ci) {
   unsigned long clock_ticks;
   struct uv_cpu_times_s ts;
   unsigned long user;
@@ -421,7 +432,7 @@ static void read_times(unsigned int numcpus, uv_cpu_info_t* ci) {
 
   fp = fopen("/proc/stat", "r");
   if (fp == NULL)
-    return;
+    return -1;
 
   if (!fgets(buf, sizeof(buf), fp))
     abort();
@@ -466,6 +477,8 @@ static void read_times(unsigned int numcpus, uv_cpu_info_t* ci) {
     ci[num++].cpu_times = ts;
   }
   fclose(fp);
+
+  return 0;
 }